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  • photosynthesis
  • Springer  (73)
  • American Meteorological Society
  • Cambridge University Press
  • Cell Press
  • 1995-1999  (44)
  • 1990-1994  (29)
  • 1955-1959
  • 1995  (44)
  • 1991  (29)
  • 1966
  • 1955
Collection
Keywords
Publisher
  • Springer  (73)
  • American Meteorological Society
  • Cambridge University Press
  • Cell Press
  • Wiley-Blackwell  (6)
Years
  • 1995-1999  (44)
  • 1990-1994  (29)
  • 1955-1959
Year
  • 1
    Electronic Resource
    Electronic Resource
    The control of the production process of phytoplankton by the physical structure of the aquatic environment with special reference to its optical properties (1991)
    Springer
    Aquatic sciences 53 (1991), S. 136-186 
    Details
    ISSN: 1420-9055
    Keywords: Phytoplankton ; primary production ; photosynthesis ; optics ; adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This tutorial was designed for nonbiologists requiring an introduction to the nature and general timescales of phytoplankton responses to physical forcing in aquatic environments. As such, an effort was made to highlight biological markers which might assist in identifying, measuring and/or validating physical processes controlling the variability in the distribution, abundance, composition and activity of phytoplankton communities. Given the recent advances in environmental optics and remote sensing capabilities, a special emphasis was placed on the nature and utility of phytoplankton optical properties in current bio-optical modelling efforts to predict temporal and spatial variability in phytoplankton productivity and growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877058
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  • 2
    Electronic Resource
    Electronic Resource
    Ozone effects on dry matter partitioning and chlorophyll fluorescence during plant development of wheat (1995)
    Springer
    Water, air & soil pollution 85 (1995), S. 1461-1466 
    Details
    ISSN: 1573-2932
    Keywords: ozone ; wheat ; Triticum aestivum ; growth ; senescence ; biomass partitioning ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In closed-chamber fumigation experiments dry matter partitioning and chlorophyll fluorescence of wheat were studied, analysing the effects of ozone during different stages of plant development. Ozone causes enhanced leaf senescence, leading to a loss of green leaf area and, consequently to a decreased supply of assimilates, affecting (in increasing order of severeness) stem, ear and grain productivity because of reduced storage pools for translocation. Leaves of plants before shooting stage were most sensitive but the lack of green leaf area after ear emergence had the most pronounced effects on grain yield. Measurements of photochemical capacity showed that evidence for negative ozone effects could be found in changes of chlorophyll fluorescence parameters in leaf sections not yet showing visible ozone injury. Negative effects on photosynthesis were more distinct with increasing accumulated ozone dose, with increasing age of leaf tissue and with increasing ozone sensitivity of the cultivar. The changes in chlorophyll fluorescence are most likely to be explained by a decreased pool size of plastoquinones caused by ozone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00477187
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  • 3
    Electronic Resource
    Electronic Resource
    The osmochemistry of electron-transfer complexes (1991)
    Springer
    Bioscience reports 11 (1991), S. 539-571 
    Details
    ISSN: 1573-4935
    Keywords: proton translocation ; respiration ; photosynthesis ; quinones ; bc complexes ; cytochrome oxidase ; NADH-quinone oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Detailed molecular mechanisms of electron transfer-driven translocation of ions and of the generation of electric fields across biological membranes are beginning to emerge. The ideas inherent in the early formulations of the chemiosmotic hypothesis have provided the framework for this understanding and have also been seminal in promoting many of the experimental approaches which have been successfully used. This article is an attempt to review present understanding of the structures and mechanisms of several osmoenzymes of central importance and to identify and define the underlying features which might be of general relevance to the study of chemiosmotic devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01130217
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  • 4
    Electronic Resource
    Electronic Resource
    Oligonucleotide-directed mutagenesis of psbB, the gene encoding CP47, employing a deletion mutant strain of the cyanobacterium Synechocystis sp. PCC 6803 (1991)
    Springer
    Plant molecular biology 17 (1991), S. 1165-1177 
    Details
    ISSN: 1573-5028
    Keywords: chlorophyll-binding proteins ; photosynthesis ; photosystem II ; site-directed mutagenesis ; Synechocystis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutant strain of the cyanobacterium Synechocystis sp. PCC (Pasteur Culture Collection) 6803 has been developed in which psbB, the gene coding for the chlorophyl a-binding protein CP47 in Photosystem II (PSII), has been deleted. This deletion mutant can be used for the reintroduction of modified psbB into the cyanobacterium. To study the role of a large hydrophilic region in CP47, presumably located on the lumenal side of the thylakoid membrane between the fifth and sixth membrane-spanning regions, specific deletions have been introduced in psbB coding for regions within this domain. One psbB mutation leads to deletion of Gly-351 to Thr-365 in CP47, another psbB mutation was targeted towards deletion of Arg-384 to Val-392 in this protein. The deletion from Gly-351 to Thr-365 results in a loss of PSII activity and of photoautotrophic growth of the mutant, but the deletion between Arg-384 and Val-392 retains PSII activity and the ability to grow photoautotrophically. The mutant strain with the deletion from Gly-351 to Thr-365 does not assemble a stable PSII reaction center complex in its thylakoid membranes, and exhibits diminished levels of CP47 and of the reaction center proteins D1 and D2. In contrast to the Arg-384 to Val-392 portion of this domain, the region between Gly-351 and Thr-365 appears essential for the normal structure and function of photosystem II.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028733
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  • 5
    Electronic Resource
    Electronic Resource
    Novel aspects of the regulation of a cDNA (Arf1) from Chlamydomonas with high sequence identity to animal ADP-ribosylation factor 1 (1995)
    Springer
    Plant molecular biology 29 (1995), S. 567-577 
    Details
    ISSN: 1573-5028
    Keywords: Cell cycle ; circadian clock ; green alga ; GTP-binding proteins ; light regulation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ADP-ribosylation factor (ARF) is a highly conserved, low molecular mass (ca. 21 kDa) GTP-binding protein that has been implicated in vesicle trafficking and signal transduction in yeast and mammalian cells. However, little is known of ARF in plant systems. A putative ARF polypeptide was identifed in subcellular fractions of the green alga Chlamydomonas reinhardtii, based on [32P]GTP binding and immunoblot assays. A cDNA clone was isolated from Chlamydomonas (Arf1), which encodes a 20.7 kDa protein with 90% identity to human ARF1. Northern blot analyses showed that levels of Arf1 mRNA are highly regulated during 12 h/12 h light/dark (LD) cycles. A biphasic pattern of expression was observed: a transient peak of Arf1 mRNA occurred at the onset of the light period, which was followed ca. 12 h later by a more prominent peak in the early to mid-dark period. When LD-synchronized cells were shifted to continuous darkness, the dark-specific peak of Arf1 mRNA persisted, indicative of a circadian rhythm. The increase in Arf1 mRNA at the beginning of the light period, however, was shown to be light-dependent, and, moreover, dependent on photosynthesis, since it was prevented by DCMU. We conclude that the biphasic pattern of Arf1 mRNA accumulation during LD cycles is due to regulation by two different factors, light (which requires photosynthesis) and the circadian clock. Thus, these studies identify a novel pattern of expression for a GTP-binding protein gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020985
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  • 6
    Electronic Resource
    Electronic Resource
    The atp1 and atp2 operons of the cyanobacterium Synechocystis sp. PCC 6803 (1991)
    Springer
    Plant molecular biology 17 (1991), S. 641-652 
    Details
    ISSN: 1573-5028
    Keywords: F-ATPase ; cyanobacteria ; operon ; evolution ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The two operons atp1 and atp2, encoding the subunits of the FOF1 ATP-synthase, have been cloned and sequenced from the cyanobacterium Synechocystis sp. PCC 6803. The organization of the different genes in the operons have been found to resemble that of the cyanobacteria Synechococcus sp. PCC 6301 and Anabaena sp. PCC 7120. The Synechocystis FOF1 ATP-synthase has nine subunits. A tenth open reading frame with unknown function was detected at the 5′ end of atp1, coding for a putative gene product similar to uncI in Escherichia coli. A promoter structure was inferred for the Synechocystis atp operons and compared to other known promoters of cyanobacteria. Even though the operon structure of atp1 and atp2 in Synechocystis resembles the corresponding operons of Synechococcus, the amino acid sequences of individual gene products show marked differences. Genetic distances between cyanobacterial genes and genes for ATP-synthase subunits from other species have been calculated and compiled into evolutionary trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037050
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  • 7
    Electronic Resource
    Electronic Resource
    Loss of chloroplast transcripts for proteins associated with photosystem II: an early event during heat-bleaching in Euglena gracilis (1995)
    Springer
    Plant molecular biology 27 (1995), S. 317-325 
    Details
    ISSN: 1573-5028
    Keywords: chloroplasts ; gene expression ; heat bleaching ; photosynthesis ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A shift in the ratio of chlorophyll (Chl) a and Chl b is an early indicator of heat bleaching in Euglena gracilis. This observation prompted us to consider whether or not changes in steady-state levels of chloroplast transcripts and in transcriptional activity could limit the synthesis of Chl a-binding proteins in bleaching plastids. We found that the mature transcripts for CP47 and CP43, the Chl a-binding apoproteins of the proximal antenna of photosystem II, decline sharply very early during bleaching. Our study also shows that transcription of psbB and psbC, the chloroplast genes encoding CP47 and CP43, remains essentially unchanged during the same interval. We conclude that posttranscriptional events, such as mRNA stability, could play a major role in initiating an irreversible loss of chloroplast function in Euglena at a moderately elevated temperature. Lack of these transcripts would eventually impair the assembly of photosystem II in thylakoids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020186
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  • 8
    Electronic Resource
    Electronic Resource
    Primary structure of the psbN-psbH-petC-petA gene cluster of the cyanobacterium Synechocystis PCC 6803 (1991)
    Springer
    Plant molecular biology 17 (1991), S. 289-293 
    Details
    ISSN: 1573-5028
    Keywords: cytochrome b 6-f complex ; photosystem II (Synechocystis PCC 6803) ; photosynthesis ; Rieske Fe-S sequence ; apocytochrome f sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039508
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  • 9
    Electronic Resource
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    Characterization of the single psbA gene of Prochlorococcus marinus CCMP 1375 (Prochlorophyta) (1995)
    Springer
    Plant molecular biology 27 (1995), S. 1189-1196 
    Details
    ISSN: 1573-5028
    Keywords: Cyanobacteria ; gene copy number ; light regulation ; photosynthesis ; photosystem II reaction center ; polymerase chain reaction ; psbA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequence, copy number, expression and phylogenetic relevance of the psbA gene from the abundant marine prokaryote P. marinus CCMP 1375 was analyzed. The 7 amino acids near the C-terminus missing in higher plant and in Prochlorothrix hollandica D1 proteins are present in the derived amino acid sequence. P. marinus contains only a single psbA gene. Thus, this organism lacks the ability to adapt its photosystem II by replacement of one type of D1 by another, as several cyanobacteria do. Phylogenetic trees suggested the D1-1 iso-form from Synechococcus PCC 7942 as the next related D1 protein and place P. Marinus separately from Prochlorothrix hollandica among the cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020892
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  • 10
    Electronic Resource
    Electronic Resource
    Light-dependent chlorophyll a biosynthesis upon chlL deletion in wild-type and photosystem I-less strains of the cyanobacterium Synechocystis sp. PCC 6803 (1995)
    Springer
    Plant molecular biology 29 (1995), S. 933-945 
    Details
    ISSN: 1573-5028
    Keywords: chlorophyll synthesis ; cyanobacteria ; chlorophyl-binding proteins ; photosynthesis ; thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Part of the chlL gene encoding a component involved in light-independent protochlorophyllide reduction was deleted in wild type and in a photosystem I-less strain of Synechocystis sp. PCC 6803. In resulting mutants, chlorophyll biosynthesis was fully light-dependent. When these mutants were propagated under light-activated heterotrophic growth conditions (in darkness except for 15 min of weak light a day) for several weeks, essentially no chlorophyll was detectable but protochlorophyllide accumulated. Upon return of the chlL - mutant cultures to continuous light, within the first 6 h chlorophyll was synthesized at the expense of protochlorophyllide at a rate independent of the presence of photosystem I. Chlorophyll biosynthesized during this time gave rise to a 685 nm fluorescence emission peak at 77 K in intact cells. This peak most likely originates from a component different from those known to be directly associated with photosystems II and I. Development of 695 and 725 nm peaks (indicative of intact photosystem II and photosystem I, respectively) required longer exposures to light. After 6 h of greening, the rate of chlorophyll synthesis slowed as protochlorophyllide was depleted. In the chlL - strain, greening occurred at the same rate at two different light intensities (5 and 50 μE m-2s-1), indicating that also at low light intensity the amount of light is not rate-limiting for protochlorophyllide reduction. Thus, in this system the rate of chlorophyll biosynthesis is limited neither by biosynthesis of photosystems nor by the light-dependent protochlorophyllide reduction. We suggest the presence of a chlorophyll-binding ‘chelator’ protein (with 77 K fluorescence emission at 685 nm) that binds newly synthesized chlorophyll and that provides chlorophyll for newly synthesized photosynthetic reaction centers and antennae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014967
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  • 11
    Electronic Resource
