ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • photosynthesis  (325)
  • Biology
  • Electron microscopy
  • Inorganic Chemistry
  • LUNAR AND PLANETARY EXPLORATION
  • Springer  (568)
  • 2000-2004  (55)
  • 1995-1999  (301)
  • 1980-1984  (212)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Defect structure of the low temperature α-cristobalite phase and the cristobalite ⇆ tridymite transformation in (Si-Ge)O2 (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 386-397 
    Details
    ISSN: 1432-2021
    Keywords: Key words Cristobalite ; Tridymite ; Phase transformation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Using minimum exposure techniques, it is feasible to perform high resolution electron microscopy on the α-cristobalite phase of (Si0.9 Ge0.1)O2, which is extremely radiation sensitive. Such images reveal atomic scale information of twins and tridymite-like stacking faults on (1 1 1)β planes, as well as of domain boundaries resulting from the β→α transition. Polytype structures are formed in certain cases. Morphological features suggest that the phase transformation cristobalite → tridymite proceeds by means of a zonal dislocation mediated synchro-shear process on (1 1 1)β planes; the geometry of this process is analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002699900082
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The need for a shared database infrastructure: combining X-ray crystallography and electron microscopy (2000)
    Springer
    European biophysics journal 29 (2000), S. 457-462 
    Details
    ISSN: 1432-1017
    Keywords: Key words X-ray crystallography ; Electron microscopy ; Biological databases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Advances in structural biology are opening greater opportunities for understanding biological structures from the cellular to the atomic level. Particularly promising are the links that can be established between the information provided by electron microscopy and the atomic structures derived from X-ray crystallography and nuclear magnetic resonance spectroscopy. Combining such different kinds of structural data can result in novel biological information on the interaction of biomolecules in large supramolecular assemblies. As a consequence, the need to develop new databases in the field of structural biology that allow for an integrated access to data from all the experimental techniques is becoming critical. Pilot studies performed in recent years have already established a solid background as far as the basic information that an integrated macromolecular structure database should contain, as well as the basic principles for integration. These efforts started in the context of the BioImage project, and resulted in a first complete database prototype that provided a versatile platform for the linking of atomic models or X-ray diffraction data with electron microscopy information. Analysis of the requirements needed to combine data at different levels of resolution have resulted in sets of specifications that make possible the integration of all these different types in the context of a web environment. The case of a structural study linking electron microscopy and X-ray data, which is already contained within the BioImage data base and in the Protein Data Bank, is used here to illustrate the current approach, while a general discussion highlights the urgent need for integrated databases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490000089
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Improved growth and water use efficiency of cherry saplings under reduced light intensity (2000)
    Springer
    Ecological research 15 (2000), S. 385-392 
    Details
    ISSN: 1440-1703
    Keywords: photosynthesis ; Prunus avium ; relative growth rate ; shading ; total plant water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Cherry (Prunus avium L.) saplings were grown under natural sunlight (controls) or moderate shading (up to 30%, depending on the incident light intensity and the hour of the day). Reduced light intensity increased the dry mass of each of the plant components studied. Consequently, the total dry mass of shaded plants was significantly greater than that of controls at the end of the growing season. However, the diurnal trend in the level of photosynthesis (per unit of leaf area) of shaded plants was similar to the controls in August, but lower in September. As the growing season proceeded, reduced photosynthetic rates, thinner mesophyll and larger specific leaf area in the shaded plants indicated that leaf development had adapted to shaded conditions throughout the growing season. It is suggested that increased growth of shaded plants was caused by a higher initial relative growth rate and a greater whole-plant photosynthesis. Shading consistently reduced transpiration over the season, therefore improving water use efficiency of shaded leaves. Our results suggest that a moderate reduction in light intensity can be a useful method for improving growth and saving water in hot and dry environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1440-1703.2000.00359.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Evidence for stable grain boundary melt films in experimentally deformed olivine-orthopyroxene rocks (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 480-494 
    Details
    ISSN: 1432-2021
    Keywords: Key words Olivine ; Grain boundary ; Partial melt ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The microstructure of olivine-olivine grain boundaries has been studied in experimentally deformed (1200–1227 °C, 300 MPa) partially molten olivine and olivine-orthopyroxene rocks. In-situ melting produced ∼1 vol% melt in all samples studied. Grain boundary analyses were carried out using a number of transmission electron microscopy techniques. The grain boundary chemistry in undeformed olivine-orthopyroxene starting material showed evidence for the presence of an intergranular phase along some, but not all, of the olivine-olivine boundaries. In the deformed samples, ultrathin Si-rich, Al- and Ca-bearing amorphous films have been observed along all investigated olivine-olivine grain boundaries. The chemistry of the grain boundaries, which is considered to be indicative for the presence of a thin film, was measured with energy-dispersive X-ray spectroscopy (EDX) and energy-filtering imaging. The amorphous nature of the films was confirmed with diffuse dark field imaging, Fresnel fringe imaging, and high-resolution electron microscopy. The films range in thickness from 0.6 to 3.0 nm, and EDX analyses show that the presence of Al and Ca is restricted to this ultrathin film along the grain boundaries. Because thin melt films have been observed in all the samples, they are thought to be stable features of the melt microstructure in deformed partially molten rocks. The transition from the occasional presence of films in the undeformed starting material to the general occurrence of the films in deformed materials suggests that deformation promotes the formation and distribution of the films. Alternatively, hot-pressing may be too short for films to develop along all grain boundaries. A difference in creep strength between the studied samples could not be attributed to grain boundary melt films, as these have been found in all deformed samples. However, a weakening effect of grain boundary melt films on olivine rheology could not be ruled out due to the lack of confirmed melt-film free experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690000090
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The Energy Budget of Coral Polyps (2000)
    Springer
    Russian journal of marine biology 26 (2000), S. 389-398 
    Details
    ISSN: 1608-3377
    Keywords: hermatypic coral ; zooxanthella ; photosynthesis ; respiration ; energy budget
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analyzed the recent data on the distribution of the photosynthetic energy of zooxanthellae in corals and the models of interactions between the plant and animal cells in the course of matter and energy exchange developed based on this information. The models of energy exchange of animals symbiotic with zooxanthellae are characterized by the following features: (1) A flow chart of carbon or energy fluxes is the main form of representation of the energetics in native symbiotic organisms. (2) The relations between the symbionts are relatively adequately revealed and correspond to the modern notions; however, the intensities of the energy fluxes ascribed to these relations are dependent on the experimental and design methods used by the authors. (3) The inputs into the energy budget consist of the autotrophic production of zooxanthellae and the heterotrophy of the polyp. The energy expenditures comprise excretion, respiration, development, and growth of the animal and algae. (4) The differences between the species, genera, and phyla of animals that develop symbiotic relations with zooxanthellae are confined to the absolute values of energy fluxes in the organism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009497303413
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Influence of chlorophyll concentrations on the reliability of measurements with an oxygen electrode when studying photosynthetic efficiency in bioassays using microalgae (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 63-67 
    Details
    ISSN: 1573-5176
    Keywords: Euglena gracilis ; Chlamydomonas reinhardtii ; photosynthesis ; oxygen electrode ; Light Pipette ; bioassay ; chlorophyll concentration ; algae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Euglena gracilis and Chlamydomonas reinhardtii were used as model organisms to establish the best conditions for studying photosynthetic efficiency using the Light Pipette – experimental system, which enables sensitive detection of changes in oxygen evolution/consumption and an easy collection and digitalisation of data. Chlorophyll concentrations of 0.005, 0.025, 0.050 and 0.075 mgmL-1 were investigated using different light regimes. Cultures of E. gracilis at the same chlorophyll concentration absorbed more light(measured at 580 μmol m-2 s-1) than those of C. reinhardtii. Cell density had a considerable effect on the reliability of measurements. Chlorophyll concentrations between 0.025 mgChl ml-1 and 0.050 mgChlml-1 can be recommended when applying the Light Pipette system in bioassays using microalgae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008189230953
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Effect of UV radiation on photoinhibition of marine macrophytes in culture systems (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 159-168 
    Details
    ISSN: 1573-5176
    Keywords: Chlorophyll fluorescence ; Chondruscrispus ; Macrocystis pyrifera ; photosynthesis ; photoinhibition ; outdoor culture system ; Ulvalactuca ; UV-radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present study examined the effect of UV andphotosynthetically active radiation (PAR) onphotoinhibition and recovery in the Phaeophyte Macrocystis pyrifera, the Rhodophyte Chondruscrispus and the Chlorophyte Ulva lactuca underoutdoor culture conditions. There was an increase inphotoinhibition as a consequence of high exposure toUV-B radiation in M. pyrifera, however, highlevels of PAR accounted for most of thephotoinhibition in C. crispus and U.lactuca. Photodamage by UV-A, UV-B and PAR wascompletely repaired within 5 h and effective quantumyield reached pretreatment values in the three speciesstudied. Species were less susceptible tophotoinhibition after being incubated for 5 d underhigh exposures of natural irradiance suggesting aphotoadaptive process. The recovery of the effectivequantum yield was impaired by long exposure to highlevels of UV-B in C. crispus and UV-A, UV-B andPAR in M. pyrifera. This suggests a differentkind of damage by UV-A and PAR radiation, one to thephotosynthetic apparatus and another which affects therepair mechanism of some species. There was anincrease in UV-absorption (λ 330 nm) in M. pyrifera and C. crispus within four days ofthe initiation of the experiment suggesting that thesespecies photoprotect their photosynthetic system whenexposed to elevated UV and PAR levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008198404529
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Effect of a cationic cellulosic polymer on gametophytes of Laminaria digitata (Laminariaceae, Phaeophyta): Improvement of dispersed `free-living' cultures (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 83-93 
    Details
    ISSN: 1573-5176
    Keywords: fluorescence ; homogeneous culture ; JR125 polymer ; Laminaria ; gametophytes ; photosynthesis ; ultrastructural studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As filament aggregation is responsible for heterogeneity of Laminariales gametophyte cultures, a project was conducted to obtain stable homogeneous `free-living' cultures of Laminaria digitatagametophytes. The alga was cultivated at 15 ° Cunder low light and in the presence of a cationic cellulosic polymer, JR125. With 0.1%polymer in the culture medium, the filaments were dispersed and did not adhere to the culture vessel. The absence of any effect of the closely related, but uncharged, polymer LR-250 Natrasol on filament aggregation indicated that the cationic nature of the JR125 molecule was involved in gametophyte dissociation. In the presence of JR125, the gametophytes showed active vegetative growth; the doubling time, measured as chlorophyll concentration, was 5 days. The outer surface of the cell wall was clearly modified by the polymer treatment, as observed by transmission electron microscopy, while neither the inner cell wall or cell organelles were affected. Physiological studies indicated that JR125 treatment did not disturb cell physiology, there being no effecton respiration, photosynthetic activity, sensitivity to high-light stress or modification of pigment or fluorescence characteristics. We have therefore established the conditions for maintaining a stable culture of mixed male and female Laminaria digitata gametophytes in active vegetative growth. The presence of JR 125 in the medium yields a homogeneous culture without cell physiology becoming modified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008118917247
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Lithophytic algae: A major threat to the karst formation of show caves (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 309-315 
    Details
    ISSN: 1573-5176
    Keywords: nuisance algae ; bio-fouling ; photosynthesis ; lightutilisation ; show caves ; control measures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Depending on the intensity, quality and duration ofthe illumination, necessary for viewing show caves,conditions conducive for algal growth are created. Although algae are the major component of this flora,ferns and mosses have also been recorded. Little isknown of the algae, except that they are considered anuisance in terms of discoloration and damage to thekarst formations. The occurrence and possible controlof the algal flora has been studied in the CangoCaves, one of the most important touristic sites inSouth Africa. The algal flora is sparse in speciesdiversity and primitive forms are present. They haveparticular physiological adaptations and usingmicro-oxygen liberation and fluorescence measurements,their photosynthetic characteristics were established. Environmentally friendly control measures wereinvestigated and a solution for their control is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008172227611
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Physiological and technological considerations for optimising mass algal cultures (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 201-206 
    Details
    ISSN: 1573-5176
    Keywords: photobioreactors ; high yields ; photosynthesis ; single stage reactors ; multistage reactors ; strain selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The successful coupling between physiology andtechnology is central to the success of algalbiotechnology. Imperative is a proper understandingof the variables and their impacts on biomass and/orbiocompound production. The crux lies inphotosynthesis and the capturing of light energy atthe optimal rate for eventual maximal photochemistry(biosynthesis). It is in the hands of algalbiotechnologists to understand the dynamics andregulatory mechanisms of especially PSII (photosystemII) activity in order to advance this technologyfurther. Biophysical and technological optimisationand design aimed at maximising photon flux capture aresome of the avenues that needs be pursued. This needsto be augmented by molecular, biochemical andphysiological inputs. Unfortunately detailedsystematic analyses of the variables, theirinteraction and possible synergism have rarely beendone. The debate regarding the merits andproductivity in closed, either plate or tubular,vertical or horizontal, and open pond reactors need tobe resolved. Exciting developments regarding onlinemeasurements and feedback control for optimalproductivities are part of the solutions andapproaches that need to be followed. Multistagesystems that not only utilise autotrophic growth andstress components, but also combinedautotrophic/heterotrophic systems could providesolutions to specific production requirements. Theseand other important issues are addressed in theoverview. The challenges facing algalbiotechnologists and future research needs are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008155125844
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Biocompatibility of MPC: in vivo evaluation for clinical application (2000)
    Springer
    Journal of artificial organs 3 (2000), S. 39-46 
    Details
    ISSN: 1619-0904
    Keywords: Poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC) ; In vivo biocompatibility ; Artificial endocrine pancreas ; Electron microscopy ; Glucose sensor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Biocompatibility is important to assure a mild body reaction to an implanted device and its long-term stability and functionality. In diabetes research, subcutaneously implanted glucose monitoring systems need biocompatible surfaces for long-term application. The biocompatibility of poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC), a material similar to the phospholipid layer of a cell membrane, was compared in vivo with the biocompatibility of polyurethane (PU), polyvinyl alcohol (PVA), and cuprophane (CUP). Needle-type glucose sensors and hollow-fiber probes used for microdialysis were coated with these four different biomaterials and implanted subcutaneously in 18 rats and 7 healthy volunteers. At set intervals, the implants and, in the case of the rats, also the surrounding tissue were removed and characterized by light and electron microscopy. MPC-coated sensors and hollow-fiber probes showed smooth and thin deposits in flat layers, whereas the surface deposits on PU- and PVA-coated sensors and those on CUP hollow-fiber probes appeared as rough, irregular, and dense attachments of aggregated cells and protein. This study confirmed results from earlier in vitro tests by showing the biocompatibility and reliability of MPC. Even though the amount of protein and cells attached to the MPC surface was not as low as expected from in vitro experiments, the biocompatibility and long-term stability of the implanted devices were superior to those of PU, PVA, and CUP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02479925
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Responses of Porphyra linearis (Rhodophyta) to environmental factors under controlled culture conditions (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 535-542 
    Details
    ISSN: 1573-5176
    Keywords: desiccation ; growth ; growth model ; inorganic carbon ; nutrients ; photoperiod ; photosynthesis ; pigments ; Porphyra linearis ; PPF ; respiration ; temperature ; water velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of environmental parameters on the growthof Porphyra linearis gametophytes was examinedunder controlled conditions, and related to themultilinear regression growth model recently developedfor this seaweed under coastal conditions in theeastern Mediterranean. Growth chambers, a gradienttable, special culture devices and analytical methodswere combined for this culture study.The major factors significantly controlling thegrowth rate of the P. linearis gametophytein glass dishes were: photoperiod, temperature, agein culture, photosynthetic photon flux (PPF), salinityand water dynamics. Maximal growth occurred underdaylength of 12 h, medium temperature (15–20 °C), low PPF (70–140 μmol photon m-2s-1), ambient salinity (30–40 ppt), 1–3 h ofdaily air exposure, and water velocity of 4 cm s-1.Photosynthesis and respiration rates weredominantly affected by daylength and temperature,while the concentration of pigments was dominantlyaffected by PPF and temperature.These conditions correspond well to the optimalnatural growth environment of this local species andare in agreement with the optimum estimated throughthe recently developed outdoor mathematical growthmodel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008138227520
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    The effect of reducing light-harvesting pigment on marine microalgal productivity (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 285-290 
    Details
    ISSN: 1573-5176
    Keywords: algal culture ; Chlamydomonas perigranulata ; light-harvesting pigment ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The productivity was evaluated of a strain of Chlamydomonas perigranulata isolated from the RedSea. A mutant with small light-harvesting pigments(LHC-1) was obtained by UV mutagenesis. Thechlorophylls content of the wild type was twice ashigh as that of LHC-1, and the initial slope of thephotosynthesis-irradiance curve was higher in the wildtype. However, the maximum photosynthetic activity ona per cell basis was almost the same. It isconcluded that LHC-1 is a mutant with lesslight-harvesting pigment (LHP) than the wild type. Aspreviously reported, the mutant with lower LHP contenthas a higher productivity in a continuous culturesystem, so we compared the productivity of the wildtype and the mutant. The maximum productivity of LHC-1was 1.5 times higher than that of the wild type. Itis suggested that the technique of reducing thecontent of light-harvesting pigment should be madeavailable for other organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008108500409
