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  • Articles  (224)
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  • photosynthesis  (224)
  • Springer  (224)
  • 2020-2024
  • 1995-1999  (224)
  • 1
    Electronic Resource
    Electronic Resource
    The impact of elevated CO2 on growth and photosynthesis in Agrostis canina L. ssp. monteluccii adapted to contrasting atmospheric CO2 concentrations (1997)
    Springer
    Oecologia 110 (1997), S. 169-178 
    Details
    ISSN: 1432-1939
    Keywords: Key words Agrostis canina ; CO2 vents ; photosynthesis ; lignification ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The aim of this study was to characterise growth and photosynthetic capacity in plants adapted to long-term contrasting atmospheric CO2 concentrations (C a). Seeds of Agrostis canina L. ssp. monteluccii were collected from a natural CO2 transect in central-western Italy and plants grown in controlled environment chambers at both ambient and elevated CO2 (350 and 700 μmol mol−1) in nutrient-rich soil. Seasonal mean C a at the source of the plant material ranged from 610 to 451 μmol CO2 mol−1, derived from C4 leaf stable carbon isotope discrimination (δ13C). Under chamber conditions, CO2 enrichment stimulated the growth of all populations. However, plants originating from elevated C a exhibited higher initial relative growth rates (RGRs) irrespective of chamber CO2 concentrations and a positive relationship was found between RGR and C a at the seed source. Seed weight was positively correlated with C a, but differences in seed weight were found to explain no more than 34% of the variation in RGRs at elevated CO2. Longer-term experiments (over 98 days) on two populations originating from the extremes of the transect (451 and 610 μmol CO2 mol−1) indicated that differences in growth between populations were maintained when plants were grown at both 350 and 700 μmol CO2 mol−1. Analysis of leaf material revealed an increase in the cell wall fraction (CWF) in plants grown at elevated CO2, with plants originating from high C a exhibiting constitutively lower levels but a variable response in terms of the degree of lignification. In vivo gas exchange measurements revealed no significant differences in light and CO2 saturated rates of photosynthesis and carboxylation efficiency between populations or with CO2 treatment. Moreover, SDS-PAGE/ LISA quantification of leaf ribulose bisphosphate carboxylase/oxygenase (Rubisco) showed no difference in Rubisco content between populations or CO2 treatments. These findings suggest that long-term adaptation to growth at elevated CO2 may be associated with a potential for increased growth, but this does not appear to be linked with differences in the intrinsic capacity for photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050146
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  • 2
    Electronic Resource
    Electronic Resource
    Gas exchange characteristics of the tropical mangrove, Pelliciera rhizophoreae (1999)
    Springer
    Mangroves and salt marshes 3 (1999), S. 147-153 
    Details
    ISSN: 1572-977X
    Keywords: conductance ; gas exchange ; mangrove ; photorespiration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic characteristics were investigated in the geographically isolated and restricted mangrove species, P.rhizophoreae. Gas exchange measurements were made on two to seven years old hydroponically grown plants maintained in 10%, 50% and 100% seawater. CO2 exchange in the 50% and 100% seawater treatments was reduced by 10% and 26%, respectively, compared to the 10% seawater treatment. CO2 response curves indicated that carboxylation efficiency was greater in 10% than in 50% seawater, while stomatal limitation increased from 11% to 16% as salinity increased from 10% to 50% seawater. Carbon losses via photorespiration (31% and 41%) and CO2 compensation point (67 and 81 μ11−1) were greater in 50% than in the 10% seawater treatment. Maximal CO2 exchange occurred at 30 °C with no differences among the salinity treatments. The results indicate that P. rhizophoreae exhibits many gas exchange characteristics previously reported for other mangroves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009943408779
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  • 3
    Electronic Resource
    Electronic Resource
    Field measurements of gas exchange in Avicennia marina and Bruguiera gymnorrhiza (1998)
    Springer
    Mangroves and salt marshes 2 (1998), S. 99-107 
    Details
    ISSN: 1572-977X
    Keywords: conductance ; mangrove ; photosynthesis ; productivity ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diurnal gas exchange characteristics were measured simultaneously in two mangrove species, Avicennia marina and Bruguiera gymnorrhiza, over 7 d in summer (February–March), to compare their productivity. The study was undertaken in the Beachwood Mangroves Nature Reserve, Durban, South Africa, using fully expanded leaves of young and mature trees at the top of the canopy. Gas exchange was strongly influenced by photosynthetic photon flux density (PPFD), leaf temperature and the accompanying leaf to air vapour pressure deficit (Δ w). Carbon dioxide exchange was saturated at a PPFD of about 600 μmol m-2s-1 in B. gymnorrhiza compared to 800 μmol m-2s-1 in A. marina. Maximal CO2 exchange occurred between 12h00 and 14h00 and was consistently greater in A. marina (8.8 μmol m-2s-1) than in B. gymnorrhiza (5.3 mu;mol m-2s-1). Mean internal CO2 concentrations ( ci) were 260 μl l-1 in A. marina and 252 μl l-1 in B. gymnorrhiza. Photorespiratory activity was 32% in A. marina and 30% in B. gymnorrhiza. Mean water use efficiency (WUE) was 8.0 μmol mmol-1 in A. marina and 10.6 μmol mmol-1 in B. gymnorrhiza. Diurnal leaf water potentials ranged from –0.8 to –3.5 MPa and were generally lower in A. marina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009939523164
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  • 4
    Electronic Resource
    Electronic Resource
    Mangrove forest productivity and biomass accumulation in Hinchinbrook Channel, Australia (1998)
    Springer
    Mangroves and salt marshes 2 (1998), S. 191-198 
    Details
    ISSN: 1572-977X
    Keywords: canopy ; Hinchinbrook ; leaf area index ; mangrove ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data on stand structure and rates of photosynthesis were used to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests in Hinchinbrook Channel, Australia. Total annual canopy net carbon fixation was estimated to be about 29 t C ha−1 yr−1. This equates to about 204,000 t C yr−1 for all mangrove forests in Hinchinbrook Channel. Of this, only about 12% was stored as living plant biomass. Although it is not yet possible to present a robust carbon balance for mangrove trees, the remainder is presumably lost through plant respiration, litter fall, root turnover and exudation of organic compounds from roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009979610871
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  • 5
    Electronic Resource
    Electronic Resource
    Recovery of net CO2 assimilation after heat stress is correlated with recovery of oxygen-evolving-complex proteins in Zea mays L. (1997)
    Springer
    Photosynthetica 34 (1997), S. 13-20 
    Details
    ISSN: 1573-9058
    Keywords: D1 protein ; internal CO2 concentration ; maize ; oxygen evolution ; phosphoenolpyruvate carboxylase ; photosynthesis ; photosystem 2 ; ribulose-1,5-bisphophate carboxylase/oxygenase ; stomatal conductance ; thermotolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem 2 (PS2) in general, and the oxygen-evolving complex (OEC) in particular, is one of the most thermolabile components of photosynthesis. We examined the effects of heat stress on net photosynthetic rate (PN) and content of several stromal and thylakoid-membrane proteins (including OEC proteins) in maize (Zea mays L.) in order to determine if decreases in PN during, and especially after, heat stress were correlated with decreases in the content of OEC proteins. The PN decreased with heat stress in maize, and post-heat stress recovery of PN required 4 d following the second of two heat-shocks. The decrease in PN was not the result of stomatal closure. Cellular levels of the 33, 23, and 16 kDa OEC proteins decreased with heat stress, and the decreases were greatest and most closely correlated with decreases in PN for OEC16. Following the second heat stress, full recovery of OEC levels (especially OEC16 and 33) coincided with full recovery of PN, more so than with other photosynthetic proteins examined. For example, decreases in levels of the 32-kDa QB-binding protein of the PS2 reaction center (D1), ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit, and phosphoenolpyruvate carboxylase were generally smaller than for the OEC proteins and full recovery of these proteins occurred at least 2 d prior to full recovery of photosynthesis. These results are consistent with previous fluorescence and in vitro studies by others in suggesting that heat-relaed effects on PS2 and the OEC are an important limitation to Pn during heat stress. Additionally, these results suggest that heat-related decreases in the content of OEC proteins may limit post-heat stress recovery of carbon fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006899314677
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in CO2 Exchange Rate, Stomatal Conductance, Activities of Photosystems 1 and 2, and Chloroplast Polypeptide Profile Induced by Simulated Acidic Rain (1998)
    Springer
    Photosynthetica 35 (1998), S. 353-359 
    Details
    ISSN: 1573-9058
    Keywords: absorption spectra ; chlorophyll fluorescence ; photosynthesis ; Vigna radiata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In seedlings of Vigna radiata (L.) R. Wilczek cultivars ADT-1 and CO-5 exposed to acidic showers (H2SO4 : HNO3 : HCl, 4 : 2 : 1, v/v) of different pH (7.0, 5.5, 4.0, and 2.5) for 10 d, net CO2 uptake and stomatal conductance were reduced. The chlorophyll (Chl) a and b contents were reduced but the carotenoid (Car) content increased. In vivo Chl a fluorescence patterns of both the cultivars were altered. No significant change in photosystem (PS) 1 activity was observed except at pH 2.5 where an inhibition was evident. By contrast, PS2 activities declined rapidly with increasing acidity. The room temperature absorption spectra of isolated chloroplasts showed very little changes. SDS-PAGE analysis revealed depletion of 23, 33, and 55 kDa polypeptides. Cultivar CO-5 was more sensitive to acidic rain than cv. ADT-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006956100605
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  • 7
    Electronic Resource
    Electronic Resource
    Differences in Field Gas Exchange and Water Relations Between a C3 Dicot (Plantago Asiatica) and a C4 Monocot (Eleusine Indica) (1999)
    Springer
    Photosynthetica 37 (1999), S. 123-130 
    Details
    ISSN: 1573-9058
    Keywords: diurnal pattern ; intercellular CO2 concentration ; leaf conductance ; leaf water potential ; micro-habitat ; photosynthesis ; seasonal dominance ; soil-to-leaf hydraulic conductance ; trampling tolerance ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field gas exchange and water potential in the leaves of a C3 dicot, Plantago asiatica L., and a C4 monocot, Eleusine indica Gaertn., which dominate in trampled vegetation in eastern Japan were surveyed during the growing periods for two consecutive years. Net photosynthetic rate (P N) of E. indica increased with photosynthetic photon flux density (PPFD) and leaf temperature (TL). P N was not saturated at PPFDs above 1500 µmol m−2 s−1 and at TL above 30 °C. On a sunny day in mid summer, maximum P N was two times higher in E. indica than in P. asiatica [42 vs. 20 µmol(CO2) m−2 s−1], but their transpiration rate (E) and the leaf water potential (ΨL) were similar. Soil-to-leaf hydraulic conductance, which probably plays a role in water absorption from the trampled compact soil, was higher in E. indica than in P. asiatica. The differences in photosynthetic traits between E. indica explain why E. indica communities more commonly develop at heavily trampled sites in summer than the P. asiatica communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007031332521
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  • 8
    Electronic Resource
    Electronic Resource
    Cd/Fe Interaction in Higher Plants - Its Consequences for the Photosynthetic Apparatus (1999)
    Springer
    Photosynthetica 36 (1999), S. 321-331 
    Details
    ISSN: 1573-9058
    Keywords: Calvin cycle enzymes ; chlorophyll ; chloroplast structure ; heavy metals ; photosynthesis ; photosystems ; plant growth ; uptake of mineral elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cadmium is one of the most dangerous environmental pollutants, affecting, among other things, plant mineral composition. It easily interacts with iron, one of the most important elements for plant growth and metabolism. This interaction, including modifying effects of lowered or excessive Fe supply on Cd-exposed plants and its consequences for the photosynthetic apparatus is reviewed. The influence of modified Fe and Cd supply on the uptake of both metals, their distribution, plant growth, and photosynthesis is also explained. Moderate Fe excess has a beneficial influence on Cd-treated plants, resulting in more intensive growth, photosynthetic pigments accumulation, and more efficient light phase of photosynthesis. Nutrient-medium Fe deficiency increases plant susceptibility to Cd. The main open questions of Cd/Fe interaction are: (1) the strong Fe-dependency of Cd mobility within the plant, and (2) photosynthetic dark phase adaptation to Cd stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007097518297
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  • 9
    Electronic Resource
    Electronic Resource
    Carbon Balance of a Winter Wheat-Root Microbiota System Under Elevated CO2 (1999)
    Springer
    Photosynthetica 36 (1999), S. 341-354 
    Details
    ISSN: 1573-9058
    Keywords: carbon partitioning ; photosynthesis ; plant growth ; microbial biomass ; respiration rate ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the carbon budget of young winter wheat plants and their associated microorganisms as affected by a doubling of the atmospheric CO2 concentration (700 µmol mol-1). Plants were grown hydroponically in pre-sterilised sand at a controlled irradiance and temperature regime. Net photosynthesis (PN) and respiration (RD) rates of roots and shoots were measured continuously, plant growth and carbon distribution in the plant-root medium-associated microorganism system were determined destructively in interval-based analyses. PN in elevated CO2 grown plants (EC) was 123% of that in the control (AC) plants when averaged over the whole life span (39-d-old plants, 34 d in EC), but the percentage varied with the developmental stage being 115, 88, and 167% in the pretillering, tillering, and posttillering phase, respectively. There was a transient depression of PN, higher amplitude of day/night fluctuations of the chloroplast starch content, and depression of carbon content in rhizosphere of EC plants during the period of tillering. After 34 d in EC, carbon content in shoots, roots, and in rhizodepositions was enhanced by the factors 1.05, 1.28, and 1.96, respectively. Carbon partitioning between above and belowground biomass was not affected by EC, however, proportionally more C in the belowground partitioning was allocated into the root biomass. Carbon flow from roots to rhizodepositions and rhizosphere microflora was proportional to PN; its fraction in daily assimilated carbon decreased from young (17%) to order (3-4%) plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007081419206
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  • 10
    Electronic Resource
    Electronic Resource
    The Development of Chloroplast Ultrastructure and Hill Reaction Activity During Leaf Ontogeny in Different Maize (Zea Mays L.) Genotypes (1999)
    Springer
    Photosynthetica 36 (1999), S. 497-507 
    Details
    ISSN: 1573-9058
    Keywords: chloroplast dimensions ; electron microscopy ; peripheral reticulum ; photosynthesis ; plastoglobuli ; starch ; stereology ; stroma ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in Hill reaction activity (HRA) and ultrastructure of mesophyll cell (MC) chloroplasts were studied during the ontogeny of third leaf of maize plants using polarographic oxygen evolution measurement, transmission electron microscopy, and stereology. The chloroplast ultrastructure was compared in young (actively growing), mature, and senescing leaves of two different inbreds and their reciprocal F1 hybrids. Statistically significant differences in both HRA and MC chloroplast ultrastructure were observed between different stages of leaf ontogeny. Growth of plastoglobuli was the most striking characteristic of chloroplast maturation and senescence. The chloroplasts in mature and senescing leaves had a more developed system of thylakoids compared to the young leaves. Higher HRA was usually connected with higher thylakoid volume density of MC chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007031818695
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  • 11
    Electronic Resource
    Electronic Resource
    Oxygenic photosynthesis–a photon driven hydrogen generator–the energetic/entropic basis of life (1998)
    Springer
    Photosynthetica 35 (1998), S. 1-11 
    Details
    ISSN: 1573-9058
    Keywords: evolution ; hydrogen ; life ; photosynthesis ; radiant energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis, as a fundamental element in the life process, is integrated in the evolution of living systems on the basis of hydrogen cycles on various hierarchic levels. Conversion of radiant energy enables the oxidation of water, whereby free oxygen accumulates in the atmosphere. Hydrogen is (reversibly) stored in organic materials formed under reductive CO2-fixation and by the incorporation of the other elements, which are necessary for living systems. All endergonic processes in living cells are finally driven by the energy released through the clean recombination of protons and electrons with oxygen to water. Duration of the stored energy and the complexity of the systems thus produced is correlated negatively with the conversion efficiency of the radiation energy. Entropy is a unifying principle in the evolution of living systems, inclusive human societies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006872110196
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  • 12
    Electronic Resource
    Electronic Resource
    Ecophysiological Responses to Neighbor Removal in an Old-Field and a Prairie in Northeastern Kansas, USA (1999)
    Springer
    Photosynthetica 36 (1999), S. 471-476 
    Details
    ISSN: 1573-9058