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    Enhanced growth of the red algaPorphyra yezoensis Ueda in high CO2 concentrations (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 355-362 
    Details
    ISSN: 1573-5176
    Keywords: CO2 ; growth ; pH ; photosynthesis ; Porphyra yezoensis ; red alga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leafy thalli of the red algaPorphyra yezoensis Ueda, initiated from conchospores released from free-living conchocelis, were cultured using aeration with high CO2. It was found that the higher the CO2 concentration, the faster the growth of the thalli. Aeration with elevated CO2 lowered pH in dark, but raised pH remarkably in light with the thalli, because the photosynthetic conversion of HCO 3 − to OH− and CO2 proceeded much faster than the dissociation of hydrated CO2 releasing H+. Photosynthesis of the alga was found to be enhanced in the seawater of elevated dissolved inorganic carbon (DIC, CO2 + HCO 3 − + CO 3 − ). It is concluded that the increased pH in the light resulted in the increase of DIC in the culture media, thus enhancing photosynthesis and growth. The relevance of the results to removal of atmospheric CO2 by marine algae is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026098
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  • 12
    Electronic Resource
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    A simple, microcomputer based data acquisition system for monitoring pH shifts (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 373-374 
    Details
    ISSN: 1573-5176
    Keywords: data acquisition ; pH ; photosynthesis ; Cladophora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The use of ‘of the shelf’ microcomputer hardware and software and a new type of laboratory style combination pH electrode with a built in preamplifier makes it possible to monitor pH shifts in a group of experimental vessels in a time frame of seconds without resorting to expensive smart switch boxes or multiple pH meters. A data acquisition system is described for monitoring pH shifts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026101
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  • 13
    Electronic Resource
    Electronic Resource
    Optimizing algal biomass production in an outdoor pond: a simulation model (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 191-201 
    Details
    ISSN: 1573-5176
    Keywords: algal mass culture ; areal density ; Isochrysis ; photosynthesis ; productivity ; respiration ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A deterministic simulation model was developed to predict production rates of the marine prymnesiophyteIsochrysis galbana in an outdoor algal mass culture system. The model consists of photoadapation, gross photosynthesis and respiration sections. Actual physiological and biophysical laboratory data, obtained from steady state cultures grown under a wide range of irradiance levels, were used in calculating productivity. The resulting values were used to assess optimal operational parameters to maximize algal biomass production. The model predicted a yearly averaged production rate of 9.7 g C m−2d−1, which compared well with field data reported in the literature. The model evaluated the effect of pond depth and chlorophyll concentration on potential production rate in various seasons. The model predicted that a yearly averaged chlorophyll areal density of 0.65 g m−2 will yield the maximal production rate. Chlorophyll areal density should be seasonally adjusted to give maximal production. This adjustment could be done either by changing pond depth or chlorophyll concentration. The model predicted that under optimal operational conditions, the diurnal respiration losses averaged 35% of gross photosynthesis. The calculated growth rate for maximal productivity ranged between 0.15 and 0.24 d−1, suggesting an optimal hydraulic retention time of 6.7 and 4.2 d for various seasons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00003577
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  • 14
    Electronic Resource
    Electronic Resource
    A simple, microcomputer based data acquisition system for monitoring pH shifts (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 373-374 
    Details
    ISSN: 1573-5176
    Keywords: data acquisition ; pH ; photosynthesis ; Cladophora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The use of ‘of the shelf’ microcomputer hardware and software and a new type of laboratory style combination pH electrode with a built in preamplifier makes it possible to monitor pH shifts in a group of experimental vessels in a time frame of seconds without resorting to expensive smart switch boxes or multiple pH meters. A data acquisition system is described for monitoring pH shifts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02392892
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  • 15
    Electronic Resource
    Electronic Resource
    Enhanced growth of the red algaPorphyra yezoensis Ueda in high CO2 concentrations (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 355-362 
    Details
    ISSN: 1573-5176
    Keywords: CO2 ; growth ; pH ; photosynthesis ; Porphyra yezoensis ; red alga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leafy thalli of the red algaPorphyra yezoensis Ueda, initiated from conchospores released from free-living conchocelis, were cultured using aeration with high CO2. It was found that the higher the CO2 concentration, the faster the growth of the thalli. Aeration with elevated CO2 lowered pH in dark, but raised pH remarkably in light with the thalli, because the photosynthetic conversion of HCO 3 − to OH− and CO2 proceeded much faster than the dissociation of hydrated CO2 releasing H+. Photosynthesis of the alga was found to be enhanced in the seawater of elevated dissolved inorganic carbon (DIC, CO2 + HCO 3 − + CO 3 − ). It is concluded that the increased pH in the light resulted in the increase of DIC in the culture media, thus enhancing photosynthesis and growth. The relevance of the results to removal of atmospheric CO2 by marine algae is discussed.
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    URL: http://dx.doi.org/10.1007/BF02392889
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  • 16
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    Photosynthetic metabolism and cell-wall polysaccharide accumulation inGelidium sesquipedale (Clem.) Born. et Thur. under different light qualities (1995)
    Springer
    Journal of applied phycology 7 (1995), S. 167-174 
    Details
    ISSN: 1573-5176
    Keywords: cell-wall polysaccharides ; chlorophylla ; Gelidium sesquipedale ; internal C and N ; light quality ; photosynthesis ; phycobiliproteins ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of different light qualities on the photosynthetic rate, dark respiration, intracellular carbon and nitrogen content, and accumulation of photosynthetic pigments and cell-wall polysaccharides during short-term incubation (5 h) of the red algaGelidium sesquipedale was investigated. The same photon irradiance of 50μmol m−2 s−2 below the light saturation point of photosynthesis was applied in each case. Blue light stimulated photosynthesis, dark respiration and the accumulation of chlorophyll and biliproteins, phycoerythrin in particular. The accumulation of internal carbon and nitrogen was greater under blue light than under the other light qualities. In contrast, the percentage of cell-wall polysaccharides was higher in red light. The content of cell-wall polysaccharides decreased during the time of incubation in all light treatments except in red light. The action of a non-photosynthetic photoreceptor in the control of cell-wall polysaccharide synthesis is suggested because the accumulation of cell-wall polysaccharides was not correlated with net photosynthesis in contrast to what occurred with carbon, chlorophyll and phycoerythrin accumulation.
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    URL: http://dx.doi.org/10.1007/BF00693064
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  • 17
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    Underwater light penetration, phytoplankton biomass and photosynthetic activity in Lake Xolotlán (Managua) (1991)
    Springer
    Aquatic ecology 25 (1991), S. 137-144 
    Details
    ISSN: 1573-5125
    Keywords: light penetration ; phytoplankton biomass ; primary productivity ; photosynthesis ; tropical lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We measured underwater light penetration, phytoplankton biomass and photosynthetic activity during three years (1987–1990) in Lake Xolotlán (L. Managua), Nicaragua. Phytoplankton biomass governed the light climate of the photic zone, but as biomass also was composed of a varying proportion of dead algae, light availability for the potential biomass of actively photosynthesizing algae (170 mg Chl-a.m−2) was reduced. The concentration of chlorophyll-a within the photic zone was thus lower and ranged between 58 and 141 mg Chl-a.m−2. Still, photosynthetic activity was high (2,162 mg 02.m-2.h−1) due to an extremely high specific rate of photosynthesis; light was the only factor that limited growth. As also other conditions in Lake Xolotlán, beside light limitation, met with the requirements of the models that have been used to analyse production and photosynthetic characteristics in tropical lakes there was a striking agreement between observed and predicted values.
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    URL: http://dx.doi.org/10.1007/BF02291245
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  • 18
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    Diurnal gas exchange characteristics and water use efficiency of three salt-secreting mangroves at low and high salinities (1995)
    Springer
    Hydrobiologia 295 (1995), S. 13-22 
    Details
    ISSN: 1573-5117
    Keywords: gas exchange ; mangrove ; photosynthesis ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Continuous measurements of gas exchange characteristics were made on two to nine year old hydroponically grown Avicennia germinans (L.) Stearn, Aegialitis annulata R. Br. and Aegiceras corniculatum (L.) Blanco maintained at 50 or 500 mol m−3 NaCl. In Avicennia germinans and Aegialitis annulata, CO2 assimilation rates were initially higher at 500 mol m−3 NaCl and decreased gradually towards the end of the photoperiod when rates were similar to those at the lower salinity. In Aegiceras corniculatum, assimilation rates were higher at 50 mol m−3 NaCl and about 55% lower at the higher salinity. In all three species, leaf conductance and transpiration exhibited trends similar to those for CO2 assimilation. Intercellular CO2 concentrations were similar at both salinities in Avicennia germinans and Aegialitis annulata, but considerably higher at the lower salinity in Aegiceras corniculatum. Water use efficiencies (WUE), although similar between salinity treatments in Avicennia germinans and Aegialitis annulata, were greater at the higher salinity in Aegiceras corniculatum. Data obtained from CO2 response curves indicated that assimilation at high salinity in Aegiceras corniculatum was limited by conductance, and to a lesser extent, by photosynthetic capacity. In Avicennia germinans and Aegialitis annulata, assimilation was greater at the higher salinity as indicated by increase in both the initial slope and the upper plateau of the CO2 response data. Greater assimilation at high salinity in Avicennia germinans and Aegialitis annulata may be attributed to lower carbon losses via photorespiration and to efficient salt excretion and sequestration.
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    URL: http://dx.doi.org/10.1007/BF00029106
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  • 19
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    The influence of photon flux density (PFD) on short term 14C incorporation into proteins, carbohydrates and lipids in freshwater algae (1995)
    Springer
    Hydrobiologia 308 (1995), S. 51-59 
    Details
    ISSN: 1573-5117
    Keywords: photon flux density ; intracellular metabolic pools ; proteins ; carbohydrates ; lipids ; polysaccharides ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of photon flux density (PFD) on the partitioning of photosynthetically fixed 14CO2-C into major intracellular end products was investigated for three species of freshwater planktonic algae (Nitzschia palea, Monoraphidium minutum and Synechococcus elongatus belonging to three different classes. This study was designed to investigate the phenomenon of polysaccharide synthesis associated with the saturation of protein synthesis and to test if this process is common to all three phytoplankton species. Protein synthesis was saturated at low PFD in all three species of algae studied. However, fixed carbon was differentially stored, namely in lipids in Nitzschia palea (Bacillariophyceae), in polysaccharides in Monoraphidium minutum (Chlorophyceae), and in low molecular weight metabolites (LMW) in Synechococcus elongatus (Cyanophyceae). The results of this transient state study indicate that the metabolic pathways of algae can easily be controlled by different irradiance. Furthermore, it appears that the difference in the patterns of synthesis is taxonomy dependent.
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    URL: http://dx.doi.org/10.1007/BF00037787
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  • 20
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    Growth and CO2 assimilation of lowland rice in response to timing and method of N fertilization (1991)
    Springer
    Plant and soil 132 (1991), S. 113-125 
    Details
    ISSN: 1573-5036
    Keywords: growth ; light response ; N uptake ; photosynthesis ; respiration ; rice (Oryza sativa L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to understand more clearly the dynamics of rice (Oryza sativa L.) yield development in relation to N fertilization, a field experiment was conducted in Laguna, Philippines. The soil, a Maahas clay (Aquic Hapludalf), was flooded, puddled, and then planted with 20-day-old seedlings of IR64 rice. Treatments were six combinations of N fertilizer timing and method: (1) 0 N control; (2) prilled urea broadcast at 15 and 60 days after transplanting (DAT) (BR-LATE); (3) prilled urea injected with a spring auger applicator at 15 DAT and broadcast at 60 DAT (INJ-LATE); (4) prilled urea broadcast and incorporated at 0 DAT and broadcast at 40 DAT (BR-EARLY); (5) urea super granules (USG) manually deep-placed at 3 DAT and prilled urea broadcast at 40 DAT (DP-EARLY); and (6) USG manually deep-placed at 3 DAT (DP). Except for the control, all treatments received a total of 58 kg N ha-1. Yield results were consistent with those of other experiments, namely, DP had the highest yields, the early-split treatments (BR-EARLY and DP-EARLY) were second best, followed by the late-split treatments (BR-LATE and INJ-LATE), with the control having the lowest yield. Sequential harvest results showed that the advantages of DP in terms of dry matter assimilation, tillering, and leaf area index (LAI) were expressed later in the season. For all treatments, midday net CO2 assimilation (Ac) peaked around 48 DAT, approximately panicle initiation. Grain yield was highly correlated with midday Ac at panicle initiation and flowering but not at other growth periods. Rates of midday Ac and night respiration depended strongly on shoot N content. We conclude that N application method and timing should be designed to give high shoot N content at panicle initiation and flowering, and that DP satisfied this requirement best among the treatments tested.