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Stromatolitic communities in Mediterranean streams: adaptations to a changing environment (2000)
    Springer
    Biodiversity and conservation 9 (2000), S. 379-392 
    Details
    ISSN: 1572-9710
    Keywords: climate change ; cyanobacteria ; ectoenzymes ; Mediterranean ; nutrient limitation ; photosynthesis ; stromatolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A stromatolitic microbial mat extensively covers La Solana streambed, a calcareous Mediterranean stream. This stromatolite shows remarkable biological and physiological diversity. It is mainly composed by cyanobacteria, with Rivularia and Schizothrix as the most abundant taxa. The stromatolite is photosynthetically adaptated to the high irradiances reaching the streambed. Photosynthetically active chlorophyll is present even in the lowest layers of the stromatolite, indicating the presence of well-preserved cyanobacteria in that part. Diffusion of gases and nutrients within the stromatolite can be possible because of the high porosity of the crust. It has been experimentally established that the stromatolite recovers heterotrophic and autotrophic activities in a few hours, after being desiccated for long periods. Recovery after desiccation is indicative of the high resilience of this community to environmental extremes, which are common in Mediterranean climatic regimes. The stromatolitic community is adapted to nutrient limitation, both to low availability of inorganic phosphorus and nitrogen (that constrain growth of primary producers), and to low dissolved organic carbon (mainly affecting heterotrophs). Stromatolitic heterotrophs mainly rely on the organic carbon stored in the crust as the main organic carbon source. These strategies are the direct response of the stromatolite to oligotrophy, and justify the restricted occurrence in stream systems affected by organic pollution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008954801397
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Potential use of Cu2+, K+ and Na+ for the destruction of Caulerpa taxifolia: differential effects on photosynthetic parameters (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 15-23 
    Details
    ISSN: 1573-5176
    Keywords: Caulerpa taxifolia ; chlorophyll fluorescence ; copper ; photosynthesis ; potassium ; respiration ; RubisCO ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chemical techniques were investigated in order to eradicate Caulerpa taxifolia, a green alga spreading at a remarkable rate in the Mediterranean Sea. The action of copper, potassium and sodium ions on survival rates and photosynthetic parameters was compared, in order to optimise the conditions of further in situ treatments. The lethal doses were determined and the impact of the studied cations on photosynthesis and respiration rates and PSII photochemistry was analysed from measurements of net oxygen exchanges and chlorophyll fluorescence. The Cu2+ concentrations required to obtain 100% mortality were 15 × 102 to 104 times lower than those of K+ and Na+. Respiration was slightly affected whatever the salt concentration,while photosynthesis could be totally inhibited depending on the applied treatment. Changes in the structure of the Ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO, EC: 4.1.1.39) were also detected when C. taxifolia under went cation treatments (10 mg L-1 Cu2+, 1h; 20 gL-1 K+, 3 h; 20 g L-1 Na+, 1 h). Given the high concentration and long incubation periods required with K+ and Na+ ions, these cations are not suitable to be used in situ. Our results make possible the utilisation of copper cations following technical approaches such asion-exchange textile covers, which allows a controlled release of cupric ions without dissemination in the marine environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008108531280
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Middle Layer Intrusion as an Important Factor Supporting Phytoplankton Productivity at a Tidal Front in Iyo Nada, the Seto Inland Sea, Japan (2000)
    Springer
    Journal of oceanography 56 (2000), S. 131-139 
    Details
    ISSN: 1573-868X
    Keywords: Tidal front ; nutrient ; phytoplankton ; photosynthesis ; stratification ; mixing ; Iyo Nada
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Field observations were conducted to examine the processes governing the phytoplankton distribution and photosynthetic activity in and around a tidal front formed in Iyo Nada, the Seto Inland Sea, Japan. The existence of a middle layer intrusion, which, it has been suggested, moves from the mixed region to the stratified region of the tidal front, was ascertained by the phytoplankton distribution in addition to a T-S diagram. Skeletonema costatum, which originally inhabited the mixed region, was used as the indicator to reveal the intrusion. However, the tip of water containing the S. costatum population did not extend deeply into the stratified region. The velocity of the intrusion seemed to be slow enough to make biological processes, such as nutrient uptake by phytoplankton and subsequent growth, as well as the decrease in cell density due to zooplankton grazing, dominate during the transportation. The patchy distribution of copepod nauplii implied that grazing has an influence on the distribution pattern of phytoplankton. The location of high photosynthetic activity did not coincide spatially with the center of high phytoplankton biomass, suggesting the importance of these biological processes. Therefore, it is considered that the middle layer intrusion plays a role as an inducer of subsequent biological processes at the tidal front by not only supplying nutrients from the mixed region but also by increasing the vertical diffusivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011126911262
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    CO2 gas exchange of benthic microalgae during exposure to air: a technique for the rapid assessment of primary production (2000)
    Springer
    Wetlands ecology and management 8 (2000), S. 273-280 
    Details
    ISSN: 1572-9834
    Keywords: light curves ; mangrove ; microphytobenthos ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method of measuring CO2gas exchange (caused, for example, by microalgal photosynthesis on emersed tidal mudflats) using open flow IR gas analyzers is described. The analyzers are integrated in a conventional portable photosynthesis system (LI-6400, LI-COR, Nebraska, USA), which allows manipulation and automatic recording of environmental parameters at the field site. Special bottomless measuring chambers are placed directly on the surface sediment. Measurements are performed under natural light conditions and ambient CO2concentrations, as well as under different CO2concentrations in air, and various PAR radiation levels produced by a LED light source built into one of the measurement chambers. First results from tidal channel banks in a north Brazilian mangrove system at Bragança (Pará, Brazil) under controlled conditions show a marked response of CO2assimilation to CO2concentration and to irradiance. Photosynthesis at 100 μmol mol−1CO2in air in one sample of a well-developed algal mat was saturated at 309 μmol photons m−2s−1, but increased with increasing ambient CO2concentrations (350 and 1000 μmol mol−1CO2) in the measuring chamber. Net CO2assimilation was 0.8 μmol CO2 m−2s−1at 100 μmol mol−1CO2, 5.9 μmol CO2m−2s−1at 350 μmol mol−1CO2and 9.8 μmol CO2m−2s−1at 1000 μmol mol−1CO2. Compensation irradiance decreased and apparent photon yield increased with ambient CO2concentration. Measurements under natural conditions resulted in a quick response of CO2exchange rates when light conditions changed. We recommend the measuring system for rapid estimations of benthic primary production and as a valuable field research tool in connection with certain ecophysiological aspects under changing environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008448729277
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Effects of photic and thermal stress on distal and proximal rhabdomeres in the crayfish eye: why are the visual membranes of the 8th retinula cell more resilient than the others? (2000)
    Springer
    Protoplasma 210 (2000), S. 156-163 
    Details
    ISSN: 1615-6102
    Keywords: Electron microscopy ; Photoreceptor ; Visual membrane ; Photic radiation damage ; Retina ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Visual membranes of the crayfish eye either belong to the small, distally placed rhabdomere of retinula cell R8 or are part of the much more voluminous proximal rhabdom, made up of rhabdomeres belonging to cells R1–R7. Under various conditions of environmental stress (e.g., prolonged darkness, elevated temperature, bright light with and without a concomitant rise in temperature, flickering lights) the visual membranes of R8 prove far more resistant to structural damage than those of R1–R7. Membrane damage is known to occur when dormant lipoxygenases become activated, for example through heat. Since R8 is the only type of visual cell in the crayfish retina that does not contain grains of screening pigment, the view that screening-pigment granules could “aggravate” or even “trigger” membrane damage in times of stress is strengthened. Functionally, R8's strong resistance to physical damage when exposed to flickering lights points to a role of the distal rhabdom in the movement detection system of the crayfish eye.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276855
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    The effects of irrigation regimes on the water use, dry matter production and physiological responses of paddy rice (2000)
    Springer
    Plant and soil 223 (2000), S. 209-218 
    Details
    ISSN: 1573-5036
    Keywords: dry matter production ; irrigation water use ; leaf senescence ; paddy rice ; photosynthesis ; soil water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In most cases, rice production is associated with flooding irrigation and the efficiency of irrigated water use (WUEi) is generally lower for production of rice than for other crops. We have examined the effects of various irrigation regimes on water consumption in a well-puddled paddy field, as well as on dry matter production, grain yield and physiological responses of the plants. Four sets of conditions were studied, with two replications, in the well-puddled paddy field: Continuous flooding irrigation treatment (CSF); three intermittent irrigation treatments, designated II-0, II-1 and II-2, in which plants were re-irrigated when the water potential of the soil fell below 0, –10, and –20 kPa at a depth of 5 cm, respectively. Water consumption was lower during II-0 than during CSF because the percolation rate was reduced by the reduction in the hydraulic head of the ponded water. Intermittent irrigation led to the repeated shrinking and swelling of soil during II-1 and II-2 and, therefore, soil cracks developed rapidly. Since they became the major routes of water percolation, these soil cracks increased water consumption during II-1 and II-2 above that during CSF and II-0. There were no significant differences in dry matter production and grain yield between CSF and II-0, but both were significantly greater than in the case of II-1 and II-2. Therefore, WUEi increased in the following order: II-0, CSF, II-2, II-1, although the difference was very small between II-1 and II-2. A lower crop growth rate (CGR) resulted from a decrease in the net assimilation rate (NAR) during II-1 and II-2, and there was also a reduction in the leaf area index (LAI) during II-2. Early senescence with ripening and water stress around midday decreased the rate of photosynthesis in leaves, causing the lower NAR. These physiological responses of the plants were responsible for the reduction on the dry matter production and grain yield in the intermittent irrigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004898504550
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Interaction effects of phosphorus and zinc on photosynthesis, growth and yield of dwarf bean grown in two environments (2000)
    Springer
    Plant and soil 220 (2000), S. 219-228 
    Details
    ISSN: 1573-5036
    Keywords: growth ; light intensity ; Phaseolus vulgaris L. ; phosphorus–zinc interaction ; photosynthesis ; yield ; zinc deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two experiments were conducted in a factorial combination of three Zn levels (0, 10 and 40 mg Zn kg-1 soil) and two P levels (0 and 200 mg P kg-1 soil). Experiment 1 was carried out during winter in a heated glasshouse, and experiment 2 during summer under a rain shelter. Plants of dwarf bean (Phaseolus vulgaris L., cv. Borlotto nano) were grown in pots filled with sandy soil. In both experiments, leaf Zn concentration was reduced by the addition of P to plants grown at low Zn supply. However, leaf Zn concentration lower than the critical level was observed only during experiment 2, and the main effects of low Zn were reductions of internode length, light use efficiency and maximum photosynthetic rate. In plants with leaf Zn concentration lower than the critical level, saturating irradiance levels fell from ∼1000 μmol m-2 s-1 PPFD to ∼300–400 μmol m-2 s-1 PPFD. Reduction of net photosynthesis was observed from the beginning of flowering and led to decreased seed production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004705008101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Leaf water characteristics and drought acclimation in sunflower genotypes (2000)
    Springer
    Plant and soil 223 (2000), S. 155-162 
    Details
    ISSN: 1573-5036
    Keywords: drought acclimation ; Helianthus annuus L. ; photosynthesis ; pressure-volume curves ; water relations ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The responses of leaf water parameters to drought were examined using three sunflower (Helianthus annuus L.) genotypes. Osmotic potential at full water saturation (π100), apoplastic water fraction (AWF) and bulk elastic modulus (BEM) were determined by pressure-volume curve analysis on well watered or on water-stressed plants (−1.0 MPa Ψ1 〈 −1.5 MPa) previously drought-pretreated or not. The drought-pretreated plants were subjected to a 7-day drought period (predawn leaf water potential reached −0.9 MPa) followed by 8 days of rewatering. In well watered plants, all genotypes in response to drought acclimation displayed a significantly decreased π100 associated with a decrease in the leaf water potential at the turgor-loss point (decrease in Ψtlp was between 0.15 and 0.21 MPa, depending on the genotype). In two genotypes, drought acclimation affected the partitioning of water between the apoplastic and symplastic fractions without any effect on the total amount of water in the leaves. As a third genotype displayed no modification of AWF and BEM after drought acclimation, the decreased π100 was only due to the net accumulation of solutes and was consistent with the adjustment of the photochemical efficiency observed previously in this genotype in response to drought acclimation. In water-stressed plants, the osmotic adjustment (OA) can increase further beyond that observed in response to the drought pretreatment. However, the maintenance of photosynthetic rate and stomatal conductance at low leaf water potentials not only depends on the extent of osmotic adjustment, but also on the interaction between OA and AWF or BEM. Adaptative responses of leaf water parameters to drought are thus quite contrasted in sunflower genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004849509673
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Photosynthesis, respiration, and carbon allocation of two cool-season perennial grasses in response to surface soil drying (2000)
    Springer
    Plant and soil 227 (2000), S. 17-26 
    Details
    ISSN: 1573-5036
    Keywords: photosynthesis ; root respiration ; carbon allocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The study was conducted to investigate carbon metabolic responses to surface soil drying for cool-season grasses. Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinaceae Schreb.) were grown in a greenhouse in split tubes consisting of two sections. Plants were subjected to three soil moisture regimes: (1) well-watered control; (2) drying of upper 20-cm soil (upper drying); and (3) drying of whole 40-cm soil profile (full drying). Upper drying for 30 d had no dramatic effects on leaf water potential (Ψleaf) and canopy photosynthetic rate (Pn) in either grass species compared to the well-watered control, but it reduced canopy respiration rate (Rcanopy) and root respiration rate in the top 20 cm of soil (Rtop). For both species in the lower 20 cm of wet soil, root respiration rates (Rbottom) were similar to the control levels, and carbon allocation to roots increased with the upper soil drying, particularly for tall fescue. The proportion of roots decreased in the 0-20 cm drying soil, but increased in the lower 20 cm wet soil for both grass species; the increase was greater for tall fescue. The Ψleaf, Pn, Rcanopy, Rtop, Rbottom, and carbon allocation to roots in both soil layers were all significantly higher for upper dried plants than for fully dried plants of both grass species. The reductions in Rcanopy and Rtop in surface drying soil and increases in root respiration and carbon allocation to roots in lower wet soil could help these grasses cope with surface-soil drought stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026512212113
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Response of tomato plants to chilling stress in association with nutrient or phosphorus starvation (2000)
    Springer
    Plant and soil 226 (2000), S. 99-106 
    Details
    ISSN: 1573-5036
    Keywords: chilling ; chlorophyll fluorescence ; nutrient ; phosphorus ; photosynthesis ; starvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The experiments were conducted on two tomato cultivars: Garbo and Robin. Mineral starvation due to plant growth in 20-fold diluted nutrient solution (DNS) combined with chilling reduced the rate of photosynthesis (P N) and stomatal conductance (g) to a greater extent than in plants grown in full nutrient solution (FNS). In phosphate-starved tomato plants the P N rate and stomatal conductance decreased more after chilling than in plants grown on FNS. In low-P plants even 2 days after chilling the recovery of CO2 assimilation rate and stomatal conductance was low. A resupply of phosphorus to low-P plants (low P + P) did not improve the rate of photosynthesis in non-chilled plants (NCh) but prevented PN inhibition in chilled (Ch) plants. The greatest effect of P resupply was expressed as a better recovery of photosynthesis and stomatal conductance, especially in non-chilled low P + P plants. The F v/F m (ratio of variable to maximal chlorophyll fluorescence) decreased more during P starvation than as an effect of chilling. Supplying phosphorus to low-P plants caused the slight increase in the F v/F mratio. In conclusion, after a short-term chilling in darkness a much more drastic inhibition of photosynthesis was observed in nutrient-starved or P-insufficient tomato plants than in plants from FNS. This inhibition was caused by the decrease in both photochemical efficiency of photosystems and the reduction of stomatal conductance. The presented results support the hypothesis that tomato plants with limited supply of mineral nutrients or phosphorus are more susceptible to chilling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026497104077
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Tolerance of a field grown soybean cultivar to elevated ozone level is concurrent with higher leaflet ascorbic acid level, higher ascorbate-dehydroascorbate redox status, and long term photosynthetic productivity (2000)
    Springer
    Photosynthesis research 64 (2000), S. 77-87 
    Details
    ISSN: 1573-5079
    Keywords: ascorbic acid ; ascorbate-glutathione cycle ; bean yield ; dehydroascorbate ; ozone ; photosynthesis ; soybean ; vegetative yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the characteristics of ascorbic acid (ASC) level, dehydroascorbate (DHA) level, and the ASC–DHA redox status in the leaflets of two soybean cultivars grown in a field environment and exposed to elevated ozone (O3) levels. These two cultivars, one that preliminary evidence indicated to be O3-tolerant (cv Essex), and one that was indicated to be O3-sensitive (cv Forrest), were grown in open-top chambers during the summer of 1997. The plants were exposed daily to a controlled, moderately high O3 level (≈58 nl l−1 air) in the light, beginning at the seedling stage and continuing to bean maturity. Concurrently, control plants were exposed to carbon-filtered, ambient air containing a relatively low O3 level (≈24 nl l−1 air) during the same period. Elevated O3 did not affect biomass per plant, mature leaf area accretion, or bean yield per plant of cv Essex. In contrast, elevated O3 level decreased the biomass and bean yield per plant of cv Forrest by approximately 20%. Daily leaflet photosynthesis rate and stomatal conductance per unit area did not decrease in either cultivar as a result of prolonged O3 exposure. A 10% lower mature leaflet area in O3-treated cv Forrest plants contributed to an ultimate limitation in long-term photosynthetic productivity (vegetative and bean yield). Possible factors causing cv Essex to be more O3 tolerant than cv Forrest were: 1) mature leaflets of control and O3-treated cv Essex plants consistently maintained a higher daily ASC level than leaflets of cv Forrest plants, and 2) mature leaflets of cv Essex plants maintained a higher daily ASC–DHA redox status than leaflets of cv Forrest plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026508227189
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Crystallization of dimers of the manganese-stabilizing protein of Photosystem II (2000)
    Springer
    Photosynthesis research 64 (2000), S. 167-177 
    Details
    ISSN: 1573-5079
