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  • photosynthesis  (263)
  • Springer  (263)
  • American Institute of Physics (AIP)
  • Blackwell Publishing Ltd
  • 1990-1994  (212)
  • 1980-1984  (51)
  • 1925-1929
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  • Springer  (263)
  • American Institute of Physics (AIP)
  • Blackwell Publishing Ltd
  • Wiley-Blackwell  (7)
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  • 101
    Electronic Resource
    Electronic Resource
    Leaf expansion, photosynthesis, and water relations of sunflower plants grown on compacted soil (1993)
    Springer
    Plant and soil 149 (1993), S. 175-184 
    Details
    ISSN: 1573-5036
    Keywords: compaction ; Helianthus annuus L. ; leaf expansion ; nitrogen ; osmotic potential ; photosynthesis ; root growth ; soil strength ; turgor ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Leaf expansion and growth response of sunflower (Helianthus annuus, L.) to soil compaction were investigated in relation to compaction effects on water relations, nitrogen nutrition, and photosynthesis. A series of field experiments were conducted with plants grown in 20 cm-diameter cylinders with soil bulk densities ranging from 1.2 to 1.7 g cm−3 at the 0–20 cm depth (equivalent to 0.8 to 2.4 MPa soil strength measured with a soil penetrometer). Relative leaf expansion rate (RLER) decreased linearly with increasing soil strength. Smaller plant size in compacted treatments was due not only to slower expansion rates, but also smaller maximum size of individual leaves. Sensitivity of leaf expansion to soil strength was best illustrated by a reduction in RLER and maximum size of the first leaf to emerge in a treatment with only the lower 10–20 cm of the profile compacted (bulk density of 1.7 g cm−3). Root growth was less affected than shoot growth by compaction and root:shoot ratios of compacted treatments were significantly higher than the control. Soil compaction had no significant effect on pre-dawn or midday leaf water potential, osmotic potential or leaf turgor. Specific leaf weight was usually higher in plants grown on compacted soil, and leaf nitrogen and photosynthesis per unit leaf area were either unaffected by treatment or significantly higher in compacted treatments. The results suggest that early growth reduction of sunflower plants grown on compacted soil was more sink- than source-limited with regard to water, nitrogen, and carbon supply. Further evaluation of this hypothesis will require verification that these whole-leaf measurements provided a sufficiently accurate approximation of treatment effects on the dynamic equilibria of expanding cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016607
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  • 102
    Electronic Resource
    Electronic Resource
    Physiological aspects of domestication in diploid wheat (1981)
    Springer
    Euphytica 30 (1981), S. 247-252 
    Details
    ISSN: 1573-5060
    Keywords: Wheat ; Triticum boeoticum ; wild einkorn ; Triticum monococcum ; einkorn ; water stress ; leaf water potential ; photosynthesis ; domestication ; adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A comparative study of photosynthetic response to water stress was conducted with one genotype of wild einkorn (Triticum boeoticum, W) and one of domesticated einkorn (T. monococcum, C). Per unit leaf area, W showed a better performance for photosynthetic and transpiration activities, even under dry air and dry soil conditions. Its leaf water potential was always higher than that of C at any level of soil water potential. The difference in photosynthetic recovery from severe drought between W and C was also obvious. The photosynthetic rate, transpiration rate and water status of the leaves observed at 20 h after rewatering was almost the same as non-stressed leaves in W, whereas in C the photosynthetic rate was about half that of the non-stressed leaves, which was accompanied with a low transpiration rate and a high gas diffusion resistance. The ability of W to maintain a proper water balance over a wide range of soil water potential and to recover rapidly from severe drought seems to be a result of adaptation to its hard habitats. However, under favourable water supply, the photosynthetic rate per unit leaf nitrogen was higher in C than in W. This may be advantageous to bring about a better plant growth than W on the arable land where the improved water supply is guaranteed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033984
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  • 103
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    Physiological factors determining yield in bread wheat. Effects of introducing dwarfism genes (1990)
    Springer
    Euphytica 51 (1990), S. 33-39 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; photosynthesis ; chlorophyll fluorescence ; harvest index ; biological yield ; economic yield ; short straw ; dwarfism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Improvements in bread wheat productivity have been related to changes in plant morphology and function associated with a large increase in the harvest index for a more or less constant biological yield. The appearance of short genotypes possessing dwarfism genes may modify markedly the objectives of breeding as the upper limits of the harvest index are approached. The aim of the investigations presented here was to identify some contrasts between short and tall genotypes in terms of the physiological characteristics associated with grain yield, so as to orientate more efficiently the selection of genotypes, with or without dwarfism genes, for productivity. Various parameters of flag leaf functioning (photosynthesis rate, chlorophyll fluorescence index, leaf area duration) were related to the biological and economic yields and the harvest index for two groups of genotypes that were differentiated by their height. For all genotypes, the relationships between the various traits and the grain yield were difficult to ascertain. For the tall genotypes without dwarfism genes, the classical relationships between grain yield, harvest index, flag leaf area duration and net photosynthesis rate were confirmed. Moreover, the rate of chlorophyll fluorescence decrease (Rfd) during the slow Kautsky kinetics phase, which is representative of the leaf photosynthesis at low light, was found to be an excellent marker of economic yield. Chlorophyll fluorescence decrease was closely related to grain yield and also with other factors that are known to be important in its expression (harvest index, flag leaf area duration). In very short genotypes, the biological yield and directly related factors (leaf area, plant height) were the main parameters associated with economic yield, since the harvest index had approached its upper limit. The selection of short genotypes must therefore maintain the biological yield through an increase in the size of the aerial organs to counterbalance the decrease in height.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022890
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  • 104
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    Sources of heat tolerance amongst potato cultivars, breeding lines, and Solanum species (1991)
    Springer
    Euphytica 55 (1991), S. 235-245 
    Details
    ISSN: 1573-5060
    Keywords: potato ; Solanum spp. ; chlorophyll fluorescence ; growth analysis ; heat tolerance ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study assessed 46 potato cultivars, breeding lines and Solanum spp. for heat-tolerance using short-term growth rates and carbon assimilation measurements of young in-vitro-derived plants. Plants of the 46 clones and species were transferred from greenhouse conditions to controlled conditions set at 33/25°C day/night with 12 h photosynthetic photon flux density (PPFD) at 430–450 μmol m-2s-1 and an 8 h daylength extension (6 μmol m-2s-1), to inhibit tuberization. Twenty eight accessions were also grown in a 20/10°C controlled environment. Plants were harvested after 10 and 20 days and dry weights of the plant components were measured for plant growth analysis. Gas exchange (leaf net photosynthesis and maintenance dark respiration) and leaf chlorophyll fluorescence parameters (O, P, and T) were measured at 30°C. Amongst the 30 accessions grown at both hot and cool temperatures, only two accessions (Yungay and AVRDC 1287.19) produced more dry weight in the hot chamber than the cool chamber. Hot/cool ratioss for net assimilation rate (NAR) and relative growth rate (RGR) exceoded unity in five and six accessions, respectively. For the 46 accessions grown under hot conditions, none had significantly greater values than those of the control clones for RGR and NAR. Differences between clones in maintenance respiration and net photosynthesis were more closely related to RGR, NAR, and total dry weight (TDWT) in clones which invested more dry weight in leaves and less in stems. Attributes of the chlorophyll fluorescence curve did not explain more of the clonal variation in RGR, NAR, and TDWT than did gas exchange parameters. No single gas exchange or fluorescence character explained more than 50% of the variability among clones for NAR, RGR, or TDWT, but combination of favourable attributes could improve potato heat tolerance in the future.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021244
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  • 105
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    Calculation of CO2 gas phase diffusion in leaves and its relation to stomatal resistance (1981)
    Springer
    Photosynthesis research 2 (1981), S. 185-194 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; plant stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new theory and experimental method was developed to measure the diffusion resistance to CO2 in the gas phase of mesophyll leaf tissue. Excised leaves were placed in a chamber and their net evaporation and CO2 assimilation rates measured at two different ambient pressures. These data were used to calculate CO2 gas phase diffusion resistances. A variety of field grown leaves were tested and the effects of various experimental errors considered. Increasing the gas phase diffusion resistance decreased transpiration more than it decreased CO2 assimilation. It was concluded that gas phase diffusion resistance associated with CO2 assimilation may sometimes be 100 or 200 s·m-1 greater than the resistance implied by transpiration rates. This may be due to longer path lengths for the CO2 diffusion, constricted in places by the shape and arrangement of mesophyll cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032357
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  • 106
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    Current perceptions of Photosystem II (1990)
    Springer
    Photosynthesis research 23 (1990), S. 131-162 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; Photosystem II ; review ; structure/function aspects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the last few years our knowledge of the structure and function of Photosystem II in oxygen-evolving organisms has increased significantly. The biochemical isolation and characterization of essential protein components and the comparative analysis from purple photosynthetic bacteria (Deisenhofer, Epp, Miki, Huber and Michel (1984) J Mol Biol 180: 385–398) have led to a more concise picture of Photosystem II organization. Thus, it is now generally accepted that the so-called D1 and D2 intrinsic proteins bind the primary reactants and the reducing-side components. Simultaneously, the nature and reaction kinetics of the major electron transfer components have been further clarified. For example, the radicals giving rise to the different forms of EPR Signal II have recently been assigned to oxidized tyrosine residues on the D1 and D2 proteins, while the so-called Q400 component has been assigned to the ferric form of the acceptor-side iron. The primary charge-separation has been meaured to take place in about 3 ps. However, despite all recent major efforts, the location of the manganese ions and the water-oxidation mechanism still remain largely unknown. Other topics which lately have received much attention include the organization of Photosystem II in the thylakoid membrane and the role of lipids and ionic cofactors like bicarbonate, calcium and chloride. This article attempts to give an overall update in this rapidly expanding field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035006
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  • 107
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    Detection of photosynthetic energy storage in a photosystem I reaction center preparation by photoacoustic spectroscopy (1990)
    Springer
    Photosynthesis research 24 (1990), S. 201-208 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; thermal emission ; P700 ; quantum yield ; energy conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thermal emission and photochemical energy storage were examined in photosystem I reaction center/core antenna complexes (about 40 Chl a/P700) using photoacoustic spectroscopy. Satisfactory signals could only be obtained from samples bound to hydroxyapatite and all samples had a low signal-to-noise ratio compared to either PS I or PS II in thylakoid membranes. The energy storage signal was saturated at low intensity (half saturation at 1.5 W m-2) and predicted a photochemical quantum yield of 〉90%. Exogenous donors and acceptors had no effect on the signal amplitudes indicating that energy storage is the result of charge separation between endogenous components. Fe(CN)6 -3 oxidation of P700 and dithionite-induced reduction of acceptors FA-FB inhibited energy storage. These data are compatible with the hypothesis that energy storage in PS I arises from charge separation between P700 and Fe-S centers FA-FB that is stable on the time scale of the photoacoustic modulation. High intensity background light (160 W m-2) caused an irreversible loss of energy storage and correlated with a decrease in oxidizable P700; both are probably the result of high light-induced photoinhibition. By analogy to the low fluorescence yield of PS I, the low signal-to-noise ratio in these preparations is attributed to the short lifetime of Chl singlet excited states in PS I-40 and its indirect effect on the yield of thermal emission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032307
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  • 108
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    Photoacoustic studies on the dependence of state transitions on grana stacking (1990)
    Springer
    Photosynthesis research 25 (1990), S. 225-232 
    Details
    ISSN: 1573-5079
    Keywords: state 1-state 2 transitions ; Mutant nicotiana (tobacco aurea mutant Su/su) ; photoacoustics ; photosynthesis ; energy distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoacoustic detection of oxygen evolution and Emerson enhancement in state 1 and state 2 were compared in a tobacco wild type and mutant (Su/su) deficient in chlorophyll. The mutant shows smaller changes in the distribution of excitation energy between the two photosystems than the wild type. Analysis of Emerson enhancement saturation curves indicates that in the mutant which is deficient in grana partitions and shows less stacking, state 1-state 2 transitions reflect changes in the yield of energy transfer from PS II to PS I (spillover). On the other hand, the wild type containing large grana shows changes in absorption cross-sections of the two photosystems upon state transitions. NaF, a specific phosphatase inhibitor, blocks the transition to state 1, indicating that LHC II phosphorylation has a role in excitation energy regulation in both the mutant as well as the wild type. It is demonstrated that N-ethylmaleimide, a specific sulfhydryl reagent, blocks the transition to state 2, suggesting that a disulfide-sulfhydryl redox couple activates the LHC II kinase in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033163
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  • 109
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    LED array spectrophotometer for measurement of time resolved difference spectra in the 530–600 nm wavelength region (1990)
    Springer
    Photosynthesis research 25 (1990), S. 317-327 
    Details
    ISSN: 1573-5079
    Keywords: LED-Array Spectrophotometer ; difference spectroscopy ; time resolved spectra ; photosynthesis ; cytochrome b/f complex ; cytochrome b 559 ; heat-stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new type of computer controlled spectrophotometer is described which is based on an array of independent, monochromatic pulsed light sources consisting of light emitting diodes (LED) equipped with narrow band interference filters. The LEDs are sequentially pulsed at a high repetition rate. The absorbance information at specific wavelengths is sampled in the μs-time range, using a computer-controlled, highly selective technique of synchronous amplification. A first prototype of this LED Array Spectrophotometer allows simultaneous recording of kinetic changes at 16 different wavelengths in the range from 530 to 600 nm, with a time resolution of 1 ms/point. Special features of the new type of spectrophotometer are: Weak integrated measuring light intensity, high signal/noise ratio even with scattering samples like intact leaves, active baseline adjustment by LED current regulation, computer control of system operation and data analysis. To deconvolute the complex absorbance changes in the cytochrome α-band region, ‘standard spectra’ of the major components are stored in computer memory and used for curve fitting of difference spectra and kinetic changes. As an example of application, the light-induced absorbance changes in a heat-pretreated spinach leaf are analysed. The system effectively separates specific absorbance changes of C550, cyt f, cyt b 559 and cyt b 563 from a large background of non-specific changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033173
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  • 110
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    Computer aided fluorescence imaging of photosynthetic systems (1990)
    Springer
    Photosynthesis research 26 (1990), S. 59-66 
    Details
    ISSN: 1573-5079
    Keywords: Video imaging ; fluorescence induction kinetics ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A fluorescence video imaging system utilizing relatively inexpensive commercial components is described. The instrument utilizes a black and white CCD video camera detector, a commercial video imaging board and a IBM-AT compatible computer. The color output of the imaging board greatly aids in the users ability to visually discriminate areas of interest in the video field. Software development that enables the user to capture kinetic traces in real time from the video images is also described. The system is used to monitor fluorescence from photosynthetic systems. The usefulness of the system in screening for photosynthetic mutants is also demonstrated. The cost of the system can be kept below $12,000.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048977
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  • 111
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    Genetic diversity of photosynthetic characters in native populations of Triticum dicoccoides (1990)
    Springer
    Photosynthesis research 25 (1990), S. 119-128 
    Details
    ISSN: 1573-5079
    Keywords: adaptation ; genetic variation ; photosynthesis ; wild emmer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wild emmer wheat (Triticum dicoccoides Korn) has shown wide genetic diversity for disease resistance and morpho-physiological traits of economic importance. Our objectives were to test for genetic variation (VG) in photosynthetic characteristics residing within and between native populations sampled from three ecogeographical regions of Israel, and to identify potential sources of high photosynthetic efficiency for future wheat improvement. Accessions sampled in the center of wild emmer distribution (upper Jordan Valley) in a relatively narrow geographical range showed the greatest diversity in CO2-assimilation rate per unit leaf area (A) or per unit chlorophyll (A/Chl). Genetic variation was absent for internal CO2 concentration (Ci) and water-use efficiency (WUE) and generally lacking for stomatal conductance (gs). Leaf area, although quite variable, was not a significant cofactor in assessing genetic potential for photosynthesis. Accessions within a given population showed 10-times more variation in A and A/Chl than populations sampled from different locations in a region. Accessions with the highest photosynthetic efficiency were derived from upland steppic populations located in marginal habitats extending southward into Israel. Some accessions having high photosynthetic capacity (A=32 μmol m-2 s-1) with no significant reduction in leaf size constitute a potentially valuable genetic resource yet untapped for genetic improvement of hexaploid (T. aestivum L.) wheat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035460
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  • 112
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    Computer-controlled pulse modulation system for analysis of photoacoustic signals in the time domain (1990)
    Springer
    Photosynthesis research 25 (1990), S. 309-316 
    Details
    ISSN: 1573-5079
    Keywords: photoacoustics ; photosynthesis ; O2-evolution ; gas-exchange ; heat evolution ; chlorophyll fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A newly developed photoacoustic system for measurement of photosynthetic reactions in intact leaves is described. The system is based on pulsed light-emitting diodes, the pulse program and pulse response analysis being computer controlled. Separation of various components in the overall photoacoustic signal is achieved by curve fitting analysis of the responses following individual measuring light pulses in the millisecond time domain. This procedure is in distinction to the conventionally used analysis in the frequency domain, with the advantage that various signal components are obtained by on-line deconvolution, yielding simultaneous recordings of photothermal (complement of energy storage) and photobaric (evolution and uptake) signals. The basic components of the new system are described by block diagrams and the principal steps for deconvolution of the overall photoacoustic response are outlined. An example of application with simultaneous recording of chlorophyll fluorescence is given. It is apparent that the photobaric uptake component represents a significant part of the overall signal, particularly during induction of photosynthesis after dark-adaptation. This component probably contains not only O2-uptake but uptake of CO2 as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033172
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  • 113
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    Leaf anatomical characteristics in Flaveria trinervia (C4), Flaveria brownii (C4-like) and their F1 hybrid (1990)
    Springer
    Photosynthesis research 26 (1990), S. 49-57 
    Details
    ISSN: 1573-5079
    Keywords: Chloroplasts ; Kranz anatomy ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several leaf anatomical and ultrastructural characteristics usually related with photosynthetic capacity were examined in two Flaveria species with strong differences in anatomy and their F1 hybrid. Flaveria trinervia (Spreng.) Mohr (C4) was the female parent and F. brownii A.M. Powell (C4-like) was the male parent. Quantitative anatomical analysis was made on transverse sections of leaves at both the light and electron microscope level. Four kinds of photosynthetic tissues were considered: bundle sheath (BS), mesophyll adjacent to the BS, mesophyll not adjacent to the BS, and larger spongy mesophyll cells. Flaveria trinvervia partitioned a larger proportion of its photosynthetic cells to BS and the mesophyll layer adjacent to BS and also possessed larger chloroplasts, especially in BS, than did F. brownii. These results suggest that although F. brownii is very C4-like, its anatomy is not as completely C4 as is the case for F. trinervia. In the F1 hybrid the relative contribution of the different tissues to the total photosynthetic tissue volume and area per unit leaf area was quite similar to that of F. trinervia. On the other hand, the chloroplast density and size of the F1 hybrid were fairly similar to those of F. brownii, especially in BS. Thus, there was no evidence of maternal inheritance in the chloroplast characteristics studied. A negative correlation (P〈0.05) between chloroplast size and density was observed among species and relicates within each kind of tissue. This correlation was highest (r=−0.94, P〈0.001) for the BS and when values were plotted on a logarithmic scale. Thus, higher chloroplast numbers for F. brownii and the F1 hybrid were offset by larger chloroplasts in F. trinervia. Less complete C4 photosynthesis in F. brownii may be partially due to incomplete development of Kranz anatomy usually associated with C4 photosynthesis.