    Keywords: Ambrosia trifida ; Apocynum cannabinum ; Aster pilosus ; competition ; Eryngium yuccifolium ; Lespedeza capitata ; photosynthesis ; Solidago canadensis ; stomatal conductance ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ecophysiological approach was used to determine if competition can be detected among plants in a recently abandoned old-field and in a native tallgrass prairie in northeastern Kansas. In situ photosynthetic parameters and water potentials (Ψ) of target plants were measured 1-2 d after neighbor (intra- and interspecific) removal as well as 1-4 weeks later, and compared with values for plants with neighbors. Only two of the six study species (four old-field and two prairie species) responded to removal of neighboring plants, and only after several weeks had elapsed. Net photosynthetic rates (PN) and stomatal conductances (gs) of Ambrosia trifida in an old-field increased after removal of both intra- and interspecific neighbors. For Apocynum cannabinum, another old-field species, PN of target plants without neighbors was significantly higher than that of target plants with neighbors. For both these species, values of Ψ were not different between target plants with and without neighbors, suggesting that increased availability of nutrients may have been responsible for the observed ecophysiological responses. Though numerous past studies indicate that competition is a major factor influencing plants in old-field and in prairie communities, the experimental approach used in this study revealed that neighbor removal had only limited effects on ecophysiology of the target plants in either community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007040506838
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  • 13
    Electronic Resource
    Electronic Resource
    Gas Exchange and Chlorophyll Fluorescence in Symbiotic and Non-Symbiotic Ryegrass Under Water Stress (1999)
    Springer
    Photosynthetica 37 (1999), S. 107-112 
    Details
    ISSN: 1573-9058
    Keywords: endophyte ; Lolium perenne ; Neotyphodium lolii ; photosynthesis ; stomatal conductance ; transpiration rate ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The symbiotic association of endophyte fungus, Neotyphodium lolii, and ryegrass improves the ryegrass resistance to drought. This is shown by a 30 % increase in the number of suckers in infected plants (E+), compared to plants lacking endophyte (E−), and by a higher water potential in the E+ than E− plants. The E+ plants have higher stomatal conductance (g s), transpiration rate, net photosynthetic rate (P N), and photorespiratory electron transport rate than the E− plants. The maximal photochemical efficiency (Fv/Fm) and the actual photochemical efficiency (ΦPS2) are not affected by the endophyte fungus. The increase in P N of the E+ plants subjected to water stress was independent from internal CO2 concentration. An increased P N was observed in E+ plants also in optimal water supply. Hence the drought resistance of E+ plants results in increased g s, P N, and photorespiratory electron transport rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007027131613
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  • 14
    Electronic Resource
    Electronic Resource
    Planting density effects on assimilation and partitioning of photosynthates during grain filling in the late-sown wheat (1997)
    Springer
    Photosynthetica 33 (1997), S. 199-204 
    Details
    ISSN: 1573-9058
    Keywords: photosynthates ; 14CO2 ; ear ; leaf insertion ; photosynthesis ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaf blades of the late-sown winter wheat produced the major portion, i.e., more than 60 %, of the total 14C-photosynthates at grain filling, but ear (rachis and glumes) only about 15 %, sheaths about 11 %, and stem internodes about 11 %. The change of plant density in this experiment had little influence on the 14CO2-photoassimilation of the ear (rachis and glumes), flag leaf lamina, sheaths and stem internodes, but markedly affected photosynthesis of the second, the third and lower leaves. The photosynthetic rate [expressed as specific radioactivity, s-1 kg-1(d.m.)] and the amount of 14CO2 photosynthates decreased significantly in the second, the third and other lower leaves at a high plant density. Upon grain-filling of the late-sown wheat, the grain was the major importer of photosynthates. Yet partitioning to the stem internodes depended on the plant density. Stem was the importer of photosynthates at a low plant density, but the exporter at a high plant density. In plants at a low plant density a fairly large proportion of photosynthates was distributed into the roots. The middle and lower above-ground parts of the late-sown wheat at a high plant density decreased or lost their function early. As a result, the plant senesced earlier. However, the grain setting, filling and yielding were restricted. An appropriately low plant density was suitable for prolonging the function of the middle and lower organs, delaying the senescence of plant, increasing the source supply for grain filling, and improving the grain yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022156112243
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  • 15
    Electronic Resource
    Electronic Resource
    Action of Mercury on the Photosynthetic Apparatus of Spinach Chloroplasts (1998)
    Springer
    Photosynthetica 35 (1998), S. 551-559 
    Details
    ISSN: 1573-9058
    Keywords: EPR spectroscopy ; fluorescence spectroscopy ; HgCl2 ; photosynthesis ; radionuclide X-ray fluorescence analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In chloroplasts of Spinacea oleracea L., Hg2+ ions interact with some sites in the photosynthetic electron transport chain: (l) with the intermediates Z+/D+ situated in the D1 and D2 proteins and with the manganese cluster in the oxygen evolving complex which are located on the donor side of photosystem (PS) 2, (2) with the chlorophyll a dimer in the core of PS1 (P700). P700 is oxidized in the dark by HgCl2. The Hg2+ ions form organometallic complexes with amino acids contained in chloroplast proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006931024202
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  • 16
    Electronic Resource
    Electronic Resource
    Relationships Between Nitrogen Content and Net Gas Exchange Components of a Cotton Leaf During Ontogeny (1998)
    Springer
    Photosynthetica 35 (1998), S. 631-635 
    Details
    ISSN: 1573-9058
    Keywords: Gossypium hirsutum ; leaf age ; photosynthesis ; stomatal conductance ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Relationships between leaf nitrogen (N) content and leaf gas exchange components of a single cotton (Gossypium hirsutum L.) leaf subtending the fruit during ontogeny were investigated under field conditions. A 20-d old leaf exhibited the highest physiological activity characterized by net photosynthetic (PN) and transpiration (E) rates, stomatal conductances to CO2 exchange (gsCO2) and water vapor transfer (gsH2O), and nitrogen (N) content. With the advent of leaf senescence, the gas exchange rates declined as exhibited by the 30-, 40-, and 60-d old leaves. Regression analysis indicated close relationships between gsCO2 and PN, and gsH2O and E as the leaves advanced towards senescence. Both PN and gsCO2 were related to N as they declined with leaf age. Thus, the declines in PN were associated with stomatal closure and removal of N during leaf ontogeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006999511907
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  • 17
    Electronic Resource
    Electronic Resource
    Effect of fruiting and drought or flooding on carbon balance of apple trees (1997)
    Springer
    Photosynthetica 33 (1997), S. 269-275 
    Details
    ISSN: 1573-9058
    Keywords: Malus domestica ; open-top cuvettes ; photosynthesis ; respiration ; water stress ; water use efficiency ; xylem water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of fruiting or deblossomed trees to water stress such as drought or flooding was investigated in six semi open-top cuvettes each containing one apple (Malus domestica Borkh. cv. Golden Delicious) tree. Xylem water potentials of leaves dropped from -1.2 to -4.1 MPa within 7 d of drought, the effect being enhanced by fruiting. Apple trees without fruits showed smaller reductions in net photosynthetic rate (P N ) and dark respiration rate (R D ) after 2 d of drought and hence more positive carbon balances relative to fruiting trees. Flooding for 4 d had a more pronounced effect on P N than on transpiration, resulting in a reduced water use efficiency (WUE). This reduction in WUE was greater in the non-fruiting trees. Flooding reduced P N of the whole apple canopies irrespective of fruiting; aple trees without fruits increased R D resulting in a less positive carbon balance relative to fruiting trees. Fruiting increased the sensitivity to drought of apple trees (R D and P N ), but decreased their sensitivity to flooding (R D and WUE), suggesting different adaptation mechanisms for the two forms of water stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022172515878
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  • 18
    Electronic Resource
    Electronic Resource
    Perpetual Adaptation in a Perpetually Changing Environment as a Survival Strategy of Plants: A Case Study in Foraminifers Concerning Coral Reef Bleaching (1999)
    Springer
    Photosynthetica 37 (1999), S. 71-85 
    Details
    ISSN: 1573-9058
    Keywords: Amphisorus ; Amphistegina ; chlorophyll fluorescence kinetics ; electron transport ; irradiance ; photosynthesis ; photosystem 2 ; quantum yield ; Sorites ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coral reef bleaching is a global phenomenon poorly understood today. We investigated during 7 d the photosynthetic behaviour of symbionts of coral reef and temperate foraminifers in hospite, by means of the JIP-test. By this screening test the fast fluorescence rise O-J-I-P, measured by a Plant Efficiency Analyser (PEA) with 10 µs time resolution and 12 bit signal resolution, was analysed. It informs about the structure and function of photosystem 2 being at different physiological states established by adaptation to different irradiance and temperature. The test needs a measuring time in vivo of only 1 to 5 s, and thus many samples can be analysed. The measurements can be done continuously even on a single cell in a test tube or on the reef. The reef foraminifers tested here were Amphistegina and Amphisorus, freshly collected in Mauritius. As a temperate foraminifer, Sorites from the Mediterranean Sea was tested. The cells are very sensitive to slight temperature changes (25 to 32 °C). The comparison showed that the more the foraminifers live in an environment with constant temperature the less they are able to respond to temperature changes and, thus, the less they can adapt. Rising the temperature increases in general the sensitivity to different stress factors, such as high irradiance, pH, CO2, etc. After the test series, the cells recovered fully and were kept in an aquarium for long time observation.
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    URL: http://dx.doi.org/10.1023/A:1007070913866
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    Ultrastructural changes in gametophytes of Acrostichum aureum L. cultured in different sodium chloride concentrations (1997)
    Springer
    Biologia plantarum 39 (1997), S. 607-614 
    Details
    ISSN: 1573-8264
    Keywords: chloroplasts ; fern ; mitochondria ; photosynthesis ; respiration ; salt stress ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gametophytes cultured in solutions containing 0.0 to 0.7 % NaCl exhibited no change in ultra structural organization of chloroplasts. In 1.0% NaCl-grown gametophytes, there were thinner granal stacks, relatively larger spaces between granal thylakoidal membranes and larger plastoglobuli in the chloroplasts. These changes were accompanied by a decrease in photosynthesis. Cup shape, horseshoe shape, ring shape, and amoeboid mitochondria were observed in gametophytes grown in 0.0 to 0.7% NaCl. Only round mitochondria were observed in the gametophytes grown in 1.0 % NaCl. Mitochondria seemed to be more resistant to salt stress compared to chloroplasts. There was no direct relationship between changes in respiration rate and changes in mitochondrial shape among gametophytes grown in different NaCl concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000939017348
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  • 20
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    Control of PAR-saturated CO2 exchange rate in some C3 and CAM plants (1997)
    Springer
    Biologia plantarum 40 (1997), S. 91-101 
    Details
    ISSN: 1573-8264
    Keywords: CER ; leaf thickness ; photosynthesis ; photosynthetic N-use efficiency succulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We measured PAR-saturated CO2 exchange rate (CER), and leaf N, P and chlorophyll (Chl) concentrations in 21 plant species, selected to encompass as broad a range in specific leaf area (SLA) as possible, and encompassing non-succulent C3 as well as succulent CAM plants. We worked with plants growing under uniform conditions in the facilities of a biological research station to ensure that any correlations found were due to inherent, genetically controlled, relationships between the measured parameters and not due to variations in resource availability in different habitats. We found CER to be strongly correlated to SLA, leaf N concentration and Chl concentration. CER increased much faster with increasing leaf N concentration (CER ≈ N3.1) than with increasing SLA (CER ≈ SLA1.2). CER also increased much faster with leaf N concentration than with increasing Chl concentration (CER ≈ Chl1.3), indicating the photosynthetic N-use efficiency (NUE) to be higher for plants with high N concentration than for plants with low N concentration (NUE ≈ N2.1). Analysis of covariance showed that these relationships exist even when comparing plants of widely different growth forms - succulent or non-succulent, and of different photosynthetic pathways, as the C3 and CAM plants compared here. Testing against scaling coefficients calculated using dimensional analysis, showed that the scaling of N, Chl and CER against SLA was not merely a result of diluting N and Chl with carbon in thicker leaves but that SLA, probably through influencing light absorptio and/or CO2 diffusion pathway, played an independent role in controlling CER.
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    URL: http://dx.doi.org/10.1023/A:1000900718932
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    Diurnal changes in leaf gas exchange and chlorophyll fluorescence in tropical tree species with contrasting light requirements (1999)
    Springer
    Ecological research 14 (1999), S. 77-88 
    Details
    ISSN: 1440-1703
    Keywords: chlorophyll fluorescence ; Macaranga gigantea ; Neobalanocarpus heimii ; photosynthesis ; Shorea leprosula ; tropical rainforest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Interspecific ecophysiological differences in response to different light environments are important to consider in regeneration behavior and forest dynamics. The diurnal changes in leaf gas exchange and chlorophyll fluorescence of two dipterocarps, Shorea leprosula (a high light-requiring) and Neobalanocarpus heimii (a low light-requiring), and a pioneer tree species (Macaranga gigantea) growing in open and gap sites were examined. In the open site, the maximum net photosynthetic rate (Pn), photosystem II (PSII) quantum yield (δ; F/Fm′), and relative electron transport rate (r-ETR) through PSII at a given photosynthetic photon flux density (PPFD) was higher in S. leprosula and M. gigantea than in N. heimii, while non-photochemical quenching (NPQ) at a given PPFD was higher in N. heimii. The maximum values of net photosynthetic rate (Pn) in M. gigantea and S. leprosula was higher in the open site (8–11 μmol m−2 s−1) than in the gap site (5 μmol m−2 s−1), whereas that in N. heimii was lower in the open site (2 μmol m−2 s−1) than in the gap site (4 μmol m−2 s−1), indicating that N. heimii was less favorable to the open site. These data provide evidence to support the hypothesis that ecophysiological characteristics link with plant’s regeneration behavior and successional status. Although Pn and stomatal conductance decreased at midday in M. gigantea and S. leprosula in the open site, both r-ETR and leaf temperature remained unchanged. This indicates that stomatal closure rather than reduced photochemical capacity limited Pn in the daytime. Conversely, there was reduced r-ETR under high PPFD conditions in N. heimii in the open site, indicating reduced photochemical capacity. In the gap site, Pn increased in all leaves in the morning before exposure to direct sunlight, suggesting a relatively high use of diffuse light in the morning.
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    URL: http://dx.doi.org/10.1046/j.1440-1703.1999.00291.x
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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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  • 23
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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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    Responses of three bottomland species with different flood tolerance capabilities to various flooding regimes (1996)
    Springer
    Wetlands ecology and management 4 (1996), S. 245-256 
    Details
    ISSN: 1572-9834
    Keywords: Anaerobiosis ; baldcypress ; cherrybark oak ; nuttall oak ; photosynthesis ; productivity ; soil redox potential ; stomatal conductance ; waterlogging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seedlings of baldcypress (Taxodium distichum), nuttall oak (Quercus nuttalli), and cherrybark oak (Quercus falcata var.pagodaefolia) were subjected to four flooding treatments: control, continuously flooded, intermittently flooded, and partially flooded for 70 days in a greenhouse. The treatments imposed various durations and intensities of soil redox potential (Eh) conditions representing a range encountered by plants in their habitats. Morphological changes and gas exchange responses to the treatments differed among the study species. Rapid development of adventitious root and hypertrophied lenticels were observed in baldcypress and nuttall oak under all flooded treatments. Cherrybark oak had the highest percentage reduction in net photosynthesis ranging from 65–87%, whereas reductions in nuttall oak ranged between 35–68% and in baldcypress between 6–21% in response to various treatments. Recovery of gas exchange was noted in baldcypress but no significant recovery was found in oaks. The recovery in baldcypress contributed to the continued growth and biomass accumulation under various treatments. Little evidence of consistent changes in biomass allocation patterns in response to the treatments was found in baldcypress but total biomass decreased significantly under the continuously flooded treatment. In oaks, total biomass decreased significantly in all flooded treatments. The present findings demonstrated that physiological functions are adversely affected by low soil Eh conditions and the extent of such effects are dependent on the intensity and duration of soil reduction as well as the species' capability to respond to such conditions rapidly. Management plans concerned with regeneration of bottomland forested ecosystems should consider the species flood response capabilities at seedling stages as well as the timing, durations, and intensities of soil reduction at the specific site.