    Keywords: dynamic light scattering ; mass spectrometry ; oxygen evolution ; photosynthesis ; protein crystallization ; protein structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The manganese-stabilizing protein (MSP) of Photosystem II was purified from spinach photosynthetic membranes. The MSP was crystallized in the presence of calcium. Despite the apparent purity of the isolated protein, the crystals grew to only about 0.05 mm in their largest dimension. The MSP was analyzed to identify possible sources of protein heterogeneity that could hinder crystal growth. Tandem reverse-phase HPLC/ electronspray ionization mass spectrometry analysis of the MSP showed a major peak and four smaller peaks. All five peaks had molecular masses of 26 535, as expected for mature MSP, indicating the absence of heterogeneities due to covalent modifications. MALDI mass spectroscopy was utilized to identify heterogeneities in the MSP oligomeric state. These measurements showed that purified MSP in solution is a mixture of monomers and dimers, while solubilized MSP crystals contained only dimers. Size-exclusion chromatography and dynamic light scattering were used to probe the effect of the crystallization conditions on the MSP. Size-exclusion chromatography of concentrated MSP showed the presence of aggregates and monomers, while dilute MSP contained monomers. Dynamic light scattering experiments in the absence, or in the presence of 10–50 mM or 100 mM calcium, yielded calculated molecular mass values of 34 kDa, 48 kDa and 68 kDa, respectively. These changes in the observed molecular mass of the MSP could have been caused by the formation of dimers and higher oligomers and/or significant conformational changes. Based on the results reported in this study, a model is presented which details the effect of oligomeric heterogeneity on the inhibition of MSP crystal growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006453718502
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Analysis of the role of detergent mixtures on the crystallization of the reaction center of Photosystem II (2000)
    Springer
    Photosynthesis research 65 (2000), S. 249-259 
    Details
    ISSN: 1573-5079
    Keywords: dynamic light scattering ; membrane protein crystallization ; photosynthesis ; thermoluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have recently reported the crystallization of the reaction center of Photosystem II in the presence of detergent mixtures [Adir N (1999) Acta Crystallogr D Biol Crystallogr D55: 891–894]. We have used high performance liquid chromatography, dynamic light scattering, native gel electrophoresis and thermoluminescence measurements to characterize the interaction between these detergent mixtures and RC II, to try and understand their role in the crystallization process. Size exclusion HPLC and dynamic light scattering confirmed that the isolated RC II used for crystallization was exclusively monomeric. Dynamic light scattering measurements show that the detergent mixtures formed single micelles within a limited range of hydrodynamic radii. Both size exclusion HPLC and dynamic light scattering were used to follow the interaction between the detergent mixtures and monomeric RC II. These techniques revealed a decrease in the detergent mixture treated RC II particle size (with respect with the untreated RC II), and that RC II from solubilized crystals contained particles of the same size. Native gel electrophoresis showed that this change in apparent size is not due to the disintegration of the internal structure of the RC II complex. Thermoluminescence measurements of solubilized RC II crystals showed charge recombination from the S2,3QA − state, indicating that RC II remains functionally viable following detergent mixture treatment and crystallization. The role of the detergent mixtures in the crystallization of RC II is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010618527974
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Kinetic imaging of chlorophyll fluorescence using modulated light (2000)
    Springer
    Photosynthesis research 66 (2000), S. 3-12 
    Details
    ISSN: 1573-5079
    Keywords: herbicide ; instrumentation ; mutant selection ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluorometers that measure the kinetics of chlorophyll fluorescence have become invaluable tools for determining the photosynthetic performance of plants. Many of these instruments use high frequency modulated light to measure the rate, efficiency and regulation of photosynthesis. The technique is non-invasive and is effective under diverse environmental conditions. Recently, imaging fluorometers have been introduced that reveal variability in photosynthesis over the surface of a leaf or between individual plants. Most imaging instruments depend on continuous light or low frequency modulated light for fluorescence excitation, which imposes serious limitations on measurements of the fluorescence parameters, especially the minimum fluorescence (F0) and variable fluorescence (FV). Here, we describe a new instrument that combines the advantage of high frequency modulated light with two-dimensional imaging of chlorophyll fluorescence. The fluorometer produces dynamic images of chlorophyll fluorescence from leaves or plants, providing accurate mapping of F0 and FV, and non-photochemical quenching. A significant feature of the instrument is that it can record fluorescence images of leaves in daylight under field conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010729821876
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Airborne test of laser pump-and-probe technique for assessment of phytoplankton photochemical characteristics (2000)
    Springer
    Photosynthesis research 66 (2000), S. 45-56 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll ; energy quenching ; fluorescence ; LIDAR ; photochemistry ; photosynthesis ; Photosystem II ; phytoplankton ; pump and probe ; remote sensing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Initial results of the airborne LIDAR measurement of photochemical quantum yield, ΦPo, and functional absorption cross-section, σPS II, of Photosystem II (PS II) are reported. NASA's AOL3 LIDAR was modified to implement short-pulse pump-and-probe (SP-P&P) LIDAR measurement protocol. The prototype system is capable of measuring a pump-induced increase in probe-stimulated chlorophyll fluorescence, ΔF/Fsat, along with the acquisition of `conventional' LIDAR-fluorosensor products from an operational altitude of 150 m. The use of a PS II sub-saturating probe pulse increases the response signal but also results in excessive energy quenching (EEQ) affecting the ΔF/Fsat magnitude. The airborne data indicated up to a 3-fold EEQ-caused decline in ΔF/Fsat, and 2-fold variability in the EEQ rate constant over a spatial scale a few hundred kilometers. Therefore, continuous monitoring of EEQ parameters must be incorporated in the operational SP-P&P protocol to provide data correction for the EEQ effect. Simultaneous airborne LIDAR measurements of ΦPo and σPS II with EEQ correction were shown to be feasible and optimal laser excitation parameters were determined. Strong daytime ΔF/Fsat decline under ambient light was found in the near-surface water layer over large aquatic areas. An example of SP-P&P LIDAR measurement of phytoplankton photochemical and fluorescent characteristics in the Chesapeake Bay mouth is presented. Prospects for future SP-P&P development and related problems are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010764420934
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Carbohydrate regulation of leaf development: Prolongation of leaf senescence in Rubisco antisense mutants of tobacco (2000)
    Springer
    Photosynthesis research 63 (2000), S. 1-8 
    Details
    ISSN: 1573-5079
    Keywords: acclimation ; photosynthesis ; rbcL ; rbcS ; source strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous investigations have shown that increased source strength as a result of elevated CO2 can alter the timing of the phases of change that occur in photosynthetic rates during dicot leaf ontogeny [Miller et al. (1997) Plant Physiol 115: 1195–1200]. To evaluate the converse situation of decreased source strength, we examined leaf development in rbcS antisense mutants of tobacco. These mutants have depressed Rubisco levels and decreased rates of carbohydrate production. We found that antisense leaves are longer-lived than wild type leaves and that this appeared to be due to a prolongation of the senescence phase of development, as monitored by photosynthetic rates, chlorophyll content, and the abundance and activity of Rubisco. Declines in these parameters during leaf ontogeny in both the wild type and mutant plants were generally accompanied by coordinate reductions in the levels of rbcS mRNA and rbcL mRNA, as well as by reductions in chloroplast rRNA, chloroplast DNA and total protein. We suggest that the prolongation of senescence in the antisense leaves is due to an impact of source strength on leaf developmental programming that occurs, at least in part, at the level of transcript abundance of nuclear and chloroplast genes for chloroplast rRNAs and proteins. We hypothesize that plants are capable of sensing a range of source strength conditions to initiate and modulate leaf developmental programming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006367719639
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    An FTIR study on the structure of the oxygen-evolving Mn-cluster of Photosystem II in different spin forms of the S2 state (2000)
    Springer
    Photosynthesis research 63 (2000), S. 47-57 
    Details
    ISSN: 1573-5079
    Keywords: Fourier transform infrared spectroscopy ; Mn-cluster ; oxygen evolution ; photosynthesis ; Photosystem II ; vibrational spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The S2 state of the oxygen-evolving Mn-cluster of Photosystem II (PS II) is known to have different forms that exhibit the g =2 multiline and g = 4.1 EPR signals. These two spin forms are interconvertible at 〉 200 K and the relative amplitudes of the two signals are dependent on the species of cryoprotectant and alcohol contained in the medium. Also, it was recently found that the mutiline form can be converted to the g = 4.1 form by absorption of near-infrared light by the Mn-cluster itself at around 150 K [Boussac et al. (1996) Biochemistry 35: 6984–6989]. We have used light-induced Fourier transform infrared (FTIR) difference spectroscopy to study the structural difference in these two S2 forms. FTIR difference spectra for S2/S1 as well as for S2QA -/S1QA measured at cryogenic temperatures using PS II membranes in the presence of various cryoprotectants, and monohydric alcohols did not show any specific differences except for intensities of amide I bands, which were larger when ethylene glycol or glycerol was present in addition to sucrose. This result was interpreted due to more flexible movement of the protein backbones upon S2 formation with a higher cryoprotectant content. Light-induced difference spectra measured at 150 K using either blue light without near-infrared light or red plus near-infrared light also did not show any detectable difference. In addition, a different spectrum upon near-infrared illumination at 150 K of the PS II sample in which the S2 state had been photogenerated at 200 K exhibited no meaningful signals. These results indicate that the two S2 forms that give rise to the multiline and g = 4.1 signals have only minor differences, if any, in the structures of amino-acid ligands and polypeptide backbones. This conclusion suggests that conversion between the two spin states is caused by a spin-state transition in the Mn(III) ion rather than valence swapping within the Mn-cluster that would considerably affect the vibrations of ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006362118267
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    New applications of photoacoustics to the study of photosynthesis (2000)
    Springer
    Photosynthesis research 66 (2000), S. 13-31 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; photoacoustic ; optoacoustic ; spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoacoustic methods offer unique capabilities for photosynthesis research. Phenomena that are readily observed by photoacoustics include the storage of energy by electron transport, oxygen evolution by leaf tissue at microsecond time resolution, and the conformational changes of photosystems caused by charge separation. Despite these capabilities, photoacoustic methods have not been widely exploited in photosynthesis research. One factor that has contributed to their slow adoption is uncertainty in the interpretation of photoacoustic signals. Careful experimentation is resolving this uncertainty, however, and technical refinements of photoacoustic methods continue to be made. This review provides an overview of the application of photoacoustics to the study of photosynthesis with an emphasis on the resolution of uncertainties in the interpretation of photoacoustic signals. Recent developments in photoacoustic technology are also presented, including a microphotoacoustic spectrometer, gas permeable photoacoustic cells, the use of photoacoustics to monitor phytoplankton populations, and the use of photoacoustics to study protein dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010788504886
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Short-pulse pump-and-probe technique for airborne laser assessment of Photosystem II photochemical characteristics (2000)
    Springer
    Photosynthesis research 66 (2000), S. 33-44 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll ; fluorescence ; LIDAR ; photosynthesis ; Photosystem II ; pump and probe ; remote sensing ; singlet-singlet quenching ; singlet-triplet quenching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of a technique for laser measurement of fPhotosystem II (PS II) photochemical characteristics of phytoplankton and terrestrial vegetation from an airborne platform is described. Results of theoretical analysis and experimental study of pump-and-probe measurement of the PS II functional absorption cross-section and photochemical quantum yield are presented. The use of 10 ns probe pulses of PS II sub-saturating intensity provides a significant, up to 150-fold, increase in the fluorescence signal compared to conventional `weak-probe' protocol. Little effect on the fluorescence yield from the probe-induced closure of PS II reaction centers is expected over the short pulse duration, and thus a relatively intense probe pulse can be used. On the other hand, a correction must be made for the probe-induced carotenoid triplet quenching and singlet-singlet annihilation. A Stern-Volmer model developed for this correction assumes a linear dependence of the quenching rate on the laser pulse fluence, which was experimentally validated. The PS II saturating pump pulse fluence (532 nm excitation) was found to be 10 and 40 μmol quanta m−2 for phytoplankton samples and leaves of higher plants, respectively. Thirty μs was determined as the optimal delay in the pump-probe pair. Our results indicate that the short-pulse pump-and-probe measurement of PS II photochemical characteristics can be implemented from an airborne platform using existing laser and LIDAR technologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010795820025
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Acclimation response of spring wheat in a free-air CO2 enrichment (FACE) atmosphere with variable soil nitrogen regimes. 2. Net assimilation and stomatal conductance of leaves (2000)
    Springer
    Photosynthesis research 66 (2000), S. 79-95 
    Details
    ISSN: 1573-5079
    Keywords: acclimation ; climate change ; CO2 ; down-regulation ; global change ; photosynthesis ; stomatal conductance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Atmospheric CO2 concentration continues to rise. It is important, therefore, to determine what acclimatory changes will occur within the photosynthetic apparatus of wheat (Triticum aestivum L. cv. Yecora Rojo) grown in a future high-CO2 world at ample and limited soil N contents. Wheat was grown in an open field exposed to the CO2 concentration of ambient air [370 μmol (CO2) mol−1; Control] and air enriched to ∼200 μmol (CO2) mol−1 above ambient using a Free-Air CO2 Enrichment (FACE) apparatus (main plot). A High (35 g m−2) or Low (7 and 1.5 g m−2 for 1996 and 1997, respectfully) level of N was applied to each half of the main CO2 treatment plots (split-plot). Under High-N, FACE reduced stomatal conductance (g s) by 30% at mid-morning (2 h prior to solar noon), 36% at midday (solar noon) and 27% at mid-afternoon (2.5 h after solar noon), whereas under Low-N, g s was reduced by as much as 31% at mid-morning, 44% at midday and 28% at mid-afternoon compared with Control. But, no significant CO2 × N interaction effects occurred. Across seasons and growth stages, daily accumulation of carbon (A′) was 27% greater in FACE than Control. High-N increased A′ by 18% compared with Low-N. In contrast to results for g s, however, significant CO2 × N interaction effects occurred because FACE increased A′ by 30% at High-N, but by only 23% at Low-N. FACE enhanced the seasonal accumulation of carbon (A′′) by 29% during 1996 (moderate N-stress), but by only 21% during 1997 (severe N-stress). These results support the premise that in a future high-CO2 world an acclimatory (down-regulation) response in the photosynthetic apparatus of field-grown wheat is anticipated. They also demonstrate, however, that the stimulatory effect of a rise in atmospheric CO2 on carbon gain in wheat can be maintained if nutrients such as nitrogen are in ample supply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010646225929
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Respiration and plasma membrane ATPase in strawberry stolons (2000)
    Springer
    Plant growth regulation 30 (2000), S. 163-170 
    Details
    ISSN: 1573-5087
    Keywords: ATPase ; bioenergetics ; Fragaria ananassa Duch ; growth ; ion transport ; photosynthesis ; proton transport ; respiration ; source-sink ; strawberry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The biochemical, physiological and anatomical properties of strawberry (Fragaria ananassa Duch.) cv. 'Cambridge Favourite' stolons were studied during growth. ATPase activity was measured, in microsomal and plasma membrane fractions, along with chlorophyll determination, in-situ photosynthesis measurements and scanning electron microscopy (SEM) and X-ray microanalysis of stolon cross-sections. Potassium-stimulated ATPase activity and proton-pumping, both together indicating the presence of plasma membrane ATPase, was greatest in the stolon tip, the tissue with the fastest growth and respiratory activity. The enzyme activity and respiration gradient from the tip of the stolon to the base was concomitant with xylem development which was more differentiated in the base than in the tip. These cross-sections also showed 30% greater amounts of calcium and potassium of the cryo-preserved basal part relative to the stolon tip. This gradient existed independent of the presence of daughter plants. A hypothesis is presented which suggests that for the long-distance longitudinal transport of nutrients this gradient between stolon tip and base is likely to be involved in stolon growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006314629955
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Chlorophyll fluorescence transients of Photosystem II membrane particles as a tool for studying photosynthetic oxygen evolution (2000)
    Springer
    Photosynthesis research 65 (2000), S. 41-52 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; EPR ; heat effect ; manganese complex ; oxygen-evolution ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rise of the chlorophyll fluorescence yield of Photosystem II (PS II) membranes as induced by high-intensity actinic light comprises only two distinct phases: (1) the initial O-J increase and (2) the subsequent J-P increase. Partial inhibition of the PS II donor side by heating or washing procedures which remove peripheral PS II proteins or cofactors of the oxygen-evolving complex results in decrease of magnitude and rate of the J-P phase. The rate constant of the J-P increase is directly proportional to the steady-state rate of oxygen evolution; complete suppression of the J-P phase corresponds to full inhibition. A characteristic dip after J-level is observed only in Tris-washed or severely heated PS II membranes; manganese release correlates with appearance of the dip after J-level as verified by EPR spectroscopy. Presence of stabilizing cosolutes (glycine betaine, sucrose) or addition of donor-side cofactors (bicarbonate, chloride, calcium) to PS II membranes before heating (47 °C, 5 min) diminishes J-P phase suppression and prevents dip appearance, whereas the addition after heating is without effect. In conclusion, analysis of chlorophyll fluorescence transients of PS II membranes is a potentially useful tool for investigations on photosynthetic oxygen evolution. A decreased rate of the J-P phase can be employed as a convenient indicator for partial inhibition of oxygen-evolution activity; the appearance of a dip after J-level is suggestive of manganese release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006469809812
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    The effect of CO2 enrichment on leaf photosynthetic rates and instantaneous water use efficiency of Andropogon gerardii in the tallgrass prairie (2000)
    Springer
    Photosynthesis research 65 (2000), S. 121-129 
    Details
    ISSN: 1573-5079