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    URL: http://dx.doi.org/10.1007/BF00048976
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  • 114
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    Conjectures and reveries (1992)
    Springer
    Photosynthesis research 33 (1992), S. 171-176 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; origin of life ; clays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The origin of photosynthesis is speculated to have involved carbon dioxide and self-replicating iron-rich clays. The later evolution of photosynthesis is considered to have undergone four distinct phases: (1) The photoreduction of carbon dioxide by ferrous ion to form oxalate and formate. (2) The entry of sulfur into the evolving clay system which led to the formation of acetyl thioesters. The polymerization of the acetyl thioeters led to the formation of quinones. The formation of Fe2S2 and Fe4S4 cores appeared in this phase. (3) The ability to fix nitrogen characterized the third phase. This led to the formation of pyrrole, flavin, nicotinamide, phycobilins, porphyrins and chlorophyll. (4) Finally, phosphate entered the evolving system. The chromophores evolved from ferrous ion through the quinones, carotenoids, phycobilins to chlorophyll. This evolution of chromophores implies that photosynthesis began in the UV and evolved through the blue, yellow, orange into the red. The electron transport chain evolved from ferrous ion through the Fe2S2 and Fe4S4 cores to the hemes.
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    URL: http://dx.doi.org/10.1007/BF00039179
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  • 115
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    Fluorescence properties of the allenic carotenoid fucoxanthin: Implication for energy transfer in photosynthetic pigment systems (1991)
    Springer
    Photosynthesis research 27 (1991), S. 221-226 
    Details
    ISSN: 1573-5079
    Keywords: carotenoid ; energy transfer ; fluorescence ; fucoxanthin ; pigment system ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fluorescence spectrum of an allenic carotenoid, all-trans-fucoxanthin isolated from a brown alga, has been reported for the first time. This carotenoid is known to function efficiently as a primary photosynthetic antenna pigment in marine algae. The emission bands were located around 630, 685 and 750 nm in CS2 at 20°C, absorption bands being located at 448, 476 and 505 nm. The energy difference between the 0-0 bands of absorption and emission spectra was about 3900 cm-1 and location of the emission maximum was less sensitive to the polarizability of solvents than that of the absorption maximum. These clearly indicate that the emission originates from the optically forbidden singlet state (2Ag). This is in contrast to other carotenoids whose emission is assigned to 1Bu state, probably due to the symmetric structure of the conjugated double bond responsible for the absorption in the visible region. A rapid internal conversion from 1Bu to 2Ag state might be facilitated by distorted structure of the conjugated double bond of fucoxanthin. The energy level responsible for the emission is almost identical to the Qy level of the acceptor molecule (Chl a), thus we propose an energy transfer pathway from the optically forbidden 2Ag state of the carotenoid to the Qy transition of Chl a in algal pigment systems.
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    URL: http://dx.doi.org/10.1007/BF00035843
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  • 116
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    Sequence similarity between Photosystems I and II. Identification of a Photosystem I reaction center transmembrane helix that is similar to transmembrane helix IV of the D2 subunit of Photosystem II and the M subunit of the non-sulfur purple and flexible green bacteria (1991)
    Springer
    Photosynthesis research 29 (1991), S. 133-147 
    Details
    ISSN: 1573-5079
    Keywords: evolution ; photosynthesis ; protein structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There are basic structural similarities between plant PS II and bacterial RCs of the Chloroflexaceae and Rhodospirillaceae. These RCs are referred to as PS II-type RCs. A similar relationship of PS I RC to PS II-type RCs has not been established. Although plant PS I and PS II RCs show structural and functional differences, they also share similarities. Therefore, the A and B polypeptides of PS I were searched for PS II D1 and D2 polypeptide-like sequences. An alignment without gaps was found between PS II-type D2/M helix IV and PS I B helix X, as well as a weaker alignment of PS II-type D1/L with PS I B helix X. No comparable alignment with PS I A was found. In the M/D2 alignment there were eight identities and some conservative substitutions in twenty nine residues. PS I B helix X appeared to contain a modified chlorophyll dimer and monomer binding site and a modified non-heme iron-quinone binding site. The conserved residue sequence was found only in RC polypeptides. The proposed chlorophyll dimer-monomer binding site was located transmembrane from the iron-sulfur cluster X binding site. The conserved residues generally are those that interact with prosthetic groups. Half of the conserved residues are located on the same side of the helix. Thus, although there are impediments to concluding firmly that PS I B helix X has a functional and evolutionary relatedness to the D2 PS II and bacterial M RC polypeptides, our analysis gives reasonable support to the idea.
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    URL: http://dx.doi.org/10.1007/BF00036217
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  • 117
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    Photosynthesis, photosynthetic enzymes and leaf area development in relation to hybrid vigour in Sorghum vulgare L. (1982)
    Springer
    Photosynthesis research 3 (1982), S. 113-122 
    Details
    ISSN: 1573-5079
    Keywords: heterosis ; PEPcase ; photosynthesis ; RuBPcase ; sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heterotic hybrids of sorghum produced more dry matter than their respective parents. Therefore, an analysis of leaf are development, rate of photosynthesis and activities of RuBP carboxylase and PEP carboxylase was made to determine whether the superior dry matter production in the hybrids could be attributed to any of these characteristics. Heterosis in leaf area was maintained at all stages in plant growth. Heterosis in photosynthesis was observed only during grain development in certain hybrids. At all other stages, the photosynthesis rate in hybrids were either intermediate or similar to one of the parents. No heterotic effect was observed in enzyme activity at any stage of growth. It is suggested that a multiplicative interaction between the heterotic leaf area and photosynthesis rate could possibly explain heterosis in dry matter production in heterotic hybrids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040709
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    Photosynthesis at ambient and elevated humidity over a growing season in soybean (1982)
    Springer
    Photosynthesis research 3 (1982), S. 307-311 
    Details
    ISSN: 1573-5079
    Keywords: Glycine max ; humidity ; photosynthesis ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Daytime rates of net photosynthesis of upper canopy leaflets of soybeans were compared on 17 days for leaflets exposed to air at the ambient humidity and at a higher humidity. Leaflets at the higher humidity had higher rates of net photosynthesis on 16 of the 17 days. The daily total of net photosynthesis of leaflets at the higher humidity was on average 1.32 times that for leaflets at ambient humidity. A strong limitation of net photosynthesis by ambient humidity was found throughout the growing season.
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    URL: http://dx.doi.org/10.1007/BF00034111
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    Changes in Photosystem II fluorescence in Chlamydomonas reinhardtii exposed to increasing levels of irradiance in relationship to the photosynthetic response to light (1992)
    Springer
    Photosynthesis research 31 (1992), S. 31-40 
    Details
    ISSN: 1573-5079
    Keywords: Chlamydomonas ; convexity ; chlorophyll a fluorescence ; Photosystem II heterogeneity ; photoinhibition ; photosynthesis ; PS II repair cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200 μmol m−2s−1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780 μmol m−2s−1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600 μmol m−2s−1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of QB-reducing centers and 3) a second photoinhibitory range above 1600 μmol m−2s−1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS IIα centers and a large increase in spill-over in energy to PS I.
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    URL: http://dx.doi.org/10.1007/BF00049534
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    End product feedback effects on photosynthetic electron transport (1993)
    Springer
    Photosynthesis research 35 (1993), S. 5-14 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; feedback limitation ; malate dehydrogenase ; photoinhibition ; photosynthesis ; xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inhibition of photosynthetic electron transport when starch and sucrose synthesis limit the overall rate of photosynthesis was studied inPhaseolus vulgaris L. andXanthium strumarium L. The starch and sucrose limitation was established by reducing photorespiration by manipulation of the partial pressure of O2 and CO2. Chlorophylla fluorescence quenching, the redox state of Photosystem I (estimated by the redox status of NADP-dependent malate dehydrogenase), and the intermediates of the xanthophyll cycle were investigated. Non-photochemical fluorescence quenching increased, NADP-dependent malate dehydrogenase remained at 100% activity, and the amount of violaxanthin decreased when starch and sucrose synthesis limited photosynthesis. In addition, O2-induced feedback caused a decrease in photochemical quenching. These results are consistent with a downward regulation of photosynthetic electron transport during end product feedback on photosynthesis. When leaves were held in high CO2 for 4 hours, the efficiency of Photosystem II was reduced when subsequently measured under low light. The results indicate that the quantum efficiency of open Photosystem II centers was reduced by the 4 hour treatment. We interpret the results to indicate that feedback from starch and sucrose synthesis on photosynthetic electron transport stimulates mechanisms for dissipating excess light energy but that these mechanisms do not completely protect leaves from long-term inhibition of photosynthetic electron transport capacity.
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    URL: http://dx.doi.org/10.1007/BF02185407
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    Species-related differences in the electrophoretic behavior of CP 29 and CP 26: An immunochemical analysis (1992)
    Springer
    Photosynthesis research 34 (1992), S. 249-262 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; light-harvesting chlorophyll-protein complex ; spinach ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The monomeric chlorophyll-protein complexes, CP 29 and CP 26 seen in the Camm and Green (1980) and Dunahay and Staehelin (1986) green gels do not always migrate in the order of the apparent molecular weight of their apoproteins as determined by denaturing gel electrophoresis. In barley and corn they do, but in spinach they do not. In addition, in some higher plant species these chlorophyll-protein complexes comigrate on green gels causing confusion in the literature. To remedy this situation and circumvent future confusion, we propose that the CP 29 and CP 26 complexes be named according to the relative molecular weight of their apoproteins on denaturing gels. Our proposal is supported by the results obtained from four antibodies used on Western blot samples of whole thylakoids, grana membranes, and PS II preparations from different plants. The higher molecular weight proteins (proposed CP 29's) react strongly to one set of antibodies, and the lower molecular weight proteins (proposed CP 26's) react strongly to a different set. In spinach, CP 26 antibodies react also with CP 29, but the extent of the cross-reactivity depends critically on the gel electrophoresis system used. Accordingly, a lack of antibody reactivity under certain conditions may not indicate two proteins are unrelated, just simply that a particular epitope is no longer accessible following gel electrophoresis with a particular buffer system.
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    URL: http://dx.doi.org/10.1007/BF00033442
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    Concerning oscillations (1992)
    Springer
    Photosynthesis research 34 (1992), S. 387-395 
    Details
    ISSN: 1573-5079
    Keywords: oscillations ; photosynthesis ; regulation ; phosphate ; down-stream
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029813
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    Chloroplast energization and oxidation of P700/plastocyanin in illuminated leaves at reduced levels of CO2 or oxygen (1992)
    Springer
    Photosynthesis research 34 (1992), S. 433-447 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; cyclic electron transport ; photorespiration ; photosynthesis ; Photosystem II ; proton gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll fluorescence, light scattering, the electrochromic shift P515 and levels of some photosynthetic intermediates were measured in illuminated leaves. Oxygen and CO2 concentrations in the gas phase were varied in order to obtain information on control of Photosystem II activity under conditions such as produced by water stress, when stomatal closure restricts access of CO2 to the photosynthetic apparatus. Light scattering and energy-dependent fluorescence quenching indicated a high level of chloroplast energization under high intensity illumination even when linear electron transport was curtailed in CO2-free air or in 1% oxygen with 35 μll-1 CO2. Calculations of the phosphorylation potential based on measurements of phosphoglycerate, dihydroxyacetone phosphate and NADP revealed ratios of intrathylakoid to extrathylakoid proton concentrations, which were only somewhat higher in air containing 35 μl l-1 CO2 than in CO2-free air or 1% oxygen/35 μl l-1 CO2. Anaerobic conditions prevented appreciable chloroplast energization. Acceptor-limitation of electron flow resulted in a high reduction level of the electron transport chain, which is characterized by decreased oxidation of P700, not only under anaerobic conditions, but also in air, when CO2 was absent, and in 1% oxygen, when the CO2 concentration was reduced to 35 μll-1. Efficient control of electron transport was indicated by the photoaccumulation of P700 + at or close to the CO2 compensation point in air. It is proposed to require the interplay between photorespiratory and photosynthetic electron flows, electron flow to oxygen and cyclic electron flow. The field-indicating electrochromic shift (P515) measured as a rapid absorption decrease on switching the light off followed closely the extent of photoaccumulation of P700 + in the light.