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    URL: http://dx.doi.org/10.1007/BF02150538
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    Picosecond fluorescence decay studies on water-stressed pea leaves: energy transfer and quenching processes in photosystem 2 (1997)
    Springer
    Photosynthetica 34 (1997), S. 97-106 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll ; DCMU ; exciton-radical pair equilibrium model ; NH2OH ; photosynthesis ; Pisum ; quinones ; relative air humidity ; wilting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Detached leaves of pea (Pisum sativum) were submitted to water stress at different relative air humidities. The photosynthetic activity of photosystem 2 (PS2) was monitored by time-resolved picosecond chlorophyll (Chl) fluorescence spectroscopy. In the first days the well-known fast Chl fluorescence decay was observed which indicated high PS2 activity. After a few days the average fluorescence decay time τm reached a maximum, depending on the wilting conditions, but always at a relative loss of leaf mass of 80%. After this maximum, τm decreased within a few hours, the fluorescence decay became similar to that one of an intact leaf, but an additional fluorescence decay component with a lifetime of 3.6 ns appeared. At first the primary quinone QA was reduced due to inhibition of the electron transfer to the secondary quinone QB. Simultaneously, water deficiency caused an electron lack at the oxidizing site of PS2. This disabled the primary electron donor of PS2, tyrosine Z, from reducing the oxidized reaction centre of PS2 (P680+). Thus a recombination of P680+-pheophytin-QA- took place, and the energy was lost as heat. With further water stress, QA was decoupled from PS2. The new fluorescence decay component could therefore be assigned to energetically decoupled antenna complexes.
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    URL: http://dx.doi.org/10.1023/A:1006867902382
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    Short-term effects of aluminium at alkaline pH on the structure and function of the photosynthetic apparatus (1997)
    Springer
    Photosynthetica 34 (1997), S. 169-177 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll fluorescence ; chloroplast ultrastructure ; photosynthesis ; photosystem 2 ; Thinopyrum bessarabicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 24 h exposure of the salt-tolerant grass Thinopyrum bessarabicum (Savul. and Rayss) A. Love seedlings to 1 mM aluminium (Al) in nutrient solution at pH of 9.0 resulted in a significant reduction of the biomass. In control samples the mesophyll chloroplasts exhibited the usual lens shape with most grana arranged in straight or slightly curving lines, and only 6.5 % of the grana were out of order. In Al-treated plants the mesophyll chloroplasts displayed a slightly distorted shape and distended size with most grana arranged in bow-like lines, while in the central region of the organelle as many as 26.7 % of the grana were independent and out of order in relation to the long axis. The morphological changes in the chloroplast shape and grana arrangement were probably due to swelling and distension of the chloroplasts in consequence to the altered membrane permeability. The initial in vivo chlorophyll (Chl) fluorescence FO, as well as the intermediate FI and peak fluorescence FP were increased under the Al stress: this indicated a destruction of photosystem (PS) 2 reaction centres and increased reduction of QA. The (FI-FO)/(FP-FO) ratio exhibited a significant increase indicating higher proportion of PS2 centres unable to reduce QB. Changes in the chloroplast ultrastructure seemed to be the reason of photosynthetic electron transport inhibition. Yet all these changes in the photosynthetic performance and chloroplast ultrastructure were considered as indirect effects of Al treatment since Al concentration in the leaves was undetectable. Disturbances in the chloroplast ultrastructure could be caused by a reduced uptake and/or transport of other nutrients.
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    URL: http://dx.doi.org/10.1023/A:1006880205108
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    Effect of cytokinins on the photosynthetic apparatus in water-stressed and rehydrated bean plants (1997)
    Springer
    Photosynthetica 34 (1997), S. 563-567 
    Details
    ISSN: 1573-9058
    Keywords: oxygen flash yields ; photochemical activity ; photosynthesis ; photosystem 2 ; thermoluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of the cytokinins 6-benzylaminopurine (BAP) and N-2-chloro-4-pyridyl-N′-phenylurea (4-PU-30) on the photochemical activity, oxygen flash yields, and thermoluminescence in bean plants under a water stress were studied. The cytokinins increased the photochemical (Hill reaction) activity and thermoluminescence "B"-band in control as well as in stressed and rehydrated plants, while the oxygen flash yields were affected only in the stressed and rehydrated plants.
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    URL: http://dx.doi.org/10.1023/A:1006821730974
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    Effects of Inorganic Nitrogen Availability on the Sporophytes of Acrostichum Aureum L. (1999)
    Springer
    Photosynthetica 36 (1999), S. 259-266 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll fluorescence ; fern ; fertilization ; growth ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants grown at low irradiance were fertilized with 0, 60, and 600 g m-3 NH4NO3 once every fortnight. Plants treated with high N concentrations showed an increased growth, producing longer and broader fronds with larger areas, and were darker green in colour. Nitrogen also increased the content of chlorophyll (Chl) and carotenoids per leaf area unit. Different N treatments did not affect the photosynthetic efficiency of photosystem 2, as reflected by the high values of Chl fluorescence kinetics Fv/Fm, ranging between 0.81 to 0.84, and Fv/F0 of 4.30 to 5.10. An increase in photochemical quenching (qP), accompanied by a decrease in non-photochemical quenching (qN), was observed in sporophytes fertilized with increased concentrations of NH4NO3. Nitrogen availability allowed sporophytes of Acrostichum aureum to become more established under natural condi tions.
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    URL: http://dx.doi.org/10.1023/A:1007055812264
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    Effects of flooding and salinity on photosynthesis and water relations of four Southeastern Coastal Plain forest species (1996)
    Springer
    Wetlands ecology and management 4 (1996), S. 31-42 
    Details
    ISSN: 1572-9834
    Keywords: baldcypress ; green ash ; flooding ; photosynthesis ; salinity ; Chinese tallow ; water relations ; water tupelo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of flooding and salinity on photosynthesis and water relations was examined for four common coastal tree species [green ash (Fraxinus pennsylvanica Marshall), water tupelo (Nyssa aquatica L.). Chinese tallow (Sapium sebiferum (L.) Roxb.), and baldcypress (Taxodium distichum (L.) Richard)]. Both chronic (as might be associated with sea level rise) and acute (similar to hurricane storm surges) exposures to these stresses were examined. Chronic freshwater flooding of green ash, water tupelo, and Chinese tallow seedlings reduced photosynthesis (A) relative to that of watered seedlings, while baldcypress was unaffected. Chinese tallow A declined with increasing length of flooding. A salinity increase of the floodwater to 2 ppt decreased A of baldcypress and water tupelo, but not A of green ash and Chinese tallow, which was already severely reduced by freshwater flooding. All seedlings of the four species died within 2 to 6 weeks when flooded with 10 ppt saltwater. Photosynthesis of all four species did not differ between 0 and 2 ppt watering. Watering with 10 ppt salinity initially reduced A of all four species, but the seedlings recovered over time. Photosynthesis was severely decreased for all species when flooded with 21 ppt salinity for 48 hours. Reduced A continued following the treatment. Photosynthesis of only green ash and water tupelo was reduced by watering with 21 ppt salinity for 48 hours. Flooding of low-lying areas with increased salinity would lead to shifts in species composition of coastal forests due to these differential tolerances.
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    URL: http://dx.doi.org/10.1007/BF01876133
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    Mechanisms of Hydroquinone-Induced Growth Reduction in Leafy Spurge (1999)
    Springer
    Journal of chemical ecology 25 (1999), S. 1611-1621 
    Details
    ISSN: 1573-1561
    Keywords: Hydroquinone ; allelopathy ; plant water balance ; photosynthesis ; chlorophyll fluorescence ; 13C isotopes ; leafy spurge ; Euphorbia esula ; small everlasting ; Antennaria microphylla Rydb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Field observations indicate leafy spurge (Euphorbia esula) is inhibited by the presence of Antennaria microphylla. Hydroquinone (HQ), one of several compounds isolated from A. microphylla has been shown to inhibit leafy spurge seed germination, root elongation, and callus culture growth. The present study was designed to analyze the effects of HQ on water relations and photosynthesis of leafy spurge. Plants grown in 0.25 mM HQ had consistently higher leaf diffusive resistance and lower transpiration rates than control plants (P 〈 0.05). Chlorophyll fluorescence was significantly lower than controls (P 〈 0.05) towards the end of the treatment period. At the end of the treatment, tissue from 0.25 mM HQ plants had higher levels of 13C, indicating there had been a sustained interference with stomatal function. These data suggest that a disruption of the plant water balance is one mechanism of leafy spurge inhibition by A. microphylla.
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    URL: http://dx.doi.org/10.1023/A:1020892917434
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    Phosphate uptake by phosphorus-starved cells of the cyanobacterium Phormidium laminosum (1997)
    Springer
    World journal of microbiology and biotechnology 13 (1997), S. 699-705 
    Details
    ISSN: 1573-0972
    Keywords: Phormidium laminosum ; phosphate uptake ; phosphorus-starved ; photosynthesis ; vanadate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Phosphorus(P)-starved cells of the cyanobacterium Phormidium laminosum have been investigated in relation to their phosphate uptake characteristics. P-deficient cells showed much higher phosphate uptake rates from ultrapure water supplemented with this anion than P-sufficient ones. After 9 days of starvation in P-free medium, the total cellular P content of P-deficient cells was approximately five times lower than that of cells grown in the presence of phosphate. Phosphate uptake by P-deficient cells occurred in both light and dark under aerobic conditions. In anaerobiosis, light was required for uptake, suggesting that the necessary energy could be derived from the respiratory electron transport chain. Phosphate uptake in P-deficient cells was sensitive to vanadate, suggesting the involvement of a plasma membrane ATPase.
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    URL: http://dx.doi.org/10.1023/A:1018583224294
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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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    Gas exchange responses of a mangrove species, Avicennia marina, to waterlogged and drained conditions (1997)
    Springer
    Hydrobiologia 352 (1997), S. 39-47 
    Details
    ISSN: 1573-5117
    Keywords: Avicennia marina ; gas exchange ; mangroves ; photosynthesis ; waterlogging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was undertaken in summer on fully expanded leaves of Avicennia marina trees in the Beachwood Mangroves Nature Reserve, Durban,South Africa. Data sets were obtained over 5–7 days of relatively dry conditions and over two periods of 5 days during which the swamp was continuously inundated with dilute seawater (〈 150 mol m−3NaCl). Gas exchange responses were strongly influenced by photosynthetic photon flux density (PPFD), leaf temperature and leaf to air vapour pressure deficit (Δw). Carbon dioxide exchange was saturated at a PPFD of about 800 µmol m−2 s−1. Maximal CO2 exchange rates ranged from 8.5 to 9.9 µmol m−2 s−1 with no differences between drained and waterlogged conditions. Under drained conditions, leaf conductance,transpiration and internal CO2 concentrations were generally lower, and water use efficiencies higher, than during waterlogging. Continuous waterlogging for 5 days had no adverse effect on CO2 exchange. Xylem water potentials ranged from −1.32to −3.53 MPa during drained and from −1.02 to −2.65 Mpa during waterlogged conditions. These results are discussed in relation to anatomical and metabolic adaptations of A. marina to waterlogging stress.
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    URL: http://dx.doi.org/10.1023/A:1003088803335
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    Phycoerythrins of the oxyphotobacterium Prochlorococcus marinus are associated to the thylakoid membrane and are encoded by a single large gene cluster (1999)
    Springer
    Plant molecular biology 40 (1999), S. 507-521 
    Details
    ISSN: 1573-5028
    Keywords: cyanobacteria ; immunogold labelling ; light-harvesting complexes ; photosynthesis ; phycobilins ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An intrinsic divinyl-chlorophyll a/b antenna and a particular form of phycobiliprotein, phycoerythrin (PE) III, coexist in the marine oxyphotobacterium Prochlorococcus marinus CCMP 1375. The genomic region including the cpeB/A operon of P. marinus was analysed. It encompasses 10 153 nucleotides that encode three structural phycobiliproteins and at least three (possibly five) different polypeptides analogous to cyanobacterial or red algal proteins involved either in the linkage of subunits or the synthesis and attachment of chromophoric groups. This gene cluster is part of the chromosome and is located within a distance of less than 110 kb from a previously characterized region containing the genes aspA-psbA-aroC. Whereas the Prochlorococcus phycobiliproteins are characterized by distinct deletions and amino acid replacements with regard to analogous proteins from other organisms, the gene arrangement resembles the organization of phycobiliprotein genes in some other cyanobacteria, in particular marine Synechococcus strains. The expression of two of the Prochlorococcus polypeptides as recombinant proteins in Escherichia coli allowed the production of individual homologous antisera to the Prochlorococcus α and β PE subunits. Experiments using these sera show that the Prochlorococcus PEs are specifically associated to the thylakoid membrane and that the protein level does not significantly vary as a function of light irradiance or growth phase.
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    URL: http://dx.doi.org/10.1023/A:1006252013008
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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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    URL: http://dx.doi.org/10.1007/BF00010281
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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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    URL: http://dx.doi.org/10.1007/BF00011785
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    Abscisic acid concentrations are correlated with leaf area reductions in two salt-stressed rapid-cycling Brassica species (1996)
    Springer
    Plant and soil 179 (1996), S. 25-33 
    Details
    ISSN: 1573-5036
    Keywords: abscisic acid ; Brassica napus ; Brassica carinata ; callus ; photosynthesis ; plant growth ; salinity ; salt tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The greater sensitivity of B. carinata to salinity in comparison to B. napus has been linked to a greater reduction in net assimilation rate. Apparently this is not due to ion toxicity; the cause is unknown. In this report, we test the hypothesis that increases in abscisic acid (ABA) are involved in the reduction of growth by salinity. Salinity (8 dS m−1) caused an increase of ABA concentrations in the shoot, root and callus of both species. ABA concentrations were lower in the salt-tolerant species, B. napus, than the salt-sensitive species, B. carinata, both in the whole plant and callus. Leaf expansion for both species was equally sensitive to ABA; salt stress did not significantly alter sensitivity to applied ABA. The growth inhibition increased in a hyperbolic manner with an increase in endogenous ABA concentration. These results indicate that ABA in salt-stressed plants may play a role in the inhibition of growth. The photosynthesis of salt-sensitive species, B. carinata, was also decreased by salinity, corresponding to the reduction in growth. The decreased photosynthesis does not appear to be the cause of the growth reduction, because photosynthesis was not inhibited by short-term exposure to salinity and photosynthesis was poorly correlated with endogenous ABA concentrations.
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    Seasonal and spatial patterns in phytoplankton photosynthetic parameters in a tidal freshwater river (1997)
    Springer
    Hydrobiologia 364 (1997), S. 199-208 
    Details
    ISSN: 1573-5117
    Keywords: Phytoplankton ; photosynthesis ; light ; temperature ; tidal freshwater ; irradiance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic response to irradiance wasquantified for phytoplankton from the tidalfreshwater Potomac River biweekly to monthly over aperiod of six years. Samples were collected from twoshallow embayments and portions of the deeper rivermainstem. Photosynthetic rate was measured in thelaboratory at in situ temperature over a range ofirradiance levels and photosynthetic parameters werecalculated using nonlinear regression.PB max,the maximum photosynthetic ratestandardized to chlorophyll a, increased withtemperature up to 25 °C with a Q10 of 2.02. Above 25 °C, PB max was essentiallyconstant with temperature. Lesser correlationbetween PB max and ambient irradiance couldbe explained by the correlation of irradiance withtemperature. α, the slope of the P–I curve atlow light, was correlated with both ambientirradiance and temperature. Highest α valueswere found in late summer when high temperature andintermediate ambient irradiance were observed. Spring and early summer were characterized by lowα. Despite low light penetration, Ik andα values were indicative of sun limitationpossibly due to intermittent high light levelsexperienced during mixing. Ik showed a clearseasonal trend directly related to days from summersolstice. Spatial patterns were minimal except thatIk was consistently lower in one shallowembayment than in the other two areas. Seasonalpatterns in photosynthetic parameters correspondedroughly to changes from a spring diatom populationto summer cyanobacterial assemblage.