    Keywords: big bluestem ; C4 ; elevated CO2 ; photosynthesis ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Open-top chambers were used to study the effects of CO2 enrichment on leaf-level photosynthetic rates of the C4 grass Andropogon gerardii in the native tallgrass prairie ecosystem near Manhattan, Kansas. Measurements were made during a year with abundant rainfall (1993) and a year with below-normal rainfall (1994). Treatments included: No chamber, ambient CO2 (A); chamber with ambient CO2 (CA); and chamber with twice-ambient CO2 (CE). Measurements of photosynthesis were made at 2-hour intervals, or at midday, on cloudless days throughout the growing season using an open-flow gas-exchange system. No significant differences in midday rates of photosynthesis or in daily carbon accumulation as a result of CO2 enrichment were found in the year with abundant precipitation. In the dry year, midday rates of photosynthesis were significantly higher in the CE treatment than in the CA or A treatments throughout the season. Estimates of daily carbon accumulation also indicated that CO2 enrichment allowed plants to maximize carbon acquisition on a diurnal basis. The increased carbon accumulation was accounted for by greater rates of photosynthesis in the CE plots during midday. During the wet year, CO2 enrichment decreased stomatal conductance, which allowed plants to decrease transpiration while still photosynthesizing at rates similar to plants in ambient conditions. During the dry year, CO2 enrichment allowed plants to maintain photosynthetic rates even though stomatal conductance and transpiration had been reduced in all treatments due to stress. Estimates of instantaneous water-use efficiency were reduced under CO2 enrichment for both years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006489919192
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Nitrogen ligation to the manganese cluster of Photosystem II in the absence of the extrinsic proteins and as a function of pH (2000)
    Springer
    Photosynthesis research 65 (2000), S. 175-185 
    Details
    ISSN: 1573-5079
    Keywords: electron paramagnetic resonance ; extrinsic proteins ; manganese cluster ; oxygen evolution ; photosynthesis ; Photosystem II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three extrinsic proteins (PsbO, PsbP and PsbQ), with apparent molecular weights of 33, 23 and 17 kDa, bind to the lumenal side of Photosystem II (PS II) and stabilize the manganese, calcium and chloride cofactors of the oxygen evolving complex (OEC). The effect of these proteins on the structure of the tetramanganese cluster, especially their possible involvement in manganese ligation, is investigated in this study by measuring the reported histidine-manganese coupling [Tang et al. (1994) Proc Natl Acad Sci USA 91: 704–708] of PS II membranes depleted of none, two or three of these proteins using ESEEM (electron spin echo envelope modulation) spectroscopy. The results show that neither of the three proteins influence the histidine ligation of manganese. From this, the conserved histidine of the 23 kDa protein can be ruled out as a manganese ligand. Whereas the 33 and 17 kDa proteins lack conserved histidines, the existence of a 33 kDa protein-derived carboxylate ligand has been posited; our results show no evidence for a change of the manganese co-ordination upon removal of this protein. Studies of the pH-dependence of the histidine–manganese coupling show that the histidine ligation is present in PS II centers showing the S2 multiline EPR signal in the pH-range 4.2–9.5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006435432185
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Characterization of chloroplast psbA transformants of Chlamydomonas reinhardtii with impaired processing of a precursor of a photosystem II reaction center protein, D1 (2000)
    Springer
    Plant molecular biology 42 (2000), S. 353-363 
    Details
    ISSN: 1573-5028
    Keywords: Chlamydomonas reinhardtii ; chloroplast transformation ; photosynthesis ; photosystem II ; processing ; psbA gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One of the photosystem II reaction center proteins, D1, is encoded by the psbA gene and is synthesized as a precursor form with a carboxyl-terminal extension that is subsequently cleaved between Ala-344 and Ser-345. We have generated three psbA transformants of the green alga Chlamydomonas reinhardtii in which Ala-344 or Ser-345 have been substituted with Pro or Glu (A344P, S345E, and S345P) to understand the effects of the amino acid substitutions on the processing of the precursor D1. S345E grew photoautotrophically and showed PSII activity like the wild type. However, A344P and S345P were unable to grow photoautotrophically and were significantly photosensitive. A344P was deficient in the processing of precursor D1 and in oxygen-evolving activity, but assembled photosystem II complex capable of charge separation. In contrast, both precursor and mature forms of D1 accumulated in S345P cells from the logarithmic phase and the cells evolved oxygen at 18% of wild-type level. However, S345P cells from the stationary phase contained mostly the mature D1 and showed a twofold increase in oxygen-evolving activity. The rate of processing of the accumulated pD1 was estimated to be about 100 times slower than in the wild type. It is therefore concluded that the functional oxygen-evolving complex is assembled when the precursor D1 is processed, albeit at a very low rate. These results suggest the functional significance of the amino acid residues at the processing site of the precursor D1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006377614863
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Characterization of site-directed mutants in manganese-stabilizing protein (MSP) of Synechocystis sp. PCC6803 unable to grow photoautotrophically in the absence of cytochrome c-550 (2000)
    Springer
    Plant molecular biology 43 (2000), S. 33-41 
    Details
    ISSN: 1573-5028
    Keywords: cytochrome c-550 ; manganese-stabilizing protein (MSP) ; photosynthesis ; PSII ; Synechocystis sp. PCC6803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To investigate the interaction between the manganese-stabilizing protein (MSP) and cytochrome c-550 (cyt. c-550) of the photosystem II (PSII) complex in the cyanobacterium Synechocystis sp. PCC6803, three site-directed amino acid substitution mutants in MSP (MSP-D159N, MSP-R163L, MSP-D159N/R163L) were created by single and double amino acid substitution mutagenesis. The modified psbO genes encoding the mutants forms of MSP were used to transform a single-deletion mutant ΔpsO strain lacking MSP as well as a double-deletion strain ΔpsbO:ΔpsbV lacking both MSP and cyt. c-550. The mutant forms of MSP were expressed in each case and all permitted autotrophic growth in strains expressing cyt. c-550. However, when the MSP mutations were introduced into a strain which lacks cyt. c-550 (ΔpsbV), the two single amino acid substitution mutants (ΔpsbV:MSP-D159N and ΔpsbV:MSP-R163L) failed to grow photoautotrophically. These strains exhibited coupled O2-evolving activity of 68–77% compared to the wild-type control using CO2 as an electron acceptor and maximal uncoupled O2-evolution rates of 42–57% using 2,6-dichloro-p-benzoquinone (DCBQ) as an artificial electron acceptor. Interestingly, when the two amino acid substitutions were together in the absence of cyt. c-550 (ΔpsbV:MSP-D159N/R163L), the mutant grew photoautotrophically and the oxygen-evolving activities were higher than in the single mutants. This indicates that the MSP-D159N mutant suppresses the non-autotrophic phenotype of MSP-R163L (or vice versa) in the absence of cyt. c-550. The possibilities of a direct (ionic) or indirect interaction between D159 and R163 of MSP are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006419928712
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Caffeic Acid-Induced Changes in Plant–Water Relationships and Photosynthesis in Leafy Spurge Euphorbia esula (2000)
    Springer
    Journal of chemical ecology 26 (2000), S. 2095-2109 
    Details
    ISSN: 1573-1561
    Keywords: Caffeic acid ; allelopathy ; plant water balance ; photosynthesis ; chlorophyll fluorescence ; 13C carbon isotopes ; leafy spurge ; Euphorbia esula ; small everlasting ; Antennaria microphylla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Leafy spurge (Euphorbia esula), a native perennial weed introduced from Eurasia around the turn of the century, disrupts natural and agroecosystems across much of the Northern Great Plains. While leafy spurge displaces many native plant species, it has been demonstrated that small everlasting (Antennaria microphylla), a native perennial, is allelopathic to leafy spurge. Caffeic acid (CA), one of three compounds isolated from small everlasting, inhibits leafy spurge seed germination, root elongation, and callus culture growth. This study investigated the mechanism of this interference at the whole-plant level. Results indicate that inhibition of growth in leafy spurge after exposure to CA is primarily due to a disruption of plant–water relations. Leafy spurge cuttings were propagated in 0.5 strength Hoagland's nutrient solution for 30 days. For treatments, six plants were transferred into nutrient medium amended with either 0.1 or 0.25 mM CA for a period of 30 days. To determine the effect of pH, two additional groups of six plants were grown in nutrient medium adjusted with HCl corresponding to pH levels of plants treated with CA (pH 5.5–5.8 for 0.1 mM CA and pH 4.5–4.8 for 0.25 mM CA). By day 12 of the treatment period, plants treated with both levels of CA had significantly higher leaf diffusive resistances than control plants. Plants grown at the corresponding pH levels experienced higher diffusive resistances later in the treatment period (day 21). Transpiration was similarly affected with treated plants showing relatively higher transpiration rates compared to controls. Chlorophyll fluorescence was significantly lower than controls in all treated plants by end of the treatment period. The stable carbon isotope ratio (13C:12C) in these plants was higher than controls. These data show that a disruption of plant water relations is the primary mechanism of plant growth inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005564315131
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Electronic Excited States of the CP29 Antenna Complex of Green Plants: A Model Based on Exciton Calculations (2000)
    Springer
    Journal of biological physics 26 (2000), S. 321-339 
    Details
    ISSN: 1573-0689
    Keywords: CP29 ; electronic excited states ; energy transfer ; LHCII ; light-harvesting complexes ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We have suggested a model for the electronic excited states of the minorplant antenna, CP29, by incorporating a considerable part of the currentinformation offered by structure determination, site-directed mutagenesis,and spectroscopy in the modeling.We have assumed that the electronic excited states of the complex havebeen decided by the chlorophyll-chlorophyll (Chl) and Chl-proteininteractions and have modeled the Coulombic interaction between a pairof Chls in the point-dipole approximation and the Chl-protein interactionsare treated as empirical fit parameters.We have suggested the Qy dipole moment orientations and the siteenergies for all the chlorophylls in the complex through a simultaneoussimulation of the absorption and linear dichroism spectra.The assignments proposed have been discussed to yield a satisfactoryreproduction of all prominent features of the absorption, linear and circulardichroism spectra as well as the key spectral and temporal characteristics ofthe energy transfer processes among the chlorophylls.The orientations and the spectral assignments obtained by relatively simpleexciton calculations have been necessary to provide a good point ofdeparture for more detailed treatments of structure-function relationship inCP29. Moreover, it has been discussed that the CP29 model suggested canguide the studies for a better understanding of the structure-functionrelationship in the major plant antenna, LHCII.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010352731838
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Electron spin-lattice relaxation studies of different forms of the S2 state multiline EPR signal of the Photosystem II oxygen-evolving complex (2000)
    Springer
    Photosynthesis research 66 (2000), S. 189-198 
    Details
    ISSN: 1573-5079
    Keywords: electron spin-lattice relaxation rate ; manganese ; oxygen-evolving complex ; photosynthesis ; Photosystem II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pulsed EPR inversion recovery sequence has been utilized to monitor the temperature dependence of the electron spin-lattice relaxation rate of the Mn cluster of the Photosystem II oxygen evolving complex poised in a variety of S 2 state forms giving rise to g = 2 multiline EPR signals. A previous study (Lorigan and Britt (1994) Biochemistry 33: 12072–12076) showed that for PS II membranes treated with 5% ethanol, the S 2 state Mn cluster relaxes via the Orbach spin-lattice relaxation mechanism, where the relaxation is enhanced via phonon scattering off an excited state spin manifold, in this case at an energy of Δ = 36.5 cm−1 above the S = 1/2 ground state giving rise to the multiline EPR signal. Parallel experiments are reported for PS II membranes with 5% methanol, treated with ammonia, and following short and long term dark adaptation. In each case, the temperature dependence of the electron spin-lattice relaxation rate is consistent with Orbach relaxation, and the range of excited state energies is relatively narrow (33.8 cm−1 ≤ Δ ≤ 39.7 cm−1). In addition, short term dark adapted (6 min, ‘active state’) PS II membranes show biphasic recovery traces which indicate that a minority fraction of the oxygen evolving complexes are trapped in a form with greatly slowed spin-lattice relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010604607891
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    The history of fruit thinning (2000)
    Springer
    Plant growth regulation 31 (2000), S. 1-16 
    Details
    ISSN: 1573-5087
    Keywords: apple ; application methods ; caustic sprays ; economics ; flowering ; growth regulators ; Malus xdomestics Borkh. ; modeling ; photosynthesis ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The history of fruit thinning is reviewed, beginning with hand removalof fruits, the effects upon subsequent flowering, and current attemptsto develop mechanical methods of fruit removal. Early experiments withcaustic compounds and growth regulators and their subsequent developmentas commercial practices are discussed, as well as the modes of action ofgrowth regulators. Brief reviews of methods of application, factorsaffecting response, modeling to improve efficiency, and the economicvalue of thinning to the grower are also included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006330009160
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Photosynthetic acclimation of shade-grown red pine (Pinus resinosa Ait.) seedlings to a high light environment (2000)
    Springer
    New forests 19 (2000), S. 1-11 
    Details
    ISSN: 1573-5095
    Keywords: chlorophyll fluorescence ; competition ; morphology ; photosynthesis ; red pine ; stomatal conductance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Photosynthetic light acclimation in red pine (Pinus resinosa Ait.) seedlings was examined in a greenhouse study to better understand the physiological response of this species to increased light intensity following release from competition. Seedlings grown in a high (HL), medium (ML) or low (LL) light environment for 12 weeks were transferred to high light. Gas exchange and chlorophyll fluorescence of ML and LL seedlings were measured prior to and following transfer and compared with the HL control treatment. Photosynthetic characteristics were related to initial light treatment and time after transfer. Acclimation of gas exchange features to high light in shade formed ML and LL foliage was relatively rapid, with similar values among light treatments within 57 days of transfer. Acclimation of net photosynthetic rate was similar in ML and LL seedlings, and was associated primarily with increased mesophyll conductance to CO2. The ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) decreased initially after transfer, especially in LL seedlings, but recovered to normal values after 57 days. Red pine seedlings appear to be well adapted for photosynthetic acclimation to high light intensity, consistent with that reported for other early successional tree species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006668928091
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Number of air exchanges, sucrose concentration, photosynthetic photon flux, and differences in photoperiod and dark period temperatures affect growth of Rehmannia glutinosa plantlets in vitro (2000)
    Springer
    Plant cell, tissue and organ culture 62 (2000), S. 219-226 
    Details
    ISSN: 1573-5044
    Keywords: acclimatization ; CO2 concentration ; photosynthesis ; reducing sugar ; total sugar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rehmannia glutinosa plantlets were cultured for 4 weeks under different culture conditions to determine the optimum environment for in vitro growth and ex vitro survival. Plantlet growth increased with an increasing number of air exchanges of the culture vessel, exhibiting greatest shoot weight, total fresh weight, leaf area, and chlorophyll content at 4.4 h−1 of air exchanges. High sucrose concentration (30 g l−1) increased root weight but reduced shoot growth. Net photosynthetic rates of the plantlets were greatest when sucrose was not added to the medium. On the other hand, ex vitro survival of the plantlets was not influenced by sucrose concentration. In the experiment on difference in photoperiod and dark period temperatures (DIF) and photosynthetic photon flux (PPF), plantlet growth increased as DIF and PPF levels increased. Particularly, increasing PPF level had a more distinctive effect on plantlet growth than increasing DIF level. The interaction of DIF × PPF was also significant, showing the greatest plantlet growth in positive DIF (+8 DIF) and a high PPF (210 μmol m−2 s−1). In conclusion, the results of this experiment suggest that increased number of air exchanges of the culture vessel, decreased sucrose concentration, and positive DIF in combination with high PPF level enhanced growth and acclimatization of Rehmannia glutinosa plantlets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006412321864
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Salinity increases CO2 assimilation but reduces growth in field-grown, irrigated rice (2000)
    Springer
    Plant and soil 218 (2000), S. 1-10 
    Details
    ISSN: 1573-5036
    Keywords: dry matter reduction ; leaf chlorophyll content ; leaf sodium uptake ; Oryza sativa ; photosynthesis ; salinity ; season effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Salinity is a major yield-reducing factor in coastal and arid, irrigated rice production systems. Salt tolerance is a major breeding objective. Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium uptake, leaf chlorophyll content, specific leaf area (SLA), sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation (PAR)-saturation. Plants were grown in Ndiaye, Senegal, at a research station of the West Africa Rice Development Association (WARDA), during the hot dry season (HDS) and the wet season (WS) 1994 under irrigation with fresh or saline water (flood water electrical conductivity = 3.5 mS cm-1). Relative leaf chlorophyll content (SPAD method) and root, stem, leaf blade and panicle dry weight were measured at weekly intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured at mid-season on the first (topmost) and second leaf. Salinity reduced yields to nearly zero and dry-matter accumulation by 90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase in CER, which was also observed in the other cultivars and seasons, was explained by a combination of two hypotheses: leaf chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation. The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly, energy-consuming processes, such as osmoregulation, interception of sodium and potassium from the transpiration stream in leaf sheaths and their subsequent storage, drained the assimilate supply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1014953504021
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Reduction of QA in the dark: Another cause of fluorescence Fo increases by high temperatures in higher plants (2000)
    Springer
    Photosynthesis research 63 (2000), S. 23-34 
    Details
    ISSN: 1573-5079
    Keywords: chlororespiration ; pheophytin a ; photosynthesis ; Photosystem II ; potato ; tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Increases in the chlorophyll fluorescence Fo (dark level fluorescence) during heat treatments were studied in various higher plants. Besides the dissociation of light-harvesting chlorophyll a/b protein complexes from the reaction center complex of PS II and inactivation of PS II, dark reduction of QA via plastoquinone (PQ) seemed to be related to the Fo increase at high temperatures. In potato leaves or green tobacco cultured cells, a part of the Fo increase was quenched by light, reflecting light-induced oxidation of QA - which had been reduced in the dark at high temperatures. Appearance of the Fo increase due to QA reduction depended on the plant species, and the mechanisms for this are proposed. The reductants seemed to be already present and formed by very brief illumination of the leaves at high temperatures. A ndhB-less mutant of tobacco showed that complex I type NAD(P)H dehydrogenase is not involved in the heat-induced reduction of QA. Quite strong inhibition of the QA reduction by diphenyleneiodonium suggests that a flavoenzyme is one of the electron mediator to PQ from the reductant in the stroma. Reversibility of the heat-induced QA reduction suggests that an enzyme(s) involved is activated at high temperatures and mostly returns to an inactive form at room temperature (25 °C).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006350706802
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Chlorophyll fluorescence quenching in the alga Euglena gracilis (2000)
    Springer
    Photosynthesis research 63 (2000), S. 159-170 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; chlororespiration ; Euglena ; photosynthesis ; spill over ; state transitions ; xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When far red light preincubated cells of Euglena gracilis are transferred to dark or light, chlorophyll fluorescence (F0 and Fm) decreases. Non-photochemical quenching in the dark is suggested to be induced partly by chlororespiration and partly by changes in the distribution of excitation energy between the photosystems. Depending on the light intensities it was possible to resolve the non-photochemical quenching into at least three different components. The slowest relaxation phase of non-photochemical quenching occurred only after exposure to high light and was assigned to photoinhibition. The other two components were an energy-dependent quenching (qE), and the one which we attribute to a spill over mechanism. We suggest that both photosystems use a common antenna system consisting of LHC I and LHC II proteins. In contrast to higher plants, qE in Euglena gracilis is independent of the xanthophyll cycle and an aggregation of LHC II.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006356421477