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    URL: http://dx.doi.org/10.1007/BF00011018
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    Relationship between net photosynthesis and nitrogen in Scots pine: Seasonal variation in seedlings and shoots (1995)
    Springer
    Plant and soil 168-169 (1995), S. 263-270 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; nutrient availability ; photosynthesis ; Scots pine ; seasonal change ; site quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship between light saturated net photosynthesis (Amax) and nitrogen concentration (N) was studied in needles of both Scots pine seedlings, grown at three relative growth rates (2,6 and 8%) controlled by nutrient addition rate, and Scots pine shoots collected from four sites with different fertility. In the seedlings, Amax was measured on 14 different dates starting at the beginning of the second growing season and ending when growth of the new shoot and the secondary needles had finished. In shoots from the natural stands Amax of the previous-year shoots was measured on 6 dates throughout the growing season. Both in seedlings and shoots, the correlation between Amax and N was poor, when data from all sampling dates were taken together. However, Amax was correlated with N in most instances when the age of the needles was considered and the data were examined either at weekly intervals (seedlings) or separately for each sampling date (shoots). The slope of the Amax vs N relationship varied greatly between sampling dates. In the seedlings the correlation between Amax and N was strongest by the time when the new needles were developing. In the shoots the correlation was significant from mid June until mid August, while no correlation was found in the beginning and at the end of the growing season. Our data indicate that in pine needles the photosynthesis-nitrogen relationship is more complex than in broadleaved species. Contrary to the broadleaved species, where the correlation is independent of sampling time, in this conifer the time of the year affects the correlation and there are phases during the growing season when the correlation is poor or nonexistent.
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    Growth and carbon economy of a fast-growing and a slow-growing grass species as dependent on nitrate supply (1995)
    Springer
    Plant and soil 171 (1995), S. 217-227 
    Details
    ISSN: 1573-5036
    Keywords: carbon budget ; growth analysis ; interspecific variation ; nitrogen supply ; photosynthesis ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In previous experiments systematic differences have been found in the morphology, carbon economy and chemical composition of seedlings of inherently fast- and slow-growing plant species, grown at a non-limiting nutrient supply. In the present experiment it was investigated whether these differences persist when plants are grown at suboptimal nutrient supply rates. To this end, plants of the inherently fast-growing Holcus lanatus L. and the inherently slow-growing Deschampsia flexuosa (L.) Trin. were grown in sand at two levels of nitrate supply. Growth, photosynthesis, respiration and carbon and nitrogen content were studied over a period of 4 to 7 weeks. At low N-supply, the potentially fast-growing species still grew faster than the potentially slow-growing one. Similarly, differences in leaf area ratio (leaf area:total dry weight), specific leaf area (leaf area:leaf dry weight) and leaf weight ratio (leaf dry weight:total dry weight), as observed at high N-supply persisted at low N-availability. The only growth parameter for which a substantial Species × N-supply interaction was found was the net assimilation rate (increase in dry weight per unit leaf area and time). Rates of photosynthesis, shoot respiration and root respiration, expressed per unit leaf, shoot and root weight, respectively, were lower for the plants at low N-availability and higher for the fast-growing species. Species-specific variation in the daily carbon budget was mainly due to variation in carbon fixation. Lower values at low N were largely determined by both a lower C-gain of the leaves and a higher proportion of the daily gain spent in root respiration. Interspecific variation in C-content and dry weight:fresh weight ratio were similar at low and high N-supply. Total plant organic N decreased with decreasing N-supply, without differences between species. It is concluded that most of the parameters related to growth, C-economy and chemical composition differ between species and/or are affected by N-supply, but that differences between the two species at high N-availability persist at low N-supply.
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    URL: http://dx.doi.org/10.1007/BF00010275
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    A method for the study of CO2 exchanges in in vitro cultured Vitis rupestris plantlets (1991)
    Springer
    Plant cell, tissue and organ culture 27 (1991), S. 175-181 
    Details
    ISSN: 1573-5044
    Keywords: CO2 ; in vitro culture ; photorespiration ; photosynthesis ; respiration ; Vitis rupestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A CO2 assay circuit adapted to in vitro culture was designed to investigate CO2 exchanges in test tube-grown Vitis rupestris plantlets. The CO2 concentration of the air in culture tubes was measured by injection of samples in the open circuit. It was observed under the culture conditions used that the CO2 content stabilized during the light phase at 3 times the CO2 compensation point. Measurements of dark respiration under closed circuit conditions at every two-hour interval during the night did not reveal any limiting by lack of the substrate under mixotrophic culture conditions. A mathematical model of the influence of ambient CO2 concentration on net CO2 uptake rates under closed circuit conditions was devised and used to compare net photosynthesis at different lighting levels. Measurement of CO2 evolution into CO2-free air under open circuit conditions revealed a post-illumination burst characteristic of photorespiration which increased with the temperature.
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    URL: http://dx.doi.org/10.1007/BF00041287
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    Variation in thylakoid proteins and photosynthesis in Syrian landraces of barley (1995)
    Springer
    Euphytica 82 (1995), S. 213-220 
    Details
    ISSN: 1573-5060
    Keywords: barley landraces ; drought ; Hordeum vulgare ; leaf colour ; photosynthesis ; photosystem I and II ; thylakoid chlorophyll-proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Barley breeders at ICARDA have observed that genotypes adapted to dry regions have leaves which are lighter in colour than those of unadapted ones. We measured photosynthesis, chlorophyll content and chlorophyll a:b ratios in two sets of genotypes which had previously been observed to have either light green or dark green leaves when grown in the field. Thylakoid membranes were also extracted and the proteins analysed on SDS-PAGE gels. The light leaf colour was associated with a higher chlorophyll a:b ratio. This was a measure of a reduction in the amount of antenna chlorophyll compared to that in the core complex of PSII. Genotypes with light green leaves had consistently less chlorophyll per unit leaf area and lower photosynthetic rates per unit area than those with dark green leaves. It is suggested that these features of light green leaves may confer the ability to adapt to high levels of irradiance under drought conditions. This ability may result from a high rate of photosynthetic electron transport through each PSII reaction centre, thus reducing the risk of damage from the overexcitation of these centres.
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    URL: http://dx.doi.org/10.1007/BF00029563
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    Resolution of components of non-photochemical chlorophyll fluorescence quenching in barley leaves (1991)
    Springer
    Photosynthesis research 27 (1991), S. 121-133 
    Details
    ISSN: 1573-5079
    Keywords: high-energy state quenching ; photoinhibition ; photosynthesis ; state transition ; 77 K fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-photochemical chlorophyll fluorescence quenching (qN) in barley leaves has been analysed by monitoring its relaxation in the dark, by applying saturating pulses of light. At least three kinetically distinct phases to qN recovery are observed, which have previously been identified (Quick and Stitt 1989) as being due to high-energy state quenching (‘fast’), excitation energy redistribution due to a state transition (‘medium’) and photoinhibition (‘slow’). However, measurements of chlorophyll fluorescence at 77 K from leaf extracts show that state transitions only occur in low light conditions, whereas the ‘medium’ component of qN is very large in high light. The source of that part of the ‘medium’ component not accounted for by a state transition is discussed.
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    URL: http://dx.doi.org/10.1007/BF00033251
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    Photosynthetic energy storage in aquatic leaves measured by photothermal deflection (1995)
    Springer
    Photosynthesis research 45 (1995), S. 157-168 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast movement ; photosynthesis ; photothermal deflection spectroscopy ; Vallisneria americana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a study of photosynthetic energy storage efficiency (ES), the adaxial surface of the leaves of Vallisneria americana exhibited the highest ES values (22%) of the four aquatic plants examined. V. americana leaves have a dispersed structure and it was possible to measure the energy storage properties of the epidermal cells independently of the rest of the leaf. The abaxial epidermis had a higher value of ES at zero light fluence than the adaxial epidermis but ES in the abaxial epidermis declined much more rapidly with light fluence. Thus the abaxial epidermis is more suited to lower light fluences than the adaxial epidermis. ES declined as the pH rose from 4.0 to 8.0 at a constant dissolved inorganic carbon concentration. This paralleled the change from carbon dioxide to bicarbonate and suggests that these leaves utilise CO2 more efficiently than bicarbonate. ES increased by about 50% at pH 8.0 as leaf sections further from the leaf tip were examined which demonstrates that the older epidermal cells are less well able to use bicarbonate. Exposure to 30 min of a saturating light fluence caused the epidermal chloroplasts to move from the periclinal walls to the anticlinal walls. This decreased the photothermal signal by increasing the thermal diffusion distance and lowering the light fluence due to greater chloroplast shading. The latter effect increased ES. It appears that chloroplast movement could assist the epidermis to survive harmful light fluences.
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    Enhanced susceptibility of the oxidized and unprotonated forms of high potential cytochrome b-559 toward DCMU (1991)
    Springer
    Photosynthesis research 27 (1991), S. 179-187 
    Details
    ISSN: 1573-5079
    Keywords: electron transport ; photosynthesis ; photosystem II ; QA ; QB ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of interaction of cytochrome b-559 high potential (HP) with electron transport on the reducing side of photosystem II was investigated by measuring the susceptibility of cytochrome b-559HP to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) under different conditions. Submicromolar DCMU concentrations decreased the rate of absorbance change corresponding to cytochrome b-559HP photoreduction while the amplitude was lowered at higher concentrations (up to 10 μM). Appreciable extents of cytochrome b-559HP photoreduction were observed at DCMU concentrations which completely abolished the electron transport from water to methyl viologen under the same experimental conditions. However, the susceptibility of cytochrome b-559HP to DCMU increased with the degree of cytochrome b-559HP oxidation, induced either by ferricyanide or by illumination of low intensity (2 W/m2) of red light in the presence of 2 μM carbonyl cyanide-m-chlorophenylhydrazone. Also, the DCMU inhibition was more severe when the pH increased from 6.5 to 8.5, indicating that the unprotonated form of cytochrome b-559HP is more susceptible to DCMU. These results demonstrate that cytochrome b-559HP can accept electrons prior to the QB site, probably via QA although both QA and QB can be involved to various extents in this reaction. We suggest that the redox state and the degree of protonation of cytochrome b-559HP alter its interaction with the reducing side of photosystem II.
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    Extrinsic polypeptides of spinach photosystem I (1991)
    Springer
    Photosynthesis research 27 (1991), S. 209-219 
    Details
    ISSN: 1573-5079
    Keywords: electron transport ; extrinsic membrane proteins ; photosynthesis ; photosystem I ; thylakoid membrane ; Triton X-114 partitioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By combining Triton X-114 partitioning with alkaline-salt and chaotropic washings of thylakoid membrane vesicles and photosystem I particles, we have studied the protein subunit composition and organization of spinach photosystem I. Upon fractionation of photosystem I particles with Triton X-114, 6 polypeptides of 5.0, 8.2 (psaE), 10.5, 16.6 (psaG), 19.3 and 22.1 kDa (psaD) were considered to be extrinsic membrane proteins. By combining this partitioning with salt washes of thylakoid membranes, the polypeptides of 8.2, 11.6 (psaH), 19.3 and 22.1 kDa were directly shown to be stromally oriented and extrinsic while no extrinsic subunits were identified at the inner thylakoid surface. The 5.0, 8.2, 10.5, 17.2, 19.3 and 22.1 kDa polypeptides appear to have regulatory rather than catalytic functions as their release from photosystem I particles upon high salt-alkali treatment does not affect photosystem I-mediated electron transport.
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    URL: http://dx.doi.org/10.1007/BF00035842
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    Effects of calcium deficiency on Coffea arabica. Nutrient changes and correlation of calcium levels with some photosynthetic parameters (1995)
    Springer
    Plant and soil 172 (1995), S. 87-96 
    Details
    ISSN: 1573-5036
    Keywords: calcium ; Coffea arabica ; fluorescence analysis ; nutrient relations ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Calcium deficiency was induced in hydroponically grown 1.5-years-old coffee plants with 12–14 pairs of leaves. Calcium was given in the form of Ca(NO3)2: 5, 2.5, 0.1, 0.01 and 0 mM. After 71 days of Ca-treatment root and shoot as well as total biomass were decreased by severe Ca-deficiency. However, a stronger decrease was observed for shoot growth as revealed by the increase in the root/shoot ratio. New leaves were affected showing decreases in the total leaf area and in Leaf Area Duration (LAD). After 91 days of deficiency, leaf protein concentration decreased (by about 45%) in the top leaves while nitrate reductase activity (NRA) and NO3 content showed no significant changes. Total nitrogen and mineral concentrations (P, K, Ca, Mg and Na) were also determined in leaves and roots. With the decrease in calcium concentration in Ca-deficiency conditions, we observed concomitant increases in the concentrations of K+, Mg2+ and Na+ in leaves (maximal changes of 32% for K+, 96% for Mg2+ and 438% for Na+) and in roots (108% for K+, 86% for Mg2+ and 38% for Na+). Accordingly, the ratio between elements changed, including the ratio N/P, showing a non-equilibrium in the balance of nutrients. Significant correlations were obtained between Ca2+ concentration and some photosynthetic parameters. Ca-deficiency conditions would increase the loss of energy as expressed by the rise in aE and decrease the photochemical efficiency, which confirms the importance of this element in the stabilization of chlorophyll and in the maintenance of good photochemical efficiency at PS II level.