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    URL: http://dx.doi.org/10.1007/BF00029817
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    Effects of polyploidy on photosynthesis (1993)
    Springer
    Photosynthesis research 35 (1993), S. 135-147 
    Details
    ISSN: 1573-5079
    Keywords: C3 plants ; C4 plants ; DNA ; photosynthesis ; polyploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In polyploid plants the photosynthetic rate per cell is correlated with the amount of DNA per cell. The photosynthetic rate per unit leaf area is the product of the rate per cell times the number of photosynthetic cells per unit area. Therefore, the photosynthetic rate per unit leaf area will increase if there is a less than proportional increase in cell volume at higher ploidal levels, or if cell packing is altered to allow more cells per unit leaf area. In autopolyploids (Medicago sativa, C3 species, and Pennisetum americanum, C4 species) there is a doubling of photosynthesis per cell and of cell volume in the tetraploid compared to the diploid. However, there is a proportional decrease in number of cells per unit leaf area with this increase in ploidy such that the rate of photosynthesis per leaf area does not change. There is more diversity in the relationship between ploidal level (gene dosage) and photosynthetic rates per unit leaf area in allopolyploids. This is likely to reflect the effects of natural selection on leaf anatomy, and novel genetic interactions from contributed genomes which can occur with allopolyploidy. In allopolyploid wheat (C3 species) a higher cell volume per unit DNA at the higher ploidal level is negatively correlated with photosynthesis rate per unit leaf area. Although photosynthesis per cell increases with ploidy, photosynthesis per leaf area decreases, being lowest in the allohexaploid, cultivated bread wheat (Triticum aestivum). Alternatively, doubling of photosynthetic rate per cell with doubling of DNA, with apparent natural selection for decreased cell volume per unit DNA, results in higher rates of photosynthesis per leaf area in octaploid compared to tetraploid Panicum virgatum (C4) which may be a case of allopolyploidy. Similar responses probably occur in Festuca arundinacea. Therefore, in some systems anatomical factors affecting photosynthesis are also affected by ploidal level. It is important to evaluate that component as well as determining the effect on biochemical processes. Current information on polyploidy and photosynthesis in several species is discussed with respect to anatomy, biochemistry and bases for expressing photosynthetic rates.
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    Cytosolic fructose-1,6-bisphosphatase: A key enzyme in the sucrose biosynthetic pathway (1993)
    Springer
    Photosynthesis research 38 (1993), S. 5-14 
    Details
    ISSN: 1573-5079
    Keywords: carbon metabolism ; cytosolic FBPase ; photosynthesis ; sucrose synthesis ; sugar beet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fructose-1,6 bisphosphatase (FBPase) is a ubiquitous enzyme controlling a key reaction. In non-photosynthetic tissues, it regulates the rate of gluconeogenesis. In photosynthetic tissues, two FBPase isozymes (chloroplastic and cytosolic) play key roles in carbon assimilation and metabolism. The cytosolic FBPase is one of the regulatory enzymes in the sucrose biosynthetic pathway — its activity is regulated by both fine and coarse control mechanisms. Kinetic and allosteric properties of the plant cytosolic FBPase are remarkably similar to the mammalian and yeast FBPase, but differ greatly from those of the chloroplastic FBPase. Cytosolic FBPase is relatively conserved among various organisms both at amino acid and nucleotide sequence levels. There is slightly higher similarity between mammalian FBPase and plant cytosolic FBPase than there is between the two plant FBPases. Expression of plant cytosolic FBPase gene is developmentally regulated and appears to be coordinated with the expression of Rubisco and other carbon metabolism enzymes. Similar to the gluconeogenic FBPase, relatively rapid end product repression of FBPase gene occurs in plant. However, unlike the gluconeogenic FBPase, a concurrent decline in plant FBPase activity does not occur in response to increased end product levels. The physiological significance of FBPase gene repression, therefore, remains unclear in plants. Both expression and activity of the cytosolic FBPase are regulated by environmental factors such as light and drought conditions. Light-dependent modulation of FBPase activity in plants appears to involve some type of posttranslational modification. In addition to elucidating the exact nature of the presumed posttranslational modification, cloning of genomic and upstream sequences is needed before we fully understand the molecular regulation of the cytosolic FBPase in plants. Use of transgenic plants with altered rates of FBPase activity offers potential for enhanced crop productivity.
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    Inhibition by phosphate of light-state transitions in cyanobacterial cells (1993)
    Springer
    Photosynthesis research 38 (1993), S. 135-140 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; light-harvesting ; light-state transition ; signal transduction ; cyanobacteria ; Synechococcus 6301 ; Synechococcus sp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light-state transitions in cyanobacteria are a rapid physiological adaptation mechanism which changes the distribution of excitation energy absorbed by the light-harvesting complexes between Photosystem II and Photosystem I. State transitions in two cyanobacterial species are shown to be inhibited by buffers containing 0.2–0.4 M phosphate. Both the state 1 and the state 2 transition are inhibited, so that cells may be locked in the state to which they were adapted before the addition of phosphate. The inhibition of the state 1 transition is due to inhibition of photosynthetic electron transport. However, the inhibition of the state 2 transition is probably due to a direct effect on the biochemical signal transduction pathway. The implications for the biochemical mechanism of state transitions are discussed.
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    Photosynthetic reaction center mutagenesis via chimeric rescue of a non-functional Rhodobacter capsulatus puf operon with sequences from Rhodobacter sphaeroides (1993)
    Springer
    Photosynthesis research 36 (1993), S. 43-58 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; recombination ; bacteria ; energy transfer ; antenna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetically active chimeric reaction centers which utilize genetic information from both Rhodobacter capsulatus and Rb. sphaeroides puf operons were isolated using a novel method termed chimeric rescue. This method involves in vivo recombination repair of a Rb. capsulatus host operon harboring a deletion in pufM with a non-expressed Rb. sphaeroides donor puf operon. Following photosynthetic selection, three revertant classes were recovered: 1) those which used Rb. sphaeroides donor sequence to repair the Rb. capsulatus host operon without modification of Rb. sphaeroides puf operon sequences (conversions), 2) those which exchanged sequence between the two operons (inversions), and 3) those which modified plasmid or genomic sequences allowing expression of the Rb. sphaeroides donor operon. The distribution of recombination events across the Rb. capsulatus puf operon was decidedly non-random and could be the result of the intrinsic recombination systems or could be a reflection of some species-specific, functionally distinct characteristic(s). The minimum region required for chimeric rescue is the D-helix and half of the D/E-interhelix of M. When puf operon sequences 3′ of nucleotide M882 are exchanged, significant impairment of excitation trapping is observed. This region includes both the 3′ end of pufM and sequences past the end of pufM.
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    Effects of nitrogen supply on the acclimation of photosynthesis to elevated CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 389-400 
    Details
    ISSN: 1573-5079
    Keywords: elevated CO2 ; nitrogen supply ; photosynthesis ; acclimation ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A common observation in plants grown in elevated CO2 concentration is that the rate of photosynthesis is lower than expected from the dependence of photosynthesis upon CO2 concentration in single leaves of plants grown at present CO2 concentration. Furthermore, it has been suggested that this apparent down regulation of photosynthesis may be larger in leaves of plants at low nitrogen supply than at higher nitrogen supply. However, the available data are rather limited and contradictory. In this paper, particular attention is drawn to the way in which whole plant growth response to N supply constitutes a variable sink strength for carbohydrate usage and how this may affect photosynthesis. The need for further studies of the acclimation of photosynthesis at elevated CO2 in leaves of plants whose N supply has resulted in well-defined growth rate and sink activity is emphasised, and brief consideration is made of how this might be achieved.
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    URL: http://dx.doi.org/10.1007/BF00014593
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    Photosynthetic characteristics of leaves developed at different irradiances and temperatures: an extension of the current hypothesis (1983)
    Springer
    Photosynthesis research 4 (1983), S. 87-97 
    Details
    ISSN: 1573-5079
    Keywords: acclimation ; irradiance ; photosynthesis ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic characteristics at high measurement irradiance were analyzed for single leaves of two C3 and one C4 species grown under twenty one combinations of irradiance level, irradiance duration, and air temperature in order to test the idea that photosynthetic characteristies developed by leaves in different environments are controlled by the daily amount of photosynthesis. Photosynthetic rates per unit area and mesophyll conductances at 25°C and air levels of CO2 and O2, and parameters for two photosynthesis models were used to characterize the photosynthetic properties of the leaves. Leaves with highest values of the photosynthetic parameters for each species were often developed in environments with irradiance levels below saturation for photosynthesis, and with only 12 hours of irradiance per day. Lower air temperature during growth increased the photosynthetic characteristics for a given irradiance regime. Photosynthetic characteristics had higher correlation coefficients with daily photosynthesis of mature leaves divided by 24-hour leaf elongation rates of young leaves, than with daily photosynthesis alone, indicating that photosynthetic characteristics may be related to a balance between photosynthesis and leaf expansion.
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    URL: http://dx.doi.org/10.1007/BF00041804
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    Photosynthetic characteristics of Amaranthus tricolor, a C4 tropical leafy vegetable (1983)
    Springer
    Photosynthesis research 4 (1983), S. 171-178 
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    ISSN: 1573-5079
    Keywords: Amaranthus tricolor ; intercellular CO2 concentration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gas exchange characteristics are reported for Amaranthus tricolor, a C4 vegetable amaranth of southeastern Asia. Maximum photosynthetic capacity was 48.3±1.0 μmol CO2 m-2 s-1 and the temperature optimum was 35°C. The calculated intercellular CO2 concentration at this leaf temperature and an incident photon flux (400–700 mm) of 2 mmol m-2 s-1 averaged 208±14 μl l-1, abnormally high for a C4 species. The photosynthetic rate, intercellular CO2 concentration, and leaf conductance all decreased with an increase in water vapor pressure deficit. However, the decrease in leaf conductance which resulted in a decrease in intercellular CO2 concentration accounted for only one fourth of the observed decrease in photosynthetic rate as water vapor pressure deficit was increased. Subsequent measurements indicated that the dependence of net photosynthesis on intercellular CO2 concentration changed with water vapor pressure deficit.
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    Strain selection and physiology in the development of Gracilaria mariculture (1984)
    Springer
    Hydrobiologia 116-117 (1984), S. 89-94 
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    ISSN: 1573-5117
    Keywords: seaweed ; Gracilaria ; photosynthesis ; mariculture ; agar ; carbon limitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00027644
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    Hydrography and characteristics of the phytoplankton in shelf and oceanic waters off southeastern Brazil during winter (July/August 1982) and summer (February/March 1984) (1990)
    Springer
    Hydrobiologia 196 (1990), S. 111-148 
    Details
    ISSN: 1573-5117
    Keywords: hydrography ; nutrients ; photosynthesis ; subsurface chlorophyll maxima ; southeastern Brazil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The physical and chemical environment, and the phytoplankton primary production of southeastern Brazil were studied in relation to the general oceanographic structure during two research cruises (winter and summer). In each cruise, a total of 91 stations were occupied. Data were collected on the spatial distribution of nutrients, phytoplankton biomass and photosynthetic capacity over the coastal, shelf and oceanic areas off São Paulo, Paraná and Santa Catarina States. During wintertime, the mixing processes between tropical warm waters of the Brazil Current and subantarctic waters of the Malvinas Current formed strong environmental gradients. The drainings of Rio de La Plata and Lagoa dos Patos are transported northwards by coastal currents, enriching the shelf waters off Santa Catarina State with inorganic nutrients and consequently increasing the chlorophyll ‘a’ to the highest concentrations (〉 3.5 mg m −3) measured during the two cruises. In slope waters chlorophyll values were always low (0.05–0.45 mg m −3). The chlorophyll within the euphotic layer varied from 8.8–36.7 and 1.2–18.5 mg m−2 during winter and summer, respectively. The surface photosynthetic rates during winter and summer cruises ranged respectively from 0.21–9.17 and 0.66–19.60 mgC/mgChl.a/h. The mean rates were higher in nearshore waters and decreased seaward. The thermal structure of the water column affected the vertical distribution of chlorophyll a and photosynthesis within the euphotic zone; During unstratified periods (winter) they were uniformly distributed but the occurrence of subsurface peaks of chlorophyll and strong photosynthetic inhibition of low light adapted cells in deeper layers are associated to the seasonal thermocline. Occasionally, upwelling of deep waters from shelf break enriched the deeper euphotic layers in offshore areas. Intensive upwelling was observed off Paranagua Bay (Parana State) and the mechanisms of its formation are discussed.
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    Comparative photosynthetic studies of Ecklonia cava (Laminariales, Phaeophyta) bladelets with and without zoosporangial sori (1990)
    Springer
    Hydrobiologia 204-205 (1990), S. 473-477 
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    ISSN: 1573-5117
    Keywords: Ecklonia cava ; Phaeophyta ; photosynthesis ; respiration ; seaweed ; zoosporangial sori
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic rates were compared between Ecklonia cava bladelets with and without zoosporangial sori sampled from the subtidal zone (about 5 m deep) in Nabeta Bay, Shimoda, Japan. Photosynthetic rates of bladelets were lower in the sorus portion than in the non-sorus portion on the basis of area, dry weight and chlorophyll a. Respiration rates were higher in the sorus portion than in the non-sorus portion on the basis of area and chlorophyll a, whereas they were almost the same on a dry weight basis. The differences were mainly due to a large difference in dry weight per unit bladelet area between the sorus and the non-sorus portion. Light compensation points were higher in the sorus portion than in the non-sorus portion.
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    Mechanisms of amplification of photosynthetically active radiation in the symbiotic deep-water coral Leptoseris fragilis (1991)
    Springer
    Hydrobiologia 216-217 (1991), S. 389-394 
    Details
    ISSN: 1573-5117
    Keywords: action spectrum ; light transformation ; photosynthesis ; scattering ; scleractinian coral ; zooxanthellae ; PAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The symbiotic coral Leptoseris fragilis lives in the Red Sea at depths of 95–145 m. Symbiotic dinoflagellates (zooxanthellae) themselves possess well known adaptations to low light intensities. In L. fragilis we found indications that light amplifying mechanisms of the host improve photosynthesis of the symbionts. Light of short wavelengths is absorbed by host pigments which transform short into longer wavelengths. The transformed light is more efficient for photosynthesis. Action spectra measurements of photosynthesis demonstrated the amplification of photosynthetically active radiation. Monochromatic light of 387 nm (outside the main absorption maxima of the algal pigments) at subsaturation photon flux densities was as effective photosynthetically as polychromatic light of 415–490 nm, which fits the absorption maxima of the zooxanthellae.