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    The golden age of biochemical research in photosynthesis (2000)
    Springer
    Photosynthesis research 63 (2000), S. 109-121 
    Details
    ISSN: 1573-5079
    Keywords: carotenoid protein ; cyanobacteria ; cytochromes ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The perspectives and enthusiasms recorded in this review describe the events I witnessed and, in small ways, contributed to. Two great rewards emerged from my experiences – the pleasure of doing experiments and the great wealth of friendships with students and colleagues. As a graduate student, phenomena appeared at the bench before me which clarified the coupling of electron transport to ATP synthesis. My first PhD graduate student measured concentrations of pyridine nucleotides in chloroplasts and his results have been often confirmed and well used. All of the many graduate students who followed contributed to our understanding of photosynthesis. I have taken much pleasure from documenting the details of photosynthetic phosphorylation and electron transport in cyanobacteria. Studies of the `c' type cytochromes in these organisms continue to fascinate me. My experiences in government in its efforts to promote research are unusual, perhaps unique. A rare event outside the laboratory – a natural bloom of cyanobacteria – stimulated new thoughts and special opportunities for laboratory science. Photosynthesis seems magisterial in its shaping of our planet and its biology and in the details of its cleverness that were revealed in the time of my witness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006469323393
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Discrimination Against 13CO2 in Leaves, Pod Walls, and Seeds of Water-stressed Chickpea (2000)
    Springer
    Photosynthetica 38 (2000), S. 155-157 
    Details
    ISSN: 1573-9058
    Keywords: Cicer arietinum ; gas exchange ; photosynthesis ; water potential ; δ13C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rate of photosynthesis (P N) in leaves and pods as well as carbon isotope content in leaves, pod walls, and seeds was measured in well-watered (WW) and water-stressed (WS) chickpea plants. The P N, on an area basis, was negligible in pods compared to leaves and was reduced by water stress (by 26%) only in leaves. WS pod walls and seeds discriminated less against 13CO2 than did the controls. This response was not observed for leaves as is usually the case. Pod walls and seeds discriminated less against 13CO2 than did leaves in both WW and WS plants. Measurement of carbon isotope composition in pods may be a more sensitive tool for assessing the impact of water stress on long-term assimilation than is the instantaneous measurement of gas exchange rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026768513073
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Turnover of D1 Protein Encoded by psbA Gene in Higher Plants and Cyanobacteria Sustains Photosynthetic Efficiency to Maintain Plant Productivity Under Photoinhibitory Irradiance (2000)
    Springer
    Photosynthetica 38 (2000), S. 161-169 
    Details
    ISSN: 1573-9058
    Keywords: irradiation stress ; lincomycin ; photosynthesis ; protein synthesis and degradation ; recovery ; Synechocystis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthesis and related plant productivity aspects of plants and cyanobacteria depend upon the functioning of photosystem 2 (PS2), associated with D1 and D2 heterodimer reaction centre core proteins. The D1 protein is encoded by psbA gene, genetically localized on the plastid genome (cpDNA), contains functional cofactors of PS2 in association with D2 protein, and also functions for radiant energy transformation through oxidation of water and reduction of plastoquinone. Surprisingly, D1 protein accounts for even less than 1% of the total thylakoid membrane protein content. In spite of that, its rate of turnover is very much comparable to ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) large subunit, most abundantly present in green tissue. The normal functioning of PS2 possesses damage-repair cycles of D1 protein. Generally, rate of photodamage does not exceed the rate of repair under optimal growth conditions, therefore, no adverse effect on photosynthetic efficiency is manifest. However, under strong irradiance coupled with elevated temperature, level of photodamage exceeds the rate of repair, resulting in photoinhibition, photodegradation of D1 protein, and lowering photosynthetic efficiency linked with plant productivity eventually. The features of D1 turnover process are reviewed, particularly with respect to molecular mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007297227403
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Photosynthetic Thermotolerance is Quantitatively and Positively Correlated with Production of Specific Heat-shock Proteins Among Nine Genotypes of Lycopersicon (Tomato) (2000)
    Springer
    Photosynthetica 38 (2000), S. 127-134 
    Details
    ISSN: 1573-9058
    Keywords: chloroplast ; heat stress ; heat tolerance ; photosynthesis ; stress proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We recently showed that the chloroplast small heat-shock protein (herein referred to as chlp Hsp24) protects photosystem 2 (PS2) during heat stress, and phenotypic variation in production of chlp Hsp24 is positively related to PS2 thermotolerance. However, the importance of chlp Hsp24 or other Hsps to other aspects of photosynthesis and overall photosynthetic thermotolerance is unknown. To begin investigating this and the importance of genetic variation in Hsp production to photosynthetic thermotolerance, the production of several prominent Hsps and photosynthetic thermotolerance were quantified in nine genotypes of Lycopersicon, and then the relationships between thermotolerance of net photosynthetic rate (P N) and production of each Hsp were examined. The nine genotypes exhibited wide variation in P N thermotolerance and production of each of the Hsps examined (chlp Hsp70, Hsp60, and Hsp24, and cytosol Hsp70). No statistically significant relationship was observed between production of chlp Hsp70 and P N thermotolerance, and only a weak positive relationship between cytosolic Hsp70 and P N was detected. However, significant positive relationships were observed between production of chlp Hsp24 and Hsp60 and P N thermotolerance. Hence natural variation in production of chlp Hsp24 and Hsp60 is important in determining variation in photosynthetic thermotolerance. This is perhaps the first evidence that chlp Hsp60 is involved in photosynthetic thermotolerance, and these in vivo results are consistent with previous in vitro results showing that chlp Hsp24 protects PS2 during heat stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026760311255
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    On the Influence of Hot-Water Discharges on Phytoplankton Communities from a Coastal Zone of the Gulf of Mexico (2000)
    Springer
    Water, air & soil pollution 119 (2000), S. 209-230 
    Details
    ISSN: 1573-2932
    Keywords: microalgal communities ; photosynthesis ; temperature ; thermal pollution ; tropical coast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The influence of thermal discharges on thephytoplankton community from a coastal zone of theGulf of Mexico was evaluated through their structureand photosynthetic behaviour focusing on responses tochanges in light and temperature. Biological andphysicochemical parameters were measured over a periodof two years in an area with permanent hot waterdischarges from a thermoelectric plant. Thetemperature in the sampling area ranged from 23.5 to36 °C with differences between the coldest andthe hottest station from 5.3 to 9.2 °C.Photosynthetically active radiation (PAR) were reducedin the discharge area water column, due to turbulence.One hundred and one different taxa were identifiedwith a strong predominance of Diatoms. The chlorophylla concentration ranged from 0.3 to 6.1 μgL-1, with highest values of thephaeophytin:chlorophyll ratio found at the hottest station.The community structure did not show significativedifferences among sampling stations with respect totemperature variations. However, in the algalassemblages influenced by thermal discharges, it waspossible to observe alterations in the photosynthesisbehaviour. Phytoplankton response to short termphotosynthesis experiments was segregated according tocomposition and origin of microalgal assemblages.Samples with larger heterogeneous composition had moreconsistent oxygen production responses. Algalcommunities exposed to hot effluent showed differentdegrees of photosynthesis rate reduction,higher light requirements (〉500 μE m2 s-1)and lower temperature (25 °C) to achieve Pmaxthan algae sampled in sites without such exposure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005161309609
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Stomatal Conductance, Photosynthetic Rate, and Pigment Content in Ruellia Tuberosa Leaves as Affected by Coal-Smoke Pollution (2000)
    Springer
    Biologia plantarum 43 (2000), S. 263-267 
    Details
    ISSN: 1573-8264
    Keywords: carotenoids ; chlorophyll ; photosynthesis ; stomatal conductance ; stomatal index ; stomatal morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Study of the effects of air pollution caused by thermal power plant emissions on some foliar traits of Ruellia tuberosa L. has shown that length and width of stomata, length of stomatal pore, stomatal density, photosynthetic rate, stomatal conductance and chlerophyll content were reduced in the polluted plants in pre-flowering, flowering as well as post-flowering phases of plant growth. Intercellular carbon dioxide concentration in the palisade tissue was increased at each stage of plant development. Stomatal index remained almost unchanged at the polluted site, except on the adaxial surface during the preflowering stage where it was higher as compared to the non-polluted plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002712528893
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Response of Scenedesmus Incrassatulus to Salt Stress as Affected by Methyl Jasmonate (2000)
    Springer
    Biologia plantarum 43 (2000), S. 625-627 
    Details
    ISSN: 1573-8264
    Keywords: ion accumulation ; iron chelators ; malondialdehyde ; photosynthesis ; proline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of the freshwater green alga Scenedesmus incrassatulus Bohl, strain R-83 to salt stress (175 mM NaCl) resulted in a reduction of its growth and 14CO2 fixation and in an increase of accumulation of free proline and malondialdehyde (MDA). The accumulation of proline in the light was higher than in dark. NaCl significantly inhibited the Fe-induced release of organic chelators from the cells. Exogenously supplied 10−4M methyl jasmonate (JA-Me) did not considerably change the 14CO2 fixation, but increased proline and MDA accumulation in the cells and moderately inhibited the release of chelators from cells. JA-Me supplied simultaneously with NaCl helps the algae to counteract the salt stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002816502941
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Gas exchange characteristics of the tropical mangrove, Pelliciera rhizophoreae (1999)
    Springer
    Mangroves and salt marshes 3 (1999), S. 147-153 
    Details
    ISSN: 1572-977X
    Keywords: conductance ; gas exchange ; mangrove ; photorespiration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic characteristics were investigated in the geographically isolated and restricted mangrove species, P.rhizophoreae. Gas exchange measurements were made on two to seven years old hydroponically grown plants maintained in 10%, 50% and 100% seawater. CO2 exchange in the 50% and 100% seawater treatments was reduced by 10% and 26%, respectively, compared to the 10% seawater treatment. CO2 response curves indicated that carboxylation efficiency was greater in 10% than in 50% seawater, while stomatal limitation increased from 11% to 16% as salinity increased from 10% to 50% seawater. Carbon losses via photorespiration (31% and 41%) and CO2 compensation point (67 and 81 μ11−1) were greater in 50% than in the 10% seawater treatment. Maximal CO2 exchange occurred at 30 °C with no differences among the salinity treatments. The results indicate that P. rhizophoreae exhibits many gas exchange characteristics previously reported for other mangroves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009943408779
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Magnetic properties of human liver and brain ferritin (1999)
    Springer
    European biophysics journal 28 (1999), S. 263-267 
    Details
    ISSN: 1432-1017
    Keywords: Key words Human liver ; Human brain ; Ferritin ; Electron microscopy ; Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Human brain (globus pallidus) and liver tissues were investigated by means of electron microscopy (EM), Mössbauer spectroscopy (MS) and SQUID magnetometry techniques. Based on MS measurements, the iron present was identified to be in the ferritin-like form (61–88%) and in the form of a low-spin iron species (the balance). Its overall concentration was estimated as 1.5(3) mg in the brain and 2.4(5) mg in the liver, per gram of lyophilized tissue. The average core diameter was determined by EM measurements to be equal to 7.5(1.3) nm for the liver and 3.3(5) nm for the brain. Magnetization measurements carried out between 5 and 300 K yielded an estimation of an average blocking temperature, KT BL, as equal to 6.7 K and 8.5 K for the liver and the brain, respectively. From the dependence of KT BL on the external magnetic field it was concluded that the ferritin-like cores in the studied samples can be regarded as non-interacting particles. Finally, the uniaxial magnetic anisotropy constant was determined to be 6×103 J/m3 for the liver and 4×104 J/m3 for the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Types, numbers and distribution of synapses on the dendritic tree of an identified visual interneuron in the brain of the locust (1999)
    Springer
    Cell & tissue research 296 (1999), S. 645-665 
    Details
    ISSN: 1432-0878
    Keywords: Key words Descending contralateral movement detector (DCMD) ; Identified neuron ; Vesicles ; Electron microscopy ; 3-D reconstruction ; Locust ; Schistocercagregaria (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The descending contralateral movement detector (DCMD), an identified descending interneuron in the brain of the locust Schistocerca gregaria has been investigated by using light and electron microscopy. We describe the fine structure, distribution and numbers of synapes that it receives from another identified brain neuron, the lobular giant movement detector (LGMD), and from unidentified neurons. The DCMD dendrites emerging from the integrative segment vary in form and number between individuals and sexes but always form a flattened dendritic domain. The arborizations and the integrative segment appear to be exclusively postsynaptic. Two types of synaptic contacts (Type 1 and 2) onto the DCMD can be discerned as having either round (Type 1) or pleiomorphic synaptic vesicles (Type 2) and by large (Type 1) or small (Type 2) subsynaptic appositions. Contact zones of Type 1 synapses are smaller than those of Type 2. LGMD-synapses are of Type 1 and occur intermingled with presynaptic sites of unidentified units. Some branches of the DCMD receiving input from unidentified units are devoid of contacting LGMD processes. Synapses of both types are randomly distributed over the DCMD integrative segment and at fibres with similar sizes.Type 1 synapses are much more frequent than Type 2 synapses and their number is negatively correlated with fibre diameter. For a whole DCMD dendritic arborization, a total of 8500 active zones of chemical synapses has been calculated, including a mininum of 2250 LGMD-synapses and about 1000 Type 2 synapses. The DCMD may thus receive a considerable amount of input from as yet unidentified neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051325
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Metaphase-specific cell death in meiotic spermatocytes in mice (1999)
    Springer
    Cell & tissue research 296 (1999), S. 359-369 
    Details
    ISSN: 1432-0878
    Keywords: Key words Apoptosis ; Electron microscopy ; Meiosis ; Spermatocytes ; Spermatogenesis ; Testis ; TUNEL ; Mouse (10 strains)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Apoptosis of male germ cells is a widespread but little-understood phenomenon in many animal species. The elucidation of its mechanisms could be useful in the understanding of male infertility. We have examined the distribution of dying cells with the terminal transferase-mediated nick-end labeling (TUNEL) method and by an electron-microscopic procedure in the testes of 10 mouse strains, viz., C57BL/10 (B10), SL/NiA (SL), C57BL/6 (B6), C3H/He (C3H), BALB/c (BALB), DBA2 (DBA), CBA/J (CBA), MRL/MpJ-+/+ (M+), MRL/MpJ-lpr/lpr (lpr), and wild-type NJL mice (Mus musculus musculus). In the testes of the B10, NJL, SL, B6, C3H, BALB, DBA, and CBA mice, very few TUNEL-positive cells are distributed in the seminiferous tubules, whereas in the testes of the M+ and lpr mice, many TUNEL-positive cells, which are restricted to stage XII seminiferous tubules, have been identified. The most important finding is that many metaphases of meiotic spermatocytes show a marked TUNEL-positive reaction. Some metaphases show apoptotic morphology electron-microscopically. These results suggest that the testes of MRL strains will provide a useful model for the study of the mechanism of metaphase-specific apoptosis in meiotic spermatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051296
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Effect of high-level oxygen exposure on the peroxidase activity and the neuromelanin-like pigment content of the nerve net in the earthworm, Lumbricus terrestris (1999)
    Springer
    Cell & tissue research 295 (1999), S. 349-354 
    Details
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051241
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Op/op mice defective in production of functional colony-stimulating factor-1 lack macrophages in muscularis externa of the small intestine (1999)
    Springer
    Cell & tissue research 295 (1999), S. 485-493 
    Details
    ISSN: 1432-0878
    Keywords: Key words Immunohistochemistry ; Electron microscopy ; Interstitial cells of Cajal ; F4/80 ; CSF-1 ; Kit-receptor ; Mouse (op/op)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The osteopetrotic (op/op) mutant mouse possesses an inactivating mutation in the colony-stimulating factor-1 (CSF-1) gene, which results in the absence of certain macrophages and in osteopetrosis, following a lack of osteoclasts. Studies of the op/op mouse indicate that CSF-1-dependent tissue macrophages may belong to a trophic and/or scavenger subpopulation, which through their effect on other cell types can significantly affect tissue functions, and that cells which are CSF-1 independent have antigen presentation and immunological functions.We have previously identified a cell system of regularly distributed macrophages in the muscularis externa of the small intestine and wanted to extend these studies to the op/op mouse.The present investigations with light- and electron-microscopic methods using fluorescent dextran, methylene blue and immunohistochemistry (F4/80, anti-kit receptor, anti-CD3, anti-CD45R/B220) show that macrophages are absent from the muscle layers, with only an occasional macrophage present in the subserosa. In the lamina propria and submucosa, macrophage numbers are reduced. In all other respects the muscularis externa appears normal, including normal organization and number of interstitial cells of Cajal. Control and op/op mice both lack cells expressing CD3 (T lymphocytes), CD45R/B220 (B lymphocytes) and mast cells in the muscularis externa. This leaves the muscularis externa macrophages as the most likely source of local cytokine production under such conditions as postoperative ileus and intussusception in infants, where the muscularis externa appears to be one target of cytokines. We conclude that the lack of macrophages, combined with the preservation of otherwise normal structure, will make the op/op mouse a valuable model by which to assess the functions and relative importance of the muscularis externa macrophages in relation to intestinal motility under normal and pathological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051254
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Caveolin and its cellular and subcellular immunolocalisation in lung alveolar epithelium: implications for alveolar epithelial type I cell function (1999)
    Springer
    Cell & tissue research 295 (1999), S. 111-120 
    Details
    ISSN: 1432-0878
    Keywords: Key words Caveolin ; Caveolae ; Lung ; Alveolar epithelial type I cell ; Immunocytochemistry ; Electron microscopy ; Confocal laser scanning microscopy ; Rat (CD)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Caveolae are flask-shaped invaginations of the plasmalemma which pinch off to form discrete vesicles within the cell cytoplasm. Biochemically, caveolae may be distinguished by the presence of a protein, caveolin, that is the principal component of filaments constituting their striated cytoplasmic coat. Squamous alveolar epithelial type I (ATI) cells, comprising approximately 95% of the surface area of lung alveolar epithelium, possess numerous plasmalemmal invaginations and cytoplasmic vesicles ultrastructurally indicative of caveolae. However, an ultrastructural appearance does not universally imply the biochemical presence of caveolin. This immunocytochemical study has utilised a novel application of confocal laser scanning and electron microscopy unequivocally to localise caveolin-1 to ATI cells. Further, cytoplasmic vesicles and flask-shaped membrane invaginations in the ATI cell were morphologically identified whose membranes were decorated with anti-caveolin-1 immunogold label. Coexistent with this, however, in both ATI and capillary endothelial cells could be seen membrane invaginations morphologically characteristic of caveolae, but which lacked associated caveolin immunogold label. This could reflect a true biochemical heterogeneity in populations of morphologically similar plasmalemmal invaginations or an antigen threshold requirement for labelling. The cuboidal alveolar epithelial type II cell (ATII) also displayed specific label for caveolin-1 but with no ultrastructural evidence for the formation of caveolae. The biochemical association of caveolin with ATI cell vesicles has broad implications for the assignment and further study of ATI cell function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051217