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    URL: http://dx.doi.org/10.1023/A:1003107306421
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    Application of photorespiration concepts to whole stream productivity (1998)
    Springer
    Hydrobiologia 389 (1998), S. 7-19 
    Details
    ISSN: 1573-5117
    Keywords: photosynthesis ; respiration ; photorespiration ; diel oxygen curve ; macrophytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We conducted two-station diel surveys of dissolved oxygen content to estimate whole-stream productivity in the experimental streams of the Monticello Ecological Research Station for two years following channel reconstruction. Community productivity measurements compare well to previous measurements in these streams, but apparent hysteresis in the P/I relation was measured in over two-thirds of the diel surveys. Apparent hysteresis in photosynthesis with solar irradiance is a characteristic of photorespiration, and modeling the effect of light on whole-stream respiratory rates reduced the magnitude of P/I curve hysteresis and improved the predictions of dissolved oxygen content (DO) in the stream. Stream productivity models normally assume respiratory rates measured at night are constant throughout the day, but when this assumption yields apparent hysteresis in the P/I curve, the inclusion of a photorespiration model in the analyses of whole-stream productivity facilitates the comparison of photosynthesis and respiratory rates between different streams. The computed total daily consumption of oxygen by photorespiratory processes is proportional to the total daily photosynthetic production of oxygen in the streams. We also found that the diel DO curves occurring in the experimental streams are best described by a photorespiration model that utilizes a four hour moving average of irradiance. Accounting for photorespiration in the streams increases the apparent efficiency of photosynthesis, improves the accuracy of DO predictions, and reduces uncertainty in photosynthesis and respiratory rate estimates.
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    URL: http://dx.doi.org/10.1023/A:1003519302002
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    Relationship of CO2 concentrations to photosynthesis of intertidal macroalgae during emersion (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 355-359 
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    ISSN: 1573-5117
    Keywords: CO2 ; emersion ; macroalgae ; photosynthesis ; seaweeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to assess the ecological impacts of the atmospheric CO2 increase on the intertidal macroalgae during emersion, the photosynthesis of Enteromorpha linza (a green alga), Ishige okamurae (a brown alga) and Gloiopeltis furcata (a red alga) was investigated in air as a function of CO2 concentrations and water loss. Their photosynthesis was not saturated at the present atmospheric CO2 level (350 μl l −1 or 15.6 μM), the CO2 compensation point and $$K_{[{\text{mCO}}_{\text{2}} ]} $$ increased with increasing desiccation, showing that desiccation lowers the CO2 affinity of the intertidal macroalgae. It was concluded that E. linza, I. okamurae and G. furcata, while exposed to air, can benefit from atmospheric CO2 rise, especially when the algae have lost some water.
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    URL: http://dx.doi.org/10.1023/A:1017072303189
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    Photosynthetic and respiratory responses of the agarophyte Gelidiella acerosa collected from tidepool, intertidal and subtidal habitats (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 321-328 
    Details
    ISSN: 1573-5117
    Keywords: photosynthesis ; respiration ; Gelidiella acerosa ; culture ; tidal habitat ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several samples of the red seaweed, Gelidiella acerosa (Forssk.) Feldmann & Hamel occurring in tidepools, high intertidal rocks, and shallow subtidal areas on a reef flat in Ilocos Norte, northern Philippines were studied in terms of their photosynthetic and respiratory responses (μl O2 gDW−1 h−1) to four salinity (22, 28, 34, 40‰) and three temperature (22, 28, 34 °C) combinations. The upper intertidal plants tolerated low salinities (22–28‰) better than high salinities (34–40‰), while tidepool and subtidal plants were not affected. Temperatures of 22 through 34 °C resulted in a one-fold increase in their photosynthetic rates and insignificant differences in their respiratory rates while tidepool and subtidal plants almost doubled their photosynthetic rates and their respiration rates increased by about 5–50 times. There were no interaction effects. Therefore, intertidal plants appe ared to be more tolerant to wide temperature fluctuations and low salinity levels; while tidepool and subtidal plants were least affected by salinity variations but were quite sensitive to temperature fluctuations. Vegetative and tetrasporic plants had similar photosynthetic and respiratory responses to salinity and temperature variations, although vegetative plants had significantly higher net photosynthesis under the minimum and maximum temperatures tested (22 and 34 °C). Reproductive G. acerosa showed greater tolerance to temperature fluctuations. These responses indicated that physiological changes may have occurred when the species became reproductive. Tolerance of G. acerosa to low salinities suggests that lowering the salinities in culture tanks could be used to eradicate contaminants, i.e., dinoflagellates and filamentous green algae. Temperature of 28 °C appeared to be optimum for all plant types as reflected by their high photosynthetic and low respiratory rates .
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    A theoretical analysis and field evaluation of a light and temperature model of production by Ecklonia cava (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 361-373 
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    ISSN: 1573-5117
    Keywords: production ; mathematical model ; Ecklonia cava ; light ; temperature ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dependence of photosynthesis on light and temperature is modelled through analysis of transition probabilities of photosystems. In the model, two transition probabilities are functions of light, and one transition probability is a function of temperature. The estimated light-saturated photosynthesis of Ecklonia cava blades at 20 °C was 0.037 mg C cm−2 h−1. The value of the activation energy, the standard enthalpy and the standard entropy were estimated to be 56.5 kJ mol−1, 204 kJ mol−1 and 678 J mol−1 K−1, respectively. A production model (an integral photosynthesis model) for an E. cava stand was developed using the photosynthesis model. Production calculated by the model agreed well with observed data during the growing period of an E. cava stand at a field observation site on the west side of Miura Peninsula, Japan. Results of the analysis of the effects of irradiance and temperature on the production of the E. cava community by the model are: 1. Production decreased with irradiance decrease. The estimated compensation irradiance was 26.5 μmol photons m−2 s−1 when the biomass was 3 kg wet mass m−2 (blade:stipe ratio = 2 kg m−2:1 kg m−2) and the temperature was 20 °C. 2. The optimum temperature decreased when irradiance decreased and when biomass increased. The highest estimated value for the optimum temperature was 24.0 °C. The estimated optimum temperature was 18.2 °C when the biomass was 12 kg wet mass m−2 and the photon irradiance was 200 μmol photons m−2 s−1. 3. The amount of biomass that resulted in the maximum production was influenced by irradiance and temperature. At 400 μmol photons m−2 s−1 and 20 °C, the estimated value of the biomass (blade:stipe = 2:1) giving the maximum pr oduction was about 5.3 kg wet mass m−2. However, at 100 μmol photons m−2 s−1 and 24 °C, the estimated value was about 3.0 kg wet mass m−2. The estimated values of the maximum production under the two conditions were 1.05 and 0.30 g C m−2 h−1, respectively.
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    New method for toxicity assessment in marine and brackish environments using the macroalga Gracilaria tenuistipitata (Gracilariales, Rhodophyta) (1996)
    Springer
    Hydrobiologia 326-327 (1996), S. 317-325 
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    ISSN: 1573-5117
    Keywords: biotest ; brackish ; Gracilaria ; growth inhibition ; marine ; photosynthesis ; Rhodophyta ; seaweed ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A growth inhibition test method was developed using the macroalga Gracilaria tenuistipitata as the test organism. This alga was chosen because of its high laboratory growth rates, commonly 30–40% d−1, which are reached in salinities between 5 and 40‰, and its epiphyte resistance. The toxicity of a number of substances, including heavy metals, herbicides and complex wastewaters towards the alga was assayed. Anti-fouling paints were tested with a modification of the method. EC50 values for heavy metals varied between 0.05 and 17 mg l−1 and for herbicides between 0.002 and 0.02 mg l−l. The sensitivity to the toxicant was generally higher at low salinity. Omitting nitrogen and phosphorus additions to the test medium increased the sensitivity and a semi-static performance was possible with maintained or increased sensitivity. Preliminary tests done with a computerised photosynthesis inhibition method produced promising results. In conclusion, this is a simple, sensitive and reproducible test method for assessing the toxicity of substances, wastewaters and anti-fouling paints in brackish and marine environments.
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    Photosynthetic plasticity in Potamogeton pectinatus L. from Argentina: strategies to survive adverse light conditions (1996)
    Springer
    Hydrobiologia 340 (1996), S. 1-5 
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    ISSN: 1573-5117
    Keywords: light climate manipulation ; Potamogeton pectinatus ; photosynthesis ; turbidity ; weed management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Argentine Potamogeton pectinatus L. was grown in The Netherlands under laboratory conditions at four light intensities (50, 100, 150 and 200 µE m−2 s−1), and photosynthetic performance was evaluated after about 1, 2 and 3 months of growth. At these moments, chlorophyll-a and -b and tissue N and P content were also determined. During the growing period, plant lengths and number of secondary shoots were measured. In the field in Argentina, photosynthetic performance of P. pectinatus was also measured at different light intensities created by artificial shading at various times during the growing season. Field and laboratory photosynthetic results were in good agreement. P. pectinatus showed a significant plasticityin its photosynthesis, rather than in morphology. A fairly constant maximum photosynthetic rate with reduced light enabled the plants to maintain netproduction rates rather unaffected at low light intensities. Still, it can be predicted that increasing turbidity from 1–2 m−1 at present to 3 m−1 could lead to a strongly light-limited growth which should reduce the present weed problem considerably. Such a turbidity increase might be achieved by the introduction of a fairly dense bottom-feeding fish population like Common carp (Cyprinus carpio L.).
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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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    Interactive effects of elevated carbon dioxide and growth temperature on photosynthesis in cotton leaves (1998)
    Springer
    Plant growth regulation 26 (1998), S. 33-40 
    Details
    ISSN: 1573-5087
    Keywords: carbohydrates ; elevated CO2 ; Gossypium hirsutum L. ; interaction ; photosynthesis ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cotton (Gossypium hirsutum L., cv DPL 5415) plants were grown in naturally lit environment chambers at day/night temperature regimes of 26/18 (T-26/18), 31/23 (T-31/23) and 36/28 °C (T-36/28) and CO2 concentrations of 350 (C-350), 450 (C-450) and 700 μL L-1 (C-700). Net photosynthesis rates, stomatal conductance, transpiration, RuBP carboxylase activity and the foliar contents of starch and sucrose were measured during different growth stages. Net CO2 assimilation rates increased with increasing CO2 and temperature regimes. The enhancement of photosynthesis was from 24 μmol CO2 m-2 s-1 (with C-350 and T-26/18) to 41 μmol m-2 s-1 (with C-700 and T-36/28). Stomatal conductance decreased with increasing CO2 while it increased up to T-31/23 and then declined. The interactive effects of CO2 and temperature resulted in a 30% decrease in transpiration. Although the leaves grown in elevated CO2 had high starch and sucrose concentrations, their content decreased with increasing temperature. Increasing temperature from T-26/18 to 36/28 increased RuBP carboxylase activity in the order of 121, 172 and 190 μmol mg-1 chl h-1 at C-350, C-450 and C-700 respectively. Our data suggest that leaf photosynthesis in cotton benefited more from CO_2 enrichment at warm temperatures than at low growth temperature regimes.
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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 
    Details
    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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    Chlorophyll fluorescence as an indicator of frost hardiness in white spruce seedlings from different latitudes (1996)
    Springer
    New forests 11 (1996), S. 233-253 
    Details
    ISSN: 1573-5095
    Keywords: variable chlorophyll fluorescence ; frost hardiness ; freezing damage ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study examined the utility of variable chlorophyll fluorescence (Fvar) to detect freezing damage in white spruce seedlings of four seedlots. Logistic regression analysis done for freezing tests in September showed that visible needle damage from freezing could be estimated by the Fvar attributes Fo/IABS(r2=0.94), Fp(r2=0.98), Fv/Fm (r2=0.99), and F1(r2=0.86). The regression curves indicated that for all four fluorescence attributes, inflection points occurred between 10 and 20% visible needle damage. The lack of a relationship between fluorescence attributes and visible seedling needle damage in October through December is because the minimum temperature (−18 and −24°C respectively) applied was insufficient to cause needle damage. Freezing-induced changes to Fvar attributes can be detected which also result in photosynthetic rate decreases when no visible needle damage, and even electrolyte conductivity changes are evident. Fvar attribute differences due to freezing can be resolved to the seedlot level. The Fvar curve feature manifested 5 seconds after dark-adapted seedlings have been exposed to light (F5s) will estimate (r2=0.76) photosynthetic rate after freezing.
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    The dependance of root growth potential on light level, photosynthetic rate, and root starch content in jack pine seedlings (1997)
    Springer
    New forests 13 (1997), S. 105-119 
    Details
    ISSN: 1573-5095
    Keywords: field performance potential ; photosynthesis ; Pinus banksiana ; root initiation ; root starch ; seedling testing ; total nonstructural carbohydrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Number of new roots (root growth potential or RGP), new root length, photosynthesis, total nonstructural carbohydrate content of needles and roots, terminal bud condition, and shoot elongation were measured on jack pine container seedlings for 4 weeks at weekly intervals under greenhouse conditions of 100%, 20%, and 10% sunlight to simulate competition-induced, lower light levels in the field. Both lower light levels significantly reduced photosynthetic rate, RGP, new root length, total nonstructural carbohydrate (especially starch) content of needles and roots, speed of terminal bud flush, and shoot growth. Both light level and photosynthetic rate were positively correlated with RGP and new root length, indicating that jack pine seedlings may use current photosynthate as an energy source to support new root growth. RGP and new root length were also both negatively correlated with root starch content suggesting that jack pine seedlings may also use stored carbohydrates as a potential carbon source for root initiation and initial root growth.
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    Mepiquat chloride (PIX)-induced changes in photosynthesis and growth of cotton (1996)
    Springer
    Plant growth regulation 20 (1996), S. 179-183 
    Details
    ISSN: 1573-5087
    Keywords: cotton ; growth ; mepiquat chloride ; photosynthesis ; PIX ; RuBP carboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mepiquat chloride (N, N-dimethylpiperidinium chloride), well known as PIX, is a potential systemic plant growth regulator. The effects of PIX on plant height, stem elongation, leaf area, net photosynthetic rates, chlorophyll content, sucrose and starch levels, and RuBP carboxylase activity in cotton (Gossypium hirsutum L. cv. DES 119) plants were measured. PIX was sprayed (0, 7.65, 15.3, 30.6 or 61.2 g active ingredient ha−1) on the plants at first square (25 days after emergence) and measurements were made at frequent intervals. Plant height was clearly reduced by PIX. The total length of vegetative branches and fruiting branches was 40% and 50% less than the control. Total leaf area in PIX treated plants was 16% less than the control. Net photosynthetic rates were 25% less in PIX-treated leaves. PIX treated leaves had more chlorophyll content. The activity of RuBP carboxylase was decreased in PIX treated plants. Starch accumulation was noticed in PIX treated leaves while sucrose content was not changed. The data reported here suggest that reduced growth responses induced by PIX results in partial loss of photosynthetic capacity in cotton at least up to 20 days after application of the growth regulator.
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    URL: http://dx.doi.org/10.1007/BF00043305
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    The modification of phytosterol profiles and in vitro photosynthetic electron transport of Galium aparine L. (cleavers) treated with the fungicide, epoxiconazole (1997)
    Springer
    Plant growth regulation 22 (1997), S. 93-100 
    Details
    ISSN: 1573-5087
    Keywords: epoxiconazole ; Galium aparine L. ; photosynthesis ; phytosterols ; thylakoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Foliar application of the triazole fungicide, epoxiconazole, retarded the growth of Galium aparine L. (cleavers). GC-MS and GC analysis clearly indicated that phytosterol biosynthesis in stem and leaflet tissue was significantly affected by this treatment. For example, in leaflet tissues, 125 g ai ha-1 (field rate) caused reductions in campesterol and sitosterol of 81percnt; and 75percnt; respectively. C14-methyl phytosterols such as 14agr;-methylergost-8-enol, obtusifoliol and dihydroobtusifoliol were detected in treated tissues indicating that epoxiconazole inhibits the cytochrome P-450 dependent obtusifoliol 14agr;-demethylase. In addition, ratios of campesterol to sitosterol were reduced. Stigmasterol was not detected in control or treated tissues. Preliminary determination of photosynthetic characteristics of isolated thylakoids from treated plants indicated that electron transport and oxygen evolution were impaired by epoxiconazole and these effects were dose-related. Ten days after treatment, oxygen evolution from thylakoids (determined as electron flow from water to ferricyanide) isolated from control plants was 24.2 micro;mol mg-1 chl h-1, whilst treatment with 125 g and 250 g ai ha-1 reduced this rate to 15.2 micro;mol and 8.2 micro;mol mg-1 chl h-1 an inhibition of 37 and 67percnt; respectively. These results suggest that epoxiconazole influences thylakoid integrity and function in addition to phytosterol biosynthesis in G. aparine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005885312748
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    Growth at high CO2 affects the chloroplast number but not the photosynthetic efficiency of photoautotrophicMarchantia polymorpha culture cells (1997)
    Springer
    Plant cell, tissue and organ culture 48 (1997), S. 103-110 
    Details
    ISSN: 1573-5044
    Keywords: bryophytes ; cell culture ; chlorophyll content ; LHC II ; photosynthesis ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoautotrophic suspension cells of Marchantia polymorpha were grown at gas phase CO2 concentrations of 0.4% and 2.0%. At the higher CO2 concentration the chloroplast shape appeared to be modified and the cells had about 70% more chloroplasts per cell. Differences in chlorophyll content per cell were much less pronounced, indicating a reduction in chlorophyll content per chloroplast. Also the cell size was affected by the CO2 concentration, and our data suggest that it was about 37% lower in high CO2 grown cells than in low CO2 grown cells. The capacity and the efficiency of photosynthetic oxygen evolution on a chlorophyll basis and the photosystem II chlorophyll fluorescence parameters were almost identical in both cell types. Immunodection showed that also the ratio of light harvesting complex II antenna proteins and ribulose 1,5 bisphosphate carboxylase/oxygenase were unaltered. These data indicate that the chloroplast density within photoautotrophic culture cells may be regulated independently of their photosynthetic efficiency.