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    Effects of calcium on growth and leaf ion concentrations of Gossypium hirsutum grown in saline hydroponic culture (1995)
    Springer
    Plant and soil 176 (1995), S. 219-227 
    Details
    ISSN: 1573-5036
    Keywords: calcium ; chloride ; cotton ; photosynthesis ; potassium ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The optimum Ca2+ concentration for growth of cotton (Gossypium hirsutum cv. Acala SJ-2) was in the range 1 to 15 mol m−3 for plants growing in hydroponic culture with 100–150 mol m−3 NaCl. Most saline (but not sodic) soils contain higher Ca2+ concentrations. CaCl2 was inhibitory to the growth of cotton above 20–50 mol m−3. Increasing concentrations of Ca2+ in the range 0–2 mol m−2 drastically reduced Na+ accumulation in the leaves. As CaCl2 concentrations were increased above the optimum for growth there was a further reduction in leaf Na+ accumulation, but this was more than offset by increased leaf Ca2+ and Cl− concentrations. Leaf K+ concentrations were not much affected by changes in external CaCl2 concentrations. The response of Mg2+ varied from an increase to a decrease with increasing external CaCl2 and was influenced by nutritional status. There was no evidence that high Ca2+ caused a deficiency of Mg2+ in cotton. Except for Cl−, whose concentrations tended to decrease initially and then increase as the CaCl2 concentration increased, the anions were largely unaffected by changes in external CaCl2.
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    Seasonal development of the photosynthetic performance of Norway spruce (Picea abies [L.] Karst.) under magnesium deficiency (1995)
    Springer
    Plant and soil 168-169 (1995), S. 255-261 
    Details
    ISSN: 1573-5036
    Keywords: magnesium deficiency ; Norway spruce ; photosynthesis ; Picea abies (L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to investigate the influence of different magnesium nutrition on photosynthesis, one hundred 6-year-old spruce trees derived from one clone were planted in October 1990 into a special out-door experimental construction, where they were cultivated in sand culture with an optimal supply of nutrients, except magnesium, via circulating nutrient solutions. Magnesium was added to the nutrient solutions in three different concentrations, varying from optimal to severe deficient supplies. During the first vegetative period in 1991, photosynthetic performance and carboxylation efficiency were measured under saturating light, controlled CO2 conditions, optimal temperature and humidity, using a minicuvette system. During summer, the trees under moderate magnesium deficiency developed tip yellowing symptoms on older needles, while the youngest needles remained green with unchanged chlorophyll contents. Trees under severe magnesium deficiency showed yellowing symptoms on all needle age classes combined with decreased chlorophyll contents in the youngest needles as well. In comparison with the controls, the photosynthetic performance of the 1-year-old needles was significantly lower in both deficiency treatments. The same was observed in the youngest needles of the trees under severe deficiency. Trees under moderate deficiency treatment decreased in photosynthetic performance during the summer without reduction of chlorophyll contents. The reduction of photosynthetic rates corresponded to a decrease in carboxylation efficiency, which is taken as a measure of the activity of the enzyme ribulose-1,5-bisphosphate carboxylase. This reduction, together with the observed increase of carbohydrate contents in needles of trees growing under magnesium deficiency, led to the assumption that the photosynthetic carbonfixation is reduced as a consequence of the accumulation of carbohydrates.
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    Effect of ammonium and nitrate on net photosynthesis, flower formation, growth and yield of eggplants (Solanum melongena L.) (1995)
    Springer
    Plant and soil 171 (1995), S. 267-274 
    Details
    ISSN: 1573-5036
    Keywords: ammonium toxicity ; buffered nutrient solution ; eggplant ; flowers ; fruit yield ; nitrate ; photosynthesis ; Solanum melongena ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eggplants (Solanum melongena L. cv. Bonica) were grown in a glasshouse during summer under natural light with one unbranched shoot or one shoot with 3 to 4 branches and with or without fruit in quartz sand buffered and not buffered with 0.5% CaCO3 (w : v), respectively. Nutrient solutions supplied contained nitrate or ammonium as the sole nitrogen source. Compared with nutrient solutions containing nitrate (10 mM), solutions containing ammonium (10 mM) caused a decrease in net photosynthesis of eggplants during early stages of vegetative growth when grown in quartz sand not buffered with CaCO3. The decrease was not observed before leaves showed interveinal chlorosis. In contrast, net photosynthesis after bloom at first increased more rapidly in eggplants supplied with ammonium than with nitrate nitrogen. However, even in this case, net photosynthesis decreased four weeks later when ammonium nutrition was continued. The decrease was accompanied by epinasty and interveinal chlorosis on the lower leaves and later by severe wilting, leaf drop, stem lesions, and hampered growth of stems, roots, and fruits. These symptoms appeared later on plants not bearing fruits than on plants bearing fruits. If nutrient solutions containing increasing concentrations of ammonium (0.5–30 mM) were supplied after the time of first fruit ripening, shoot growth and set of later flowers and fruits were promoted. In contrast, vegetative growth and reproduction was only slightly affected by increasing the concentration of nitrate in the nutrient solutions. In quartz sand buffered with CaCO3 ammonium nutrition caused deleterious effects only under low light conditions (shade) and on young plants during rapid fruit growth. If eggplants were supplied with ammonium nitrogen before bloom, vegetative growth was promoted, and set of flowers and fruit occurred earlier than on plants supplied with nitrate. Furthermore, the number of flowers and fruit yield increased. These effects of ammonium nutrition were more pronounced when plants were grown with branched shoots than with unbranched shoots. The results indicate that vegetative and reproductive growth of eggplants may be manipulated without causing injury to the plants by supplying ammonium nitrogen as long as the age of the plants, carbohydrate reserves of the roots, quantity of ammonium nitrogen supplied, and pH of the growth medium are favourable. T W Rufty Section editor
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    Sources of heat tolerance amongst potato cultivars, breeding lines, and Solanum species (1991)
    Springer
    Euphytica 55 (1991), S. 235-245 
    Details
    ISSN: 1573-5060
    Keywords: potato ; Solanum spp. ; chlorophyll fluorescence ; growth analysis ; heat tolerance ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study assessed 46 potato cultivars, breeding lines and Solanum spp. for heat-tolerance using short-term growth rates and carbon assimilation measurements of young in-vitro-derived plants. Plants of the 46 clones and species were transferred from greenhouse conditions to controlled conditions set at 33/25°C day/night with 12 h photosynthetic photon flux density (PPFD) at 430–450 μmol m-2s-1 and an 8 h daylength extension (6 μmol m-2s-1), to inhibit tuberization. Twenty eight accessions were also grown in a 20/10°C controlled environment. Plants were harvested after 10 and 20 days and dry weights of the plant components were measured for plant growth analysis. Gas exchange (leaf net photosynthesis and maintenance dark respiration) and leaf chlorophyll fluorescence parameters (O, P, and T) were measured at 30°C. Amongst the 30 accessions grown at both hot and cool temperatures, only two accessions (Yungay and AVRDC 1287.19) produced more dry weight in the hot chamber than the cool chamber. Hot/cool ratioss for net assimilation rate (NAR) and relative growth rate (RGR) exceoded unity in five and six accessions, respectively. For the 46 accessions grown under hot conditions, none had significantly greater values than those of the control clones for RGR and NAR. Differences between clones in maintenance respiration and net photosynthesis were more closely related to RGR, NAR, and total dry weight (TDWT) in clones which invested more dry weight in leaves and less in stems. Attributes of the chlorophyll fluorescence curve did not explain more of the clonal variation in RGR, NAR, and TDWT than did gas exchange parameters. No single gas exchange or fluorescence character explained more than 50% of the variability among clones for NAR, RGR, or TDWT, but combination of favourable attributes could improve potato heat tolerance in the future.
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    Fluorescence properties of the allenic carotenoid fucoxanthin: Implication for energy transfer in photosynthetic pigment systems (1991)
    Springer
    Photosynthesis research 27 (1991), S. 221-226 
    Details
    ISSN: 1573-5079
    Keywords: carotenoid ; energy transfer ; fluorescence ; fucoxanthin ; pigment system ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fluorescence spectrum of an allenic carotenoid, all-trans-fucoxanthin isolated from a brown alga, has been reported for the first time. This carotenoid is known to function efficiently as a primary photosynthetic antenna pigment in marine algae. The emission bands were located around 630, 685 and 750 nm in CS2 at 20°C, absorption bands being located at 448, 476 and 505 nm. The energy difference between the 0-0 bands of absorption and emission spectra was about 3900 cm-1 and location of the emission maximum was less sensitive to the polarizability of solvents than that of the absorption maximum. These clearly indicate that the emission originates from the optically forbidden singlet state (2Ag). This is in contrast to other carotenoids whose emission is assigned to 1Bu state, probably due to the symmetric structure of the conjugated double bond responsible for the absorption in the visible region. A rapid internal conversion from 1Bu to 2Ag state might be facilitated by distorted structure of the conjugated double bond of fucoxanthin. The energy level responsible for the emission is almost identical to the Qy level of the acceptor molecule (Chl a), thus we propose an energy transfer pathway from the optically forbidden 2Ag state of the carotenoid to the Qy transition of Chl a in algal pigment systems.
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    Sequence similarity between Photosystems I and II. Identification of a Photosystem I reaction center transmembrane helix that is similar to transmembrane helix IV of the D2 subunit of Photosystem II and the M subunit of the non-sulfur purple and flexible green bacteria (1991)
    Springer
    Photosynthesis research 29 (1991), S. 133-147 
    Details
    ISSN: 1573-5079
    Keywords: evolution ; photosynthesis ; protein structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There are basic structural similarities between plant PS II and bacterial RCs of the Chloroflexaceae and Rhodospirillaceae. These RCs are referred to as PS II-type RCs. A similar relationship of PS I RC to PS II-type RCs has not been established. Although plant PS I and PS II RCs show structural and functional differences, they also share similarities. Therefore, the A and B polypeptides of PS I were searched for PS II D1 and D2 polypeptide-like sequences. An alignment without gaps was found between PS II-type D2/M helix IV and PS I B helix X, as well as a weaker alignment of PS II-type D1/L with PS I B helix X. No comparable alignment with PS I A was found. In the M/D2 alignment there were eight identities and some conservative substitutions in twenty nine residues. PS I B helix X appeared to contain a modified chlorophyll dimer and monomer binding site and a modified non-heme iron-quinone binding site. The conserved residue sequence was found only in RC polypeptides. The proposed chlorophyll dimer-monomer binding site was located transmembrane from the iron-sulfur cluster X binding site. The conserved residues generally are those that interact with prosthetic groups. Half of the conserved residues are located on the same side of the helix. Thus, although there are impediments to concluding firmly that PS I B helix X has a functional and evolutionary relatedness to the D2 PS II and bacterial M RC polypeptides, our analysis gives reasonable support to the idea.
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    Function and organization of Photosystem I polypeptides (1995)
    Springer
    Photosynthesis research 44 (1995), S. 23-40 
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    ISSN: 1573-5079
    Keywords: chloroplasts ; cyanobacteria ; ferredoxin ; photosynthesis ; plastocyanin ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem I functions as a plastocyanin:ferredoxin oxidoreductase in the thylakoid membranes of chloroplasts and cyanobacteria. The PS I complex contains the photosynthetic pigments, the reaction center P700, and five electron transfer centers (A0, A1, FX, FA, and FB) that are bound to the PsaA, PsaB, and PsaC proteins. In addition, PS I complex contains at least eight other polypeptides that are accessory in their functions. Recent use of cyanobacterial molecular genetics has revealed functions of the accessory subunits of PS I. Site-directed mutagenesis is now being used to explore structure-function relations in PS I. The overall architecture of PSI complex has been revealed by X-ray crystallography, electron microscopy, and biochemical methods. The information obtained by different techniques can be used to propose a model for the organization of PS I. Spectroscopic and molecular genetic techniques have deciphered interaction of PS I proteins with the soluble electron transfer partners. This review focuses on the recent structural, biochemical and molecular genetic studies that decipher topology and functions of PS I proteins, and their interactions with soluble electron carriers.