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Estimation of phytoplankton photosynthesis and nutrient limitation in the Eastern Scheldt estuary using variable fluorescence (1999)
    Springer
    Aquatic ecology 33 (1999), S. 101-104 
    Details
    ISSN: 1573-5125
    Keywords: chlorophyll fluorescence ; nutrient limitation ; phytoplankton ; photosynthesis ; quantum efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009900124650
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Fortnightly light and temperature variability in estuarine intertidal sediments and implications for microphytobenthos primary productivity (1999)
    Springer
    Aquatic ecology 33 (1999), S. 235-241 
    Details
    ISSN: 1573-5125
    Keywords: intertidal areas ; photosynthetically active radiation ; photosynthesis ; Tagus estuary ; tides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetically active radiation (PAR) and temperature were measured continuously at the surface of estuarine intertidal sediments in the Tagus estuary, Portugal, along two spring-neap tidal cycles. PAR and temperature were strongly conditioned by the periodic tidal inundation, with large and abrupt variations occurring during flooding and ebbing. PAR levels reaching the sediment surface decreased very rapidly to zero or very low values during most of the daytime immersion. Inundation during high tide had the general effect of attenuating the amplitude of daily temperature fluctuation, with the incoming water usually warmer than the sediment during the night or early morning and cooler during the day. The daily progression of tidal emersion resulted in a clear fortnightly variation in total daily PAR reaching the sediment surface, while both daily mean temperature and mean temperature of diurnal low tide periods failed to exhibit a well-defined fortnightly periodicity. The obtained results indicate that the estuarine intertidal environment is dominated, at sub-seasonal time scales, by fortnightly periodicity in irradiance and temperature conditions favourable for benthic photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009989229098
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Improvement of microalgal photosynthetic productivity by reducing the content of light harvesting pigment (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 195-201 
    Details
    ISSN: 1573-5176
    Keywords: dense algal suspension ; light-harvesting pigment ; photosynthesis ; productivity ; cyanobacterium ; Synechocystis PCC 6714
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microalgal productivity was examined using both a wild type and a phycocyanin-deficient mutant of Synechocystis PCC 6714 (PD-1). The culture was conducted at various light intensities under low and high cell densities in a continuous culture system. At low light intensity, photosynthetic productivity was almost the same for both low and high cell densities. However, at higher light intensities photosynthetic productivity was higher in mutant PD-1 than in the wild type. At 2000 μmol photon m−2 s−1 the productivity was 50% higher in mutant PD-1. This result is consistent with our first report (Nakajima & Ueda, 1997), which showed that photosynthetic productivity can be improved by reducing the light harvesting pigment content in high cell density cultures at high light intensities. It is concluded that the technology for reducing LHP content is a useful method for improving photosynthetic productivity in algal mass production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008015224029
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 157-163 
    Details
    ISSN: 1573-5176
    Keywords: Euglena gracilis ; photosynthesis ; waste water ; pulp and paper industry ; ultraviolet-B radiation (280–320 nm) ; pentachlorophenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008032211771
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Photosynthetic inorganic carbon utilization and growth of Porphyra linearis (Rhodophyta) (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 447-453 
    Details
    ISSN: 1573-5176
    Keywords: algal growth ; Porphyra ; inorganic carbon (Ci) ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic (oxygen evolution) and growth (biomass increase) responses to ambient pH and inorganic carbon (Ci) supply were determined for Porphyralinearis grown in 0.5 L glass cylinders in the laboratory, or in 40 L fibreglass outdoor tanks with running seawater. While net photosynthetic rates were uniform at pH 6.0–8.0, dropping only at pH 8.7, growth rates were significantly affected by pH levels other than that of seawater (c. pH 8.3). In glass cylinders, weekly growth rates averaged 76% at external pH 8.0, 13% at pH 8.7 and 26% at pH 7.0. Photosynthetic O2 evolution on a daily basis(i.e. total O2 evolved during day time less total O2 consumed during night time) was similar to the growth responses at all experimental pH levels, apparently due to high dark respiration rates measured at acidic pH. Weekly growth rates averaged 53% in algae grown in fibreglass tanks aerated with regular air (360 mg L-1 CO2) and 28% in algae grown in tanks aerated with CO2-enriched air (750 mg L-1 CO2). The pH of the seawater medium in which P. linear is was grown increased slightly during the day and only rarely reached 9.0. The pH at the boundary layer of algae submerged in seawater increased in response to light reaching, about pH 8.9 within minutes, or remained unchanged for algae submerged in a CO2-free artificial sea water medium. Photosynthesis of P. linearissaturated at Ci concentrations of seawater (K0.5560 μM at pH 8.2) and showed low photosynthetic affinity for CO2(K0.5 61 μM) at pH 6.0. It is therefore concluded that P. linearisuses primarily CO2 with HCO3 - being an alternative source of Ci for photosynthesis. Its fast growth could be related to the enzyme carbonic anhydrase whose activity was detected intra- and extracellularly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008122306268
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Effects of different levels of CO2 on photosynthesis and cell components of the red alga Porphyra leucosticta (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 455-461 
    Details
    ISSN: 1573-5176
    Keywords: CO2 ; inorganic carbon ; macroalgae ; photosynthesis ; PAM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis and cell composition of Porphyraleucosticta discs grown at low (〈 0.0001% in air), current (control) and high (1% CO2 in air)inorganic carbon (Ci) concentrations were analyzed. Carbohydrate content in discs grown at high Ci increased (15.1 mg g-1 FW) with respect to the control (6.4 mg g FW-1), whereas soluble protein content decreased to one-third (5.6 to2.1 mg g-1 FW). Carbohydrate content was unaffected and soluble protein slightly increased in discs grown at low Ci. As a consequence of these changes, a lower C/N molar ratio (8.6) was found in the discs grown at low compared to high Ci(12.4). Nitrate reductase activity increased at high Ci from 0.3 ± 0.2 to 1.7 ± 0.4 μmolNO2 - g-1 FW h-1indicating that reduction and assimilation of nitrate were uncoupled. The response of photosynthesis to increasing irradiance, estimated from O2evolution vs. irradiance curves, was affected by the treatments. Maximum quantum yield (Φ O2°) and effective quantum yield (Φ O2) at 150 μmol photon m-2s-1 decreased by 20% and 50%, respectively, at low Ci. These differences could be due to changes in photosynthetic electron flow between PSII and PSI. Treatments also produced changes in maximal (Fv/Fm) and effective (ΔF/Fm′)quantum yield for photosystem II charge separation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008194223558
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    A preliminary comparison of the mariculture potential of Porphyra purpurea and Porphyra umbilicalis (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 473-477 
    Details
    ISSN: 1573-5176
    Keywords: aquaculture ; light ; photosynthesis ; Porphyra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Due to their rapid growth and nutrient assimilation,Porphyra spp. are good candidates for bioremediation and polyculture. The production potential of two strains of P. purpurea and P. umbilicalis from north-east USA was evaluated by measuring rates of photosynthesis (as O2evolution) of material grown at 20 °C. Photosynthetic rates of P. umbilicalis were 80%higher than P. purpurea over the temperature range 5–20 °C, at both sub-saturating andsaturating irradiances (37 and 289 μmol photonm-2 s-1). Porphyra umbilicalis was more efficient at low irradiances (higher α) and had a higher Pmax (23.0 vs 15.6 μmolO2 g-1 DW min-1) than P.purpurea, suggesting that P. umbilicalis is a better choice for mass culture, where self-shading maybe severe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008102426752
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Dried field populations of Nostoc flagelliforme (Cyanophyceae) require exogenous nutrients for their photosynthetic recovery (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 535-541 
    Details
    ISSN: 1573-5176
    Keywords: cyanobacterium ; Nostoc flagelliforme ; nutrients ; photosynthesis ; potassium ; re-hydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nutrients on the photosynthetic recovery of Nostoc flagelliforme during re-hydration were investigated in order to see if their addition was necessary. Net photosynthesis was negligible in distilled water without nutrient-enrichment. Addition of K+ resulted in significant enhancement of net photosynthesis, whereas other nutrients (Fe3+, Mg2+, Na+, NO3 -, PO4 3-, Cl-) and trace-metals (A5) showed little effect. The recovered net photosynthetic activity increased with the increased K+, and reached the maximum at concentrations above 230 μM. Desiccation and re-hydration did not affect the dependence of photosynthetic recovery on K+. It was concluded that dried field populations of N. flagelliforme require exogenous addition of potassium for photosynthetic recovery and that growth may be potassium-limited in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008146722229
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Partial Pressure of Carbon Dioxide in Coral Reef Lagoon Waters: Comparative Study of Atolls and Barrier Reefs in the Indo-Pacific Oceans (1999)
    Springer
    Journal of oceanography 55 (1999), S. 731-745 
    Details
    ISSN: 1573-868X
    Keywords: Carbon dioxide ; coral reefs ; atoll ; lagoon ; photosynthesis ; calcification ; total alkalinity ; partial pressure ; topography ; residence time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Factors controlling the CO2 system parameters, including the partial pressure of CO2 (PCO2) in coral reef waters, were investigated in three mid-oceanic reefs of the Indo-Pacific region. Surface water PCO2 in the lagoons of Majuro Atoll and Palau barrier reef in the Pacific were 25 µatm and 48 µatm higher than those of the offshore waters, respectively, while South Male Atoll lagoon of the Maldives in the Indian Ocean exhibited relatively small difference in PCO2 compared to the offshore water. Observations from Majuro Atoll and Palau barrier reef are consistent with the view that calcium carbonate production predominates in coral reefs. On the other hand, results from South Male Atoll can be attributed to the thorough flushing of the lagoon, which is connected to the open ocean by numerous deep channels. The offshore-lagoon PCO2 difference depends on system-level net organic-to-inorganic carbon production ratio while reef topography, especially residence time of the lagoon, has a secondary effect on the magnitude of the offshore-lagoon difference. A potential for releasing CO2 might be more evident in an enclosed atoll where the reef water has a longer residence time. Oceanic atoll and barrier reef lagoons, which are in the terminal stage of evolutionary history of oceanic volcanic islands, have the potential to release CO2 to the atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007872314591
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Auxiliary Photosynthetic Functions of Arabidopsis thaliana—Studies in vitro and in vivo (1999)
    Springer
    Bioscience reports 19 (1999), S. 499-509 
    Details
    ISSN: 1573-4935
    Keywords: Arabidopsis ; auxiliary enzymes ; light stress ; photosynthesis ; protein phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An improved cultivation system for Arabidopsis thaliana was developed, allowing advanced biochemical studies in vitro and in vivo of this important model plant. Highly functional Arabidopsis thylakoids were isolated and used to study both basic and regulatory photosynthetic functions with the aim to create a platform for the characterization of mutants deficient in auxiliary proteins. Light-induced proteolytic degradation of the D1 protein could be followed and shown to be a subsequent event to photoinactivation of electron transport. The phosphorylation and dephosphorylation of thylakoid proteins resembled that seen in spinach leaves although phospho-CP43 revealed an unusual regulatory behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020280710067
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Phase and aggregation behaviour of double-chain cationic surfactants from the class of N-alkyl-N-alkyl′-N, N-dimethylammonium bromide surfactants (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 856-867 
    Details
    ISSN: 1435-1536
    Keywords: Key words Double chain surfactants ; Aggregates ; Phase diagrams ; Lamellar phases ; Electron microscopy ; SANS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [C x C y DMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies: unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and viscosity measurements for phase characterisation were carried out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050462
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Partitioning of P and the activity of root acid phosphatase in white clover (Trifolium repens L.) are modified by increased atmospheric CO2 and P fertilisation (1999)
    Springer
    Plant and soil 210 (1999), S. 159-166 
    Details
    ISSN: 1573-5036
    Keywords: elevated CO2 ; leaf transpiration ; nonstructural carbohydrate ; P nutrition ; photosynthesis ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growth response of white clover (Trifolium repens L.) to the expected increase in atmospheric partial pressure of CO2 (pCO2) may depend on P availability. A decrease in the rate of transpiration due to increased pCO2 may reduce the amount of P transported to the shoot, thereby causing a change in the partitioning of P between the root and shoot. To test these hypotheses, four concentrations of P in the nutrient solution, combined with two pCO2 treatments, were applied to nodulated white clover plants. Compared to ambient pCO2 (35 Pa), twice ambient pCO2 (70 Pa) reduced the rate of transpiration but did not impair the total P uptake per plant. However, at twice ambient pCO2 and a moderate to high supply of P, concentrations of structural P and soluble P (Pi) were lower in the leaves and higher in the roots. The activity of root acid phosphatase was lower at twice ambient pCO2 than at ambient pCO2; it depended on the Pi concentration in the roots. At the highest P concentration, twice ambient pCO2 stimulated photosynthesis and the growth rate of the plant without affecting the concentration of nonstructural carbohydrates in the leaves. However, at the lower P concentrations, plants at twice ambient pCO2 lost their stimulation of photosynthesis in the afternoon, they accumulated nonstructural carbohydrates in the leaves and their growth rate was not stimulated; indicating C-sink limitation of growth. P nutrition will be crucial to the growth of white clover under the expected future conditions of increased pCO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004625801141
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Effects of phosphorus nutrition on tiller emergence in wheat (1999)
    Springer
    Plant and soil 209 (1999), S. 283-295 
    Details
    ISSN: 1573-5036
    Keywords: leaf emergence ; phosphorus ; photosynthesis ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency limits the yield of wheat, particularly by reducing the number of ears per unit of area because of a poor tiller emergence. The objectives of this work were to (i) determine whether tiller emergence under low phosphorus availability is a function of the availability of assimilates for growth or a direct result of low P availability, (ii) attempt to establish a quantitative relation between an index of the availability of P in the plant and the effects of P deficiency on tiller emergence, and (iii) to provide a better understanding of the mechanisms involved in tiller emergence in field-grown wheat. Wheat (Triticum aestivum L., cv. INTA Oasis), was grown in the field under drip irrigation on a typic Argiudol, low in P (5.5 μg P g-1 soil Bray & Kurtz I) in Balcarce, Argentina. Treatments consisted of the combination of three levels of P fertilization 0, 60 and 200 kg P2O5 ha-1, and two levels of assimilate availability, a control (non-shaded) and 65% of reduction in incident irradiance from seedling emergence until the end of tillering (shaded). Phosphorus treatments significantly modified the pattern of growth and development of the plants. Shading reduced the growth and concentration of water-soluble carbohydrates in leaves and stems. Leaf photosynthetic rate at saturating irradiance was reduced by P deficiency, but was not affected by shading. At shoot P concentrations less than 4.2 g P kg-1 the heterogeneity in the plant population increased with respect to the number of plants bearing a certain tiller. At a shoot P concentration of 1.7 g P kg-1 tillering ceased completely. Phosphorus deficiency directly altered the normal pattern of tiller emergence by slowing the emergence of leaves on the main stem (i.e. increasing the phyllochron), and by reducing the maximum rate of tiller emergence for each tiller.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004690404870
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Rubisco activase transcript (rca) abundance increases when the marine unicellular green alga Chlorococcum littorale is grown under high-CO2 stress (1999)
    Springer
    Plant molecular biology 41 (1999), S. 627-635 
    Details
    ISSN: 1573-5028
    Keywords: green algae ; high-CO2 stress ; photosynthesis ; regulation ; Rubisco activase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract cDNA and the corresponding genomic DNA region encoding Rubisco activase were isolated from the unicellular green alga Chlorococcum littorale. The deduced amino acid sequence encoded by the cDNA was 403 amino acids long and exhibited important homology with those of other known Rubisco activases. Its N-terminal sequence was similar to the chloroplastic transit peptides in Chlamydomonas reinhardtii. The mature protein had a predicted molecular mass of 42 kDa. Five introns were located inside the genomic gene encoding Rubisco activase (rca). Genomic Southern blots indicated that two copies of the rca gene were present in the genome of C. littorale. The level of rca messenger RNA increased when cells of C. littorale were subjected to high-CO2 stress (i.e. grown under at least 20% CO2). Hsp70 heat-shock protein was also induced under high-CO2 conditions and, as expected, was also induced at 35 °C. The rca gene, in contrast, was not induced at 35 °C, indicating that this gene was induced in response to the high CO2 concentration and not to general stress. A search of the promoter-binding proteins by a gel retardation assay showed that, under the high-CO2 conditions, a protein(s) which was probably an activator of the rca transcription was synthesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006371905597
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Phycoerythrins of the oxyphotobacterium Prochlorococcus marinus are associated to the thylakoid membrane and are encoded by a single large gene cluster (1999)
    Springer
    Plant molecular biology 40 (1999), S. 507-521 
    Details
    ISSN: 1573-5028
    Keywords: cyanobacteria ; immunogold labelling ; light-harvesting complexes ; photosynthesis ; phycobilins ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An intrinsic divinyl-chlorophyll a/b antenna and a particular form of phycobiliprotein, phycoerythrin (PE) III, coexist in the marine oxyphotobacterium Prochlorococcus marinus CCMP 1375. The genomic region including the cpeB/A operon of P. marinus was analysed. It encompasses 10 153 nucleotides that encode three structural phycobiliproteins and at least three (possibly five) different polypeptides analogous to cyanobacterial or red algal proteins involved either in the linkage of subunits or the synthesis and attachment of chromophoric groups. This gene cluster is part of the chromosome and is located within a distance of less than 110 kb from a previously characterized region containing the genes aspA-psbA-aroC. Whereas the Prochlorococcus phycobiliproteins are characterized by distinct deletions and amino acid replacements with regard to analogous proteins from other organisms, the gene arrangement resembles the organization of phycobiliprotein genes in some other cyanobacteria, in particular marine Synechococcus strains. The expression of two of the Prochlorococcus polypeptides as recombinant proteins in Escherichia coli allowed the production of individual homologous antisera to the Prochlorococcus α and β PE subunits. Experiments using these sera show that the Prochlorococcus PEs are specifically associated to the thylakoid membrane and that the protein level does not significantly vary as a function of light irradiance or growth phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006252013008