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    Dynamic versus static models for photosynthesis (1992)
    Springer
    Hydrobiologia 238 (1992), S. 189-196 
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    ISSN: 1573-5117
    Keywords: photosynthesis ; phytoplankton ; time scales ; environmental variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Static P(I) curves relating photosynthesis to the instantaneous light might not be adequate to describe the activity of algal cells in lakes or oceans where mixing can cause a complex pattern of light variation. In recent years experimental results have provided evidence that, subsequent to changes in light, the rate of photosynthesis may be delayed or exhibit complex temporal dynamics. The model DYPHORA (DYnamic model for the PHOtosynthetic Rate of Algae) takes these dynamics into account by introducing two characteristic response times for the biological processes: (1) the effect of light inhibition having a time scale of minutes to a few hours and (2) the time lag of the rate of photosynthesis for increasing light intensities having a time scale of seconds to minutes. The importance of the dynamic relative to the static description of photosynthesis depends on the time scales of the changes in the environment and the biological response, becoming significant when the time scales are comparable.
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    Effects of clay discharges on streams (1992)
    Springer
    Hydrobiologia 248 (1992), S. 215-234 
    Details
    ISSN: 1573-5117
    Keywords: suspended solids ; turbidity ; algae ; photosynthesis ; light ; mining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Placer gold-mining on the West Coast of the South Island of New Zealand provided a field test-bed for investigating the impacts of fine inorganic suspensoids (clays) on streams not subjected to other abuses. The suspensions of clays (40% between 0.55 and 1 µm in diameter) seeping into the streams from gold mines were colloidally stable. The clay particles attenuated light in the streamwater with near maximum efficiency leading to severe degradation of stream optical quality. Turbidity increased from a median of 2.4 NTU upstream often to 〉 100 NTU (median 15 NTU) downstream. The stream waters, which were strongly-coloured by humic substances, were changed from a dark organge colour to a bright ‘muddy’ appearance downstream of mining, and visual clarity was reduced from a few metres to as low as 0.03 m (median 0.33 m). The clay discharges decreased light penetration into the stream water such that irradiance averaged over a 12 hr photoperiod at the bed (typically about 0.3 m depth in runs at baseflow) fell from about 340 µE m−2 s−1 upstream to as low as 80 µE m−2 s−1 (median 190 µE m−2 s−1) at matched downstream sites. This reduction in light proportionally reduced benthic primary productivity downstream of the mining activity. In turn this reduced benthic algal biomass and lowered the phototrophic content of the epilithon. In spite of their extremely low settling velocities (〈 1 µm s−1) some clay particles were deposited on the stream bed owing to entrapment in the epilithon matrix. This decreased the organic content of the epilithon (from an average of 19% upstream to 8.5% downstream) so reducing its quality as food for invertebrate animals.
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    The use of acetic acid as a source of carbon by cultured Chondrus crispus (Gigartinales, Rhodophyta) stackhouse (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 451-456 
    Details
    ISSN: 1573-5117
    Keywords: Chondrus ; culture ; carbon ; pH control ; acetic acid ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When growing seaweeds in tanks, pH and carbon source supply have to be controlled in order to maximize photosynthesis. pH can be controlled either by adding various inorganic acids which requires the extra addition of carbon, or by combining pH control and carbon source with for instance CO2 or an organic acid such as acetic acid (CH3COOH). We have found comparable productivity of Chondrus using CO2 or CH3COOH in tank culture with an increase in production of 25.0 and 27.5%, respectively, over the control. Laboratory experiments showed that acetic acid enabled us to maintain a steady state total inorganic carbon in the medium, the algae displaying an active photosynthesis. Experiments using labelled acetic acid CH3-14COOH showed that the acid molecule or at least the -14COOH group is taken up by Chondrus although the mechanism was not elucidated. Preliminary extractions with hot ethanol showed that 67.9% of the label was solubilized from labelled tissue. Few counts were found in the carrageenans (〈 1 %) and between 25.6 and 45.1% were found in the cellulosic residues. Acetic acid is suggested as an interesting means of regulating the pH and adding carbon in macrophyte culture.
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    Spatial and temporal variation in community composition and photosynthetic characteristics of phytoplankton in the upper Westerschelde estuary (Belgium, SW Netherlands) (1993)
    Springer
    Hydrobiologia 269-270 (1993), S. 263-273 
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    ISSN: 1573-5117
    Keywords: composition ; estuary ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Community composition, biomass and primary production of phytoplankton were studied in the east- ernmost section of the Westerschelde estuary in 1984. Photosynthetic characteristics were compared with distribution of some dominant phytoplankton species along a salinity gradient from 5 to 22‰ Spring phytoplankton, with Cyclotella meneghiniana (freshwater) and Skeletonema costatum (marine) as the dominant species grew faster than summer phytoplankton. In summer, biomass achieved its maximum, due to the riverine Scenedesmus species and the marine diatoms Thalassiosira levanderi and Ditylum brightwellii, as dominants. Growth conditions were more favourable to phytoplankton communities above 15%, than below this salinity. The data were compared with previous studies (1972) of species composition in the area.
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    The influence of ammonia on the growth and photosynthesis of Ruppia drepanensis Tineo from Doñana National Park (SW Spain) (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 219-231 
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    ISSN: 1573-5117
    Keywords: Ruppia drepanensis ; ammonia toxicity ; temperature effects ; photosynthesis ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in Southern Spain were grown at 20 and 30 °C, at three different nitrogen levels. These levels were obtained by the addition of a slow release fertilizer (23% NH4NO3 by weight) to a sediment mixture of sand and clay (3:1). Several morphometric parameters were recorded during the first five weeks of the experiment, and photosynthesis and respiration were measured after 7 weeks of growth. Results showed a significant reduction of growth and development with increasing nitrogen and temperature levels. Dark respiration increased strongly at high nitrogen levels. At the same time, net photosynthesis at 250 and 500 µE m-2 s-1, Pm, Km and LCP were not affected by either factor. We attribute these phenomena to ammonia toxicity, since relatively high total ammonia (NH3 + NHf4 p+) levels were found in the interstitial water.
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    Photosynthetic performance of deep-water macroalgae (Phaeophyta, Dictyotales) off Bermuda (1992)
    Springer
    Hydrobiologia 231 (1992), S. 93-98 
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    ISSN: 1573-5117
    Keywords: photosynthesis ; macroalgae ; deep-water ; Bermuda ; Dictyotales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic performance and dark respiration rates were determined in situ for abundant macroalgae occurring between 27–49 m depths off Bermuda. Brown algae, particularly members of the order Dictyotales, predominated at all deep-water sites, and Stypopodium zonale was the most abundant species. Species showed net photosynthesis at very low ambient irradiances (〈0.01 maximum Io). Lobophora variegata, a species with a highly decumbent growth form, had low productivity across all irradiances. In contrast, Dictyota spp. (D. bartayresii, D. dichotoma, D. divaricata) and S. zonale had high photosynthetic capacity (ca. 400 µmol O2 gdw−1 h−1), and light saturation was not evidenced at the highest ambient irradiance level (300 µE m−1 s−1) for species with thin, flat thalli. Light-harvesting pigment concentrations reflected tissue-nitrogen levels. C:N atom ratios, except for L. variegata and D. divaricata, were within the ratio for balanced growth. The repeated occurrence and photosynthetic efficiency of these Dictyotalean species in subtropical and tropical deep-water habitats emphasize their successful adaptation to low-light, nutrient-poor environments.
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    Physiological basis for the cultivation of the Gelidiaceae (1991)
    Springer
    Hydrobiologia 221 (1991), S. 83-90 
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    ISSN: 1573-5117
    Keywords: Gelidium ; mass culture ; photosynthesis ; plant physiology ; Pterocladia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An understanding of the physiological factors important to growth and agar production of the Gelidiales would be useful for successful mariculture of these commercially valuable plants. Several environmental factors, including light, nitrogen, carbon, temperature and water motion, have been shown to have potential significance for growth rates, reproduction and carbon partitioning in defining optimal conditions for cultivation. Limiting and optimal growth conditions, where known, are presented, and evaluation of data reported in the literature is addressed.
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    Diel periodicity in phytoplankton productivity (1992)
    Springer
    Hydrobiologia 238 (1992), S. 1-35 
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    ISSN: 1573-5117
    Keywords: periodicity ; diel ; circadian ; clocks ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Daily variation in phytoplankton productivity influences the dynamics and linkages between several large scale processes in aquatic ecosystems. As part of an opening address to the 5th International workshop for the Group for Aquatic Productivity (GAP), the daily patterns of variability in photosynthesis for different algal classes was introduced and accompanied by a discussion of the sources of environmental and endogenous regulation of repeating biological oscillations that occur in phytoplankton on timescales of one day. It is suggested that one way to develop a database that serves to sort and predict phytoplankton variability over the day may be to encourage the creation of a ‘temporal library’. Such a library would be comprised of temporally fixed maps of circadian clock-controlled rhythms for individual species, as well as temporally variable maps of diel periodicities that only can be defined for a selected set of environmental conditions.
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    High biomass and production of picoplankton in a Chinese integrated fish culture pond (1992)
    Springer
    Hydrobiologia 237 (1992), S. 15-23 
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    ISSN: 1573-5117
    Keywords: picoplankton ; photosynthesis ; primary production ; cyprinids ; fish farm pond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phytoplankton dynamics of a Chinese integrated fish culture pond in the suburbs of Shanghai were studied in September and October 1989. The chlorophyll a concentration was high with a range of 62.5–127.3 µg l−1; however, daily net production of phytoplankton was relatively low, with a range of 0.53–1.94 gC m −2 d−1. Of the total phytoplankton biomass, 70–87% was composed of nanoplankton (〈10 µm) and picoplankton, probably because of the selective feeding by phytoplanktivorous carp. In particular, the chlorophyll a concentration of picoplankton was 2.1 – 14.1 mg m −3, and its contribution to total phytoplankton production rate was high (18–68%).
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    Effect of vertical cycling on photosynthesis during the annual algal succession in the northern Baltic (1993)
    Springer
    Hydrobiologia 254 (1993), S. 159-167 
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    ISSN: 1573-5117
    Keywords: photosynthesis ; 14C method ; vertical cycling ; the Baltic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the phytoplankton succession in 1984 and 1985, the effect of fluctuating light on algal photosynthesis (incorporation of 14C, acidified water sample) was studied in the northern Baltic. Bottles were mounted on moving racks that mimicked vertical transport caused by Langmuir circulations in the trophogenic layer. Assuming that the photoinhibition observed near the surface in fixed-depth incubations (from 1 to 8% of integral photosynthesis) was avoided in cycled samples, vertical cycling conducted around noon resulted in on average 10% lower photosynthesis than fixed-depth incubations (n = 17). This difference lies within the 5% confidence limits of the measurement, and hence it was concluded that the lack of short-term fluctuations in light associated with the vertical circulation of natural phytoplankton communities does not seriously bias conventional in situ 14CO2 fixation measurements performed at fixed depths in the study area.
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    Photosynthetic activity of phytoplankton in a high altitude lake (Emerald Lake, Sierra Nevada, California) (1992)
    Springer
    Hydrobiologia 230 (1992), S. 37-48 
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    ISSN: 1573-5117
    Keywords: photosynthesis ; alpine lake ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic activity by phytoplankton was measured during the ice-free seasons of 1984, 1985 and 1987 using the 14C radioassay in high altitude Emerald Lake (California). Relative quantum yield (αB) and light-saturated chlorophyll-specific carbon uptake (Pm B) were calculated from the relationship of light and photosynthesis fitted to a hyperbolic tangent function. Temporal changes in Pm B showed no regular pattern. Seasonal patterns of αB generally had peaks in the summer and autumn. Phytoplankton biomass (as measured by chlorophyll a) and light-saturated carbon uptake (Pm) had peaks in the summer and autumn which were associated with vertical mixing. Estimates of mean daily carbon production were similar among the three years: 57 mg C m−2 2 d−1 in 1984, 70 mg C m−2 2 d−1 in 1985 and 60 mg C m−2 d−1 in 1987. Primary productivity in Emerald Lake is low compared to other montane lakes of California and similar to high-altitude or high-latitude lakes in other regions.
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    Physiological comparison between gametophytes and tetrasporophytes of Gelidium canariensis (Gelidiaceae: Rhodophyta) (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 445-449 
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    ISSN: 1573-5117
    Keywords: Calorific content ; enzyme activity ; gametophytes ; Gelidium canariensis ; photosynthesis ; respiration ; tetrasporophytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The physiological performances of tetrasporophytes and gametophytes of Gelidium canariensis (Grunow) Seoane-Camba were compared to estimate whether the field predominance of tetrasporophytes is due to lower fitness of gametophytes. No significant differences between tetrasporophytes and gametophytes were detected for calorific content, protein and pigment concentrations, NADH-Diaphorase, alkaline phosphatase and glucose-6-phosphate dehydrogenase activities and photosynthesis and respiration at 15, 20 and 25 °C, and pH 6.5, 8.2 and 9.2. Our results indicate that these physiological characteristics are not responsible for the scarcity of gametophytes in the field populations of G. canariensis.
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    Environmental control of phytoplankton productivity in turbulent turbid systems (1994)
    Springer
    Hydrobiologia 289 (1994), S. 65-72 
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    ISSN: 1573-5117
    Keywords: photosynthesis ; selective environments ; resuspension ; disturbance ; rivers ; shallow lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Factors affecting phytoplankton productivity are analysed in turbid systems, such as shallow lakes and rivers. When resuspension from the sediment or loading from the catchment significantly increases inorganic (non-algal) turbidity and hence light attenuation potentials for high production are not realised. Energy available for phytoplankton growth is strongly regulated by underwater light availability which depends on the critical mixing depth, fluctuating light intensities and algal circulation patterns. Higher production rates in shallow waters are often compensated by greater algal respiration due to higher water temperatures when compared to deeper lakes. Total daily integral production of turbulent, turbid environments can be predicted from a combination of easily measured variables such as maximum photosynthetic rates, algal biomass, surface irradiance and some measure of underwater light attenuation.
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    Effects of homobrassinolide application on plant metabolism and grain yield under irrigated and moisture-stress conditions of two wheat varieties (1994)
    Springer
    Plant growth regulation 14 (1994), S. 173-181 
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    ISSN: 1573-5087
    Keywords: homobrassinolide ; irrigated ; membrane stability ; moisture-stress ; nitrate reductase activity ; photosynthesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Homobrassinolide (BR) was applied either as a seed treatment or foliar spray to two contrasting wheat varieties, viz. C306 (drought tolerant) and HD2329 (drought susceptible), to examine its effects on plant metabolism and grain yield under irrigated and moisture-stress/rainfed conditions. BR application resulted in increased relative water content, nitrate reductase activity, chlorophyll content and photosynthesis under both conditions. BR application also improved membrane stability (lower injury). These beneficial effects resulted in higher leaf area, biomass production, grain yield and yield related parameters in the treated plants. All the treatments were significantly better than the untreated control. Generally, 0.05 ppm either as a seed treatment or foliar spray was more effective than the 0.01 ppm treatment. The drought-tolerant genotype C306 showed more response to BR application under moisture-stress/rainfed condition than HD 2329. Increased water uptake, membrane stability and higher carbon dioxide and nitrogen assimilation rates under stress seemed to be related to homobrassinolide-induced drought tolerance.