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    URL: http://dx.doi.org/10.1007/BF00018294
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    Isolation of membrane bound light-harvesting-complexes from the dinoflagellates Heterocapsa pygmaea and Prorocentrum minimum (1995)
    Springer
    Photosynthesis research 44 (1995), S. 127-138 
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    ISSN: 1573-5079
    Keywords: diadinoxanthin ; dinoflagellate ; light-harvesting-complex ; peridinin ; photoacclimation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated Chl a-Chl c-carotenoid binding proteins from the dinoflagellates Prorocentrum minimum and Heterocapsa pygmaea grown under high (500 μmol m−2 s−1, HL) and low (35 μmol m−2 s−1, LL) light conditions. We compared various isolation procedures of membrane bound light harvesting complexes (LHCs) and assayed the functionality of the solubilized proteins by determining the energy transfer efficiency from the accessory pigments to Chl a by means of fluorescence excitation spectra. The identity of the newly isolated protein-complexes were confirmed by immunological cross-reactions with antibodies raised against the previously described membrane bound Chl a-c proteins (Boczar et al. (1980) FEBS Lett 120: 243–247). Spectroscopic analysis demonstrated the relatedness of these proteins with the recently described Chl-a-c 2-peridinin (ACP) binding protein (Hiller et al. (1993) Photochem Photobiol 57: 125–131; Iglesias Prieto et al. (1993) Phil Trans R Soc London B 338: 381–392). The water-soluble peridinin-Chl a binding-protein (PCP) was not detectable in P. minimum. Two functional forms of ACP with different pigmentation were isolated. A variant of ACP which was isolated from high-light grown cells, that specifically binds increased amounts of diadinoxanthin was compared to the previously described ACPs that bind proportionately more peridinin.
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    URL: http://dx.doi.org/10.1007/BF00018303
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    The unusually strong stabilizing effects of glycine betaine on the structure and function of the oxygen-evolving Photosystem II complex (1995)
    Springer
    Photosynthesis research 44 (1995), S. 243-252 
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    ISSN: 1573-5079
    Keywords: glycine betaine ; osmolyte ; oxygen-evolving complex ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural osmoregulatory substances (osmolytes) allow a wide variety of organisms to adjust to environments with high salt and/or low water content. In addition to their role in osmoregulation, some osmolytes protect proteins from denaturation and deactivation by, for example, elevated temperature and chaotropic compounds. A ubiquitous protein-stabilizing osmolyte is glycine betaine (N-trimethyl glycine). Its presence has been reported in bacteria, in particular cyanobacteria, in animals and in plants from higher plants to algae. In the present review we describe the experimental evidence related to the ability of glycine betaine to enhance and stabilize the oxygen-evolving activity of the Photosystem II protein complexes of higher plants and cyanobacteria. The osmolyte protects the Photosystem II complex against dissociation of the regulatory extrinsic proteins (the 18 kD, 23 kD and 33 kD proteins of higher plants and the 9 kD protein of cyanobacteria) from the intrinsic components of the Photosystem II complex, and it also stabilizes the coordination of the Mn cluster to the protein cleft. By contrast, glycine betaine has no stabilizing effect on partial photosynthetic processes that do not involve the oxygen-evolving site of the Photosystem II complex. It is suggested that glycine betaine might act, in part, as a solute that is excluded from charged surface domains of proteins and also as a contact solute at hydrophobic surface domains.
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    URL: http://dx.doi.org/10.1007/BF00048597
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    Energy transfer for low temperature fluorescence in PS II mutant thylakoids (1995)
    Springer
    Photosynthesis research 44 (1995), S. 117-125 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; chlorophyll-protein complex ; maize mutant ; photosynthesis ; thylakoid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Chl-protein complexes of three maize (Zea mays L.) mutants and one barley (Hordeum vulgare L.) mutant were analyzed using low temperature Chl fluorescence emissions spectroscopy and LDS-polyacrylamide gel electrophoresis. The maize mutants hcf-3, hcf-19, and hcf-114 all exhibited a high Chl fluorescence (hcf) phenotype indicating a disruption of the energy transfer within the photosynthetic apparatus. The mutations in each of these maize mutants affects Photosystem II. The barley mutant analyzed was the well characterized Chl b-less mutant chlorina-f2, which did not exhibit the hcf phenotype. Chlorina-f2 was used because no complete Chl b-less mutant of maize is available. Analysis of hcf-3, hcf-19, and hcf-114 revealed that in the absence of CP43, LHC II can still transfer excitation energy to CP47. These results suggest that in mutant membranes LHC II can interact with CP47 as well as CP43. This functional interaction of LHC II with CP47 may only occur in the absence of CP43, however, it is possible that LHC II is positioned in the thylakoid membranes in a manner which allows association with both CP43 and CP47.
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    URL: http://dx.doi.org/10.1007/BF00018302
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    Functional phycobilisome core structures in a phycocyanin-less mutant of cyanobacterium Synechococcus sp. PCC 7942 (1995)
    Springer
    Photosynthesis research 45 (1995), S. 61-70 
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    ISSN: 1573-5079
    Keywords: circular dichroism (CD) ; cyanobacteria ; energy transfer ; fluorescence ; light-harvesting antennae ; photosynthesis ; core particle ; allophycocyanin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have constructed a mutant Synechococcus sp. PCC 7942, termed R2HECAT, in which the entire phycobilisome rod operon has been deleted. In the whole cell absorption spectra of R2HECAT, the peak corresponding to phycocyanin (PC), λmax≈620 nm, could not be detected. However, a single pigment-protein fraction with λmax=654 nm could be isolated on sucrose gradients from R2HECAT. Analysis of this pigment-protein fraction by non-denaturing PAGE indicates an apparent molecular mass of about 1200–1300 kDa. On exposure to low temperature, the isolated pigment-protein complex dissociated to a protein complex with a molecular mass of about 560 kDa. When analysed by SDS-PAGE, the pigment-protein fraction was found to consist of the core polypeptides but lacked PC, 27, 33, 30, and the 9 kDa polypeptides which are a part of the rods. All the chromophore bearing polypeptides of the core were found to be chromophorylated. CD as well as absorption spectra showed the expected maxima around 652 and 675 nm from allophycocyanin (APC) and allophycocyanin B (APC-B) chromophores. Low temperature fluorescence and excitation spectra also showed that the core particles were fully functional with respect to the energy transfer between the APC chromophores. We conclude that PC and therefore the rods are dispensable for the survival of Synechococcus sp. PCC 7942. The results indicate that stable and functional core can assemble in absence of the rods. These rod-less phycobilisome core is able to transfer energy to Photosystem II.
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    URL: http://dx.doi.org/10.1007/BF00032236
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    Turnover of the D1 protein and of Photosystem II in a Synechocystis 6803 mutant lacking Tyrz (1995)
    Springer
    Photosynthesis research 45 (1995), S. 99-104 
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    ISSN: 1573-5079
    Keywords: chlorophyll radicals ; cyanobacteria ; photosynthesis ; photoinhibition ; protein degradation ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Photosystem II reaction center is rapidly inactivated by light, particularly at higher light intensity. One of the possible factors causing this phenomenon is the oxidized primary donor, P680+, which may be harmful to Photosystem II because of its highly oxidizing nature. However, no direct evidence specificially implicating P680+ in photoinhibition has been obtained yet. To investigate whether P680+ is harmful to Photosystem II, turnover of the D1 protein and of the Photosystem II reaction center complex were measured in vivo in a mutant of the cyanobacterium Synechocystis sp. PCC 6803, in which the physiological donor to P680+, Tyrz, was genetically deleted. In this mutant, D1 degradation in the light is an order of magnitude faster than in wild type. The most straightforward explanation of this phenomenon is that accumulation of P680+ leads to an increased rate of turnover of the Photosystem II reaction center complex, which is compatible with the hypothesis of destructive oxidation by P680+ that is damaging to the Photosystem II complex.
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    Imaging of chlorophyll-a-fluorescence in leaves: Topography of photosynthetic oscillations in leaves of Glechoma hederacea (1995)
    Springer
    Photosynthesis research 45 (1995), S. 225-237 
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    ISSN: 1573-5079
    Keywords: chlorophyll-a-fluorescence ; imaging ; oscillations ; photosynthesis ; minor veins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Images of chlorophyll-a-fluorescence oscillations were recorded using a camera-based fluorescence imaging system. Oscillations with frequencies around 1 per min were initiated by a transient decrease in light intensity during assimilation at an elevated CO2-concentration. The oscillation was inhomogenously distributed over the leaf. In cells adjacent to minor veins, frequency and damping rate was high, if there was any oscillation. In contrast, the amplitude was highest in cells most distant from phloem elements (maximal distance about 300 μm). The appearance of minor veins in oscillation images is explained by a gradient in the metabolic control in the mesophyll between minor veins and by transport of sugar from distant cells to phloem elements. The potential of fluorescence imaging to visualize ‘microscopic’ source-sink interactions and metabolic domains in the mesophyll is discussed.
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    URL: http://dx.doi.org/10.1007/BF00015563
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    Alternative photophosphorylation, inorganic pyrophosphate synthase and inorganic pyrophosphate (1995)
    Springer
    Photosynthesis research 46 (1995), S. 87-91 
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    ISSN: 1573-5079
    Keywords: bioenergetics ; photosynthesis ; chromatophores ; energy coupling ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This minireview in memory of Daniel I. Arnon, pioneer in photosynthesis research, concerns properties of the first and still only known alternative photophosphorylation system, with respect to the primary phosphorylated end product formed. The alternative to adenosine triphosphate (ATP), inorganic pyrophosphate (PPi), was produced in light, in chromatophores from the photosynthetic bacterium Rhodospirillum rubrum, when no adenosine diphosphate (ADP) had been added to the reaction mixture (Baltscheffsky H et al. (1966) Science 153: 1120–1122). This production of PPi and its capability to drive energy requiring reactions depend on the activity of a membrane bound inorganic pyrophosphatase (PPase) (Baltscheffsky M et al. (1966) Brookhaven Symposia in Biology, No. 19, pp 246–253); (Baltscheffsky M (1967) Nature 216: 241–243), which pumps protons (Moyle J et al. (1972) FEBS Lett 23: 233–236). Both enzyme and substrate in the PPase (PPi synthase) are much less complex than in the case of the corresponding adenosine triphosphatase (ATPase, ATP synthase). Whereas an artificially induced proton gradient alone can drive the synthesis of PPi, both a proton gradient and a membrane potential are required for obtaining ATP. The photobacterial, integrally membrane bound PPi synthase shows immunological cross reaction with membrane bound PPases from plant vacuoles (Nore BF et al. (1991) Biochem Biophys Res Commun 181: 962–967). With antibodies against the purified PPi synthase clones of its gene have been obtained and are currently being sequenced. Further structural information about the PPi synthase may serve to elucidate also fundamental mechanisms of electron transport coupled phosphorylation. The existence of the PPi synthase is in line with the assumption that PPi may have preceded ATP as energy carrier between energy yielding and energy requiring reactions.
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    URL: http://dx.doi.org/10.1007/BF00020419
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    Characterization of a 160 kD Photosystem II reaction center complex isolated from photoinhibited Dunaliella salina thylakoids (1995)
    Springer
    Photosynthesis research 46 (1995), S. 207-211 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; photoinhibition ; Photosystem II ; reaction center ; damage and repair cycle ; Dunaliella salina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoinhibition in the green alga Dunaliella salina is accompanied by the formation of inactive Photosystem II reaction centers. In SDS-PAGE analysis, the latter appear as 160 kD complexes. These complexes are structurally stable, enough to withstand re-electrophoresis of excised gel slices from the 160 kD region. Western blot analyses with specific polyclonal antibodies raised against the D1 or D2 reaction center proteins provided evidence for the presence of both of these polypeptides in the re-electrophoresed 160 kD complex. Incubation of excised gel slices from the 160 kD region, under aerobic conditions at 4°C for a prolonged period of time, caused a break-up of the 160 kD complex into a ∽52 kD D1-containing and ∽80 and ∽26 kD D2-containing pieces. Western blot analysis with polyclonal antibodies raised against the apoproteins of CPI (reaction center proteins of PS I) did not show cross-reaction either with the 160 kD complex or with the ∽52, ∽80 and ∽26 kD pieces. The results show the presence of both D1 and D2 in the 160 kD complex and strengthen the notion of a higher molecular weight D1- and D2-containing complex that forms upon disassembly of photodamaged PS II units.