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Forty years of microbial photosynthesis research: Where it came from and what it led to (1999)
    Springer
    Photosynthesis research 62 (1999), S. 1-29 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast ; chlorosome ; chromatophore ; granules ; inositol ; Neurospora ; path of carbon ; photosynthesis ; polythdroxyalkanoate (PHA) ; prokaryote cellular inclusions ; protozoan biochemistry ; ribulose 1 ; 5-bis-phosphate ; Tetrahymena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract What follows is a very personal account of my professional life and the early years that preceded it. I have described the social and economic conditions in America and how the nineteen twenties and thirties nurtured our scientific future. The description of the early part of post-World War II research covers my experience in the areas of nutritional biochemistry, biochemical genetics and proceeds to photosynthesis. The latter era lasted around 35 years. For me the most memorable research accomplishments in which I was a participant during this period was the first demonstration of the primary carboxylation enzyme in an in vitro system in algal and higher plants as well to show that it was structurally associated with the chloroplast.Our group while at Oak Ridge and the University of Massachusetts assembled data that described the complete macromolecular assembly of the photosynthetic apparatus of the unusual photosynthetic green bacterium Chloroflexus aurantiacus and created a model of that system which differed greatly from the chomatophore system for the purple bacteria. For the last decade, my scientific journey, with numerous new colleagues has turned to the exciting area of biomaterials.We characterized and modeled the completely new bacterial intracellular inclusions responsible for the synthesis and degredation of biosynthetic, biodegradable and biocompatible bacterial polyesters in the cytoplasm of Pseudomonads.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006373926725
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Minimal requirements for in vitro reconstitution of the structural subunit of light-harvesting complexes of photosynthetic bacteria (1999)
    Springer
    Photosynthesis research 62 (1999), S. 85-98 
    Details
    ISSN: 1573-5079
    Keywords: (bacterio)chlorophyll ; energy transfer ; light harvesting ; membrane proteins ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Unlike the α and β polypeptides of the core light-harvesting complex (LH1) of Rhodobacter (Rb.) sphaeroides, the α and β polypeptides of the peripheral light-harvesting complex (LH2) of this organism will not form a subunit complex by in vitro reconstitution with bacteriochlorophyll. Guided by prior experiments with the LH1 β polypeptides of Rb. sphaeroides and Rhodospirillum rubrum, which defined a set of interactions required to stabilize the subunit complex, a series of mutations to the Rb. sphaeroides LH2 β polypeptide was prepared and studied to determine the minimal changes necessary to enable it to form a subunit-type complex. Three mutants were prepared: Arg at position −10 was changed to Asn (numbering is from the conserved His residue which is known to be coordinated to bacteriochlorophyll); Arg at position −10 and Thr at position +7 were changed to Asn and Arg, respectively; and Arg at position −10 was changed to Trp and the C-terminus from +4 to +10 was replaced with the amino acids found at the corresponding positions in the LH1 β polypeptide of Rb. sphaeroides. Only this last multiple mutant polypeptide formed subunit-type complexes in vitro. Thus, the importance of the C-terminal region, which encompasses conserved residues at positions +4, +6 and +7, is confirmed. Two mutants of the LH1 β polypeptide of Rb. sphaeroides were also constructed to further evaluate the interactions stabilizing the subunit complex and those necessary for oligomerization of subunits to form LH1 complexes. In one of these mutants, Trp at position −10 was changed to Arg, as found in LH2 at this position, and in the other His at position −18 was changed to Val. The results from these mutants allow us to conclude that the residue at the −10 position is unimportant in subunit formation or oligomerization, while the strictly conserved His at −18 is not required for subunit formation but is very important in oligomerization of subunits to form LH1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006337827672
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    A theoretical analysis and field evaluation of a light and temperature model of production by Ecklonia cava (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 361-373 
    Details
    ISSN: 1573-5117
    Keywords: production ; mathematical model ; Ecklonia cava ; light ; temperature ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dependence of photosynthesis on light and temperature is modelled through analysis of transition probabilities of photosystems. In the model, two transition probabilities are functions of light, and one transition probability is a function of temperature. The estimated light-saturated photosynthesis of Ecklonia cava blades at 20 °C was 0.037 mg C cm−2 h−1. The value of the activation energy, the standard enthalpy and the standard entropy were estimated to be 56.5 kJ mol−1, 204 kJ mol−1 and 678 J mol−1 K−1, respectively. A production model (an integral photosynthesis model) for an E. cava stand was developed using the photosynthesis model. Production calculated by the model agreed well with observed data during the growing period of an E. cava stand at a field observation site on the west side of Miura Peninsula, Japan. Results of the analysis of the effects of irradiance and temperature on the production of the E. cava community by the model are: 1. Production decreased with irradiance decrease. The estimated compensation irradiance was 26.5 μmol photons m−2 s−1 when the biomass was 3 kg wet mass m−2 (blade:stipe ratio = 2 kg m−2:1 kg m−2) and the temperature was 20 °C. 2. The optimum temperature decreased when irradiance decreased and when biomass increased. The highest estimated value for the optimum temperature was 24.0 °C. The estimated optimum temperature was 18.2 °C when the biomass was 12 kg wet mass m−2 and the photon irradiance was 200 μmol photons m−2 s−1. 3. The amount of biomass that resulted in the maximum production was influenced by irradiance and temperature. At 400 μmol photons m−2 s−1 and 20 °C, the estimated value of the biomass (blade:stipe = 2:1) giving the maximum pr oduction was about 5.3 kg wet mass m−2. However, at 100 μmol photons m−2 s−1 and 24 °C, the estimated value was about 3.0 kg wet mass m−2. The estimated values of the maximum production under the two conditions were 1.05 and 0.30 g C m−2 h−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017086012839
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Heat sensitivity of chloroplasts and leaves: Leakage of protons from thylakoids and reversible activation of cyclic electron transport (1999)
    Springer
    Photosynthesis research 59 (1999), S. 81-93 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; cyclic electron flow ; high temperature ; light scattering ; photosynthesis ; Photosystems II and I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In illuminated intact spinach chloroplasts, warming to and beyond 40 °C increased the proton permeability of thylakoids before linear electron transport through Photosystem II was inhibited. Simultaneously, antimycin A-sensitive cyclic electron transport around Photosystem II was activated with oxygen or CO2, but not with nitrite as electron acceptors. Between 40 to 42 °C, activation of cyclic electron transport balanced the loss of protons so that a sizeable transthylakoid proton gradient was maintained. When the temperature of darkened spinach leaves was slowly increased to 40°C, reduction of the quinone acceptor of Photosystem II, QA, increased particularly when respiratory CO2 production and autoxidation of plastoquinones was inhibited by decreasing the oxygen content of the atmosphere from 21 to 1%. Simultaneously, Photosystem II activity was partially lost. The enhanced dark QA reduction disappeared after the leaf temperature was decreased to 20 °C. No membrane energization was detected by light-scattering measurements during heating the leaf in the dark. In illuminated spinach leaves, light scattering and nonphotochemical quenching of chlorophyll fluorescence increased during warming to about 40 °C while Photosystem II activity was lost, suggesting extra energization of thylakoid membranes that is unrelated to Photosystem II functioning. After P700 was oxidized by far-red light, its reduction in the dark was biphasic. It was accelerated by factors of up to 10 (fast component) or even 25 (slow component) after short heat exposure of the leaves. Similar acceleration was observed at 20 °C when anaerobiosis or KCN were used to inhibit respiratory oxidation of reductants. Methyl viologen, which accepts electrons from reducing side of Photosystem II, completely abolished heat-induced acceleration of P700+ reduction after far-red light. The data show that increasing the temperature of isolated chloroplasts or intact spinach leaves to about 40 °C not only inhibits linear electron flow through Photosystem II but also activates Photosystem I-driven cyclic electron transport pathways capable of contributing to the transthylakoid proton gradient. Heterogeneity of the kinetics of P700+ reduction after far-red oxidation is discussed in terms of Photosystem I-dependent cyclic electron transport in stroma lamellae and grana margins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006149317411
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers (1999)
    Springer
    Photosynthesis research 59 (1999), S. 95-104 
    Details
    ISSN: 1573-5079
    Keywords: bacteriochlorophyll a ; electron transfer ; light harvesting ; photosynthesis ; Rhodobacter sphaeroides ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for the primary electron transfer reaction through an effect on the reduction potential of the primary donor. A lowering of the redox potential of the primary donor due to the presence of the core antenna is consistently observed in a series of reaction center mutants in which the reduction potential of the primary donor was varied over a 130 mV range. Estimates of the magnitude of the change in driving force for charge separation from time-resolved delayed fluorescence measurements in the mutant reaction centers suggest that the mutations exert their effect on the driving force largely through an influence on the redox properties of the primary donor. The results demonstrate that the energetics of light-driven electron transfer in reaction centers are sensitive to the environment of the complex, and provide indirect evidence that the kinetics of electron transfer are modulated by the presence of the LH1 antenna complexes that surround the reaction center in the natural membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006169201579
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Feedback inhibition of photosynthesis in rice measured by O2 dependent transients (1999)
    Springer
    Photosynthesis research 59 (1999), S. 187-200 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; CO2 ; oxygen ; photosynthesis ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kinetic properties of photosynthesis (both transient and steady-state) were monitored using three non-invasive techniques to evaluate limitations on triose-phosphate (triose-P) conversion to carbohydrate in rice. These included analyzing the O2 sensitivity of CO2 fixation and the assimilatory charge (AC) using gas exchange (estimate of the ribulose 1,5- bisphosphate pool) and measuring Photosystem II activity by chlorophyll fluorescence analysis under varying light, temperature and CO2 partial pressures. Photosynthesis was inhibited transiently upon switching from 20 to 2 kPa O2 (reversed O2 sensitivity), the degree of which was correlated with a terminal, steady-state suppression of low O2 enhancement of photosynthesis. Under current ambient levels of CO2 and moderate to high light, the transient pattern was more obvious at 18 °C than at 26 °C while at 34 °C no tra nsient response was observed. The transient inhibition at 18 °C ranged from 15% to 31% depending on the pre-measurement temperature. This pattern, symptomatic of feedback, was observed with increasing light and CO2 partial pressures with the degree of feedback decreasing from moderate (18 °C) up to high temperature (34 °C). Under feedback conditions, the rate of assimilation is shifted from being photorespiration limited to being triose-P utilization limited. Transitory changes in CO2 assimilation rates (A) under low O2 indicative of feedback coincided with a transitory drop in assimilatory charge (AC) and inhibition of electron transport. In contrast to previous studies with many C3 species, our studies indicate that rice shows susceptibility to feedback inhibition under moderate temperatures and current atmospheric levels of CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006180102395
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Diurnal changes in leaf gas exchange and chlorophyll fluorescence in tropical tree species with contrasting light requirements (1999)
    Springer
    Ecological research 14 (1999), S. 77-88 
    Details
    ISSN: 1440-1703
    Keywords: chlorophyll fluorescence ; Macaranga gigantea ; Neobalanocarpus heimii ; photosynthesis ; Shorea leprosula ; tropical rainforest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Interspecific ecophysiological differences in response to different light environments are important to consider in regeneration behavior and forest dynamics. The diurnal changes in leaf gas exchange and chlorophyll fluorescence of two dipterocarps, Shorea leprosula (a high light-requiring) and Neobalanocarpus heimii (a low light-requiring), and a pioneer tree species (Macaranga gigantea) growing in open and gap sites were examined. In the open site, the maximum net photosynthetic rate (Pn), photosystem II (PSII) quantum yield (δ; F/Fm′), and relative electron transport rate (r-ETR) through PSII at a given photosynthetic photon flux density (PPFD) was higher in S. leprosula and M. gigantea than in N. heimii, while non-photochemical quenching (NPQ) at a given PPFD was higher in N. heimii. The maximum values of net photosynthetic rate (Pn) in M. gigantea and S. leprosula was higher in the open site (8–11 μmol m−2 s−1) than in the gap site (5 μmol m−2 s−1), whereas that in N. heimii was lower in the open site (2 μmol m−2 s−1) than in the gap site (4 μmol m−2 s−1), indicating that N. heimii was less favorable to the open site. These data provide evidence to support the hypothesis that ecophysiological characteristics link with plant’s regeneration behavior and successional status. Although Pn and stomatal conductance decreased at midday in M. gigantea and S. leprosula in the open site, both r-ETR and leaf temperature remained unchanged. This indicates that stomatal closure rather than reduced photochemical capacity limited Pn in the daytime. Conversely, there was reduced r-ETR under high PPFD conditions in N. heimii in the open site, indicating reduced photochemical capacity. In the gap site, Pn increased in all leaves in the morning before exposure to direct sunlight, suggesting a relatively high use of diffuse light in the morning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1440-1703.1999.00291.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Synthesis of colloids and films of Pr, Er and Yb with nonaqueous solvents (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 164-173 
    Details
    ISSN: 1435-1536
    Keywords: Keywords Nanostructures ; Thin films ; Vapor deposition ; Electron microscopy ; Optical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Colloidal dispersions of Yb, Er and Pr have been prepared by chemical liquid deposition. The metals were cocondensed at 77 K with 2-methoxyethanol and ethanol to produce solvated metal atoms. The particle size of the dispersions was determined by transmission electron microscopy to range from 52 to 1080 Å; the particles had spherical shapes. After solvent evaporation under vacuum, active solids and amorphous powder were deposited over Cu and Al metal. Dispersion stability, particle size, UV/Vis absorption and zeta potential were studied. The solids prepared by solvent evaporation were characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The films prepared on Al were studied by scanning electron microscopy. The most stable colloid was obtained using 2-methoxyethanol: several concentrations were stable for several months and the zeta potential indicated that this colloid stability is mainly due to solvation effects. FTIR spectroscopy of the solids indicated solvent incorporation in the film. This observation was corroborated by thermal analysis. Information on the thermal stability of the films was obtained by TGA. The UV/Vis absorption spectrum was measured at several concentrations under different conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050381
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Improvement of acclimatization of micropropagated grapevine: Photosynthetic competence and carbon allocation (1999)
    Springer
    Plant cell, tissue and organ culture 58 (1999), S. 31-37 
    Details
    ISSN: 1573-5044
    Keywords: carbohydrates ; chlorophylls ; photosynthesis ; tissue culture ; Vitis vinifera L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grapevine plantlets multiplied in vitro were acclimatized at 40 or 90 μmol m−2 s−1 photon flux density for 12 or 16 h per day, respectively. In the high-light regime a decrease in total chlorophyll and an increase in chlorophyll a/chlorophyll b ratio occurred. However, at high-light intensity lower photosynthetic capacities and higher apparent photosynthesis were measured than at the low-light regime. In leaves expanded during acclimatization, the light compensation point was higher in plantlets under high-light while quantum yield was higher in low-light conditions. High-light also gave rise to an increase in carbohydrate concentration. As a whole, the results suggest that high-light increases carbon assimilation and growth although with a low investment in the photosynthetic apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006323129593
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Questions about the complexity of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase (1999)
    Springer
    Photosynthesis research 60 (1999), S. 29-42 
    Details
    ISSN: 1573-5079
    Keywords: enzyme catalysis ; evolution ; genetic engineering ; photosynthesis ; protein assembly ; protein degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) has played a central role in our understanding of chloroplast biogenesis and photosynthesis. In particular, its catalysis of the rate-limiting step of CO2 fixation, and the mutual competition of CO2 and O2 at the active site, makes Rubisco a prime focus for genetically engineering an increase in photosynthetic productivity. Although it remains difficult to manipulate the chloroplast-encoded large subunit and nuclear-encoded small subunit of crop plants, much has been learned about the structure/function relationships of Rubisco by expressing prokaryotic genes in Escherichia coli or by exploiting classical genetics and chloroplast transformation of the green alga Chlamydomonas reinhardtii. However, the complexity of chloroplast Rubisco in land plants cannot be completely addressed with the existing model organisms. Two subunits encoded in different genetic compartments have coevolved in the formation of the Rubisco holoenzyme, but the function of the small subunit remains largely unknown. The subunits are posttranslationally modified, assembled via a complex process, and degraded in regulated ways. There is also a second chloroplast protein, Rubisco activase, that is responsible for removing inhibitory molecules from the large-subunit active site. Many of these complex interactions and processes display species specificity. This means that attempts to engineer or discover a better Rubisco may be futile if one cannot transfer the better enzyme to a compatible host. We must frame the questions that address this problem of chloroplast-Rubisco complexity. We must work harder to find the answers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006240202051
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Part of the fluorescence of chlorophyll a may originate in excited triplet states (1999)
    Springer
    Photosynthesis research 60 (1999), S. 165-177 
    Details
    ISSN: 1573-5079
    Keywords: absorption ; Kennard–Stepanov theory ; photosynthesis ; spectral equilibration ; thermal equilibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Absorption and fluorescence spectra of chlorophyll a have been analyzed on the basis of an extended version of Kennard–Stepanov (KS) theory. It is proposed that at least one new electronic state lies just below the normal S1 − S0 transition (Qy), borrowing approximately 2–4% of its strength and contributing to the fluorescence in the tail. The KS anomalies leading to this hypothesis occur in a wide variety of cases, including chlorophyll a in solution and protein-bound chlorophyll a, suggesting that the phenomenon is an intrinsic property of the molecule. Natural candidates for the new state(s) are the second and third triplet states. The relationship of the fluorescence excitation spectrum to KS theory is investigated and applied to explain a red drop in yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006284510090
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Molecular rearrangements of thylakoids after heavy metal poisoning, as seen by Fourier transform infrared (FTIR) and electron spin resonance (ESR) spectroscopy (1999)
    Springer
    Photosynthesis research 61 (1999), S. 241-252 
    Details
    ISSN: 1573-5079