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    Development and application of a technique for estimating nutrient deficiency in soft sediments (1990)
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    Hydrobiologia 203 (1990), S. 93-97 
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    ISSN: 1573-5117
    Keywords: sediments ; nitrogen ; phosphorus ; nutrient limitation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A diffusion enrichment technique is presented which allows for chemical enrichment of soft surficial and shallow subsurface sediments and subsequent measurement of O2 production. The sediment is enriched by inserting a perforated tube containing dialysis tubing filled with a nutrient/agar mixture. O2 production by surficial sediment is measured using an inverted, translucent, polyethylene chamber over the sediment. The inside of the chamber contains a collapsible bag connected to the water outside the chamber. When water overlying the sediment is withdrawn from a sampling port, it is displaced with water from outside the chamber, thus preventing contamination of water samples with pore water from below. The technique was tested by enriching near-shore sediments in a large oligotrophic lake with inorganic N and P. NHinf4/p+ additions significantly stimulated benthic primary production as measured by 02 production, whereas enrichment with POinf4/3- had no effect.
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    Growth, photosynthesis and agar in wild-type strains of Gracilaria verrucosa and G. conferta (Gracilariales, Rhodophyta), as a strain selection experiment (1990)
    Springer
    Hydrobiologia 204-205 (1990), S. 381-387 
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    ISSN: 1573-5117
    Keywords: Gracilaria ; growth ; light ; photosynthesis ; RuBPcase ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The local species Gracilaria conferta and the foreign G. verrucosa were grown together under a wide range of photon flux density and temperature conditions. Gracilaria verrucosa showed a higher growth rate, especially under low temperatures, and higher photosynthetic performances as well as higher ribulose-1,5-bisphosphate carboxylase activity as compared with G. conferta. Gracilaria verrucosa also showed a better quality and yield of agar, suggesting that this species could be more suitable than G. conferta for outdoor cultivation in Israel and may improve winter growth in ponds. Growth rate and agar quality (gel strength) were rated as the most suitable characteristics influencing the preference of strains for outdoor cultivation.
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    Physiological responses of Pterocladia and Gelidium (Gelidiales, Rhodophyta) from the Azores, Portugal (1990)
    Springer
    Hydrobiologia 204-205 (1990), S. 479-482 
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    ISSN: 1573-5117
    Keywords: Gelidium ; photosynthesis ; physiological responses ; Pterocladia ; Rhodophyta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Manometric studies were conducted on Pterocladia capillacea, Gelidium latifolium and Gelidium spinulosum from the Azores, Portugal to determine optimal values of temperature, light and salinity for growth. Physiological responses were considered in relation to vertical distribution patterns of these species commonly observed throughout the Azores. Optimal parameters for the growth of Pterocladia capillacea, Gelidium latifolium and G. spinulosum were 17 to 25 °C, a photon flux density between 200 and 300 µmol m−2 s−1 and salinities of 25 to 35‰.
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    Influence of medium frequency light/dark cycles of equal duration on the photosynthesis and respiration of Chlorella pyrenoidosa (1992)
    Springer
    Hydrobiologia 238 (1992), S. 53-62 
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    ISSN: 1573-5117
    Keywords: light/dark cycles ; photosynthesis ; Chlorella ; diurnal variations ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorella pyrenoidosa was grown in three continuous cultures each receiving a different light regime during the light period of a diurnal cycle. Hourly samples taken during the light period were subjected to medium frequency light/dark oscillations of equal duration, ranging from 3 to 240 seconds. The oxygen consumption and production of each sample were measured with an oxygen electrode in a small oxygen chamber. Although the light/dark cycles had little overall influence on photosynthetic activity, the microalgae appeared to adapt to the light regime to which they were subjected. Large differences were found between the maximum chlorophyll-specific production rates (P infmax supB ), the chlorophyll-specific production rates (PB) and the respiration rates between the cultures and treated subsamples. Respiration rates increased during the light period, whilst PB either increased, or had a mid light period minimum or maximum. The culture which received an hourly light oscillation during the light period had the highest P infmax supB and lowest respiration rates, and it is suggested that these algae react as in nature, whereas either a sinusoidal or a block light pattern is ‘unnatural’. The latter light regime is commonly used in laboratory studies.
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    The effect of dynamic light regimes on Chlorella II. Minimum quantum requirement and photosynthesis-irradiance parameters (1992)
    Springer
    Hydrobiologia 238 (1992), S. 79-88 
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    ISSN: 1573-5117
    Keywords: dynamic light regime ; photosynthesis ; respiration ; quantum requirement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comparisons were made of photosynthesis in three light limited cyclostat cultures (LD = 8:16, dilution rate 0.7 d−1) of Chlorella pyrenoidosa, differing only in the dynamics of irradiance supply: as a constant rate, i.e. a block culture; as a sine function of the light period, i.e. a sinusoidal culture; as an 8 h sine function superimposed by an 1 h sine function, i.e. an oscillating culture. The sinusoidal culture had a constant minimum quantum requirement for oxygen evolution (QR) of 10.8 over the photoperiod. The OR of the oscillating culture increased from 24 to 37 during the photoperiod. From changes in α and P max we suggest that: (1) photosynthetic units (PSU) of the block and sinusoidal sulture increased in number; (2) increasingly fewer chlorophyll molecules participated in oxygenic photosynthesis with a decreasing turnover time of the PSU's during an oscillating photoperiod. Values of I k decreased slightly in the block culture, increased slightly in the sinusoidal culture and showed a twofold increase in the oscillating culture. From the ratio of in situ oxygen production (qO2) and P max we infer a balanced equilibrium between photosystem activity and electron transport capacity for the block and sinusoidal culture. We hypothesize that the qO2 values of the oscillating culture underestimated true oxygen production rates due to a nonlinear response at peak light intensities. The results show that a dynamical photoperiod provoked significantly different photosynthetic responses, even though the overall growth rate was unaffected.
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    Photosynthesis in thick cyanobacterial films: a comparison of annual and perennial antarctic mat communities (1993)
    Springer
    Hydrobiologia 252 (1993), S. 203-209 
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    ISSN: 1573-5117
    Keywords: Antarctica ; cyanobacterial mats ; periphyton ; photosynthesis ; self-shading ; streams
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Annual and perennial cyanobacterial mats from streams on Signy Island, Antarctica, show similar areal concentrations of chlorophyll-a and areal rates of photosynthesis. Maximum rates of photosynthesis were temperature dependant over the range 0–14 C, with a Q10 of approximately 2.5. Rates of photosynthesis per unit chlorophyll-a were comparable to other Antarctic mat communities but low compared to phytoplankton from upstream lakes. Areal rates of photosynthesis were however much higher than for phytoplankton. Low chlorophyll-specific rates of photosynthesis are interpreted as the effect of self shading within the mats. It is hypothesised that these mats rapidly attenuate incoming radiation and that photosynthesis in most of the mat is effectively light-limited. This situation is likely to occur in all thick periphyton films.
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    Epilithic chlorophyll a, photosynthesis, and respiration in control and fertilized reaches of a tundra stream (1992)
    Springer
    Hydrobiologia 240 (1992), S. 121-131 
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    ISSN: 1573-5117
    Keywords: streams ; arctic ; tundra ; epilithon ; photosynthesis ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis and respiration by the epilithic community on cobble in an arctic tundra stream, were estimated from oxygen production and consumption in short-term (4–12 h), light and dark, chamber incubations. Chlorophyll a was estimated at the end of each incubation by quantitatively removing the epilithon from the cobble. Fertilization of the river with phosphate alone moderately increased epilithic chlorophyll a, photosynthesis, and respiration. Fertilization with ammonium sulfate and phosphate, together, greatly increased each of these variables. Generally, under both control and fertilized conditions, epilithic chlorophyll a concentrations (mg m−2), photosynthesis, and respiration (mg O2 m−2, h−1) were higher in pools than in riffles. Under all conditions, the P/R ratio was consistent at ∼ 1.8 to 2.0. The vigor of epilithic algae in riffles, estimated from assimilation coefficients (mg O2 [mg Chl a]−1 h−1) was greater than the vigor of epilithic algae in pools. However, due to the greater accumulation of epilithic chlorophyll a in pools, total production (and respiration) in pools exceeded that in riffles. The epilithic community removed both ammonium and nitrate from water in chambers. Epilithic material, scoured by high discharge in response to storm events and suspended in the water column, removed ammonium and may have increased nitrate concentrations in bulk river water. However, these changes were small compared to the changes exerted by attached epilithon.
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    Development and ecological importance of phytoplankton in a large lowland river (River Meuse, Belgium) (1994)
    Springer
    Hydrobiologia 289 (1994), S. 139-155 
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    ISSN: 1573-5117
    Keywords: potamoplankton ; regulated river ; transport of carbon and nutrients ; photosynthesis ; respiration ; dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ecological importance of the River Meuse phytoplankton with regard to carbon and nutrient transport has been examined in two reaches of the Belgian course of the river. Field measurements of total particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate phosphorus (PP) show that the large autochtonous production of organic matter strongly affects the carbon and nutrient budget of the aquatic system. During the growing season, phytoplankton accounts for nearly 60% of the POC and dominates the PON. Calculations of the carbon and oxygen budget in the upper reach of the Belgian Meuse demonstrates that the ecosystem is autotrophic, i.e. that autochtonous FPOM (fine particulate organic matter) production is the major carbon input. This suggests that in large lowland rivers, primary production (P) may exceed community respiration (R), i.e. P:R〉1, whereas they are assumed to be heterotrophic (P:R〈1) in the River Continuum concept. The question of maintenance of phytoplankton in turbid mixed water columns is also addressed, and the case of the River Meuse is treated on the basis of studies of photosynthesis and respiration (ETS measurements). The results suggest that the potamoplankton may show some low-light acclimation, through an increase of chlorophyll a relative to biomass, when it comes to deep downstream reaches, and that algal respiration rate may be reduced. A simulation of the longitudinal development of the algal biomass shows the different phases of algal growth and decline along the river and brings support to the ‘importation hypothesis’ for explaining maintenance of potamoplankton in the downstream reaches.
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    A control mechanism of the phytoplankton respiration in a eutrophic reservoir (1980)
    Springer
    Hydrobiologia 72 (1980), S. 125-129 
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    ISSN: 1573-5117
    Keywords: Phytoplankton ; respiration ; photosynthesis ; growth ; feedback mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the eutrophic Bautzen reservoir (German Democratic Republic) the compensation light intensities (photosynthesis = respiration of the phytoplankton) have been found to be extremely low if no free carbon dioxide is available. This result is interpreted as a minimization of the cell respiration under CO2-limitation of the photosynthesis.
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    An automatic system to study the responses of respiration and photosynthesis by submerged macrophytes to environmental variables (1981)
    Springer
    Hydrobiologia 77 (1981), S. 277-285 
    Details
    ISSN: 1573-5117
    Keywords: metabolic chamber ; submerged aquatic macrophytes ; Ranunculus ; respiration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An apparatus to measure the rates of respiration and photosynthesis of aquatic plants in water at velocities of up to 200 mm s−1 in a closed water-flow system with partial recirculation, is described. The temperature, the light regime and the concentration of dissolved oxygen are controlled automatically. Typical results are given for Ranunculus penicillatus var. calcareus which were repeatable between the same season in different years and compared with published data.
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    The effect of glycerol on the Chlorella symbiosis in Hydra viridis (1981)
    Springer
    Hydrobiologia 85 (1981), S. 59-65 
    Details
    ISSN: 1573-5117
    Keywords: symbiosis ; hydra ; Chlorella ; glycerol bleaching ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In green hydra strains that are bleached by glycerol, photosynthesis is arrested in both intact hydra and freshly extracted algae whereas photosynthesis is not affected by glycerol in ‘resistant’ hydra strains and their algae. Glycerol sensitivity is an inherent property of the algae and sensitivity can be transferred to ‘resistant’ aposymbiotic hydra by infecting them with ‘sensitive’ algae. It is suggested that the host hydra recognizes glycerol induced changes, other than photosynthetic incompetance, in the algae and either ejects or digests them.
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    URL: http://dx.doi.org/10.1007/BF00011345
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    Community photosynthesis and respiration in experimental streams (1982)
    Springer
    Hydrobiologia 87 (1982), S. 3-10 
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    ISSN: 1573-5117
    Keywords: benthos ; diurnal oxygen curve ; lotic ecology ; macrophytes ; photosynthesis ; reaeration ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in relative contribution to total stream photosynthetic and respiratory rates by various community components of an open channel stream were estimated. Rates of photosynthetic production of plankton, benthos and macrophytes (with associated epiphytes) were followed through the growing season and compared with total estimates from a diurnal oxygen technique. Photosynthetic production by macrophytes was extremely high early in the growing season; but later declined and heterotrophic processes became predominant. In contrast, benthos production was initially low but became the primary source of photosynthesis later in the season. Plankton contributed little to stream photosynthesis and respiration.
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    URL: http://dx.doi.org/10.1007/BF00016656
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    Respiration and photosynthesis in energy-transducing membranes of cyanobacteria (1982)
    Springer
    Journal of bioenergetics and biomembranes 14 (1982), S. 271-286 
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    ISSN: 1573-6881
    Keywords: Respiration ; photosynthesis ; cyanobacteria ; thylakoids ; energy-transducing membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Cyanobacteria are photolithotrophic organisms exhibiting oxygenic photosynthesis. In the dark they satisfy their need for energy with respiration. These reactions occur in the same compartment and probably on the same energy-transducing membranes. The characterization of the electron transport chain in the light and in the dark, photophosphorylation and oxidative phosphorylation, as well as possible common pathways in photosynthesis and respiration, are discussed.
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    URL: http://dx.doi.org/10.1007/BF00743057
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    The role of plasma membrane redox activity in light effects in plants (1991)
    Springer
    Journal of bioenergetics and biomembranes 23 (1991), S. 393-408 
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    ISSN: 1573-6881
    Keywords: Signal transduction ; photosynthesis ; blue light ; plasma membrane redox ; light-induced absorbance change ; flavin ; cytochromeb ; sphingoid bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Stimulations by light of electron transport at the plasma membrane make it possible that redox activity is involved in light-induced signal transduction chains. This is especially true in cases where component(s) of the chain are also located at the plasma membrane. Photosynthetic reactions stimulate transplasma membrane redox activity of mesophyll cells. Activity is measured as a reduction of the nonpermeating redox probe, ferricyanide. The stimulation is due to production of a cytosolic electron donor from a substance(s) transported from the chloroplast. It is unknown whether the stimulation of redox activity is a requirement for other photosynthetically stimulated processes at the plasma membrane, but a reduced intermediate may regulate proton excretion by guard cells. Blue light induces an absorbance change (LIAC) at the plasma membrane whose difference spectrum resembles certainb-type cytochromes. This transport of electrons may be due to absorption of light by a flavoprotein. The LIAC has been implicated as an early step in certain blue light-mediated morphogenic events. Unrelated to photosynthesis, blue light also stimulates electron transport at the plasma membrane to ferricyanide. The relationship between LIAC and transmembrane electron flow has not yet been determined, but blue light-regulated proton excretion and/or growth may depend on this electron flow. No conclusions can be drawn regarding any role for phytochrome because of a paucity of information concerning the effects of red light on redox activity at the plasma membrane.