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    Analysis of the proposed Fe-SX binding region of Photosystem 1 by site directed mutation of PsaA in Chlamydomonas reinhardtii (1995)
    Springer
    Photosynthesis research 46 (1995), S. 257-264 
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    ISSN: 1573-5079
    Keywords: Chlamydomonas ; mutation ; photosynthesis ; Photosystem 1 ; PsaA ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The psaA and psaB genes of the chloroplast genome in oxygenic photosynthetic organisms code for the major peptides of the Photosystem 1 reaction center. A heterodimer of the two polypeptides PsaA and PsaB is thought to bind the reaction center chlorophyll, P700, and the early electron acceptors A0, A1 and Fe-SX. Fe-SX is a 4Fe4S center requiring 4 cysteine residues as ligands from the protein. As PsaA and PsaB have only three and two conserved cysteine residues respectively, it has been proposed by several groups that Fe-SX is an unusual inter-peptide center liganded by two cysteines from each peptide. This hypothesis has been tested by site directed mutagenesis of PsaA residue C575 and the adjacent D576. The C575D mutant does not assemble Photosystem 1. The C575H mutant contains a photoxidisable chlorophyll with EPR properties of P700, but no other Photosystem 1 function has been detected. The D576L mutant assembles a modified Photosystem 1 in which the EPR properties of the Fe-SA/B centers are altered. The results confirm the importance of the conserved cysteine motif region in Photosystem 1 structure.
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    Coupled cyclic electron transport in intact chloroplasts and leaves of C3 plants: Does it exist? if so, what is its function? (1995)
    Springer
    Photosynthesis research 46 (1995), S. 269-275 
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    ISSN: 1573-5079
    Keywords: 9-aminoacridine fluorescence ; chlorophyll fluorescence ; cyclic electron transport ; light scattering ; photosynthesis ; transthylakoid proton gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transthylakoid proton transport based on Photosystem I-dependent cyclic electron transport has been demonstrated in isolated intact spinach chloroplasts already at very low photon flux densities when the acceptor side of Photosystem I (PS I) was largely closed. It was under strict redox control. In spinach leaves, high intensity flashes given every 50 s on top of far-red, but not on top of red background light decreased the activity of Photosystem II (PS II) in the absence of appreciable linear electron transport even when excitation of PS II by the background light was extremely weak. Downregulation of PS II was a consequence of cyclic electron transport as shown by differences in the redox state of P700 in the absence and the presence of CO2 which drained electrons from the cyclic pathway eliminating control of PS II. In the presence of CO2, cyclic electron transport comes into play only at higher photon flux densities. At H+/e=3 in linear electron transport, it does not appear to contribute much ATP for carbon reduction in C3 plants. Rather, its function is to control the activity of PS II. Control is necessary to prevent excessive reduction of the electron transport chain. This helps to protect the photosynthetic apparatus of leaves against photoinactivation under light stress.
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  • 47
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    Mechanisms of amplification of photosynthetically active radiation in the symbiotic deep-water coral Leptoseris fragilis (1991)
    Springer
    Hydrobiologia 216-217 (1991), S. 389-394 
    Details
    ISSN: 1573-5117
    Keywords: action spectrum ; light transformation ; photosynthesis ; scattering ; scleractinian coral ; zooxanthellae ; PAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The symbiotic coral Leptoseris fragilis lives in the Red Sea at depths of 95–145 m. Symbiotic dinoflagellates (zooxanthellae) themselves possess well known adaptations to low light intensities. In L. fragilis we found indications that light amplifying mechanisms of the host improve photosynthesis of the symbionts. Light of short wavelengths is absorbed by host pigments which transform short into longer wavelengths. The transformed light is more efficient for photosynthesis. Action spectra measurements of photosynthesis demonstrated the amplification of photosynthetically active radiation. Monochromatic light of 387 nm (outside the main absorption maxima of the algal pigments) at subsaturation photon flux densities was as effective photosynthetically as polychromatic light of 415–490 nm, which fits the absorption maxima of the zooxanthellae.
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    Physiological basis for the cultivation of the Gelidiaceae (1991)
    Springer
    Hydrobiologia 221 (1991), S. 83-90 
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    ISSN: 1573-5117
    Keywords: Gelidium ; mass culture ; photosynthesis ; plant physiology ; Pterocladia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An understanding of the physiological factors important to growth and agar production of the Gelidiales would be useful for successful mariculture of these commercially valuable plants. Several environmental factors, including light, nitrogen, carbon, temperature and water motion, have been shown to have potential significance for growth rates, reproduction and carbon partitioning in defining optimal conditions for cultivation. Limiting and optimal growth conditions, where known, are presented, and evaluation of data reported in the literature is addressed.
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    Physiological recovery of freezer-stored white and Engelmann spruce seedlings planted following different thawing regimes (1995)
    Springer
    New forests 10 (1995), S. 55-77 
    Details
    ISSN: 1573-5095
    Keywords: Key words ; Water relations ; photosynthesis ; chlorophyll a fluorescence ; artificial forest regeneration ; cold storage ; frost hardiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Logistic problems of large-scale reforestation necessitate freezer-storage of conifer seedlings. Frozen stock is typically thawed slowly at low temperatures for up to several weeks before shipping to the plantation site, but the necessity of this practice is questionable. Experiments were conducted to study effects of different thawing regimes on photosynthetic recovery, frost hardiness, water relations and growth initiation in “interior spruce” (white spruce (Picea glauca (Moench) Voss) and Engelmann spruce (Picea engelmannii Parry) hybrid complex). One year-old container-grown seedlings were planted after 9 days post-storage thawing at 5–15 °C or still frozen, directly from the freezer. During a 29 day observation period after planting, both groups showed changes in xylem water potential (Ψw), carbon fixation (A), stomatal conductance (g s ), chlorophyll a fluorescence and xanthophyll cycle pigments. Treatment differences in fluorescence and pigments peaked within one hour after planting. All differences in Ψw, A, g s , ratio of internal to external CO2 concentration (Ci/Ca), fluorescence, pigments and root number disappeared after 5 to 8 days. Terminal bud burst occurred 2.6 days earlier in the pre-thawed seedlings. When seedlings were rapidly thawed in the dark at 21 °C they achieved maximum Ψw (−0.2 MPa) in 3–4 hour. When evaluated 45 min after planting, A, g s , Ci/Ca and fluorescence values of rapidly thawed seedlings were intermediate between those for seedlings planted frozen or after 9 days slow thawing, showing that the recovery process was well underway a few hours after removal from the freezer. These results suggested that a suitable on-site operational protocol for rapid thawing might be to lay frozen bundles on the ground at ambient temperature overnight. In field trials of this method, rapidly thawed seedlings broke bud 3.3 days later than slowly thawed stock and also had greater frost hardiness at time of planting. Height, shoot and root mass did not differ after 3 months growth.
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    Effects of shade on the morphology and physiology of amabilis fir and western hemlock seedlings (1995)
    Springer
    New forests 10 (1995), S. 79-98 
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    ISSN: 1573-5095
    Keywords: Abies, acclimation ; photosynthesis ; shade tolerance ; Tsuga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Successful regeneration of coastal montane sites harvested using alternative silvicultural systems may depend on the degree to which tree species can acclimate morphologically and physiologically to a variety of light environments. In a study to determine shade acclimation in montane conifers, one-year-old amabilis fir (Abies amabilis (Dougl.) Forbes) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings were grown in a nursery under four shade treatments: full sunlight (0% shade), 60% and 30% shade using shade cloth, and 30% shade using lath slats. Shading influenced shoot development, foliar physiology and morphological characteristics of both amabilis fir and western hemlock but in general, the effects were small. Shade levels of 60% were required to induce significant acclimation, and western hemlock appeared to respond more positively than amabilis fir and therefore was considered more shade tolerant than amabilis fir. Light quality had little influence on growth and development, as indicated by a lack of significant differences in physiology or morphology between seedlings grown under shade cloth or lath slats. There were indications that adequate nutrition levels may mitigate the effects of shade on seedling morphology and physiology.
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    The role of plasma membrane redox activity in light effects in plants (1991)
    Springer
    Journal of bioenergetics and biomembranes 23 (1991), S. 393-408 
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    ISSN: 1573-6881
    Keywords: Signal transduction ; photosynthesis ; blue light ; plasma membrane redox ; light-induced absorbance change ; flavin ; cytochromeb ; sphingoid bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Stimulations by light of electron transport at the plasma membrane make it possible that redox activity is involved in light-induced signal transduction chains. This is especially true in cases where component(s) of the chain are also located at the plasma membrane. Photosynthetic reactions stimulate transplasma membrane redox activity of mesophyll cells. Activity is measured as a reduction of the nonpermeating redox probe, ferricyanide. The stimulation is due to production of a cytosolic electron donor from a substance(s) transported from the chloroplast. It is unknown whether the stimulation of redox activity is a requirement for other photosynthetically stimulated processes at the plasma membrane, but a reduced intermediate may regulate proton excretion by guard cells. Blue light induces an absorbance change (LIAC) at the plasma membrane whose difference spectrum resembles certainb-type cytochromes. This transport of electrons may be due to absorption of light by a flavoprotein. The LIAC has been implicated as an early step in certain blue light-mediated morphogenic events. Unrelated to photosynthesis, blue light also stimulates electron transport at the plasma membrane to ferricyanide. The relationship between LIAC and transmembrane electron flow has not yet been determined, but blue light-regulated proton excretion and/or growth may depend on this electron flow. No conclusions can be drawn regarding any role for phytochrome because of a paucity of information concerning the effects of red light on redox activity at the plasma membrane.
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    Reaction centers of Rhodobacter sphaeroides R26 containing C-3 acetyl and vinyl (bacterio)pheophytins at sites HA,B (1995)
    Springer
    Photosynthesis research 44 (1995), S. 55-65 
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    ISSN: 1573-5079
    Keywords: asymmetry ; bacteriopheophytins ; electron transfer ; pigment replacement ; photosynthesis ; plant-type pheophytins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The native bacteriopheophytin a in reaction centers of Rb. sphaeroides R26 has been exchanged with modified bacteriopheophytins (bacteriochlorins), as well as with plant-type pheophytins (chlorins). Emphasis is on four pigments, which differ by their C-3 substituents (vinyl or acetyl) or their state of oxidation (chlorin or bacteriochlorin). The native BPhe a, which is a member of this group, can be replaced by the other three at both binding sites, HA and HB. However, exchange at HB proceeds more readily. Optical spectra (absorption, cd) show characteristic shifts, and the cd spectra indicate induced interactions between HA,B and BA,B and possibly also with P. Upon flash illumination, all modified reaction centers show reversible electron transfer to QB with recombination times comparable to native reaction centers. Forward rates and electron-transfer yields are also reported for some of the pigments.
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    Genetic engineering of thylakoid protein complexes by chloroplast transformation in Chlamydomonas reinhardtii (1995)
    Springer
    Photosynthesis research 44 (1995), S. 191-205 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; specific mutagenesis ; chloroplast DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chloroplast transformation of Chlamydomonas reinhardtii has developed into a powerful tool for studying the structure, function and assembly of thylakoid protein complexes in a eukaryotic organism. In this article we review the progress that is being made in the development of procedures for efficient chloroplast transformation. This focuses on the development of selectable markers and the use of Chlamydomonas mutants, individually lacking thylakoid protein complexes, as recipients. Chloroplast transformation has now been used to engineer all four major thylakoid protein complexes, photosystem II, photosystem I, cytochrome b 6/f and ATP synthase. These results are discussed with an emphasis on new insights into assembly and function of these complexes in chloroplasts as compared with their prokaryotic counterparts.
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    URL: http://dx.doi.org/10.1007/BF00018309
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    Effects of sucrose on starch accumulation and rate of photosynthesis in Rosa cultured in vitro (1991)
    Springer
    Plant cell, tissue and organ culture 25 (1991), S. 21-26 
    Details
    ISSN: 1573-5044
    Keywords: in vitro culture ; photosynthesis ; Rosa multiflora ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shootlets of Rosa multiflora L. cv. Montse were cultured in vitro with four different levels of sucrose (0, 1, 3 and 5%). Chloroplasts of shootlets grown in a medium without sucrose contained numerous, large plastoglobuli and were lacking in starch granules. The size and number of starch granules increased with the level of sucrose in the culture medium. Starch content in leaves of shootlets grown with 5% sucrose was higher (ca 1, 3%) than those grown with 3% (ca 0, 45%) and 1% sucrose (ca 0, 27%). Starch might be used by the in vitro shootlets during the acclimation period.
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    URL: http://dx.doi.org/10.1007/BF00033908
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    Effect of gibberellic acid on photosynthesis and glycollate dehydrogenase in Anacystis nidulans (1995)
    Springer
    World journal of microbiology and biotechnology 11 (1995), S. 649-653 
    Details
    ISSN: 1573-0972
    Keywords: Anacystis nidulans ; gibberellic acid ; glycollate dehydrogenase ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Gibberellic acid at 10-4 Mxxx was optimal for enhancement of growth, O2 evolution, photosystem II and I and the activity of glycollate dehydrogenase of Anacystis nidulans. A stimulatory effect was observed on photosystem II. Other concentrations of gibberellic acid were inhibitory to O2 evolution and photosystem I. Syntheses of phycocyanin, phycoerythrin and β-carotene were significantly enhanced after 48 h incubation with gibberellic acid at 10-3 Mxxx but the chlorophyll content began to increase 3 h after adding 10-4 Mxxx gibberellic acid.