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    URL: http://dx.doi.org/10.1023/A:1005893311140
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    Development of photoautotrophy and photoinhibition of Gardenia jasminoides plantlets during micropropagation (1996)
    Springer
    Plant cell, tissue and organ culture 45 (1996), S. 1-16 
    Details
    ISSN: 1573-5044
    Keywords: chlorophyll fluorescence ; leaf anatomy ; photosynthesis ; root induction ; shoot multiplication ; stable carbon isotope composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper reports on the fast fluorescence responses of Gardenia jasminoides Ellis plantlets, at two successive stages (shoot multiplication and root induction) of culture in vitro. We test whether plantlets in vitro suffer photoinhibition during culture and whether the degree of photoautotrophy of these mixotrophic plantlets has any effect on the extent of photoinhibitory impairment. In this regard the effects of different sucrose levels in the medium and PPFD during growth on the development of photoautotrophy and the extent of photoinhibition were evaluated. Plantlets were grown under low, intermediate, and high (50, 100, and 300 μmol m-2 s-1) PPFD, and at 3 different sucrose concentrations (0.5, 1.5, and 3.0%, w/v) in the medium, during shoot multiplication. During root induction the same growth conditions were assayed except for the high PPFD. The development of photoautotrophy was assessed via the difference between the stable carbon isotope composition of sucrose used as heterotrophic carbon source and that of leaflets grown in vitro. Plantlets from root induction showed more developed photoautotrophy than those from shoot multiplication. For both stages the low-sucrose medium stimulated the photoautotrophy of plantlets in vitro. In addition, intermediate PPFD induced photoautotrophy during shoot multiplication. For plantlets of both culture stages at the lowest PPFD no photoinhibition occurred irrespective of the sucrose concentration in media. However, during the shoot multiplication stage chlorophyll fluorescence measurements showed a decrease in F v /F m and in t 1/2 as growing PPFD increased, indicating photoinhibitory damage. The decline of F v /F m was caused mostly by an increase in F o , indicating the inactivation of PSII reaction centers. However plantlets growing under low sucrose showed reduced susceptibility to photoinhibition. During root induction, only plantlets cultured with high sucrose showed a decrease in F v /F m as PPFD increased, although t 1/2 remained unchanged. In this case, the decline of F v /F m was mostly due to a decrease in F m , which indicates increased photoprotection rather than occurrence of photodamage. Therefore, growth in low-sucrose media had a protective effect on the resistance of PSII to light stress. In addition, plantlets were more resistant to photoinhibition during root induction than during shoot multiplication. Results suggest that increased photoautotrophy of plantlets reduces susceptibility to photoinhibition during gardenia culture in vitro.
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    URL: http://dx.doi.org/10.1007/BF00043422
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    Inheritance and mapping of a light green mutant in cultivated diploid potatoes (1998)
    Springer
    Euphytica 103 (1998), S. 83-88 
    Details
    ISSN: 1573-5060
    Keywords: chlorophyll ; lethal ; marker gene ; photosynthesis ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A light green mutant was found in a population of adapted cultivated diploid potatoes. Genetic analysis indicates that this trait is controlled by a single nuclear gene. The gene symbol lg is proposed. The segregation ratios fit a pattern which strongly suggest that there is a close linkage between the Lg allele and a locus which confers lethality in its homozygous recessive state. Some crossing over between the lg locus and the lethal was found to occur but LgLg genotypes were not observed in progenies from sib-matings. The lg locus mapped to the potato linkage group VI between the restriction fragment length polymorphism (RFLP) loci CP18 and GP24.
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    URL: http://dx.doi.org/10.1023/A:1018373726995
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    Effect of genome and ploidy on photosynthesis of wheat (1997)
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    Euphytica 94 (1997), S. 303-309 
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    ISSN: 1573-5060
    Keywords: photosynthesis ; hexaploid wheat ; A genome ; D genome ; polyploidy ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We assessed (1) the effects of addition and doses of the D genome from different sources and (2) the addition of either the A genome or the D genome on the photosynthesis of synthesized hexaploid wheats. On average, the increased doses of the D genome reduced photosynthesis, but the depression was dependent on the source of the D genome. Two accessions of Aegilops squarrosa had depressed photosynthetic rates, but not another accession of Ae. squarrosa. The D genome of cv. Thatcher did not contribute to depress photosynthetic rate. Triticum monococcum had considerably higher photosynthetic rates than Ae. squarrosa. However, addition of the A genome from T. monococcum did not increase the photosynthetic rates of hexaploids. Chlorophyll a : b ratio, functional photosystem II and the core complex of photosystem II did not account for the variation in photosynthetic rate among the genotypes studied. In our experiment, photosynthesis of polyploids was not dependent on photosynthesis rates of the donor genomes.
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    URL: http://dx.doi.org/10.1023/A:1002936019332
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    One thing leading to another (1995)
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    Photosynthesis research 46 (1995), S. 45-46 
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    ISSN: 1573-5079
    Keywords: phosphoenolpyruvate carboxylase ; photophosphorylation ; photosynthesis ; respiration ; sugar biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020415
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    Energy transfer for low temperature fluorescence in PS II mutant thylakoids (1995)
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    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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    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 
    Details
    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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    The structure and function of the chloroplast photosynthetic membrane — a model for the domain organization (1995)
    Springer
    Photosynthesis research 46 (1995), S. 141-149 
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    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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    Evidence of singlet oxygen evolution by whole living cells of Chlamydomonas reinhardtii (1996)
    Springer
    Photosynthesis research 47 (1996), S. 99-102 
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    ISSN: 1573-5079
    Keywords: Chlamydomonas ; photosynthesis ; singlet oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The oxygen evolved by Chlamydomonas reinhardtii in the light is measured simultaneously with a Clark electrode and with the nitrosodimethylaniline-imidazole colorimetric method which is specific for singlet oxygen. Experiments with wild-type and FuD7 mutant cells (unable to synthesize the D1 protein of Photosystem II), with dichlorophenyldimethylurea (which blocks electron transfer from Photosystem II to Photosystem I) and with dibromothymoquinone (which diverts electrons from their normal path between the two photosystems), as well as with hydroxylamine (an inactivator of the water-splitting part of Photosystem II and a competitor of water for electron donation to it), all point to the dependence of detected singlet oxygen on photolysis of water by Photosystem II.
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    Two forms of the Photosystem II D1 protein alter energy dissipation and state transitions in the cyanobacterium Synechococcus sp. PCC 7942 (1996)
    Springer
    Photosynthesis research 47 (1996), S. 131-144 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; electron transport ; light-acclimation ; light-harvesting ; photosynthesis ; quenching analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Synechococcus sp. PCC 7942 (Anacystis nidulans R2) contains two forms of the Photosystem II reaction centre protein D1, which differ in 25 of 360 amino acids. D1: 1 predominates under low light but is transiently replaced by D1:2 upon shifts to higher light. Mutant cells containing only D1:1 have lower photochemical energy capture efficiency and decreased resistance to photoinhibition, compared to cells containing D1:2. We show that when dark-adapted or under low to moderate light, cells with D1:1 have higher non-photochemical quenching of PS II fluorescence (higher qN) than do cells with D1:2. This is reflected in the 77 K chlorophyll emission spectra, with lower Photosystem II fluorescence at 697–698 nm in cells containing D1:1 than in cells with D1:2. This difference in quenching of Photosystem II fluorescence occurs upon excitation of both chlorophyll at 435 nm and phycobilisomes at 570 nm. Measurement of time-resolved room temperature fluorescence shows that Photosystem II fluorescence related to charge stabilization is quenched more rapidly in cells containing D1:1 than in those with D1:2. Cells containing D1:1 appear generally shifted towards State II, with PS II down-regulated, while cells with D1:2 tend towards State I. In these cyanobacteria electron transport away from PS II remains non-saturated even under photoinhibitory levels of light. Therefore, the higher activity of D1:2 Photosystem II centres may allow more rapid photochemical dissipation of excess energy into the electron transport chain. D1:1 confers capacity for extreme State II which may be of benefit under low and variable light.
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    Self quenching of chlorosome chlorophylls in water and hexanol-saturated water (1996)
    Springer
    Photosynthesis research 47 (1996), S. 207-218 
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    ISSN: 1573-5079
    Keywords: aggregate ; antenna ; atomic force microscopy ; bacteriochlorophyllc ; chlorosome ; concentration quenching ; energy transfer ; green bacteria ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The optical properties of a methyl ester homolog of bacteriochlorophylld (BChld M ) and bacteriochlorophyllc (BChlc) in H2O, hexanol-saturated H2O and methanol were studied by absorption, fluorescence emission, and circular dichroism (CD). In H2O, BChld M spontaneously forms an aggregate similar to that formed in hexane, with absorption maximum at 730 nm and fluorescence emission at 748 nm. For the pigment sample in hexanol-saturated H2O, while the absorption peaks at 661 nm, only slightly red-shifted compared to the monomer, the fluorescence emission is highly quenched. When diluted 2–3 fold with H2O, the absorption returns to around 720 nm, characteristic of an aggregate. The CD spectrum of the H2O aggregate exhibits a derivative-shaped feature with positive and negative peaks, while the amplitude is lower than that of chlorosomes. The Fourier transform infrared spectra of BChld M aggregates in H2O and hexane were measured. A 1644 cm−1 band, indicative of a bonded 131-keto group, is detected for both samples. A marker band for 5-coordinated Mg was observed at 1611 cm−1 for the two samples as well. To study the kinetic behavior of the samples, both single-photon counting (SPC) fluorescence and transient absorption difference spectroscopic measurements were performed. For BChld M in hexanol-saturated H2O, a fast decay component with a lifetime of 10 to 14 ps was detected using the two different techniques. The fast decay could be explained by the concentration quenching phenomenon due to a high local pigment concentration. For the pigment sample in H2O, SPC gave a 16 ps component, whereas global analysis of transient absorption data generated two fast components: 3.5 and 26 ps. The difference may arise from the different excitation intensities. With a much higher excitation in the latter measurements, other quenching processes, e.g. annihilation, might be introduced, giving the 3.5 ps component. Finally, atomic force microscopy was used to examine the ultrastructure of BChld M in H2O and hexanol-saturated H2O. Pigment clusters with diameters ranging from 15 to 45 nm were observed in both samples.
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    Chromatic regulation inChlamydomonas reinhardtii alters photosystem stoichiometry and improves the quantum efficiency of photosynthesis (1996)
    Springer
    Photosynthesis research 47 (1996), S. 253-265 
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    ISSN: 1573-5079
    Keywords: Chlamydomonas reinhardtii ; chromatic acclimation ; photosynthesis ; photosystem stoichiometry ; quantum yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The work addressed the adjustment of the photosystem ratio in the green algaChlamydomonas reinhardtii. It is shown that green algae, much like cyanophytes and higher plants, adjust and optimize the ratio of the two photosystems in chloroplasts in response to the quality of irradiance during growth. Such adjustments are compensation reactions and helpC. reinhardtii to retain a quantum efficiency of oxygen evolution near the theoretical maximum. Results show variable amounts of PS I and a fairly constant amount of PS II in chloroplasts and suggest that photosystem stoichiometry adjustments, occurring in response to the quality of irradiance during plant growth, are mainly an adjustment in the concentration of PS I. The work delineates chromatic effects on chlorophyll accumulation in the chloroplast ofC. reinhardtii from those pertaining to the regulation of the PS I/PS II ratio. The detection of the operation of a molecular feedback mechanism for the PS I/PS II ratio adjustment in green algae strengthens the notion of the highly conserved nature of this mechanism among probably all oxygen evolving photosynthetic organisms. Findings in this work are expected to serve as the basis of future biochemical and mutagenesis experiments for the elucidation of the photosystem ratio adjustment in oxygenic photosynthesis.
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    On the relation between absorption and fluorescence emission spectra of photosystems: Derivation of a Stepanov relation for pigment culsters (1996)
    Springer
    Photosynthesis research 48 (1996), S. 139-145 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; energy transfer ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stepanov (1957a, Soviet Physics-Doklady 2: 81–84) obtained an equation which relates the absorption spectrum and the fluorescence emission spectrum of a single dye molecule. Here, a similar equation is derived for a cluster of interacting pigments, e.g. the antenna pigments of a photosystem. This relation can be used to assess the possibility of occurrence of rapid exciton equilibration (Dau and Sauer, 1996, Biochim. Biophys. Acta, 1273: 175–190). The excited state potential of a pigment cluster is discussed and compared to the excited state potential of a single pigment.
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    Chimaeric CP47 mutants of the cyanobacterium Synechocystis sp. PCC 6803 carrying spinach sequences: Construction and function (1996)
    Springer
    Photosynthesis research 48 (1996), S. 147-162 
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    ISSN: 1573-5079
    Keywords: gene replacement ; Photosystem II ; photosynthesis ; thylakoid membranes ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimaeric mutants of the cyanobacterium Synechocystis sp. PCC 6803 have been generated carrying part or all of the spinach psbB gene, encoding CP47 (one of the chlorophyll-binding core antenna proteins in Photosystem II). The mutant in which the entire psbB gene had been replaced by the homologous gene from spinach was an obligate photoheterotroph and lacked Photosystem II complexes in its thylakoid membranes. However, this strain could be transformed with plasmids carrying selected regions of Synechocystis psbB to give rise to photoautotrophs with a chimaeric spinach/cyanobacterial CP47 protein. This process involved heterologous recombination in the cyanobacterium between psbB sequences from spinach and Synechocystis 6803; which was found to be reasonably effective in Synechocystis. Also other approaches were used that can produce a broad spectrum of chimaeric mutants in a single experiment. Functional characterization of the chimaeric photoautotrophic mutants indicated that if a decrease in the photoautotrophic growth rates was observed, this was correlated with a decrease in the number of Photosystem II reaction centers (on a chlorophyll basis) in the thylakoid membrane and with a decrease in oxygen evolution rates. Remaining Photosystem II reaction centers in these chimaeric mutants appeared to function rather normally, but thermoluminescence and chlorophyll a fluorescence measurements provided evidence for a destabilization of QB −. This illustrates the sensitivity of the functional properties of the PS II reaction center to mild perturbations in a neighboring protein.
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    Excitation energy transfer in the green photosynthetic bacterium Chloroflexus aurantiacus: A specific effect of 1-hexanol on the optical properties of baseplate and energy transfer processes (1996)
    Springer
    Photosynthesis research 48 (1996), S. 263-270 
    Details
    ISSN: 1573-5079
    Keywords: Chloroflexus aurantiacus ; chlorophyll ; chlorosome ; energy transfer ; green bacteria ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of 1-hexanol on spectral properties and the processes of energy transfer of the green gliding photosynthetic bacterium Chloroflexus aurantiacus was investigated with reference to the baseplate region. On addition of 1-hexanol to a cell suspension in a concentration of one-fourth saturation, a specific change in the baseplate region was induced: that is, a bleach of the 793-nm component, and an increase in absorption of the 813-nm component. This result was also confirmed by fluorescence spectra of whole cells and isolated chlorosomes. The processes of energy transfer were affected in the overall transfer efficiency but not kinetically, indicating that 1-hexanol suppressed the flux of energy flow from the baseplate to the B806-866 complexes in the cytoplasmic membranes. The fluorescence excitation spectrum suggests a specific site of interaction between bacteriochlorophyll (BChl) c with a maximum at 771 nm in the rod elements and BChl a with a maximum at 793 nm in the baseplate, which is a funnel for a fast transfer of energy to the B806-866 complexes in the membranes. The absorption spectrum of chlorosomes was resolved to components consistently on the basis, including circular dichroism and magnetic circular dichroism spectra; besides two major BChl c forms, bands corresponding to tetramer, dimer, and monomer were also discernible, which are supposed to be intermediary components for a higher order structure. A tentative model for the antenna system of C. aurantiacus is proposed.