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    URL: http://dx.doi.org/10.1007/BF00771011
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    Thebc 1 complexes ofRhodobacter sphaeroides andRhodobacter capsulatus (1993)
    Springer
    Journal of bioenergetics and biomembranes 25 (1993), S. 195-209 
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    ISSN: 1573-6881
    Keywords: Cytochrome ; bc 1 ; complex III ; Q-cycle ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Photosynthetic bacteria offer excellent experimental opportunities to explore both the structure and function of the ubiquinol-cytochromec oxidoreductase (bc 1 complex). In bothRhodobacter sphaeroides andRhodobacter capsulatus, thebc 1 complex functions in both the aerobic respiratory chain and as an essential component of the photosynthetic electron transport chain. Because thebc 1 complex in these organisms can be functionally coupled to the photosynthetic reaction center, flash photolysis can be used to study electron flow through the enzyme and to examine the effects of various amino acid substitutions. During the past several years, numerous mutations have been generated in the cytochromeb subunit, in the Rieske iron-sulfur subunit, and in the cytochromec 1 subunit. Both site-directed and random mutagenesis procedures have been utilized. Studies of these mutations have identified amino acid residues that are metal ligands, as well as those residues that are at or near either the quinol oxidase (Qo) site or the quinol reductase (Qi) site. The postulate that these two Q-sites are located on opposite sides of the membrane is supported by these studies. Current research is directed at exploring the details of the catalytic mechanism, the nature of the subunit interactions, and the assembly of this enzyme.
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    An active Mehler-peroxidase reaction sequence can prevent cyclic PS I electron transport in the presence of dioxygen in intact spinach chloroplasts (1994)
    Springer
    Photosynthesis research 41 (1994), S. 429-437 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; ascorbate peroxidase ; Mehler reaction ; cyclic PS I ; chlorophyll fluorescence ; 9-aminoacridine fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of 9-aminoacridine (9-AA) fluorescence quenching, O2-uptake and chlorophyll fluorescence of intact spinach chloroplasts were carried out to assess the relationship between the transthylakoidal ΔpH and linear electron flux passing through Photosystem II. Three different types of O2-dependent electron flow were investigated: (1) Catalysed by methyl viologen; (2) in the absence of a catalyst and presence of an active ascorbate peroxidase (Mehler-peroxidase reaction); (3) in the absence of a catalyst and with the ascorbate peroxidase being inhibited by KCN (Mehler reaction). The aim of this study was to assess the relative contribution of ΔpH-formation which is not associated with electron flow through Photosystem II and, which should reflect Photosystem I cyclic flow under the different conditions. The relationship between the extent of 9-AA fluorescence quenching and O2-uptake rate was found to be almost linear when methyl viologen was present. In the absence of methyl viologen (Mehler reaction) an increase of 9-AA fluorescence quenching to a value of 20% at low light intensities was associated with considerably less O2-uptake than in the presence of methyl viologen, indicating the involvement of cyclic flow. These findings are in agreement with a preceding study of Kobayashi and Heber (1994). However, when no KCN was added, such that the complete Mehler-peroxidase reaction sequence was operative, the relationship between 9-AA fluorescence quenching and the flux through PS II, as measured via the chlorophyll fluorescence parameter ΔF/Fm′ × PAR, was identical to that observed in the presence of methyl viologen. Under the assumption that methyl viologen prevents cyclic flow, it is concluded that there is no significant contribution of cyclic electron flow to ΔpH-generation in intact spinach chloroplasts.
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    Photosynthetic characteristics of Cymbidium plantlet in vitro (1990)
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    Plant cell, tissue and organ culture 22 (1990), S. 205-211 
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    ISSN: 1573-5044
    Keywords: CO2 enrichment ; Cymbidium ; in vitro ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic characteristics of the Cymbidium plantlet in vitro cultured on Hyponex-agar medium with 2% sucrose were determined based on the measurements of CO2 concentration inside and outside of the culture vessels. The CO2 measurements were made with a gas chromatograph at a PPF (photosynthetic photon flux) of 35, 102 and 226 μmol m-2 s-1, a chamber air temperature of 15, 25 and 35°C and a CO2 concentration outside the vessel of approximately 350, 1100 and 3000 ppm. The net photosynthetic rates were determined on individual plantlets and were expressed on a dry weight basis. The steady-state CO2 concentration during the photoperiod was lower inside the vessel than outside the vessel at any PPF greater than 35 μmol m-2s-1 and at any chamber air temperature. The photosynthetic response curves relating the net photosynthetic rate, PPF, and CO2 concentration in the vessel and chamber air temperature were similar to those for Cymbidium plants grown outside and other C3 plants grown outside under shade. The results indicate that CO2 enrichment for the plantlets in vitro at a relatively high PPF would promote photosynthesis and hence the growth of chlorophyllous shoots/plantlets in vitro and that the plantlets in vitro would make photoautotrophic growth under environmental conditions favorable for photosynthesis.
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    Effects of sucrose on starch accumulation and rate of photosynthesis in Rosa cultured in vitro (1991)
    Springer
    Plant cell, tissue and organ culture 25 (1991), S. 21-26 
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    ISSN: 1573-5044
    Keywords: in vitro culture ; photosynthesis ; Rosa multiflora ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shootlets of Rosa multiflora L. cv. Montse were cultured in vitro with four different levels of sucrose (0, 1, 3 and 5%). Chloroplasts of shootlets grown in a medium without sucrose contained numerous, large plastoglobuli and were lacking in starch granules. The size and number of starch granules increased with the level of sucrose in the culture medium. Starch content in leaves of shootlets grown with 5% sucrose was higher (ca 1, 3%) than those grown with 3% (ca 0, 45%) and 1% sucrose (ca 0, 27%). Starch might be used by the in vitro shootlets during the acclimation period.
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    Carbon isotope ratio and photosynthetic activity of phytoplankton in the eutrophic Mikawa Bay, Japan (1992)
    Springer
    Ecological research 7 (1992), S. 355-361 
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    ISSN: 1440-1703
    Keywords: carbon isotope ratio ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primary production by phytoplankton in the eutrophic Mikawa Bay, Japan, was studied by simultaneous measurements of natural carbon isotope ratio (δ 13C) and short-term carbon uptake rates (13C tracer study) of size-fractionated nannoplankton (〈10 μm) and net plankton (〉10 μm) samples. Short-term photosynthetic rates, which represent the physiological state of algae, were variable regardless of standing stock sizes. Theδ 13C values of particulate organic carbon (POC) in June and July displayed horizontal variations for both the net plankton fraction (−19.8 to −12.7‰) and the nannoplankton fraction (−22.0 to −12.8‰). For both fractions, low concentrations of POC had more negativeδ 13C values (−22 to −18‰). Highδ 13C values for the net plankton were found when POC concentrations were much higher, due to red tide. This suggests that the increase in algal standing crop for the net plankton fraction resulted from accelerated photosynthetic activity. However the nannoplankton fractions with higher POC values have relatively lowδ 13C values.
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    Effects of two sesquiterpene lactones isolated fromArtemisia annua on physiology ofLemna minor (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 969-978 
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    ISSN: 1573-1561
    Keywords: Artemisinin ; arteannuic acid ; photosynthesis ; respiration ; chlorophyll ; Lemna minor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of artemisinin and arteannuic acid extracted fromArtemisia annua on the physiology ofLemna minor were evaluated. Changes in frond production, growth, dry weight, and chlorophyll content ofL. minor were determined. Photosynthesis and respiration were evaluated with a differential respirometer. Artemisinin (5 µM) inhibitedL. minor frond production and dry weight 82 and 83%, relative to methanol controls. Chlorophyll content was reduced 44% by artemisinin (2.5 µM). Arteannuic acid (10 µM) was less active, inhibiting frond production 61% and reducing chlorophyll content 66% at 5 µM. Artemisinin (1 µM) reducedL. minor photosynthesis 30% and 2.5 µM reduced respiration 39%. Arteannuic acid had no significant effect on photosynthesis or respiration at the levels tested.
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    Red fluorescence spectra as a new means of determining the rate of damage to photosynthesis apparatus in plants caused by stress (1991)
    Springer
    Journal of biological physics 18 (1991), S. 57-63 
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    ISSN: 1573-0689
    Keywords: Red fluorescence ; stress ; photosynthesis ; entropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A new method is presented for determining the rate of damage to photosynthesis apparatus efficiency ε caused by stress using the red fluorescence spectra of plant leaves. A direct connection was found between the position of the red fluorescence maximum ν max and the photosynthesis apparatus efficiency ε. The method was tested on several examples and good results were obtained.
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    Photosynthetic electron transport and anaerobic metabolism in purple non-sulfur phototrophic bacteria (1994)
    Springer
    Antonie van Leeuwenhoek 66 (1994), S. 151-164 
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    ISSN: 1572-9699
    Keywords: purple non-sulfur bacteria ; Rhodobacter ; photosynthesis ; CO2 fixation ; anaerobic respiration ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Purple non-sulfur phototrophic bacteria, exemplifed byRhodobacter capsulatus andRhodobacter sphaeroides, exhibit a remarkable versatility in their anaerobic metabolism. In these bacteria the photosynthetic apparatus, enzymes involved in CO2 fixation and pathways of anaerobic respiration are all induced upon a reduction in oxygen tension. Recently, there have been significant advances in the understanding of molecular properties of the photosynthetic apparatus and the control of the expression of genes involved in photosynthesis and CO2 fixation. In addition, anaerobic respiratory pathways have been characterised and their interaction with photosynthetic electron transport has been described. This review will survey these advances and will discuss the ways in which photosynthetic electron transport and oxidation-reduction processes are integrated during photoautotrophic and photoheterotrophic growth.
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    Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 311-329 
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    ISSN: 1572-9699
    Keywords: photosynthesis ; chlorophyll ; bacteriochlorophyll ; reaction center ; electron transfer ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.
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    Thigmomorphogenesis: the effect of mechanical perturbation on plants (1993)
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    Plant growth regulation 12 (1993), S. 313-324 
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    ISSN: 1573-5087
    Keywords: ethylene ; mechanical perturbation ; photosynthesis ; respiration ; thigmomorphogenesis ; wind
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thigmomorphogenetic responses occur in many environmental settings. The most pronounced effects are found under conditions of extremely high rates of turbulent wind or water flow. However, it is an ubiquitous phenomenon, since mechanical perturbations are to be encountered under all but the most stringent laboratory conditions. Our present understanding of these phenomena is the result of studies at the ecological, anatomical, physiological, biochemical, biophysical and molecular biological levels.
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    The stable level of coral primary production in a wide light range (1991)
    Springer
    Hydrobiologia 216-217 (1991), S. 383-387 
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    ISSN: 1573-5117
    Keywords: coral ; production ; photosynthesis ; light adaptation ; PAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light adaptation and photosynthetic productivity were studied in common reef-building corals on islands of the Indian Ocean and the South China Sea. When light is attenuated, both in shade and at depth, adaptations by zooxanthellae permit maximal absorption and utilization of light. Better utilization of incident light in shade-dwelling and deep-water coral forms is reflected by higher values of gross photosynthesis on the plateau and linear portion of the photosynthesis-irradiance curve. It was shown that outer branches of reef-building corals are autotrophic in a major part of their light-range distribution and have a high and stable level of primary production.
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    Influence of the mixing regime on algal photosynthetic performance in laboratory scale enclosures (1992)
    Springer
    Hydrobiologia 238 (1992), S. 111-118 
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    ISSN: 1573-5117
    Keywords: mixing regime ; Laboratory Scale Enclosures ; phytoplankton ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthesis of plankton sampled from the eutrophic Lake Loosdrecht was studied in Laboratory Scale Enclosures (LSEs) with regard to the rate of mixing. First, two LSEs were operated at different mixing rates. No significant differences in photosynthetic performance were found, with the exception of a depressed photosynthesis in the afternoon in the LSE which had a low mixing rate. Secondly, when mixing was stopped, the phytoplankton which stayed in the dark due to the steep light gradient in the LSE responded by changing its maximal photosynthetic capacity. The results show that the filamentous cyanobacteria in the lake can respond rapidly to changes in the depth of the mixed layer by altering their photosynthetic performance.
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    Heterosis in growth and photosynthetic rate in hybrids of cotton (1981)
    Springer
    Euphytica 30 (1981), S. 129-133 
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    ISSN: 1573-5060
    Keywords: Gossypium hirsutum ; Gossypium barbadense ; cotton ; interspecific hybrids ; heterosis ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The intraspecific (Gossipium hirsutum) and interspecific (G. hirsutum x G. barbadense) F1 hybrids of cotton were found to exhibit a high degree of heterosis in the production of fruiting branches, number of bolls (fruits), yield of seed cotton and photosynthetic rates over the parent plants. The developing bolls of the hybrids had significantly higher weights than their parents until the 20th day after anthesis. The patterns of leaf area development among interspecific hybrids differed when compared with the parent plants. The photosynthetic rates of the hybrids were comparable with those of maize and sorghum and much higher than the average rate reported so far for the cotton plant.
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    Leaf thickness and response of leaf photosynthesis to water stress in soybean varieties (1982)
    Springer
    Euphytica 31 (1982), S. 657-664 
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    ISSN: 1573-5060
    Keywords: Glycine max ; soybean varieties ; water stress ; soil water potentials ; photosynthesis ; leaf thickness ; illuminance history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A comparative study of photosynthetic response to soil moisture was conducted with soybean varieties (Harosoy, Norin No. 1 and Hogyoku). When the plants were grown in May before the rainy season under a high radiation level, per unit leaf area the photosynthetic rate of Harosoy leaves was significantly higher throughout the entire range of soil water potentials and leaf water potentials than that of Norin No. 1 leaves. The high photosynthetic rate of Harosoy under non-stress conditionsaand mild water stress was associated with both the high specific leaf weight and the high leaf areal nitrogen content. The photosynthetic response of the Harosoy leaves developed during rainy season under a low radiation level, however, was similar to that of Norin No. 1; no significant difference was observed between these two varieties in the specific leaf weight and in the leaf areal nitrogen content. On the other hand, Hogyoku cultivated especially along the footpaths between the paddy field was very sensitive to water stress, closing the stomata at higher soil water potentials. Under non-stress conditions, as compared with per unit leaf nitrogen content, however, Hogyoku performed higher leaf photosynthesis even with a thinner leaf than Harosoy.
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    The physiological basis for genetic improvement of oil palm in Malaysia (1992)
    Springer
    Euphytica 60 (1992), S. 179-184 
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    ISSN: 1573-5060
    Keywords: breeding ; Elaeis guineensis ; harvest index ; oil palm ; photosynthesis ; selection progress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Yield of Deli dura oil palms after four generations of selection was 60% greater than that of the unselected base population. Total above-ground dry matter production was increased by selection, apparently through better utilisation of solar radiation. The dry matter requirement for vegetative growth was unchanged, so a greater surplus remained for fruit production in the selected palms. Crossing the dura and pisifera to give the thin-shelled tenera fruit type improved partitioning of dry matter within the fruit, giving a 30% increase in oil yield at the expense of shell, without changing total dry matter production.
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    Genetic variation for resistance to low-temperature photoinhibition of photosynthesis in maize (Zea mays L.) (1994)
    Springer
    Euphytica 80 (1994), S. 85-93 
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    ISSN: 1573-5060
    Keywords: maize ; Zea mays ; photoinhibition ; photosynthesis ; low-temperature adaptation ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixty-seven inbred lines of maize were evaluated for resistance to low-temperature photoinhibition of photosynthesis, using a pulse-modulated chlorophyll fluorescence technique. The evaluation procedure was based on leaf discs, which were exposed to a high irradiance (1000 µmol/m2/s) at 7°C. The efficiency of open PSII reaction centres as a reflection of overall photosynthesis was measured before and after a photoinhibition-inducing treatment. Exposure of leaf discs to photoinhibitory condition for 2, 4, and 8 hours resulted in an efficiency reduction of 30, 53 and 83%, respectively. Testing of inbred lines showed large differences for photoinhibition susceptibility. The difference in photosynthetic efficiency between the most extreme lines after a treatment of eight hours was 39%. Resistance to photoinhibition was shown to be relevant under cool field conditions. It proved to be a trait strongly amenable to selection.