    Keywords: ESR ; electron transport ; FTIR ; lipid ; membrane structure ; protein ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The specific effects exerted by different heavy metals on both the function and the structure of the photosynthetic apparatus were addressed. The functional analysis performed via the fluorescence induction kinetics revealed that the applied toxic heavy metals can be classified into two groups: Cd and Ni had no significant effect on the photosynthetic electron transport, while Cu, Pb and Zn strongly inhibited the Photosystem II (PS II) activity, as evidenced by the dramatic decreases in both the variable (Fv) and the maximal (Fm) fluorescence. The structural effects of the heavy metal ions on the thylakoid membranes were considered in three relations: (1) lipids, (2) proteins — studied by Fourier transform infrared (FTIR) spectroscopy, and (3) lipid—protein interactions — investigated by electron spin resonance (ESR) spectroscopy using spin-labeled probe molecules. The studied heavy metal ions had only a non-specific rigidifying effect on the thylakoid lipids. As regards proteins, Cd and Ni had no effect on the course of their heat denaturation. The heat denaturation of the proteins was accompanied by a decrease in the α-helix content (1656 cm-1), a parallel increase in the disordered segments (1651 cm-1), a decrease in the intramolecular β-sheet (1636 cm-1) content and the concomitant appearance of an intermolecular β-structure (1621 cm-1). In contrast with Cd and Ni, Cu and Zn blocked the appearance of the intermolecular β-structure. Pb represented an intermediate case. It seems that these heavy metals alter the native membrane structure in such a way that heat-induced aggregation becomes more limited. The ESR data revealed that certain heavy metals also affect the lipid—protein interactions. While Cd and Ni had hardly any effect on the solvation fraction of thylakoid lipids, Cu, Pb and Zn increased the fraction of lipids solvating the proteins. On the basis of the FTIR and ESR data, it seems that Cu, Pb, and Zn increase the surfaces available for lipid—protein interactions by dissociating membrane protein complexes, and that these ‘lipidated’ proteins have a smaller chance to aggregate upon heat denaturation. The data presented here indicate that the damaging effects of poisonous heavy metals are element-specific, Cu, Pb and Zn interact directly with the thylakoid membranes of the photosynthetic apparatus, while Cd and Ni interfere rather with other metabolic processes of plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006345523919
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Homeostatic regulation upon changes of enzyme activities in the Calvin cycle as an example for general mechanisms of flux control. What can we expect from transgenic plants? (1999)
    Springer
    Photosynthesis research 61 (1999), S. 227-239 
    Details
    ISSN: 1573-5079
    Keywords: CO2 assimilation ; metabolic control analysis ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to explain the mechanisms of Calvin-cycle regulation, the general properties of metabolic systems under homeostatic flux control are analyzed. It is shown that the main characteristic point for an enzyme in such a system can be the value of a sharp transition from some constant homeostatic flux to a limitation by this enzyme. A special method for the quantitative treatment of the experimental dependence of a metabolic flux such as photosynthesis on enzyme content is developed. It is pointed out that reactions close to a thermodynamic equilibrium under normal conditions can considerably limit the homeostatic fluxes with a decrease of the enzyme content. Calvin-cycle enzymes are classified as non-limiting, near-limiting and limiting. The deduced rules for the regulation of a homeostatic metabolic pathway are used to explain the data obtained for transgenic plants with reduced activities of Calvin-cycle enzymes. The role of compensating mechanisms that maintain the photosynthesis rate constant upon the changes of enzyme contents is analyzed for the Calvin cycle. The developed analysis explains the sharp transitions between limiting and non-limiting conditions that can be seen in transgenic plants with reduced content of some Calvin-cycle enzymes, and the limiting role of such reversible enzymes as aldolase, transketolase and others. The attempt is made to predict the properties of plants with increased enzyme contents in the Calvin cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006342812049
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Microbial ribulose 1,5-bisphosphate carboxylase/oxygenase: A different perspective (1999)
    Springer
    Photosynthesis research 60 (1999), S. 1-28 
    Details
    ISSN: 1573-5079
    Keywords: biodiversity ; carboxylase ; genetic selection ; photosynthesis ; regulation ; specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Marine and terrestrial photosynthetic and chemoautotrophic microorganisms assimilate considerable amounts of carbon dioxide. Like green plastids, the predominant means by which this process occurs is via the Calvin-Benson-Bassham reductive pentose phosphate pathway, where ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) plays a paramount role. Recent findings indicate that this enzyme is subject to diverse means of control, including specific and elaborate means to guarantee its high rate and extent of synthesis. In addition, powerful and specific means to regulate Rubisco activity is a characteristic feature of many microbial systems. In many respects, the diverse properties of microbial Rubisco enzymes suggest interesting strategies to elucidate the molecular basis of CO2/O2 specificity, the ‘holy grail’ of Rubisco biochemistry. These systems thus provide, as the title suggests, ‘different perspectives’ to this fundamental problem. These include vast possibilities for imaginative biological selection using metabolically versatile organisms with well-defined genetic transfer capabilities to solve important issues of Rubisco specificity and molecular control. This review considers the major issues of Rubisco biochemistry and regulation in photosynthetic microoganisms including proteobacteria, cyanobacteria, marine nongreen algae, as well as other interesting prokaryotic and eukaryotic microbial systems recently shown to possess this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006211417981
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Estimation of rate constants of the partial reactions of carboxylation of ribulose-1,5-bisphosphate in vivo (1999)
    Springer
    Photosynthesis research 60 (1999), S. 247-256 
    Details
    ISSN: 1573-5079
    Keywords: irradiance ; kinetics ; method ; photosynthesis ; regulation ; rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An in vivo method for the estimation of kinetic parameters of partial reactions of carboxylation of ribulose 1,5-bisphosphate (RuBP) catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is described. Rubisco in barley, wheat and bean is different in the ability of its active centers to bind RuBP. The rate constant of the formation of the Rubisco-RuBP complex in these plants at 25 °C is 0.414, 0.245 and 0.660 mM-1 s-1, respectively. The rate constant of the reaction of the Rubisco-bound enediol with CO2 does not differ significantly in barley and wheat, and averages 66 mM-1 s-1. Decreased irradiance inhibits Rubisco in two ways: by reducing the concentration of operating catalytic sites and by decreasing the rate constant of binding of RuBP to Rubisco. High concentrations of CO2 inhibit Rubisco by decreasing the concentration of competent carboxylation centers, without any s ignificant influence upon the rate constants of partial reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006249215156
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Modification of electron transfer from the quinone electron carrier, A1, of Photosystem 1 in a site directed mutant D576→L within the Fe-Sx binding site of PsaA and in second site suppressors of the mutation in Chlamydomonas reinhardtii (1999)
    Springer
    Photosynthesis research 61 (1999), S. 33-42 
    Details
    ISSN: 1573-5079
    Keywords: EPR ; iron-sulphur ; photosynthesis ; P700 ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A site directed mutant of the Photosystem I reaction center of Chlamydomonas reinhardtii has been described previously. [Hallahan et al. (1995) Photosynth Res 46: 257–264]. The mutation, PsaA: D576L, changes the conserved aspartate residue adjacent to one of the cysteine ligands binding the Fe-SX center to PsaA. The mutation, which prevents photosynthetic growth, was observed to change the EPR spectrum of the Fe-SA/B centers bound to the PsaC subunit. We suggested that changes in binding of PsaC to the PsaA/PsaB reaction center prevented efficient electron transfer. Second site suppressors of the mutation have now been isolated which have recovered the ability to grow photosynthetically. DNA analysis of four suppressor strains showed the original D576L mutation is intact, and that no mutations are present elsewhere within the Fe-SX binding region of either PsaA or PsaB, nor within PsaC or PsaJ. Subsequent genetic analysis has indicated that the suppressor mutation(s) is nuclear encoded. The suppressors retain the altered binding of PsaC, indicating that this change is not the cause of failure to grow photosynthetically. Further analysis showed that the rate of electron transfer from the quinone electron carrier A1 to Fe-SX is slowed in the mutant (by a factor of approximately two) and restored to wild type rates in the suppressors. ENDOR spectra of A1 ·– in wild-type and mutant preparations are identical, indicating that the electronic structure of the phyllosemiquinone is not changed. The results suggest that the quinone to Fe-SX center electron transfer is sensitive to the structure of the iron-sulfur center, and may be a critical step in the energy conversion process. They also indicate that the structure of the reaction center may be modified as a result of changes in proteins outside the core of the reaction center.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006205811407
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Effects of growth-light quantity, growth-light quality and CO2 concentration on Rubisco deactivation during low PFD or darkness (1999)
    Springer
    Photosynthesis research 61 (1999), S. 65-75 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; photosynthetic induction ; sunflecks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of CO2 concentration and the effects of growth-light conditions on Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) deactivation were examined for Spinacea oleracea (spinach). Rubisco deactivation kinetics and the degree that Rubisco activation limited the rise in photosynthesis following an increase in photon flux density (PFD) were determined from gas-exchange time courses. There were no significant differences in the apparent relaxation time for Rubisco deactivation among leaves exposed to high or low CO2 (50 or 1000 μmol mol-1) and low PFD (170 μmol m-2 s-1) or darkness. However, when PFD was increased to 1700 μmol m-2 s-1 following a period of low PFD or darkness, leaves exposed to low CO2 × low PFD showed a lower contribution to the photosynthetic induction process by the activation of Rubisco than leaves exposed to the other treatments. For the growth-light experiments, spinach was grown under high PFD × high red:far-red ratio (R:FR), low PFD × high R:FR, or low PFD × low R:FR light environments. Leaves that matured under the low PFD × low R:FR treatment showed a lower percent change in photosynthesis due to Rubisco activation than leaves exposed to the other growth-light treatments. However, there were no significant differences among the growth-light treatments in the maximum contribution of Rubisco activation to the induction response or in the apparent relaxation time for Rubisco deactivation during shade events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006289901858
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Relationship of CO2 concentrations to photosynthesis of intertidal macroalgae during emersion (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 355-359 
    Details
    ISSN: 1573-5117
    Keywords: CO2 ; emersion ; macroalgae ; photosynthesis ; seaweeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to assess the ecological impacts of the atmospheric CO2 increase on the intertidal macroalgae during emersion, the photosynthesis of Enteromorpha linza (a green alga), Ishige okamurae (a brown alga) and Gloiopeltis furcata (a red alga) was investigated in air as a function of CO2 concentrations and water loss. Their photosynthesis was not saturated at the present atmospheric CO2 level (350 μl l −1 or 15.6 μM), the CO2 compensation point and $$K_{[{\text{mCO}}_{\text{2}} ]} $$ increased with increasing desiccation, showing that desiccation lowers the CO2 affinity of the intertidal macroalgae. It was concluded that E. linza, I. okamurae and G. furcata, while exposed to air, can benefit from atmospheric CO2 rise, especially when the algae have lost some water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017072303189
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Photosynthetic and respiratory responses of the agarophyte Gelidiella acerosa collected from tidepool, intertidal and subtidal habitats (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 321-328 
    Details
    ISSN: 1573-5117
    Keywords: photosynthesis ; respiration ; Gelidiella acerosa ; culture ; tidal habitat ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several samples of the red seaweed, Gelidiella acerosa (Forssk.) Feldmann & Hamel occurring in tidepools, high intertidal rocks, and shallow subtidal areas on a reef flat in Ilocos Norte, northern Philippines were studied in terms of their photosynthetic and respiratory responses (μl O2 gDW−1 h−1) to four salinity (22, 28, 34, 40‰) and three temperature (22, 28, 34 °C) combinations. The upper intertidal plants tolerated low salinities (22–28‰) better than high salinities (34–40‰), while tidepool and subtidal plants were not affected. Temperatures of 22 through 34 °C resulted in a one-fold increase in their photosynthetic rates and insignificant differences in their respiratory rates while tidepool and subtidal plants almost doubled their photosynthetic rates and their respiration rates increased by about 5–50 times. There were no interaction effects. Therefore, intertidal plants appe ared to be more tolerant to wide temperature fluctuations and low salinity levels; while tidepool and subtidal plants were least affected by salinity variations but were quite sensitive to temperature fluctuations. Vegetative and tetrasporic plants had similar photosynthetic and respiratory responses to salinity and temperature variations, although vegetative plants had significantly higher net photosynthesis under the minimum and maximum temperatures tested (22 and 34 °C). Reproductive G. acerosa showed greater tolerance to temperature fluctuations. These responses indicated that physiological changes may have occurred when the species became reproductive. Tolerance of G. acerosa to low salinities suggests that lowering the salinities in culture tanks could be used to eradicate contaminants, i.e., dinoflagellates and filamentous green algae. Temperature of 28 °C appeared to be optimum for all plant types as reflected by their high photosynthetic and low respiratory rates .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017024421845
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Cd/Fe Interaction in Higher Plants - Its Consequences for the Photosynthetic Apparatus (1999)
    Springer
    Photosynthetica 36 (1999), S. 321-331 
    Details
    ISSN: 1573-9058
    Keywords: Calvin cycle enzymes ; chlorophyll ; chloroplast structure ; heavy metals ; photosynthesis ; photosystems ; plant growth ; uptake of mineral elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cadmium is one of the most dangerous environmental pollutants, affecting, among other things, plant mineral composition. It easily interacts with iron, one of the most important elements for plant growth and metabolism. This interaction, including modifying effects of lowered or excessive Fe supply on Cd-exposed plants and its consequences for the photosynthetic apparatus is reviewed. The influence of modified Fe and Cd supply on the uptake of both metals, their distribution, plant growth, and photosynthesis is also explained. Moderate Fe excess has a beneficial influence on Cd-treated plants, resulting in more intensive growth, photosynthetic pigments accumulation, and more efficient light phase of photosynthesis. Nutrient-medium Fe deficiency increases plant susceptibility to Cd. The main open questions of Cd/Fe interaction are: (1) the strong Fe-dependency of Cd mobility within the plant, and (2) photosynthetic dark phase adaptation to Cd stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007097518297
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    The Development of Chloroplast Ultrastructure and Hill Reaction Activity During Leaf Ontogeny in Different Maize (Zea Mays L.) Genotypes (1999)
    Springer
    Photosynthetica 36 (1999), S. 497-507 
    Details
    ISSN: 1573-9058
    Keywords: chloroplast dimensions ; electron microscopy ; peripheral reticulum ; photosynthesis ; plastoglobuli ; starch ; stereology ; stroma ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in Hill reaction activity (HRA) and ultrastructure of mesophyll cell (MC) chloroplasts were studied during the ontogeny of third leaf of maize plants using polarographic oxygen evolution measurement, transmission electron microscopy, and stereology. The chloroplast ultrastructure was compared in young (actively growing), mature, and senescing leaves of two different inbreds and their reciprocal F1 hybrids. Statistically significant differences in both HRA and MC chloroplast ultrastructure were observed between different stages of leaf ontogeny. Growth of plastoglobuli was the most striking characteristic of chloroplast maturation and senescence. The chloroplasts in mature and senescing leaves had a more developed system of thylakoids compared to the young leaves. Higher HRA was usually connected with higher thylakoid volume density of MC chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007031818695
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Carbon Balance of a Winter Wheat-Root Microbiota System Under Elevated CO2 (1999)
    Springer
    Photosynthetica 36 (1999), S. 341-354 
    Details
    ISSN: 1573-9058
    Keywords: carbon partitioning ; photosynthesis ; plant growth ; microbial biomass ; respiration rate ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the carbon budget of young winter wheat plants and their associated microorganisms as affected by a doubling of the atmospheric CO2 concentration (700 µmol mol-1). Plants were grown hydroponically in pre-sterilised sand at a controlled irradiance and temperature regime. Net photosynthesis (PN) and respiration (RD) rates of roots and shoots were measured continuously, plant growth and carbon distribution in the plant-root medium-associated microorganism system were determined destructively in interval-based analyses. PN in elevated CO2 grown plants (EC) was 123% of that in the control (AC) plants when averaged over the whole life span (39-d-old plants, 34 d in EC), but the percentage varied with the developmental stage being 115, 88, and 167% in the pretillering, tillering, and posttillering phase, respectively. There was a transient depression of PN, higher amplitude of day/night fluctuations of the chloroplast starch content, and depression of carbon content in rhizosphere of EC plants during the period of tillering. After 34 d in EC, carbon content in shoots, roots, and in rhizodepositions was enhanced by the factors 1.05, 1.28, and 1.96, respectively. Carbon partitioning between above and belowground biomass was not affected by EC, however, proportionally more C in the belowground partitioning was allocated into the root biomass. Carbon flow from roots to rhizodepositions and rhizosphere microflora was proportional to PN; its fraction in daily assimilated carbon decreased from young (17%) to order (3-4%) plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007081419206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Perpetual Adaptation in a Perpetually Changing Environment as a Survival Strategy of Plants: A Case Study in Foraminifers Concerning Coral Reef Bleaching (1999)
    Springer
    Photosynthetica 37 (1999), S. 71-85 
    Details
    ISSN: 1573-9058
    Keywords: Amphisorus ; Amphistegina ; chlorophyll fluorescence kinetics ; electron transport ; irradiance ; photosynthesis ; photosystem 2 ; quantum yield ; Sorites ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coral reef bleaching is a global phenomenon poorly understood today. We investigated during 7 d the photosynthetic behaviour of symbionts of coral reef and temperate foraminifers in hospite, by means of the JIP-test. By this screening test the fast fluorescence rise O-J-I-P, measured by a Plant Efficiency Analyser (PEA) with 10 µs time resolution and 12 bit signal resolution, was analysed. It informs about the structure and function of photosystem 2 being at different physiological states established by adaptation to different irradiance and temperature. The test needs a measuring time in vivo of only 1 to 5 s, and thus many samples can be analysed. The measurements can be done continuously even on a single cell in a test tube or on the reef. The reef foraminifers tested here were Amphistegina and Amphisorus, freshly collected in Mauritius. As a temperate foraminifer, Sorites from the Mediterranean Sea was tested. The cells are very sensitive to slight temperature changes (25 to 32 °C). The comparison showed that the more the foraminifers live in an environment with constant temperature the less they are able to respond to temperature changes and, thus, the less they can adapt. Rising the temperature increases in general the sensitivity to different stress factors, such as high irradiance, pH, CO2, etc. After the test series, the cells recovered fully and were kept in an aquarium for long time observation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007070913866
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...