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    URL: http://dx.doi.org/10.1007/BF00041017
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    Halcyon days with Bill Arnold (1996)
    Springer
    Photosynthesis research 48 (1996), S. 11-18 
    Details
    ISSN: 1573-5079
    Keywords: aging ; delayed light production ; firefly ATP assay ; plant luminescence ; loss of rDNA ; luminous bacteria ; neuronal memory storage and pulse pattern coding ; organic mass spectroscopy ; plant luminescence ; photosynthetic ATP production ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The circumstances that led to the discovery that plants luminesce after they are illuminated are described, as are other discoveries that would not have been possible were it not for the fortuitous association I had with my dear and most admirable friend, W.A. Arnold, to whom this special issue is dedicated.
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    Acclimation of photosynthesis to elevated CO2 through feedback regulation of gene expression: Climate of opinion (1996)
    Springer
    Photosynthesis research 48 (1996), S. 353-365 
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    ISSN: 1573-5079
    Keywords: catabolite repression ; glucose sensing ; high CO2 acclimation ; Lycopersicon esculentum ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although down-regulation of photosynthesis in higher C3 plants exposed to long-term elevated CO2 has been recognized in plants with low sink activity or poor nutrient status, the underlying molecular mechanisms remain unclear. This review covers aspects of rising CO2 on plant productivity in general, and then focuses on photosynthesis, biochemistry (stroma and thylakoid proteins, Rubisco activities and metabolites), and gene expression in tomato plants grown under ambient or elevated CO2. Taking into account these data and the recent discovery that glucose triggers repression of photosynthetic gene transcription, a molecular mechanism is proposed for feedback regulation of photosynthesis under high CO2. Different living organisms such as bacteria, yeast, and mammals have been investigated for the sensing mechanisms of the carbohydrate status of their cells, and this information is used together with some recent data obtained for plants to propose how hexose levels might be sensed in higher plant cells.
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    URL: http://dx.doi.org/10.1007/BF00029468
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    Kinetic and functional characterization of a membrane-bound NAD(P)H dehydrogenase located in the chloroplasts of Pleurochloris meiringensis (Xanthophyceae) (1996)
    Springer
    Photosynthesis research 49 (1996), S. 183-193 
    Details
    ISSN: 1573-5079
    Keywords: algae ; chlororespiration ; NAD(P)H: plastoquinone oxidoreductase ; photosynthesis ; chloroplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using isolated chloroplasts or purified thylakoids from photoautotrophically grown cells of the chromophytic alga Pleurochloris meiringensis (Xanthophyceae) we were able to demonstrate a membrane bound NAD(P)H dehydrogenase activity. NAD(P)H oxidation was detectable with menadione, coenzyme Q0, decylplastoquinone and decylubiquinone as acceptors in an in vitro assay. K m-values for both pyridine nucleotides were in the μmolar range (K m[NADH]=9.8 μM, K m[NADPH]=3.2 μM calculated according to Lineweaver-Burk). NADH oxidation was optimal at pH 9 while pH dependence of NADPH oxidation showed a main peak at 9.8 and a smaller optimum at pH 7.5–8. NADH oxidation could be completely inhibited with rotenone, an inhibitor of mitochondrial complex I dehydrogenase, while NADPH oxidation revealed the typical inhibition pattern upon addition of oxidized pyridine nucleotides reported for ferredoxin: NADP+ reductase. Partly-denaturing gel electrophoresis followed by NAD(P)H dehydrogenase activity staining showed that NADPH and NADH oxidizing proteins had different electrophoretic mobilities. As revealed by denaturing electrophoresis, the NADH oxidizing enzyme had one main subunit of 22 kDa and two further polypeptides of 29 and 44 kDa, whereas separation of the NADPH depending protein yielded five bands of different molecular weight. Measurement of oxygen consumption due to PS I mediated methylviologen reduction upon complete inhibition of PS II showed that the NAD(P)H dehydrogenase is able to catalyze an input of electrons from NADH to the photosynthetic electron transport chain in case of an oxidized plastoquinone-pool. We suggest ferredoxin: NADP+ reductase to be the main NADPH oxidizing activity while a thylakoidal NAD(P)H: plastoquinone oxidoreductase involved in the chlororespiratory pathway in the dark acts mainly as an NADH oxidizing enzyme.
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    The role of chromophore coupling in tuning the spectral properties of peripheral light-harvesting protein of purple bacteria (1996)
    Springer
    Photosynthesis research 50 (1996), S. 5-10 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; antenna complex ; LH2 ; bacteriochlorophyll
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The publication of a structure for the peripheral light-harvesting complex of a purple photosynthetic bacterium (McDermott et al. (1995), Nature 374: 517–521) provides a framework within which we can begin to understand various functional aspects of these complexes, in particular the relationship between the structure and the red-shift of the bacteriochlorophyll Qy transition. In this article we describe calculations of some of the spectral properties expected for an array of chromophores with the observed geometry. We report the stability of the calculated absorption spectrum to minor structural alterations, and deduce that the observed red shift of the 850 nm Qy transition in the B800–850 antenna complexes is about equally attributable to chromophore-chromophore and chromophore-protein interactions, while chromophore-chromophore interactions predominate in generating the red-shift of the 820 nm Qy transition in B800–820 type peripheral liggt-harvesting complexes. Finally we suggest that the red shift in the absorbance of the monomeric Bchl a found in antenna complexes to 800 nm, from 770 nm as observed in most solvents, is largely attributable to a hydrogen bond with the 2-acetyl group of this chromophore.
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    URL: http://dx.doi.org/10.1007/BF00018216
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    A comparative flash-photolysis study of electron transfer from pea and spinach plastocyanins to spinach Photosystem 1. A reaction involving a rate-limiting conformational change (1996)
    Springer
    Photosynthesis research 50 (1996), S. 11-21 
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    ISSN: 1573-5079
    Keywords: blue copper protein ; gated electron transfer ; photosynthesis ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two mutants of plastocyanin have been constructed by site-directed mutagenesis in spinach and pea to elucidate the binding and electron transfer properties between plastocyanin and spinach Photosystem 1. The conserved, surface-exposed Tyr-83 has been replaced by phenylalanine and leucine in plastocyanin from both species and the proteins have been expressed in Escherichia coli. The reaction mechanism of electron transfer from plastocyanins to photooxidized P700 in Photosystem 1 has been studied by laser-flash absorption spectroscopy. The experimental data were interpreted with a model involving a rate-limiting conformational change, preceding the intracomplex electron transfer. The pea proteins show an overall facilitated reaction with spinach Photosystem 1, compared to spinach plastocyanins. The changes are small but significant, indicating a more efficient electron transfer within the transient complex. In addition, for the spinach leucine mutant, the equilibrium within the plastocyanin-Photosystem 1 complex is more displaced towards the active conformation than for the corresponding wild-type. Absorption spectra, EPR and reduction potentials for the mutants are similar to those of the corresponding wild-type, although small shifts are observed in the spectra of the Tyr83Leu proteins. Based on these results, it is suggested that Photosystem 1 from spinach is capable of using both pea and spinach plastocyanin as an efficient electron donor and that the former even can stimulate the Photosystem 1 reduction. The origin of the stimulation is discussed in terms of differences in surface-exposed residues. Since the effects of the mutations are small, it can be concluded that electron transfer to Photosystem 1 does not occur via Tyr-83.
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    The relationship of intercompartmental excitation transfer rate constants to those of an underlying physical model (1996)
    Springer
    Photosynthesis research 50 (1996), S. 117-131 
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    ISSN: 1573-5079
    Keywords: compartment theory ; electronic excitation transport ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In studies on photosynthetic systems it is common practice to interpret the results of time-resolved fluorescence experiments on the basis of compartmental, or target, models. Each compartment represents a group of molecules with similar fluorescence characteristics. In cases of practical interest, the members of each compartment are spatially contiguous and make up part of an overall energy-transferring system. Since a rate constant describing the overall transfer between compartments is not that of any pair of molecules in the system, this question naturally rises: what do we learn about the microscopic structure from these data? In this note we introduce ‘compartment melting’, a smooth mathematical connection between the compartmental and microscopic levels. We then show, on the basis of model calculations on finite lattices in one, two, and three dimensions, that average microscopic rates at the interfaces between compartments may be estimated from observed intercompartmental rates. The estimate involves a modest number of structural assumptions about the system. As examples of the method, which is applicable mainly to systems containing homogeneous pigment pools, some recent chlorophyll-protein antenna studies are analyzed.
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    Leaflet photosynthesis rate and carbon metabolite accumulation patterns in nitrogen-limited, vegetative soybean plants (1996)
    Springer
    Photosynthesis research 50 (1996), S. 133-148 
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    ISSN: 1573-5079
    Keywords: anaplerotic carbon metabolites ; dark respiration ; hexose phosphates ; nitrogen-limitation ; orthophosphate ; photosynthesis ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Prolonged inorganic nitrogen (NO3 −+NH4 +) limitation of non-N2-fixing soybean plants affected leaflet photosynthesis rates, photosynthate accumulation rates and levels, and anaplerotic carbon metabolite levels. Leaflets of nitrogen-limited (N-Lim), 27–31-day-old plants displayed ≈ 15 to 23% lower photosynthesis rates than leaflets of nitrogen-sufficient (N-Suff) plants. In contrast, N-Lim plant leaflets displayed higher sucrose and starch levels and rates of accumulation, as well as higher levels of carbon metabolites associated with sucrose and starch synthesis, e. g., glycerate-3-phosphate and glucose phosphates, than N-Suff plant leaflets. Concurrently, levels of soluble protein, chlorophyll, and anaplerotic metabolites, e.g., malate and phosphoenolpyruvate, were lower in leaflets of N-Lim plants than N-Suff plants, suggesting that the enzymes of the anaplerotic carbon metabolite pathway were lower in activity in N-Lim plant leaflets. Malate net accumulation rates in the earliest part of the illumination period were lower in N-Lim than in N-Suff plant leaflets; however, by the midday period, malate accumulation rate in N-Lim plant leaflets exceeded that in leaflets of N-Suff plants. Further, soluble protein accumulation rates in leaflets of N-Suff and N-Lim plants were similar, and the rate of dark respiration, measured in the early part of the dark period, was higher in N-Lim plant leaflets than in N-Suff plant leaflets. It was concluded that during prolonged N-limitation, foliar metabolite conditions favored the channelling of a large proportion of the carbon assimilate into sucrose and starch, while assimilate flow through the anaplerotic pathway was diminished. However, in some daytime periods, there was a normal level of carbon assimilate channelled through the anaplerotic pathway for ultimate use in amino acid and protein synthesis.
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    Analysis of the chloroplast protein complexes by blue-native polyacrylamide gel electrophoresis (BN-PAGE) (1997)
    Springer
    Photosynthesis research 53 (1997), S. 35-44 
    Details
    ISSN: 1573-5079
    Keywords: b 6 f complex ; chloroplast ATP synthase ; light-harvesting complexes ; photosynthesis ; photosystems ; ribulose-bisphosphate carboxylase/oxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blue-native polyacrylamide gel electrophoresis (BN-PAGE) is a powerful procedure for the separation and characterization of the protein complexes from mitochondria. Membrane proteins are solubilized in the presence of aminocaproic acid and n-dodecylmaltoside and Coomassie-dyes are utilized before electrophoresis to introduce a charge shift on proteins. Here, we report a modification of the procedure for the analysis of chloroplast protein complexes. The two photosystems, the light-harvesting complexes, the ATP synthase, the cytochrome b 6 f complex and the ribulose-bisphosphate carboxylase/oxygenase are well resolved. Analysis of the protein complexes on a second gel dimension under denaturing conditions allows separation of more than 50 different proteins which are part of chloroplast multi-subunit enzymes. The resolution capacity of the blue-native gels is very high if compared to 'native green gel systems' published previously. N-terminal amino acid sequences of single subunits can be directly determined by cyclic Edman degradation as demonstrated for eight proteins. Analysis of chloroplast protein complexes by blue-native gel electrophoresis will allow the generation of 'protein maps' from different species, tissues and developmental stages or from mutant organelles. Further applications of blue-native gel electrophoresis are discussed.
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    URL: http://dx.doi.org/10.1023/A:1005882406718
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    Determination of the quenching efficiency of the oxidized primary donor of Photosystem I, P700+: Implications for the trapping mechanism (1997)
    Springer
    Photosynthesis research 54 (1997), S. 237-240 
    Details
    ISSN: 1573-5079
    Keywords: fluorescence induction ; fluorescence yield ; photosynthesis ; P700 ; internal conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1023/A:1005981016835
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    Formation of the tight-binding inhibitor, 3-ketoarabinitol-1,5-bisphosphate by ribulose-1,5-bisphosphate carboxylase/oxygenase is O2-dependent (1998)
    Springer
    Photosynthesis research 55 (1998), S. 67-74 
    Details
    ISSN: 1573-5079
    Keywords: epimerization ; isomerization ; inhibitor binding ; photosynthesis ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) (EC 4.1.1.39) not only catalyzes carboxylation and oxygenation of ribulose-1,5-bisphosphate (RuBP), but it can also act either as an epimerase or isomerase converting RuBP into xylulose-1,5-bisphosphate (XuBP) or 3-ketoarabinitol-1,5-bisphosphate (KABP), respectively, a process called misfire. XuBP is formed as a result of misprotonation at C3 of the RuBP-enediol. It is released from Rubisco active sites and accumulates in the reaction mixture. Increasing the amounts of CO2 or O2 decreases XuBP production. However, KABP synthesis, which has been proposed to be only a product due to C2 misprotonation of the RuBP-endiol, is dependent upon the presence of O2. KABP remains tightly bound to Rubisco active sites after its formation, causing the loss of Rubisco activity (‘fallover’). The results suggest that the non-stabilized form of the peroxy-intermediate in the oxygenase reaction can be converted in a backreaction to KABP and molecular oxygen. The stabilization of the peroxy-intermediate due to the presence of Mn2+ instead of Mg2+ eliminates the formation of KABP.
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    Symmetry-related mutants in the quinone binding sites of the bacterial reaction center – the effects of changes in charge distribution (1998)
    Springer
    Photosynthesis research 55 (1998), S. 275-280 
    Details
    ISSN: 1573-5079
    Keywords: electron transfer ; phenotypic revertants ; photosynthesis ; proton transfer ; site-specific mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To probe the structural elements that contribute to the functional asymmetries of the two ubiquinone10 binding pockets in the reaction center of Rhodobacter capsulatus, we targeted the L212Glu–L213Asp (near QB) and the M246Ala-M247Ala (near QA) pairs of symmetry-related residues for site-specific mutagenesis. We have constructed site-specific mutants that eliminate the sequence differences at these positions (L212Glu–L213Asp→Ala-Ala or M246Ala–M247Ala→Glu-Asp), and have reversed that asymmetry by constructing a quadruple-mutant strain, ‘RQ’ (L212Glu–L213Asp-M246Ala–M247Ala→Ala-Ala-Gl u-Asp). The mutations were designed to change the charge distribution in the quinone-binding region of the reaction center; none of the strains is capable of photosynthetic growth. In photocompetent phenotypic revertants of the RQ strain, second-site mutations which affect QB function are coupled to mutations in the QA site which restore an Ala or substitute a Tyr at the M247 site; one strain carries an additional Met→Leu substitution at M260 near QA. All of the RQ revertants retain the engineered M246Ala→Glu mutation in the QA site as well as the L212Ala–L213Ala mutations in the QB site. Kinetic characterization of the RQ revertants will give us an idea of what structural and functional elements are important for restoring efficiency to electron and proton transfer pathways in the RQ RC, which is far from native. To date, these preliminary results underscore the importance of an asymmetric distribution of polar amino acids in the quinone binding pockets and its influence on the functional properties of the reaction center.