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    URL: http://dx.doi.org/10.1007/BF00361009
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    Red fluorescence spectra as a new means of determining the rate of damage to photosynthesis apparatus in plants caused by stress (1991)
    Springer
    Journal of biological physics 18 (1991), S. 57-63 
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    ISSN: 1573-0689
    Keywords: Red fluorescence ; stress ; photosynthesis ; entropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A new method is presented for determining the rate of damage to photosynthesis apparatus efficiency ε caused by stress using the red fluorescence spectra of plant leaves. A direct connection was found between the position of the red fluorescence maximum ν max and the photosynthesis apparatus efficiency ε. The method was tested on several examples and good results were obtained.
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    URL: http://dx.doi.org/10.1007/BF00383790
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    The stable level of coral primary production in a wide light range (1991)
    Springer
    Hydrobiologia 216-217 (1991), S. 383-387 
    Details
    ISSN: 1573-5117
    Keywords: coral ; production ; photosynthesis ; light adaptation ; PAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light adaptation and photosynthetic productivity were studied in common reef-building corals on islands of the Indian Ocean and the South China Sea. When light is attenuated, both in shade and at depth, adaptations by zooxanthellae permit maximal absorption and utilization of light. Better utilization of incident light in shade-dwelling and deep-water coral forms is reflected by higher values of gross photosynthesis on the plateau and linear portion of the photosynthesis-irradiance curve. It was shown that outer branches of reef-building corals are autotrophic in a major part of their light-range distribution and have a high and stable level of primary production.
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    URL: http://dx.doi.org/10.1007/BF00026490
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    Leaf cavity CO2 concentrations and CO2 exchange in onion, Allium cepa L. (1995)
    Springer
    Photosynthesis research 44 (1995), S. 253-260 
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    ISSN: 1573-5079
    Keywords: CO2 conductance ; CO2 recycling ; membrane ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Onion (Allium cepa L.) plants were examined to determine the photosynthetic role of CO2 that accumulates within their leaf cavities. Leaf cavity CO2 concentrations ranged from 2250 μL L−1 near the leaf base to below atmospheric (〈350 μL L−1) near the leaf tip at midday. There was a daily fluctuation in the leaf cavity CO2 concentrations with minimum values near midday and maximum values at night. Conductance to CO2 from the leaf cavity ranged from 24 to 202 μmol m−2 s−1 and was even lower for membranes of bulb scales. The capacity for onion leaves to recycle leaf cavity CO2 was poor, only 0.2 to 2.2% of leaf photosynthesis based either on measured CO2 concentrations and conductance values or as measured directly by 14CO2 labeling experiments. The photosynthetic responses to CO2 and O2 were measured to determine whether onion leaves exhibited a typical C3-type response. A linear increase in CO2 uptake was observed in intact leaves up to 315 μL L−1 of external CO2 and, at this external CO2 concentration, uptake was inhibited 35.4±0.9% by 210 mL L−1 O2 compared to 20 mL L−1 O2. Scanning electron micrographs of the leaf cavity wall revealed degenerated tissue covered by a membrane. Onion leaf cavity membranes apparently are highly impermeable to CO2 and greatly restrict the refixation of leaf cavity CO2 by photosynthetic tissue.
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    URL: http://dx.doi.org/10.1007/BF00048598
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    Functional analysis of the iron-stress induced CP 43′ polypeptide of PS II in the cyanobacterium Synechococcus sp. PCC 7942 (1995)
    Springer
    Photosynthesis research 45 (1995), S. 51-60 
    Details
    ISSN: 1573-5079
    Keywords: absorption cross-section ; cyanobacterium ; 77 K fluorescence ; fluorescence decay ; iron-stress ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Under conditions of iron-stress, the Photosystem II associated chlorophyll a protein complex designated CP 43′, which is encoded by the isiA gene, becomes the major pigment-protein complex in Synechococcus sp. PCC 7942. The isiB gene, which is located immediately downstream of isiA, encodes the protein flavodoxin, which can functionally replace ferredoxin under conditions of iron stress. We have constructed two cyanobacterial insertion mutants which are lacking (i) the CP 43′ apoprotein (designated isiA −) and (ii) flavodoxin (designated isiB −). The function of CP 43′ was studied by comparing the cell characteristics, PS II functional absorption cross-sections and Chl a fluorescence parameters from the wild-type, isiA − and isiB − strains grown under iron-stressed conditions. In all strains grown under iron deprivation, the cell number doubling time was maintained despite marked changes in pigment composition and other cell characteristics. This indicates that iron-starved cells remained viable and that their altered phenotype suggests an adequate acclimation to low iron even in absence of CP 43′ and/or flavodoxin. Under both iron conditions, no differences were detected between the three strains in the functional absorption crossection of PS II determined from single turnover flash saturation curves of Chl a fluorescence. This demonstrates that CP 43′ is not part of the functional light-harvesting antenna for PS II. In the wild-type and the isiB − strain grown under iron-deficient conditions, CP 43′ was present in the thylakoid membrane as an uncoupled Chl-protein complex. This was indicated by (1) an increase of the yield of prompt Chl a fluorescence (Fo) and (2) the persistence after PS II trap closure of a fast fluorescence decay component showing a maximum at 685 nm.
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    URL: http://dx.doi.org/10.1007/BF00032235
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    pH sensitivity of the redox state of cytochrome b559 may regulate its function as a protectant against donor and acceptor side photoinhibition (1995)
    Springer
    Photosynthesis research 46 (1995), S. 193-202 
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    ISSN: 1573-5079
    Keywords: cytochrome b 559 ; electron transport ; pH ; pheophytin ; photosynthesis ; Photosystem II ; reaction center ; redox potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A series of experiments have been conducted with isolated reaction centers of photosystem two (PS II) with the aim to elucidate the functional role of cytochrome (Cyt b 559). At pH 6.5 it was found that Cyt b 559 was reversibly photoreduced by red actinic light when Mn2+ was present as an electron donor while at pH 8.5 a photo-oxidation was observed under the same lighting conditions, which was dark reversible in the presence of hydroquinone. These pH dependent light induced changes were measured under anaerobic conditions and correlated with changes in the relative levels of high (HP) and low (LP) potential forms of the cytochrome. At pH 6.5 the cytochrome was mainly in its LP form while at pH 8.5 a significant proportion was converted to the HP form as detected by dark titrations with hydroquinone. This pH dependent difference in the levels of HP and LP Cyt b 559 was also detected when bright white light was used to monitor the level of the LP form using a novel reaction involving direct electron donation from the flavin of glucose oxidase (present in the medium and used together with glucose and catalase as an oxygen trap). The results suggest that PS II directly oxidises and reduces the HP and LP forms, respectively and that the extent of these photo-reactions is dependent on the relative levels of the two forms, which are in turn governed by the pH. This conclusion is interpreted in terms of the model presented previously (Barber J and De Las Rivas J (1993) Proc Natl Acad Sci USA 90: 10942–10946) whereby the pH induced effect is considered as a possible mechanism by which interconversion of LP and HP forms of Cyt b 559 is achieved. In agreement with this was the finding that as the extent of photo-oxidisable HPCyt b 559 increases, with increasing pH, the rate of irreversible photo-oxidation of β-carotene decreases, a result expected if the HP form protects against donor side photoinhibition.
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    Acclimation of photosynthesis, respiration and ecosystem carbon flux of a wetland on Chesapeake Bay, Maryland to elevated atmospheric CO2 concentration (1995)
    Springer
    Plant and soil 187 (1995), S. 111-118 
    Details
    ISSN: 1573-5036
    Keywords: acclimation ; ecosystem carbon balance ; elevated CO2 ; global change ; photosynthesis ; respiration ; soil carbon ; soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acclimation of photosynthesis and respiration in shoots and ecosystem carbon dioxide fluxes to rising atmospheric carbon dioxide concentration (C a ) was studied in a brackish wetland. Open top chambers were used to create test atmospheres of normal ambient and elevated C a (=normal ambient + 34 Pa CO2) over mono-specific stands of the C3 sedge Scirpus olneyi, the dominant C3 species in the wetland ecosystem, throughout each growing season since April of 1987. Acclimation of photosynthesis and respiration were evaluated by measurements of gas exchange in excised shoots. The impact of elevated C a on the accumulation of carbon in the ecosystem was determined by ecosystem gas exchange measurements made using the open top chamber as a cuvette. Elevated C a increased carbohydrate and reduced Rubisco and soluble protein concentrations as well as photosynthetic capacity(A) and dark respiration (R d ; dry weight basis) in excised shoots and canopies (leaf area area basis) of Scirpus olneyi. Nevertheless, the rate of photosynthesis was stimulated 53% in shoots and 30% in canopies growing in elevated C a compared to normal ambient concentration. Elevated C a inhibited R d measured in excised shoots (−19 to −40%) and in seasonally integrated ecosystem respiration (R e ; −36 to −57%). Growth of shoots in elevated C a was stimulated 14–21%, but this effect was not statistically significant at peak standing biomass in midseason. Although the effect of elevated C a on growth of shoots was relatively small, the combined effect of increased number of shoots and stimulation of photosynthesis produced a 30% stimulation in seasonally integrated gross primary production (GPP). The stimulation of photosynthesis and inhibition of respiration by elevated C a increased net ecosystem production (NEP=GPP−R e ) 59% in 1993 and 50% in 1994. While this study consistently showed that elevated C a produced a significant increase in NEP, we have not identified a correspondingly large pool of carbon below ground.
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    An improved model of C3 photosynthesis at high CO2: Reversed O2 sensitivity explained by lack of glycerate reentry into the chloroplast (1991)
    Springer
    Photosynthesis research 27 (1991), S. 169-178 
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    ISSN: 1573-5079
    Keywords: amino acids ; phosphate ; photorespiration ; photosynthesis ; O2 insensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Current models of C3 photosynthesis incorporate a phosphate limitation to carboxylation which arises when the capacity for starch and sucrose synthesis fails to match the capacity for the production of triose phosphates in the Calvin cycle. As a result, the release of inorganic phosphate in the chloroplast stroma fails to keep pace with its rate of sequestration into triose phosphate, and phosphate becomes limiting to photosynthesis. Such a model predicts that when phosphate is limiting, assimilation becomes insensitive to both CO2 and O2, and is thus incapable of explaining the experimental observation that assimilation, under phosphate-limited conditions, frequently exhibits reversed sensitivity to both CO2 and O2, i.e., increasing O2 stimulates assimilation and increasing CO2 inhibits assimilation. We propose a model which explains reversed sensitivity to CO2 and O2 by invoking the net release of phosphate in the photorespiratory oxidation cycle. In order for this to occur, some fraction of the glycollate carbon which leaves the stroma and which is recycled to the chloroplast by the photorespiratory pathway as glycerate must remain in the cytosol, perhaps in the form of amino acids. In that case, phosphate normally used in the stromal glycerate kinase reaction to generate PGA from glycerate is made available for photophosphorylation, stimulating RuBP regeneration and assimilation. The model is parameterized for data obtained on soybean and cotton, and model behavior in response to CO2, O2, and light is demonstrated.
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    The cloning and sequencing of Synechococcus sp. PCC 7002 petCA operon: Implications for the cytochrome c-553 binding domain of cytochrome f (1991)
    Springer
    Photosynthesis research 30 (1991), S. 71-84 
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    ISSN: 1573-5079
    Keywords: electron transport ; photosynthesis ; membrane proteins ; cytochrome f ; Rieske iron-sulfur protein ; protein-protein binding domains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genes encoding the Rieske iron-sulfur protein and cytochrome f from a unicellular, naturally transformable, photoheterotrophic cyanobacterium, Synechococcus sp. PCC 7002, formerly Agmenellum quadruplicatum, have been isolated and sequenced. The two genes were found to be on a single operon, petCA. The Synechococcus sp. PCC 7002 iron-sulfur protein contains 181 amino acids, the conserved putative iron-binding domains CTHLGCV, residues 108–114, and CPCHGS, residues 128–133, no presequence and has a 73% sequence identity to the Nostoc PCC 7906 iron-sulfur protein. The 325 amino acid apocytochrome f sequence contains a 42 amino acid presequence, a CANCH heme binding domain, residues 20–24 from the presumed start of the mature protein, and a predicted hydrophobic membrane-spanning domain, residues 250–269. The mature cytochrome f sequence has a 71.5% sequence identity with Nostoc PCC 7906 cytochrome f and possesses a large (-14) negative charge and low calculated pI of 4.47 compared to higher plant chloroplast sequences. Nine separate domains showing differences in charged residues among cyanobacteria and plants have been identified and the possibility that these domains are involved in the ionic interactions with plastocyanin or cytochrome c-553 is discussed.