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    The effect of O2 and CO2 concentration on photosynthesis and glycolate accumulation in bean leaves treated with α-hydroxy-2-pyridinemethanesulfonic acid (α-HPMS), the glycolate oxidase inhibitor (1980)
    Springer
    Photosynthesis research 1 (1980), S. 45-51 
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    ISSN: 1573-5079
    Keywords: glycolate production ; O2 and CO2 effect ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 14CO2 assimilation, 14C incorporation into glycolate and glycolate accumulation in α-HPMS† treated bean leaves at various O2 and CO2 concentrations were studied. In 1% CO2 oxygen concentration had no significant effect on glycolate accumulation and 14C incorporation into glycolate. In the CO2 concentration range of 0.03% to 0.01%, increased oxygen concentration decreased not only 14CO2 assimilation but also glycolate accumulation and 14C incorporation into glycolate. In 1% and 0.1% CO2, no matter what O2 concentration was supplied, and in 0.03% CO2 with 2% and 21% O2, all of the glycolate accumulated was formed from newly assimilated carbon. In 0.01% CO2 and 2%, 21% and 100% O2, and in 0.03% CO2 with 100% O2, a substantial portion of the glycolic acid that accumulated in leaves originated from endogenous unlabelled substrates. These findings are discussed in terms of possible changes in the ratio of RuBP carboxylation to RuBP oxygenation and of changes of RuBP pool size, induced by changing O2 and CO2 concentrations.
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    Plastoquinone as a common link between photosynthesis and respiration in a blue-green alga (1980)
    Springer
    Photosynthesis research 1 (1980), S. 149-162 
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    ISSN: 1573-5079
    Keywords: blue-green algae ; cytochrome 553 ; electron transport ; photosynthesis ; plastoquinone ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of plastoquinone in a thermophilic blue-green alga, Shynechococcus sp., was studied by measuring reduction kinetics of cytochrome 553 which was oxidized with red flash preferentially exciting photosystem I. Sensitivity of the cytochrome reduction to DBMIB Abbreviations: DCMU = 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DBMIB = 2,5-dib romo-3-methyl-6-isopropyl-p-benzoquinone; HOQNO = 2-n-heptyl-4-hydroxyquinoline-N-oxide indicates that cytochrome 553 accepts electrons from reduced plastoquinone. Plastoquinone is in turn reduced in cells without electrons from photosystem II, since DCMU Abbreviations: DCMU = 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DBMIB = 2,5-dib romo-3-methyl-6-isopropyl-p-benzoquinone; HOQNO = 2-n-heptyl-4-hydroxyquinoline-N-oxide , which inhibited methyl viologen photoreduction more strongly than DBMIB, failed to affect the cytochrome reduction. Participation of cyclic electron transport around photosystem I in cytochrome reduction in the presence of DCMU was excluded, because methyl viologen and antimycin A had no effect on the cytochrome kinetics. On the other hand, electron donation from endogenous substrates to plastoquinone was suggested from decreases in rate of the cytochrome reduction by dark starvation of cells and also from restoration of fast reduction kinetics by the addition of exogenous substrates to or by reillumination of starved cells. KCN, which completely suppressed respiratory O2-uptake, induced a marked acceleration of the cytochrome reduction in starved cells. The poison was less or not effective in stimulating the cytochrome reduction in more extensively starved or reilluminated cells. Results indicate that plastoquinone is functioning not only in the photosynthetic but also in the respiratory electron transport chain, thereby forming a common link between the two energy conservation systems of the blue-green alga.
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    Changes in ribulosebisphosphate carboxylase/oxygenase and ribulose 5-phosphate kinase abundances and photosynthetic capacity during leaf senescence (1990)
    Springer
    Photosynthesis research 23 (1990), S. 223-230 
    Details
    ISSN: 1573-5079
    Keywords: Glycine max L. ; photosynthesis ; ribulose 1,5-bisphosphate carboxylase/oxygenase ; ribulose 5-phosphate kinase ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The abundances of ribulose-1,5-bisphosphate carboxylate/oxygenase (Rubisco) and ribulose-5-phosphate (Ru5P) kinase in field-grown soybean (Glycine max L. Merr.) leaves were quantified by a Western blot technique and related to changes in chlorophyll and photosynthetic capacity during senescence. Even though the leaf content of Rubisco was approximately 80-fold greater than that of Ru5P kinase, the decline in the levels of these two Calvin cycle enzymes occurred in parallel during the senescence of the leaves. Moreover, the decrease in the content of Rubisco was accompanied by parallel decreases of both the large and small subunits of this enzyme but not by an accumulation of altered large or small subunit isoforms. With increasing senescence, decreases in abundances of Rubisco, Ru5P kinase and chlorophyll were closely correlated with the decline in photosynthetic capacity; thus, the specific photosynthetic capacity when expressed per abundance of any of these parameters was rather constant despite an 8-fold decrease in photosynthetic capacity. These results suggest that during senescence of soybean leaves the chloroplast is subject to autolysis by mechanisms causing an approximately 80-fold greater rate of loss of Rubisco than Ru5P kinase.
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    URL: http://dx.doi.org/10.1007/BF00035013
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    The carotenoid zeaxanthin and ‘high-energy-state quenching’ of chlorophyll fluorescence (1990)
    Springer
    Photosynthesis research 25 (1990), S. 187-197 
    Details
    ISSN: 1573-5079
    Keywords: excessive light ; photoprotection ; photosynthesis ; photosystem II regulation ; xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possibility that zeaxanthin mediates the dissipation of an excess of excitation energy in the antenna chlorophyll of the photochemical apparatus has been tested through the use of an inhibitor of violaxanthin de-epoxidation, dithiothreitol (DTT), as well as through the comparison of two closely related organisms (green and blue-green algal lichens), one of which (blue-green algal lichen) naturally lacks the xanthophyll cycle. In spinach leaves, DTT inhibited a major component of the rapidly relaxing high-energy-state quenching' of chlorophyll fluorescence, which was associated with a quenching of the level of initial fluorescence (F′0) and exhibited a close correlation with the zeaxanthin content of leaves when fluorescence quenching was expressed as the rate constant for radiationless energy dissipation in the antenna chlorophyll. Green algal lichens, which possess the xanthophyll cycle, exhibited the same type of fluorescence quenching as that observed in leaves. Two groups of blue-green algal lichens were used for a comparison with these green algal lichens. A group of zeaxanthin-free blue-green algal lichens did not exhibit the type of chlorophyll fluorescence quenching indicative of energy dissipation in the pigment bed. In contrast, a group of blue-green algal lichens which had formed zeaxanthin slowly through reactions other than the xanthophyll cycle, did show a very similar response to that of leaves and green algal lichens. Fluorescence quenching indicative of radiationless energy dissipation in the antenna chlorophyll was the predominant component of ‘high-energy-state quenching’ in spinach leaves under conditions allowing for high rates of steady-state photosynthesis. A second, but distinctly different type of ‘high-energy-state quenching’ of chlorophyll fluorescence, which was not inhibited by DTT (i.e., it was zeaxanthin independent) and which is possibly associated with the photosystem II reaction center, occurred in addition to that associated with zeaxanthin in leaves under a range of conditions which were less favorable for linear photosynthetic electron flow. In intact chloroplasts isolated from (zeaxanthin-free) spinach leaves a combination of these two types of rapidly reversible fluorescence quenching occurred under all conditions examined.
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    Responses of photosynthesis to irradiance and temperature in soybean, Glycine max (L.) Merr (1982)
    Springer
    Photosynthesis research 3 (1982), S. 31-43 
    Details
    ISSN: 1573-5079
    Keywords: CO2 assimilation ; diffusion resistances ; photosynthesis ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of photosynthesis to irradiance and temperature during growth was investigated in two soybean genotypes. Soybean is a species that can modify its structure and metabolism so as to adapt to differing light conditions; its responses to rapid changes in irradiance are characterized by their flexibility. However, the temperature during growth can change the response to irradiance: moreover, there may be a marked interaction with genotype. The response of photosynthesis to irradiance consists of changes in leaf thickness, which bring about variations in the mesophyll resistance to CO2 transfer. The increase in net photosynthesis per unit of leaf area is due to the increase in the amount of assimilating material beneath unit of area, as corroborated by the stability of the net photosynthesis per unit volume. Moreover, the response of photosynthesis to temperature is due to the mesophyll diffusion ‘constant’ which decreases with the growth temperature.
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    URL: http://dx.doi.org/10.1007/BF00030047
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    A new infra-red gas analyser and portable photosynthesis meter (1982)
    Springer
    Photosynthesis research 3 (1982), S. 141-151 
    Details
    ISSN: 1573-5079
    Keywords: infra-red gas analysis ; photosynthesis ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The new infra-red gas analyser for measurement of CO2 concentration described uses a focussed, dual optical path. The 2W radiation source is a heated alumina bead and a cooled lead selenide photoconductive detector measures the difference in radiation absorption at 4.26 μm by the gas in sample and reference tubes. Radiation is chopped alternately between these tubes at 120 Hz. The signal from the detector is processed through an a.c. coupled amplifier, phase sensitive detector and low pass filter. Incorporated into the photosynthesis meter, the sample tube of the analyser is connected to a leaf chamber and circulating pump forming a closed gas circuit. As a leaf in the chamber removes carbon dioxide from the air in the closed circuit, the decrease in its concentration is sensed by the analyser. The time taken for the concentration to decrease by a predetermined amount (typically 30 ppm) is displayed and rate of net photosynthesis can be calculated from this and the volume of the closed circuit. A measurement of the light-saturated rate of net photosynthesis of a healthy flag leaf of wheat can be made in 10–15 seconds. The system is fully portable and has been used intensively in the field for two summers.
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    URL: http://dx.doi.org/10.1007/BF00040712
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    Comparison of chlorophyll a spectra in wild-type and mutant barley chloroplasts grown under day or intermittent light (1982)
    Springer
    Photosynthesis research 3 (1982), S. 19-30 
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    ISSN: 1573-5079
    Keywords: absorption ; chlorophyll ; chloroplasts ; fluorescence ; photosynthesis ; spectral curve analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The absorption (640–710 nm) and fluorescence emission (670–710 nm) spectra (77 K) of wild-type and Chl b-less, mutant, barley chloroplasts grown under either day or intermittent light were analysed by a RESOL curve-fitting program. The usual four major forms of Chl a at 662, 670, 678 and 684 nm were evident in all of the absorption spectra and three major components at 686, 693 and 704 nm in the emission spectra. A broad Chl a component band at 651 nm most likely exists in all chlorophyll spectra in vivo. The results show that the mutant lacks not only Chl b, but also the Chl a molecules which are bound to the light-harvesting, Chl a/b, protein complex of normal plants. It also appears that the absorption spectrum of this antenna complex is not modified appreciably by its isolation from thylakoid membranes.
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    A differential effect of 3-(3′4′ dichlorophenyl)-1,1 dimethyl urea and atrazine on fluorescence kinetics in chloroplasts (1992)
    Springer
    Photosynthesis research 31 (1992), S. 139-148 
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    ISSN: 1573-5079
    Keywords: Fe ; photosynthesis ; Photosystem II ; variable fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It was found that DCMU had a differential effect at two concentration ranges on variable fluorescence kinetics in isolated chloroplasts. The increase in fluorescence rate at low concentrations of DCMU was abolished by preincubation of chloroplasts with ferricyanide or formate, treatments which were shown to convert Fe in the PS II reaction center (i.e., the FeQA complex) into a non-oxidizable form, but it was not affected by Tris treatment. Increase in fluorescence kinetics (at the initial linear rate) at high concentrations of DCMU was found to be abolished by Tris treatment but it was only marginally affected by ferricyanide or formate treatments. The effect of Tris could be abolished by addition of hydroquinone-ascorbate, which restored electron flow to the pool of secondary acceptors. Contrary to the effect of DCMU, no such differential concentration dependence of the variable fluorescence kinetics was found for atrazine. The increase in fluorescence kinetics (at the initial linear rate) at a low concentration rate of DCMU is presumably restricted to units which contain an oxidizable Fe in the FeQA complex. Increase in fluorescence kinetics (at the initial linear rate) at high DCMU concentration is probably related to the effect of DCMU at the QB site.
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    URL: http://dx.doi.org/10.1007/BF00028790
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    Physiological effects of sublethal atrazine on barley chloroplast thylakoid membranes (1992)
    Springer
    Photosynthesis research 32 (1992), S. 1-10 
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    ISSN: 1573-5079
    Keywords: chlorophyll a/b ratio ; chlorophyll-proteins ; electron transport ; herbicide ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was conducted to more clearly define the physiological effects of PS II herbicides on chloroplast thylakoid membrane activity and composition. Barley (Hordeum vulgare L. cv Boone) was grown in hydroponic culture at 20°C in a growth chamber with a light intensity of 500 μmole photons m-2 s-1. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), a Photosystem II herbicide, was supplied continuously via the roots to 7-day-old plants. Atrazine concentrations greater than 0.07 ppm (0.32 μM) were associated with decreased leaf chlorophyll (chl), lowered chl a/b ratio, inhibition of chloroplast electron transport, and plant death within 1 to 2 weeks. Atrazine at 0.07 ppm was defined as sublethal because no toxic effects were observed. Sublethal atrazine induced a decrease in chl a/b ratio with no effect on leaf chl content. Photosynthetic electron transport was either unaffected in fully expanded leaves or slightly stimulated in expanding leaves by treatment of intact plants with 0.07 ppm atrazine. The major effect of sublethal atrazine was on the chl-protein complex composition. Sublethal atrazine increased the level of the Photosystem II light-harvesting complex (LHC-II) and lowered the level of the CP1a Photosystem I complex relative to controls. The numbers of Photosystem II and Photosystem I reaction centers and cytochrome b 6/f complexes per unit chl were not affected by sublethal atrazine. The overall result was an atrazine-induced redistribution of light-harvesting chl from Photosystem I to Photosystem II with no effect on the number of thylakoid membrane-protein complexes associated with electron transport.
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    URL: http://dx.doi.org/10.1007/BF00028793
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    Simultaneous photoreduction and photooxidation of cytochrome b-559 in Photosystem II treated with carbonylcyanide-m-chlorophenylhydrazone (1992)
    Springer
    Photosynthesis research 33 (1992), S. 203-212 
    Details
    ISSN: 1573-5079
    Keywords: Cytochrome b-559 ; ADRY agent ; electron transport ; photosynthesis ; QA ; QB ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possibility of a Photosystem II (PS II) cyclic electron flow via Cyt b-559 catalyzed by carbonylcyanide m-chlorophenylhydrazone (CCCP) was further examined by studying the effects of the PS II electron acceptor 2,6-dichloro-p-benzoquinone (DCBQ) on the light-induced changes of the redox states of Cyt b-559. Addition to barley thylakoids of micromolar concentrations of DCBQ completely inhibited the changes of the absorbance difference corresponding to the photoreduction of Cyt b-559 observed either in the presence of 10 μM ferricyanide or after Cyt b-559 photooxidation in the presence of 2 μM CCCP. In CCCP-treated thylakoids, the concentration of photooxidized Cyt b-559 decreased as the irradiance of actinic light increased from 2 to 80 W m-2 but remained close to the maximal concentration (0.53 photooxidized Cyt b-559 per photoactive Photosystem II) in the presence of 50 μM DCBQ. The stimulation of Cyt b-559 photooxidation in parallel with the inhibition of its photoreduction caused by DCBQ demonstrate that the extent of the light-induced changes of the redox state of Cyt b-559 in the presence of CCCP is determined by the difference between the rates of photooxidation and photoreduction of Cyt b-559 occuring simultaneously in a cyclic electron flow around PS II. We also observed that the Photosystem I electron acceptor methyl viologen (MV) at a concentration of 1 mM barely affected the rate and extent of the light-induced redox changes of Cyt b-559 in the presence of either FeCN or CCCP. Under similar experimental conditions, MV strongly quenched Chl-a fluorescence, suggesting that Cyt b-559 is reduced directly on the reducing side of Photosystem II.