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    URL: http://dx.doi.org/10.1023/A:1005901510444
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    Free energy dependence of the direct charge recombination from the primary and secondary quinones in reaction centers from Rhodobacter sphaeroides (1998)
    Springer
    Photosynthesis research 55 (1998), S. 227-233 
    Details
    ISSN: 1573-5079
    Keywords: electron transfer ; hydrogen bond ; photosynthesis ; purple bacteria ; recombination rates ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The direct charge recombination rates from the primary quinone, k AD (D+Q A − → DQA) and the secondary quinone, k BD (D+Q B − → DQB), in reaction centers from Rhodobacter sphaeroides were measured as a function of the free energy differences for the processes, ΔG AD 0 and ΔG BD 0 , respectively. Measurements were performed at 21 °C on a series of mutant reaction centers that have a wide range of dimer midpoint potentials and consequently a large variation in ΔG AD 0 and ΔG BD 0 . As –ΔG AD 0 varied from 0.43 to 0.78 eV, k AD varied from 4.6 to 28.6 s−1. The corresponding values for the wild type are 0.52 eV and 8.9 s−1. Observation of the direct charge recombination rate k BD was achieved by substitution of the primary quinone with naphthoquinones in samples in which ubiquinone was present at the secondary quinone site, resulting specifically in an increase in the free energy of the D+Q A − state relative to the D+QAQ B − state. As –ΔG BD 0 varied from 0.37 to 0.67 eV, k BD varied from 0.03 to 1.4 s−1. The corresponding values for the wild type are 0.46 eV and 0.2 s−1. A fit of the two sets of data to the Marcus theory for electron transfer yielded significantly different reorganization energies of 0.82 and 1.3 eV for k AD and k BD, respectively. In contrast, the fitted values for the coupling matrix element, or equivalently the maximum possible rate, were comparable (∼25 s−1) for the two charge recombination processes. These results are in accord with QB having more interactions with dipoles, from both the surrounding protein and bound water molecules, than QA and with the primary determinant of the maximal rate being the quinone-donor distance.
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    Photosynthetic electrogenic events in native membranes of Chloroflexus aurantiacus. Flash-induced charge displacements in the acceptor quinone complex of the photosynthetic reaction center (1998)
    Springer
    Photosynthesis research 56 (1998), S. 75-82 
    Details
    ISSN: 1573-5079
    Keywords: electrometry ; electron transfer ; membrane ; menaquinone ; photosynthesis ; potential ; proton transfer ; Rhodobacter sphaeroides ; Rhodopseudomonas viridis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The thermophilic phototroph Chloroflexus aurantiacus possesses a photosynthetic reaction center (RC) containing a pair of menaquinones acting as primary (MQa) and secondary (MQB) electron acceptors and a tetraheme cytochrome c554 as an electron donor. We used native, chlorosome-containing photosynthetic membranes of this bacterium to study the MQB turnover. The binary oscillations of the semiquinone form MQB − in response to a train of short light flashes were monitored at 416 nm, in the isosbestic point of the light-induced difference spectrum of cytochrome c554. After the first flash MQB − was formed, after the second one it disappeared due to the MQa −MQB − → MQaMQBH2 transition. The latter reaction was kinetically resolved by means of electrometry. For this purpose chromatophores of Chl. aurantiacus were adsorbed onto a phospholipid and menaquinone-impregnated collodion film. We found that after the second excitation flash, but not after the first one, the photoelectric response included, in addition to the fast kinetic components reflecting the charge separation between the tetraheme cytochrome c and MQa, a slower kinetic component with a rise time of 3 µs (pH = 8.3) and a relative amplitude of about 10% of the charge separation phase in the RC. We attributed this reaction to the electrogenic proton transfer which accompanied the transfer of the second electron during the MQa −MQB − → MQaMQBH2 transition. The rise time of the same reaction was reported to be almost three orders of magnitude slower in the isolated, proteoliposome-incorporated RC from this bacterium. The possible reasons of the faster turnover rates observed in the chlorosome-carrying native membrane preparations from Chl. aurantiacus are discussed.
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    Photosystem-II repair and chloroplast recovery from irradiance stress: relationship between chronic photoinhibition, light-harvesting chlorophyll antenna size and photosynthetic productivity in Dunaliella salina (green algae) (1998)
    Springer
    Photosynthesis research 56 (1998), S. 175-184 
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    ISSN: 1573-5079
    Keywords: chlorophyll antenna size ; damage and repair cycle ; Dunaliella salina ; photoinhibition ; photosynthesis ; Photosystem-II ; photosystem stoichiometry ; productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High-light (HL) grown Dunaliella salina cells exhibit lower pigment content, a highly truncated chlorophyll (Chl) antenna size, and accumulation of photodamaged PS II centers in the chloroplast thylakoids (chronic photoinhibition). In HL-grown cells, the rate of photosynthesis saturated at higher irradiances and the quantum yield was lower compared to that of normally-pigmented low-light (LL) grown cells. In spite of these deficiencies, the light-saturated rate of photosynthesis for the HL-cells, when measured on a per chlorophyll basis, was ∼3 times greater than that of the LL-grown cells. To delineate the effect of photoinhibition from the Chl antenna size on quantum yield and rate of photosynthesis, HL-acclimated cells were switched to LL-conditions. Repair of photodamaged PS II, estimated from the recovery of functional PS II centers and from the increase in the quantum yield of photosynthesis, occurred with a half-time of ∼1 h. Chlorophyll accumulation in the cells occurred with a half-time of ∼4 h. The differential kinetics in repair versus Chl accumulation provided a ‘window of opportunity’, within about 2–3 h after the HL→LL shift, when cells exhibited a high quantum yield of photosynthesis, a small Chl antenna size and a light-saturated rate that was ∼6–9 times greater than that of the normally pigmented LL-grown cells. The work provides insight on the temporal sequence of events at the chloroplast and thylakoid membrane levels, leading from a chronic photoinhibition of PS II to repair and recovery. It is suggested that it is possible to maximize photosynthetic productivity and light utilization in mass microalgal cultures by minimizing the light-harvesting Chl antenna size of the photosystems.
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    URL: http://dx.doi.org/10.1023/A:1006024827225
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    Nonstructural carbohydrates of soybean plants grown in subambient and superambient levels of CO2 (1998)
    Springer
    Photosynthesis research 56 (1998), S. 143-155 
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    ISSN: 1573-5079
    Keywords: carbon dioxide ; Glycine max ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Elevated carbon dioxide (CO2) concentration increases plant photosynthesis, biomass and carbohydrate accumulation. Since plants have grown in low CO2 (200 to 300 µmol mol−1) for the last several million years, how will they use extra photoassimilate as the atmospheric CO2 continues to rise? The objectives were to determine the effects of past, present and projected future levels of CO2 on diurnal and seasonal patterns of total nonstructural carbohydrate (TNC) concentration of soybean [Glycine max (L.) Merr.] tissues. Plants were grown at 160, 220, 280, 330, 660 and 990 µmol mol−1 CO2 in outdoor, sunlit chambers wherein CO2 uptake rates were measured continuously. Early morning and late afternoon plant samples were taken at eight dates. The TNC concentration of leaves, petioles and stems increased as CO2 increased. Canopy photosynthetic rates also increased with increasing CO2, apparently without any negative impact of increased leaf TNC. Concentrations of TNC in all vegetative tissues were lower in the morning than the afternoon, which indicates overnight mobilization and utilization of carbohydrates for growth processes. The concentration of TNC was lowest in all plant components during rapid vegetative growth at V8 to R2 developmental stages. Leaves of all plants, especially those grown in superambient CO2, contained large pools of TNC at plant maturity, which indicated that not all of the reserves were utilized for seed yield. Soybean cultivars for the future should be designed to utilize carbohydrates more readily for seed production so that greater benefit can be realized from rising atmospheric CO2.
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    URL: http://dx.doi.org/10.1023/A:1006016009305
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    Photosystem I-dependent cyclic electron flow in intact spinach chloroplasts: Occurrence, dependence on redox conditions and electron acceptors and inhibition by antimycin A (1998)
    Springer
    Photosynthesis research 57 (1998), S. 61-70 
    Details
    ISSN: 1573-5079
    Keywords: electron transport ; nitrite ; oxaloacetate ; photosynthesis ; proton transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem I-dependent cyclic electron transport is shown to operate in intact spinach chloroplasts with oxaloacetate, but not with nitrite or methylviologen as electron acceptors. It is regulated by the redox state of the chloroplast NADP system. Inhibition of cyclic electron transport by antimycin A occurs immediately on addition of this antibiotic in the light. It is unrelated to a different function of antimycin A, inhibition of nonphotochemical quenching of chlorophyll fluorescence, which requires prior dissipation of the transthylakoid proton gradient before antimycin A can become effective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006072230864
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    Effects of high temperatures on the photosynthetic systems in spinach: Oxygen-evolving activities, fluorescence characteristics and the denaturation process (1998)
    Springer
    Photosynthesis research 57 (1998), S. 51-59 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; high-temperature stress ; O2 evolution ; photosynthesis ; Photosystem II ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Activities of oxygen evolution, fluorescence Fv (a variable part of chlorophyll fluorescence) values, and amounts of the 33 kDa protein remaining bound to the thylakoids in intact spinach chloroplasts were measured during and after high-temperature treatment. The following results were obtained. (1) Both the Fv value and the flash-induced oxygen evolution measured by an oxygen electrode were decreased at high temperatures, but they showed partial recovery when the samples were cooled down and incubated at 25°C for 5 min after high-temperature treatment. (2) Oxygen evolution was more sensitive to high temperatures than the Fv value, and the decrease in the Fv/Fm ratio at high temperatures rather corresponded to that in the oxygen evolution measured at 25°C after high-temperature treatment. (3) Photoinactivation of PS II was very rapid at high temperatures, and this seems to be a cause of the difference between the Fv values and the oxygen-evolving activities at high temperatures. (4) At around 40°C, the manganese-stabilizing 33 kDa protein of PS II was supposed to be released from the PS II core complexes during heat treatment and to rebind to the complexes when the samples were cooled down to 25°C. (5) At higher temperatures, the charge separation reaction of PS II was inactivated, and the PS II complexes became less fluorescent, which was recovered partially at 25°C. (6) Increases in the Fv value due to a large decrease in the electron flow from QA to QB became prominent after high-temperature treatment at around 50°C. This was the main cause of the discrepancy between the Fv values and the oxygen-evolving activities measured at 25°C. Relationship between the process of heat inactivation of PS II reaction center complexes and the fluorescence levels is discussed.
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    URL: http://dx.doi.org/10.1023/A:1006019102619
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    Massive breakdown of the Photosystem II polypeptides in a mutant of the cyanobacterium Synechocystis sp. PCC 6803 (1998)
    Springer
    Photosynthesis research 57 (1998), S. 81-91 
    Details
    ISSN: 1573-5079
    Keywords: D1 degradation fragments ; D1 proteolysis ; photosynthesis ; thylakoid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Degradation of the D1 protein of the Photosystem II (PS II) complex was studied in the Fad6/desA::Kmr mutant of a cyanobacterium Synechocystis sp. PCC 6803. The D1 protein of the mutant was degraded during solubilization of thylakoid membranes with SDS at 0°C in darkness, giving rise to the 23 kDa amino-terminal and 10 kDa carboxy-terminal fragments. Moreover, the D2 and CP43 proteins were also degraded under such conditions of solubilization. Degradation of the D2 protein generated 24, 17 and 15.5 kDa fragments, and degradation of the CP43 protein gave rise to 28, 27.5, 26 and 16 kDa fragments. The presence of Ca2+ and urea protected the D1, D2 and CP43 proteins against degradation. Degradation of the D1 protein was also inhibited by the presence of a serine protease inhibitor suggesting that the putative protease involved belonged to the serine class of proteases. The protease had the optimum activity at pH 7.5; it was active at low temperature (0°C) but a brief heating (65°C) during solubilization destroyed the activity. Interestingly, the protease was active in isolated thylakoid membranes in complete darkness, suggesting that proteolysis may be a non-ATP-dependent process. Proteolytic activity present in thylakoid membranes seemed to reside outside of the PS II complex, as demonstrated by the 2-dimensional gel electrophoresis. These results represent the first (in vitro) demonstration of strong activity of a putative ATP-independent serine-type protease that causes degradation of the D1 protein in cyanobacterial thylakoid membranes without any induction by visible or UV light, by active oxygen species or by any chemical treatments.
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    URL: http://dx.doi.org/10.1023/A:1006039929839
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    Alterations in Photosystem II electron transport as revealed by thermoluminescence of Cu-poisoned chloroplasts (1998)
    Springer
    Photosynthesis research 57 (1998), S. 175-181 
    Details
    ISSN: 1573-5079
    Keywords: copper ; electron transport ; photosynthesis ; TyrosineZ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The thermoluminescence characteristics of functionally intact thylakoids and TRIS-washed BBY particles were studied under Cu(II) poisoned conditions. In thylakoids, both the A and B thermoluminescence bands corresponding to S3QA - and S2S3QB - charge recombinations, respectively showed specific responses to Cu(II) treatment. The amplitude of the B band was gradually decreased, which corresponds to the Cu(II) induced inactivation of TyrZ. The simultaneous stepwise shift in the peak position of the B band indicated, however, that S3QB - charge recombination is more resistant to Cu(II) poisoned conditions. The shifted peak position of the A band toward the higher temperature in Cu(II) treated thylakoids also showed a change in the redox span between the recombination partners generating the A band of the glow curve. The AT band due to the His+QA - recombination in TRIS-washed BBY particles was insensitive to Cu(II) addition indicating that Cu(II) did not affect either His+ or QA -. The unaffected intensity of the A and AT bands when Cu(II) inhibits TyrZ function favours the assumption of an alternative pathway in which functional TyrZ is not required. In addition, Cu-induced changes of the TL bands were compared to those produced by the Tyr and His modifiers NBD and DEPC, respectively. We obtained very similar results regarding TL bands by either adding NBD or Cu-poisoning in functional thylakoids. Regarding DEPC, the A and AT bands were abolished by increasing concentrations of the His modifier. This effect was associated with the decrease of the B band and its replacement by the Q band at around 0 °C. Comparing our data obtained by Cu, NBD and DEPC treatments, we have found a strong interrelation between His+ and S3 state. We assume that in some inhibitory conditions in the S3 state His is oxidized in place of Mn and this alternative pathway does not require functional TyrZ.
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    URL: http://dx.doi.org/10.1023/A:1006051815176
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    Characterization of the Photosystem I subunits PsaI and PsaL from two strains of the marine oxyphototrophic prokaryote Prochlorococcus (1998)
    Springer
    Photosynthesis research 57 (1998), S. 183-191 
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    ISSN: 1573-5079
    Keywords: cyanobacteria ; photosynthesis ; Photosystem I ; prochlorophyte ; psaI ; psaL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 25 kDa protein associated with Photosystem I (PS I) of the divinyl-chlorophyll a/b-containing oxychlorobacterium Prochlorococcus marinus SS120 (CCMP 1375) was isolated, and the amino acid sequences of the N-terminus and one internal peptide were determined. Polymerase chain reaction (PCR) with degenerate primers yielded a 92 bp fragment, which was used to isolate the complete gene from a genomic library. The corresponding gene was isolated from a library of Prochlorococcus sp. MED4 (CCMP 1378). In both Prochlorococcus strains, the gene encodes a protein of 199 amino acids. The gene products show a strong sequence similarity to the PS I subunit PsaL. The N-terminus contains a hydrophilic domain that has not been found in PsaL proteins from other organisms. In both strains, sequences encoding a protein similar to PsaI were found upstream of the psaL gene. Both genes are transcribed in the same direction.
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    URL: http://dx.doi.org/10.1023/A:1006098510768
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    The effect of Photosystem II inhibitors DCMU and BNT on the high-light induced D1 turnover in two cyanobacterial strains Synechocystis PCC 6803 and Synechococcus PCC 7942 (1998)
    Springer
    Photosynthesis research 57 (1998), S. 193-202 
    Details
    ISSN: 1573-5079
    Keywords: herbicides ; photoinhibition ; photosynthesis ; protein degradation and synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the Photosystem II (PSII) inhibitors dichlorophenyldimethylurea (DCMU) and bromonitrothymol (BNT) on the rate of the high-light induced D1 protein turnover was studied in whole cells of two cyanobacterial strains Synechocystis PCC 6803 and Synechococcus PCC 7942. In Synechocystis the D1 degradation was slowed down to a similar extent in the presence of either inhibitor compared with control cells. This slower degradation corresponded with the retardation of Photosystem II photoinactivation (PSIIPI) measured as a decline of PS II activity in the illuminated cells treated with chloramphenicol (CAP). The ongoing D1 synthesis in the presence of both PS II inhibitors was confirmed by unchanging PS II activity and the steady-state level of D1 during illumination in the absence of CAP. In Synechococcus cells both DCMU and BNT blocked the turnover of the 'low-light' D1 form (D1:1) but did not prevent the exchange of the 'high-light' form D1:2 for the D1:1 form. The similar effect of both herbicides on the D1 exchange was in contrast with their influence on the rate of PSIIPI. While DCMU had a pronounced protective effect, BNT significantly increased the rate of PS II photodamage. The fast BNT-induced decline of PS II activity was also observed in Synechocystis cells treated with azide, an inhibitor of reactive oxygen species scavenging enzymes. Therefore, we assume that the distinct sensitivity of the two cyanobacterial strains to BNT can be caused by different content and/or activity of these enzymes in each strain.