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    One thing leading to another (1995)
    Springer
    Photosynthesis research 46 (1995), S. 45-46 
    Details
    ISSN: 1573-5079
    Keywords: phosphoenolpyruvate carboxylase ; photophosphorylation ; photosynthesis ; respiration ; sugar biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00020415
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    The structure and function of the chloroplast photosynthetic membrane — a model for the domain organization (1995)
    Springer
    Photosynthesis research 46 (1995), S. 141-149 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; chloroplast thylakoid ; Photosystem I ; Photosystem II ; linear and cyclic electron transport ; plastocyanin ; plastoquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work on the domain organization of the thylakoid is reviewed and a model for the thylakoid of higher plants is presented. According to this model the thylakoid membrane is divided into three main domains: the stroma lamellae, the grana margins and the grana core (partitions). These have different biochemical compositions and have specialized functions. Linear electron transport occurs in the grana while cyclic electron transport is restricted to the stroma lamellae. This model is based on the following results and considerations. (1) There is no good candidate for a long-range mobile redox carrier between PS II in the grana and PS I in the stroma lamellae. The lateral diffusion of plastoquinone and plastocyanin is severely restricted by macromolecular crowding in the membrane and the lumen respectively. (2) There is an excess of 14±18% chlorophyll associated with PS I over that of PS II. This excess is assumed to be localized in the stroma lamellae where PS I drives cyclic electron transport. (3) For several plant species, the stroma lamellae account for 20±3% of the thylakoid membrane and the grana (including the appressed regions, margins and end membranes) for the remaining 80%. The amount of stroma lamellae (20%) corresponds to the excess (14–18%) of chlorophyll associated with PS I. (4) The model predicts a quantum requirement of about 10 quanta per oxygen molecule evolved, which is in good agreement with experimentally observed values. (5) There are at least two pools of each of the following components: PS I, PS II, cytochrome bf complex, plastocyanin, ATP synthase and plastoquinone. One pool is in the grana and the other in the stroma compartments. So far, it has been demonstrated that the PS I, PS II and cytochrome bf complexes each differ in their respective pools.
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    Reconstitution of iron-sulfur center FB results in complete restoration of NADP+ photoreduction in Hg-treated Photosystem I complexes from Synechococcus sp. PCC 6301 (1995)
    Springer
    Photosynthesis research 46 (1995), S. 249-255 
    Details
    ISSN: 1573-5079
    Keywords: iron-sulfur cluster FA ; iron-sulfur cluster FB ; midpoint potential ; photosynthesis ; Photosystem I ; PsaC ; Synechococcus sp. PCC 6301
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The FB iron-sulfur cluster is destroyed preferentially by treating Photosystem I complexes with HgCl2(Kojima Y, Niinomi Y, Tsuboi S, Hiyama T and Sakurai H (1987) Bot Mag 100: 243–53). When FB is 95% depleted but FAis quantitatively retained in cyanobacterial PS I complexes, the reduction potential of FA remains highly electronegative (Em=−530 mV, n=1), the EPR spectral and spin relaxation properties of FA and FXremain unchanged, but NADP+ photoreduction rates decline from 552 to 72 μmol mg Chl−1 h−1.When FB is reconstituted with FeCl3, Na2S and β-mercaptoethanol, NADP+photoreduction rates recover to 528 μmol mg Chl−1 h−1. The correlation between the presence of FBand NADP+ photoreduction provides direct experimental evidence that this iron-sulfur cluster is required for electron throughput from cytochromec 6 to flavodoxin or ferredoxin in Photosystem I.
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    Nucleotide sequence of the psaD gene from the thermophilic cyanobacterium Synechococcus vulcanus (1995)
    Springer
    Photosynthesis research 46 (1995), S. 265-268 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; photosystem I ; psaD ; reaction center ; subunit ; sequence ; thermophilic cyanobacterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucleotide sequence was determined for the psaD gene of a thermophilic cyanobacterium, Synechococcus vulcanus, which encoded the PsaD subunit (Subunit II) of the Photosystem I reaction center complex. Except for some differences in the peripherals, the nucleotide sequence of the gene encoding PsaD was identical to that of another thermophilic cyanobacterium Synechococcus elongatus reported previously. Relationship between these primary structures and thermostability was also discussed.
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    Photosynthetic and respiratory characterization of field grown tomato (1991)
    Springer
    Photosynthesis research 28 (1991), S. 21-32 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; respiration ; internal CO2 ; pressure ; leaf age ; fruit ; light saturation ; nitrogen content ; temperature effect ; tomato ; Lycopersicum esculentum Mill.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic responses of tomato (Lycopersicum esculentum Mill.) leaves to environmental and ontogenetic factors were determined on plants grown in the field under high radiation and high nitrogen fertilization. Response curves showed net photosynthesis to only approach light saturation at a photosynthetic photon flux density (PPFD) of 2200 μmol m-2 s-1, with rates of approx. 40 μmol CO2 m-2 s-1. A broad temperature optimum was observed between 25° and 35°C, with 50% of the photosynthetic rates remaining even at 47°C. The high rate, the lack of saturation at the equivalent of full sunlight, and the tolerance to high temperature of tomato were unusual in light of the literature on this C3 species. Apparently, acclimation to the field environment of high radiation and hot daytime temperature, coupled with the high nitrogen nutrition, made possible the high photosynthetic performance normally associated with C4 species. Photosynthetic ability of the leaf reached a maximum near the time of its full expansion and declined steadily thereafter, regardless of the time of leaf initiation. Leaf nitrogen content showed a similar decline with leaf ontogeny. Photosynthesis was linearly correlated with nitrogen content, whether the nitrogen variation was due to leaf age or rates of nitrogen fertilization. Internal CO2 concentrations (Ci) of the leaf indicated that stomatal function was well coordinated with photosynthetic capacity as leaf age and fluence rate varied down to a PPFD of 500 μmol m-2 s-1. As PPFD decreased further, there was less stomatal control and Ci increased to as high as 320 μ bar bar-1. Dark respiration was highest for expanding leaves and increased nearly exponentially with temperature. Respiration was also highest for young and expanding fruits, and next highest for fruits just turning pink. Fruit respiration increased approximately linearly with temperature, and was estimated to be an important component of the CO2 flux of the plant near maturity because of the heavy fruit load and low leaf photosynthesis at that time. The results are significant for model simulation of tomato productivity in the field.
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    Down regulation of photosynthesis in Artabotrys hexapetatus by high light (1995)
    Springer
    Photosynthesis research 46 (1995), S. 393-397 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; down-regulation ; variable fluorescence ; dark recovery ; Artabotrys hexapetatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using variable to maximum fluorescence (Fv/Fm) as the criterion, the down regulation of photosynthesis by high light stress was characterized in the detached leaves of Artabotrys hexapetatus. The decrease in Fv/Fm was corelated with the decrease in oxygen evolution by thylakoids isolated from high light exposed leaves. The decrease in Fv/Fm was linear with increasing time of exposure to high light. A comparison of recovery measured as Fv/Fm, in low light versus dark, revealed that the recovery in darkness was as significant as in low light. Since the relaxation of fluorescence was a rapid response after exposure to high light and the fact that the recovery occurs in total darkness, it is concluded that photoinhibition and down regulation of photosynthesis by high light are independent events.
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    Contribution of the wheat (Triticum aestivum L.) flag leaf to grain yield in response to plant growth regulators (1995)
    Springer
    Plant growth regulation 16 (1995), S. 293-297 
    Details
    ISSN: 1573-5087
    Keywords: chlormequat chloride ; flag leaf ; grain filling ; imazaquin ; photosynthesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In West-Europe, intensive cereal management uses plant growth regulators (PGRs) especially for wheat. A green-house experiment compared the effects of two PGRs on flag leaf characteristics and yield of winter wheat. Chlormequat chloride + choline chloride (CCC) and chlormequat chloride + choline chloride + imazaquin (CCC+I) were applied to winter wheat at growth stage 5 (Feekes Large scale). CCC and CCC+I significantly increased flag leaf surface area at anthesis. Both treatments also enhanced chlorophyll content of the main stem flag leaf. The grain filling period was extended with PGR application by 2 days. CCC and CCC+I significantly increased net CO2 assimilation rates during the flag leaf life. No effects of PGR spraying were observed on the pattern of 14C labelled assimilate distribution. Increased grain yield was due to the increase in average grain weight. The results indicate that PGR treatments increased flag leaf contribution to grain filling. The addition of imazaquin (I) to chlormequat (CCC) improved the effects of CCC.
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    Long term in situ measurements of gas exchange in a Norway spruce canopy at ambient and elevated ozone levels using a light weight chamber system — System designs and first results (1995)
    Springer
    Water, air & soil pollution 85 (1995), S. 1413-1418 
    Details
    ISSN: 1573-2932
    Keywords: Age classes ; branch cuvette ; chamber design ; CO2 ; gas exchange ; ozone ; Picea abies ; photosynthesis ; transpiration ; twigs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The gas exchange system is computer controlled and is designed to measure and control 14 temperature regulated chambers enclosing spruce twigs for several months with minimum ozone absorption. The system is mounted on sun exposed single year classes of a Norway spruce stand in western Jutland, Denmark. Since July 1994 the temperature control system has been in function. Results show that 95% of the temperature measurements inside the cuvettes are within the range −2 to +3 °C of the ambient temperature. Gas exchange measurements show that the current year shoots have a higher net photosynthesis than the older shoots. The net photosynthesis in current year needles on sunny days is significantly reduced by the 6 h daily 30–40 ppb ozone addition.
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    Electronic Resource
    A gas-exchange study of the differential response of Quercus species to long-term fumigations with a gradient of sulphur dioxide (1995)
    Springer
    Water, air & soil pollution 85 (1995), S. 1257-1262 
    Details
    ISSN: 1573-2932
    Keywords: air pollution ; SO2 ; photosynthesis ; Quercus pubescens ; Quercus cerris ; oaks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Young oak plants (Quercus pubescens Willd. and Q. cerris L.) were exposed for 23 weeks to a gradient of sulphur dioxide concentrations (28, 61, 93 ppb in vol., compared with charcoal filtered-air ventilated controls) in fumigation chambers. Foliar gas exchange was analyzed by an IRGA methodology after 11 weeks and chlorophyll was assessed in a non-destructive way. At the end, foliar biomass produced during the experimental period was determined and its total sulphur and carbohydrate content analyzed. Visible foliar injury, as well as reduction in chlorophyll content was not observed. Carbon dioxide assimilation was linearly depressed by sulphur dioxide in both the species, with a maximum depression of 25% in Q. pubescens and 44% in Q. cerris. Stomatal conductance and transpiration were negatively affected only in Q. pubescens, with a linear trend. The two species showed a similar behaviour in water use efficiency, this parameter being reduced in a linear fashion. The intracellular/ambient carbon dioxide concentration ratio was affected in a differential way: while in Q. pubescens no alteration was evident, a linear increase was shown by Q. cerris. Total foliar sulphur content was dramatically increased in both the species. Average leaf area was unaffected in both the species. Reduction in foliar dry weight was only observed in Q. cerris (−30% at the highest sulphur dioxide concentration). We speculate that in Q. pubescens photosynthetic limitations are mainly of stomatal nature, and in Q. cerris the major constraints are probably associated with mesophyll disturbances. Foliar starch content was linearly increased by the pollutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00477154
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    Electronic Resource
    Electronic Resource
    Simulation of damage in winter wheat caused by the grain aphid Sitobion avenae. 2. Construction and evaluation of a simulation model (1991)
    Springer
    European journal of plant pathology 97 (1991), S. 25-54 
    Details
    ISSN: 1573-8469
    Keywords: photosynthesis ; carbon dioxide assimilation ; sink-source relations ; honeydew ; validation ; sensitivity analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To evaluate the relative importance of various components of damage caused by grain aphid (Sitobion avenae F.) populations in winter wheat, a simulation model of crop growth and development is combined with a model of aphid injury. The model applies to the time interval from flowering to ripeness which constitutes the main period of grain aphid immigration and development in winter wheat in the Netherlands. The crop model describes crop growth and development as a function of the prevailing weather and the available amount of soil nitrogen and consists of sink-source relations and distribution functions for carbohydrates and nitrogen. Injury byS. avenae affects crop growth both directly and indirectly. Direct effects on growth are due to aphid feeding. Indirect effects are caused by the aphid excretion product honeydew which affects leaf net carbon dioxide assimilation. Alternative hypotheses on the nature of the direct effects are formulated. Inputs to the model are average daily temperature, daily global radiation, the amount of nitrogen in the soil and the density of the aphid population. The major output is grain weight. The accuracy of the model is assessed by visual and statistical comparison to field data. The accuracy of both crop and damage model is satisfactory except for the final part of the growing season. Then, insufficient information on processes involved in leaf death and the termination of phloem transport to the grains results in overestimation of the rate of grain filling. The consequences of the lack of detailed information on the relation between environmental factors and the effect of honeydew on leaf carbon dioxide assimilation are assessed in a sensitivity analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01995782
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