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    URL: http://dx.doi.org/10.1007/BF00030031
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    Thermoluminescence study of the in vivo effects of bicarbonate depletion and acetate/formate presence in the two algae Chlamydobotrys stellata and Chlamydomonas reinhardtii (1992)
    Springer
    Photosynthesis research 34 (1992), S. 279-285 
    Details
    ISSN: 1573-5079
    Keywords: acetate ; bicarbonate effect ; CO2-depletion ; electron transport ; formate ; photosynthesis ; thermoluminescence ; Chlamydobotrys stellata ; Chlamydomonas reinhardtii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigated the influence of CO2/HCO3 −-depletion and of the presence of acetate and formate on the in vivo photosynthetic electron transport in the two green algae Chlamydobotrys stellata and Chlamydomonas reinhardtii by means of thermoluminescence technique and mathematical glow curve analysis. The main effects of the removal of CO2 from the algal cultures was: (1) A shift of the glow curve peak position to lower temperatures resulting from a decrease of the B band and an increase of the Q band. (2) Treatment of CO2-deficient Chl. stellata with DCMU yielded two thermoluminescence bands in the Q band region peaking at around +12°C and +5°C; in case of Chl. reinhardtii DCMU treatment induced only one band with an emission maximum at +5°C. The presence of acetate or formate in CO2-depleted algal cultures lowered the intensities of all of the individual TL bands but that of a HT band (TL+37). The effects of CO2-depletion and of the presence of anions were fully reversible.
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    URL: http://dx.doi.org/10.1007/BF00033445
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    Second-site mutation at M43 (Asn→Asp) compensates for the loss of two acidic residues in the QB site of the reaction center (1992)
    Springer
    Photosynthesis research 32 (1992), S. 147-153 
    Details
    ISSN: 1573-5079
    Keywords: electron transfer ; proton transfer ; photosynthesis ; quinone ; reaction center ; site-specific mutagenesis ; suppressor mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two acidic residues, L212Glu and L213Asp, in the QB binding sites of the photosynthetic reaction centers of Rhodobacter capsulatus and Rhodobacter sphaeroides are thought to play central roles in the transfer of protons to the quinone anion(s) generated by photoinduced electron transfer. We constructed the site-specific double mutant L212Ala-L213Ala in R. capsulatus, that is incapable of growth under photosynthetic conditions. A photocompetent derivative of that strain has been isolated that carries the original L212Ala-L213Ala double mutation and a second-site suppressor mutation at residue M43 (Asn→Asp), outside of the QB binding site, that is solely responsible for restoring the photosynthetic phenotype. The Asp,Asn combination of residues at the L213 and M43 positions is conserved in the five species of photosynthetic bacteria whose reaction center sequences are known. In R. capsulatus and R. sphaeroides, the pair is L213Asp-M43Asn. But, the reaction centers of Rhodopseudomonas viridis, Rhodospirillum rubrum and Chloroflexus aurantiacus reverse the combination to L213Asn-M43Asp. In this respect, the QB site of the suppressor strain resembles that of the latter three species in that it couples an uncharged residue at L213 with an acidic residue at M43. These reaction centers, in which L213 is an amide, must employ an alternative proton transfer pathway. The observation that the M43Asn→Asp mutation in R. capsulatus compensates for the loss of both acidic residues at L212 and L213 suggests that M43Asp is involved in a new proton transfer route in this species that resembles the one normally used in reaction centers of Rps. virddis, Rsp. rubrum and C. aurantiacus.
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    URL: http://dx.doi.org/10.1007/BF00035949
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    Light-dependent modulation of ribulose-1,5-bisphosphate carboxylase/oxygenase activity in the genus Phaseolus (1993)
    Springer
    Photosynthesis research 35 (1993), S. 219-226 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Rubisco ; 2-carboxyarabinitol 1-phosphate ; Phaseolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Modulation of the activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in low light and darkness was measured in A) 25 genotypes from the four cultivated species of Phaseolus (P. vulgaris, P. acutifolius, P. lunatus and P. coccineus), B) 8 non-cultivated Phaseolus species, and C) the related species Macroptileum atropurpureum. The activity ratio of Rubisco (the ratio of initial and total Rubisco activities, which reflects Rubisco carbamylation), and the molar activity of fully-activated Rubisco (which primarily reflects the inhibition of Rubisco activity by carboxyarabinitol 1-phosphate, CA1P) were assayed in leaves from the cultivated species sampled at midday in full sunlight, in low light at dusk (60 to 100 μmol photons m-2s-1), and after at least 4 h in darkness. Dark inhibition of Rubisco molar activity was compared in both cultivated and non-cultivated species. In all cultivated genotypes, a significant reduction of the activity ratio of Rubisco was measured in leaves sampled at low light; however, the molar activity of fully activated Rubisco was not greatly reduced in these low light samples. In darkened leaves, molar activities substantially declined in most Phaseolus species with 11 of 13 exhibiting greater than 60% reduction. In P. vulgaris, the reduction of molar activity was extensive (greater than 69%) in all genotypes studied, which included wild progenitors as well as ancient and advanced cultivars. These results indicate that at low light late in the day, modulation of Rubisco activity is primarily through changes in carbamylation state, with CA1P playing a more limited role. By contrast in the dark, binding of CA1P dominates the modulation of Rubisco activity in Phaseolus in a pattern that appears to be conserved within a species, but can vary significantly between species within a genus. The degree of CA1P inhibition in Phaseolus was associated with phylogenetic affinities within the genus, as the species with extensive dark-inhibition of Rubisco activity tended to be more closely related to each other than to species with reduced inhibition of Rubisco activity.
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    Leaf gas exchange of beech (Fagus sylvatica L.) seedlings in lightflecks: A system for measuring rapid changes in CO2 partial pressures (1993)
    Springer
    Photosynthesis research 35 (1993), S. 299-304 
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    ISSN: 1573-5079
    Keywords: gas exchange system ; photosynthesis ; lightflecks ; effective volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A system is described for the measurement of fast transient responses of leaf gas exchange to lightflecks. Any chamber adulterates a true signal unless in the steady-state; therefore, a procedure for estimating an ‘effective chamber volume’ is presented which is an essential parameter for correcting a measured transient signal. A common correction is critically commented on. With the system, responses of net photosynthesis to lightflecks as short as 1 s have been observed in leaves of seedlings of Fagus sylvatica L.
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    The relationship between Photosystem II intrinsic quantum yield and millisecond luminescence in thylakoids (1993)
    Springer
    Photosynthesis research 37 (1993), S. 131-138 
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    ISSN: 1573-5079
    Keywords: luminescence ; Photosystem II ; quantum efficiency ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between charge recombination at Photosystem II (PS II), as indicated by millisecond luminescence, and PS II quantum yield was studied in spinach thylakoids during electron flow to methylviologen. Under the low magnesium conditions used, a decrease in quantum yield was observed in the absence of non-photochemical excitation quenching, and therefore cannot be due to a restriction in excitation delivery to the reaction centre. It was found that the decrease of the parameter Φp, which is a measure of the intrinsic quantum yield of ‘open’ PS II centers, correlates with an increase in luminescence per ‘open’ center. The relationship between these two parameters was the same whether Φp was manipulated by dissipation of the transthylakoid pH gradient or of the electrical potential. This indicates that the mechanism by which Φp decreases depends in the same way on the two components of the protonmotive force as does the charge recombination at PS II. Calculation of the yield of luminescence with respect to the back reaction will be necessary to determine whether the charge recombination occurs at a sufficiently high rate to be directly responsible for the Φp decrease.
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    Optimal acclimation of the C3 photosynthetic system under enhanced CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 401-412 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; elevated CO2 ; source-sink interactions ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A range of studies of C3 plants have shown that there is a change in both the carbon flux and the pattern of nitrogen allocation when plants are grown under enhanced CO2. This paper examines evidence that allocation of nitrogen both to and within the photosynthetic system is optimised with respect to the carbon flux. A model is developed which predicts the optimal relative allocation of nitrogen to key enzymes of the photosynthetic system as a function of CO2 concentration. It is shown that evidence from flux control analysis is broadly consistent with this model, although at high nitrogen and under certain conditions at low nitrogen experimental data are not consistent with the model. Acclimation to enhanced CO2 is also assessed in terms of resource allocation between photosynthate sources and sinks. A means of assessing the optimisation of this source-sink allocation is proposed, and several studies are examined within this framework. It is concluded that C3 plants probably possess the genetic feedback mechanisms required to efficiently ‘smooth out” any imbalance within the photosynthetic system caused by a rise in atmospheric CO2.
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    URL: http://dx.doi.org/10.1007/BF00014594
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    Biochemical and molecular basis for impairment of photosynthetic potential (1994)
    Springer
    Photosynthesis research 39 (1994), S. 453-462 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Rubisco ; ozone ; oxidative stress ; rbcS mRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ozone induces reductions in net photosynthesis in a large number of plant species. A primary mechanism by which photosynthesis is reduced is through impact on carbon dioxide fixation. Ozone induces loss in Rubisco activity associated with loss in concentration of the protein. Evidence is presented that ozone may induce oxidative modification of Rubisco leading to subsequent proteolysis. In addition, plants exposed to ozone sustain reduction in rbcS, the mRNA for the small subunit of Rubisco. This loss in rbcS mRNA may lead to a reduced potential for synthesis of the protein. The regulation of O3-induced loss of Rubisco, and implications of the decline in this protein in relation to accelerated senescence are discussed.
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    URL: http://dx.doi.org/10.1007/BF00014598
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    Isolation and characterization of a 23 kDa protein essential for photosynthetic oxygen evolution (1983)
    Springer
    Photosynthesis research 4 (1983), S. 271-279 
    Details
    ISSN: 1573-5079
    Keywords: electron transport ; inside-out thylakoids ; oxygen evolution ; photosynthesis ; thykoid polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041823
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  • 197
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    Electronic Resource
    A new evaluation of chlorophyll absorption in photosynthetic membranes (1983)
    Springer
    Photosynthesis research 4 (1983), S. 375-383 
    Details
    ISSN: 1573-5079
    Keywords: absorption spectra ; chlorophyll-proteins ; curve resolution ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The three major chlorophyll-proteins of spinach chloroplasts were solubilized with digitonin and isolated by electrophoresis with deoxycholate. The gel bands were identified from their absorption and fluorescence spectra measured at 77 K. The slowest moving band was a Photosystem I complex (CPI); the second, a Photosystem II complex (Cpa); and the third, a chlorophyll a-b, antenna complex (LHCP). When absorption spectra (630–730 nm) of the bands were added in the proportions found in the gel, the sum closely matched the absorption of the chloroplasts both before and after solubilization. Thus these spectra represent the native absorption of the major antenna chlorophyll-proteins of green plants. Each of these spectra was resolved with a computer assisted, curve-fitting program into 8 mixed Gaussian-Lorentzian shaped components. The major, Chl a components in the 3 fractions were different both in peak positions and bandwidths. This result suggests that each chlorophyll-protein has its own unique set of chlorophyll a spectral forms or components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041834
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  • 198
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    Electronic Resource
    Isolation and characterization of a 23 kDa protein essential for photosynthetic oxygen evolution (1983)
    Springer
    Photosynthesis research 4 (1983), S. 271-279 
    Details
    ISSN: 1573-5079
    Keywords: electron transport ; inside-out thylakoids ; oxygen evolution ; photosynthesis ; thykoid polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00052131
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  • 199
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    Reminiscence about‘Chloropseudomonas ethylicum’ and the FMO-protein (1994)
    Springer
    Photosynthesis research 41 (1994), S. 3-5 
    Details
    ISSN: 1573-5079
    Keywords: bacteriochlorophylla-protein ; green sulfur bacteria ; Prosthecochloris aestuarii ; Chlorobium limicola ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 1961 the green sulfur bacterium-containing mixed culture known as‘Chloropseudomonas ethylicum’ was brought to Brookhaven National Laboratory (USA) from Moscow State University (USSR). The water-soluble bacteriochlorophylla-protein (FMO-protein) was extracted, purified and characterized by absorption and circular dichroism spectroscopy, by X-ray crystallography and by primary structure determination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184138
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  • 200
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    Rates of vectorial proton transport supported by cyclic electron flow during oxygen reduction by illuminated intact chloroplasts (1994)
    Springer
    Photosynthesis research 41 (1994), S. 419-428 
    Details
    ISSN: 1573-5079
    Keywords: 9-aminoacridine fluorescence ; cyclic electron transport ; Mehler reaction ; photosynthesis ; photosystems ; transthylakoid proton gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The light-dependent quenching of 9-aminoacridine fluorescence was used to monitor the state of the transthylakoid proton gradient in illuminated intact chloroplasts in the presence or absence of external electron acceptors. The absence of appreciable light-dependent fluorescence quenching under anaerobic conditions indicated inhibition of coupled electron transport in the absence of external electron acceptors. Oxygen relieved this inhibition. However, when DCMU inhibited excessive reduction of the plastoquinone pool in the absence of oxygen, coupled cyclic electron transport supported the formation of a transthylakoid proton gradient even under anaerobiosis. This proton gradient collapsed in the presence of oxygen. Under aerobic conditions, and when KCN inhibited ribulose bisphosphate carboxylase and ascorbate peroxidase, fluorescence quenching indicated the formation of a transthylakoid proton gradient which was larger with oxygen in the Mehler reaction as electron acceptor than with methylviologen at similar rates of linear electron transport. Apparently, cyclic electron transport occured simultaneously with linear electron transport, when oxygen was available as electron acceptor, but not when methylviologen accepted electrons from Photosystem I. The ratio of cyclic to linear electron transport could be increased by low concentrations of DCMU. This shows that even under aerobic conditions cyclic electron transport is limited in isolated intact chloroplasts by excessive reduction of electron carriers. In fact, P700 in the reaction center of Photosystem I remained reduced in illuminated isolated chloroplasts under conditions which resulted in extensive oxidation of P700 in leaves. This shows that regulation of Photosystem II activity is less effective in isolated chloroplasts than in leaves. Assuming that a Q-cycle supports a H+/e ratio of 3 during slow linear electron transport, vectorial proton transport coupled to Photosystem I-dependent cyclic electron flow could be calculated. The highest calculated rate of Photosystem I-dependent proton transport, which was not yet light-saturated, was 330 μmol protons (mg chlorophyll h)−1 in intact chloroplasts. If H+/e is not three but two proton transfer is not 330 but 220 μmol (mg Chl H)−1. Differences in the regulation of cyclic electron transport in isolated chloroplasts and in leaves are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183044
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