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    URL: http://dx.doi.org/10.1023/A:1006015214868
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    Characterization of a chloroplast inner envelope P-ATPase proton pump (1998)
    Springer
    Photosynthesis research 57 (1998), S. 323-333 
    Details
    ISSN: 1573-5079
    Keywords: ATPase phosphorylation ; chloroplast ; envelope ATPase ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract P-ATPases such as the plasma membrane proton pump are known to generate a phosphorylated intermediate as a step in their reaction mechanism; phosphoenzyme formation is a basis for classification of an ATPase as a member of this subfamily of ion pumps. The chloroplast inner envelope is known to contain a H+-ATPase which acts to maintain an alkaline stroma and, thus, optimal photosynthesis. Our characterization of this chloroplast envelope proton pump described in this report focused on determining whether purified chloroplast inner envelope membrane protein preparations containing this ATPase form a phosphorylated intermediate. Incubation of envelope membranes with [γ-32P]ATP documented the formation of P-type ATPase phosphoenzyme intermediates by these membrane protein preparations. Our work cannot discount the possibility that more than one chloroplast inner envelope ATPase contributes to this phosphoenzyme formation. However, the kinetics of this phosphoenzyme formation, along with the sensitivity of phosphoenzyme formation to inhibitors and other assay conditions suggested that one of the envelope membrane proteins which is covalently radiolabeled by [γ-32P]ATP is a P-type H+-ATPase. Autoradiography of chloroplast envelope membrane proteins size fractionated on lithium dodecyl sulfate-PAGE indicated that the phosphoenzyme intermediate corresponds to a 103 kDa polypeptide. P-type proton pumps are known to be comprised of a single type of ∼100 kDa subunit. Experimental evidence presented in this report is consistent with the classification of a chloroplast inner envelope H+-ATPase as a P-type proton pump.
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    URL: http://dx.doi.org/10.1023/A:1006081309068
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    Diurnal rhythms in metabolism: A day in the life of a unicellular, diazotrophic cyanobacterium (1998)
    Springer
    Photosynthesis research 58 (1998), S. 25-42 
    Details
    ISSN: 1573-5079
    Keywords: circadian rhythms ; fluorescence ; gene regulation ; N2 fixation ; photosynthesis ; state transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract N2 fixation and oxygenic photosynthesis are important metabolic processes that are at odds with each other, since the N2-fixing enzyme, nitrogenase, is highly sensitive to oxygen. This review will discuss the strategies devised by the unicellular, diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142, to permit N2 fixation and photosynthesis to coexist in the same cell. This strain, like a number of other unicellular and filamentous (non-heterocystous) cyanobacteria, has developed a type of temporal regulation in which N2 fixation and photosynthesis occur at different times throughout a diurnal cycle. For nitrogenase, everyday dawns anew. The nifHDK operon is tightly regulated, such that transcription and translation occur within the first four hours of the dark period; nitrogenase is then proteolytically degraded. Photosynthesis also varies throughout the day reaching a minimum at the peak of nitrogenase activity and a maximum by late afternoon. This review will mainly concentrate on the various changes that occur in the photosynthetic apparatus as the cell modulates O2 evolution. The results indicate that the redox poise of the plastoquinone pool and the overall cellular energy needs are the basic driving forces behind these changes in the photosynthetic apparatus. Throughout the course of the diurnal cycle, Photosystem II becomes very heterogeneous as determined by 77 K fluorescence spectra, PAM fluorescence and O2-flash yield experiments. This system provides some important insight into cyanobacterial state transitions and, especially, on the organization of the photosystems within the membrane. Overall, PS II is altered on both the oxidizing and reducing sides of the photosystem.
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    URL: http://dx.doi.org/10.1023/A:1006137605802
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    Studies on photoacoustic uptake signals in tobacco leaves under high carbon dioxide levels (1998)
    Springer
    Photosynthesis research 58 (1998), S. 293-302 
    Details
    ISSN: 1573-5079
    Keywords: CO2 solubilization ; carbonic anhydrase ; Far-red light ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoacoustic signals were measured in expanded tobacco leaves, exposed to a controlled atmosphere by being only partly enclosed within the photoacoustic cell. It was aimed to corroborate the conjecture of Reising and Schreiber (Photosynthesis Research 42: 65-73, 1994) that under exceptionally high CO2 levels (ca. 1–5%) the photobaric uptake contribution reflects CO2 uptake induced by light dependent stromal alkalinization. This is shown here by: (1) the shallower damping of the uptake signal vs. the modulation frequency, compared to a normal oxygen evolution signal; (2) the partial inhibition of the uptake signal under 5% CO2 by nigericin; (3) the complete absence of uptake signals under 5% CO2 in a carbonic-anhydrase-deficient mutant, which gave rather a normal oxygen evolution signal. The photoacoustic signals from the wild type and the transgenic tobacco in air could not be distinguished, indicating that the CO2 uptake signal is negligible under this condition. Uptake photobaric signals were also measured in modulated far-red light (ca. 715–750 nm), following addition of white background light (in light limiting intensity). In normal tobacco under 5% CO2, the background light induced an uptake transient, lasting about a minute, then declining to a low steady level. Significantly smaller transients were obtained under normal air, and in the carbonic-anhydrase deficient mutant also under 5% CO2. Extrapolation to zero frequency of the signal damping vs. modulation frequency, in both tobacco genotypes, suggests however similar magnitudes of the uptake transients. On the other hand, no proportional steady-state uptake was observed for the last two cases. Presumably, the steady uptake under 5% CO2 in modulated far-red light reflects CO2 solubilization, while it is an open question whether the transient could be partly contributed also by oxygen photoreduction by PS I (Mehler reaction). It is reasoned that, under conditions of low light, the respiratory activity results in accumulation of CO2 in the photoacoustic cell, which is sufficient to induce an uptake phenomenon, giving a more satisfactory interpretation for the so-called 'low light state' [Cananni and Malkin (1984) Biochim Biophys Acta 766: 525–532].
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    URL: http://dx.doi.org/10.1023/A:1006184626089
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    Heat sensitivity of chloroplasts and leaves: Leakage of protons from thylakoids and reversible activation of cyclic electron transport (1999)
    Springer
    Photosynthesis research 59 (1999), S. 81-93 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; cyclic electron flow ; high temperature ; light scattering ; photosynthesis ; Photosystems II and I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In illuminated intact spinach chloroplasts, warming to and beyond 40 °C increased the proton permeability of thylakoids before linear electron transport through Photosystem II was inhibited. Simultaneously, antimycin A-sensitive cyclic electron transport around Photosystem II was activated with oxygen or CO2, but not with nitrite as electron acceptors. Between 40 to 42 °C, activation of cyclic electron transport balanced the loss of protons so that a sizeable transthylakoid proton gradient was maintained. When the temperature of darkened spinach leaves was slowly increased to 40°C, reduction of the quinone acceptor of Photosystem II, QA, increased particularly when respiratory CO2 production and autoxidation of plastoquinones was inhibited by decreasing the oxygen content of the atmosphere from 21 to 1%. Simultaneously, Photosystem II activity was partially lost. The enhanced dark QA reduction disappeared after the leaf temperature was decreased to 20 °C. No membrane energization was detected by light-scattering measurements during heating the leaf in the dark. In illuminated spinach leaves, light scattering and nonphotochemical quenching of chlorophyll fluorescence increased during warming to about 40 °C while Photosystem II activity was lost, suggesting extra energization of thylakoid membranes that is unrelated to Photosystem II functioning. After P700 was oxidized by far-red light, its reduction in the dark was biphasic. It was accelerated by factors of up to 10 (fast component) or even 25 (slow component) after short heat exposure of the leaves. Similar acceleration was observed at 20 °C when anaerobiosis or KCN were used to inhibit respiratory oxidation of reductants. Methyl viologen, which accepts electrons from reducing side of Photosystem II, completely abolished heat-induced acceleration of P700+ reduction after far-red light. The data show that increasing the temperature of isolated chloroplasts or intact spinach leaves to about 40 °C not only inhibits linear electron flow through Photosystem II but also activates Photosystem I-driven cyclic electron transport pathways capable of contributing to the transthylakoid proton gradient. Heterogeneity of the kinetics of P700+ reduction after far-red oxidation is discussed in terms of Photosystem I-dependent cyclic electron transport in stroma lamellae and grana margins.
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    URL: http://dx.doi.org/10.1023/A:1006149317411
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    Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers (1999)
    Springer
    Photosynthesis research 59 (1999), S. 95-104 
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    ISSN: 1573-5079
    Keywords: bacteriochlorophyll a ; electron transfer ; light harvesting ; photosynthesis ; Rhodobacter sphaeroides ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for the primary electron transfer reaction through an effect on the reduction potential of the primary donor. A lowering of the redox potential of the primary donor due to the presence of the core antenna is consistently observed in a series of reaction center mutants in which the reduction potential of the primary donor was varied over a 130 mV range. Estimates of the magnitude of the change in driving force for charge separation from time-resolved delayed fluorescence measurements in the mutant reaction centers suggest that the mutations exert their effect on the driving force largely through an influence on the redox properties of the primary donor. The results demonstrate that the energetics of light-driven electron transfer in reaction centers are sensitive to the environment of the complex, and provide indirect evidence that the kinetics of electron transfer are modulated by the presence of the LH1 antenna complexes that surround the reaction center in the natural membrane.
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    Feedback inhibition of photosynthesis in rice measured by O2 dependent transients (1999)
    Springer
    Photosynthesis research 59 (1999), S. 187-200 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; CO2 ; oxygen ; photosynthesis ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kinetic properties of photosynthesis (both transient and steady-state) were monitored using three non-invasive techniques to evaluate limitations on triose-phosphate (triose-P) conversion to carbohydrate in rice. These included analyzing the O2 sensitivity of CO2 fixation and the assimilatory charge (AC) using gas exchange (estimate of the ribulose 1,5- bisphosphate pool) and measuring Photosystem II activity by chlorophyll fluorescence analysis under varying light, temperature and CO2 partial pressures. Photosynthesis was inhibited transiently upon switching from 20 to 2 kPa O2 (reversed O2 sensitivity), the degree of which was correlated with a terminal, steady-state suppression of low O2 enhancement of photosynthesis. Under current ambient levels of CO2 and moderate to high light, the transient pattern was more obvious at 18 °C than at 26 °C while at 34 °C no tra nsient response was observed. The transient inhibition at 18 °C ranged from 15% to 31% depending on the pre-measurement temperature. This pattern, symptomatic of feedback, was observed with increasing light and CO2 partial pressures with the degree of feedback decreasing from moderate (18 °C) up to high temperature (34 °C). Under feedback conditions, the rate of assimilation is shifted from being photorespiration limited to being triose-P utilization limited. Transitory changes in CO2 assimilation rates (A) under low O2 indicative of feedback coincided with a transitory drop in assimilatory charge (AC) and inhibition of electron transport. In contrast to previous studies with many C3 species, our studies indicate that rice shows susceptibility to feedback inhibition under moderate temperatures and current atmospheric levels of CO2.
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    Down regulation of photosynthesis in Artabotrys hexapetatus by high light (1995)
    Springer
    Photosynthesis research 46 (1995), S. 393-397 
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    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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    URL: http://dx.doi.org/10.1007/BF00032293
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    The mechanism of Rubisco activase: Insights from studies of the properties and structure of the enzyme (1996)
    Springer
    Photosynthesis research 47 (1996), S. 1-11 
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    ISSN: 1573-5079
    Keywords: chaperone chloroplast ; enzyme regulation ; photosynthesis ; protein-protein interaction ; ribulose-1,5-bisphosphate carboxylase/oxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rubisco, the primary carboxylating enzyme in photosynthesis, must be activated to catalyze CO2 fixation. The concept of an ‘activase’, a specific protein for activating Rubisco, was first introduced in 1985 based largely on biochemical and genetic studies of a high CO2-requiring mutant of Arabidopsis (Salvucci et al. (1985) Photosynth Res 7: 193–201). Over the past ten years, details about the occurrence, structure, and properties of Rubisco activase have been elucidated. However, the mechanism of action of Rubisco activase remains elusive. This review discusses the need for and function of Rubisco activase and summarizes information about the properties and structure of Rubisco activase. The information is evaluated in the context of the mechanism of Rubisco activase.
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    URL: http://dx.doi.org/10.1007/BF00017748
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    Measurement of chlorophyll fluorescence within leaves using a modified PAM Fluorometer with a fiber-optic microprobe (1996)
    Springer
    Photosynthesis research 47 (1996), S. 103-109 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; quenching analysis ; photosynthesis ; quantum yield ; photoinhibition ; fiber-optic microsensor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By using a fiber-optic microprobe in combination with a modified PAM Fluorometer, chlorophyll fluorescence yield was measured within leaves with spatial resolution of approximately 20 μm. The new system employs a miniature photomultiplier for detection of the pulse-modulated fluorescence signal received by the 20 μm fiber tip. The obtained signal/noise ratio qualifies for recordings of fluorescence induction kinetics (Kautsky effect), fluorescence quenching by the saturation pulse method and determination of quantum yield of energy conversion at Photosystem II at different sites within a leaf. Examples of the system performance and of practical applications are given. It is demonstrated that the fluorescence rise kinetics are distinctly faster when chloroplasts within the spongy mesophyll are illuminated as compared to palisade chloroplasts. Photoinhibition is shown to affect primarily the quantum yield of the palisade chloroplasts when excessive illumination is applied from the adaxial leaf side. The new system is envisaged to be used in combination with light measurements within leaves for an assessment of the specific contributions of different leaf regions to overall photosynthetic activity and for an integrative modelling of leaf photosynthesis.
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    URL: http://dx.doi.org/10.1007/BF00017758
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    Characterisation of a H2O2-oxidisable cytochrome b-559 in intact chloroplasts with a new type of LED Array Spectrophotometer (1996)
    Springer
    Photosynthesis research 47 (1996), S. 187-197 
    Details
    ISSN: 1573-5079
    Keywords: cyt b-559 ; photosynthesis ; heat stress ; light stress ; hydrogen peroxide ; ascorbate peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytochrome (cyt) b-559 absorbance changes in intact chloroplasts were deconvoluted using a previously described LED-Array-Spectrophotometer (Klughammer et al. (1990), Photosynth Res 25: 317–327). When intact chloroplasts were isolated in the presence of ascorbate, approx. 15% of the total cyt b-559 could be transiently oxidised by 200 μM H2O2 in the dark. This fraction displays low-potential properties, as it can be also oxidised by menadione in the presence of 5 mM ascorbate. Heat pretreatment increased the size of this fraction by a factor of 3–4. Low concentrations of cyanide (in the μM range) prolonged the oxidation time while high concentrations suppressed the oxidation (I50=1.5 mM KCN). The former KCN-effect relates to inhibition of ascorbate dependent H2O2-reduction which is catalysed by ascorbate peroxidase, whereas the latter effect reflects competition between H2O2 and CN− for the same binding site at the cytochrome heme. In the light, much lower concentrations of H2O2 were required to obtain oxidation, the amplitude depending on light intensity and on the concentration of the added H2O2, but never exceeding approx. 15% of the total cyt b-559. In the light, but not in the dark, H2O2 also induced the transient oxidation of a cyt f fraction similar in size to the H2O2-oxidisable cyt b-559 fraction. In this case, H2O2 serves as an acceptor of Photosystem I in conjunction with the ascorbate peroxidase detoxification system. Light can also induce oxidation of a 15% cyt b-559 fraction without H2O2-addition, if nitrite is present as electron acceptor and the chloroplasts are depleted of ascorbate. It is concluded that light-induced cyt b-559 oxidation in vivo is likely to be restricted to the H2O2-oxidisable cyt b-559 LP fraction and is normally counteracted by ascorbate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016181
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