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  • photosynthesis  (224)
  • Pyrophosphate
  • Springer  (226)
  • MDPI Publishing
  • 1995-1999  (226)
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  • 101
    Electronic Resource
    Electronic Resource
    Can stomatal closure caused by xylem ABA explain the inhibition of leaf photosynthesis under soil drying? (1997)
    Springer
    Photosynthesis research 51 (1997), S. 149-159 
    Details
    ISSN: 1573-5079
    Keywords: abscisic acid ; t Acacia confusa ; t Leucaenaleucocephala ; photosynthesis ; soil drying ; stomatal conductance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of leaf water deficit and increase in endogenous ABA on photosynthesis of two tropical trees, t Acacia confusa and t Leucaena leucocephala, were investigated with two soil-drying methods, i.e. half or whole root system was subjected to soil drying. Half-root drying was achieved by allowing upper layer of soil column to dry and lower layer of soil column to remain watered. Half-root drying had little effect on leaf water potential, but when compared to the well-watered control, both methods of soil drying substantially increased the ABA concentration in xylem and reduced leaf conductance in both species. There was a significant relationship between leaf conductance and xylem ABA concentrations in both species, which was comparable to the same relationship that was generated by feeding ABA to excised twigs. The rate of photosynthesis was inhibited substantially in both soil-drying treatments and in both species, but photochchemical efficiency, measured as a ratio of variable fluorescence to a peak fluorescence emission of a dark-adapted leaf (Fv/Fm), was not reduced except in the whole root-dried t L. leucocephala plants where leaf water potential was reduced to –2.5 MPa. In all the cases where photosynthesis was inhibited, there was a concomitant reduction in both leaf conductance and calculated internal CO2 concentration. After two days of rewatering, leaf water potential and xylem ABA concentration rapidly returned to pre-treatment levels, but leaf conductance and photosynthesis of both whole-root and half root dried t L. leucocephala remained inhibited substantially. Rewatering led to a full recovery of both stomatal conductance and photosynthesis in soil-dried t A. confusa, although its photosynthesis of whole-root dried plants did not recover fully but such difference was not significant statistically. These results suggest that drought-induced decline of photosynthesis was mainly a result of the stomatal factor caused by the increase of ABA concentration in the xylem sap. Non-stomatal factors, e.g. reduced photochemical activity and/or carbon metabolic activity, were species-specific and were brought about only at very low water potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005797410190
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  • 102
    Electronic Resource
    Electronic Resource
    Regulation of photosynthesis in developing leaves of soybean chlorophyll-deficient mutants (1997)
    Springer
    Photosynthesis research 51 (1997), S. 185-192 
    Details
    ISSN: 1573-5079
    Keywords: CAB ; cytochrome f ; photosynthesis ; Rubisco ; Rubisco activase ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this report we examine the factors that regulate photosynthesis during leaf ontogeny in y3y3 and Y11y11, two chlorophyll-deficient mutants of soybean. Photosynthetic rates were similar during wild type and Y11y11 leaf development, but the senescence decline in photosynthesis was accelerated in y3y3. Photosynthetic rates fell more rapidly than chlorophyll concentrations during senescence in wild type leaves, indicating that light harvesting is not strongly limiting for photosynthesis during this phase of leaf development. Chlorophyll concentrations in Y11y11, though significantly lower than normal, were able to support normal photosynthetic rates throughout leaf ontogeny. Chlorophyll a/b ratios were constant during leaf development in the wild type, but in the mutants they progressively increased (y3y3) or decreased (Y11y11). In all three sets of plants, photosynthetic rates were directly proportional to Rubisco contents and activities, suggesting that Rubisco plays a dominant role in regulating photosynthesis throughout leaf ontogeny in these plants. The expression of some photosynthetic proteins, such as Rubisco activase, was coordinately regulated with that of Rubisco in all three genotypes, i.e. an early increase, coincident with leaf expansion, followed by a senescence decline in the fully-expanded leaf. On the other hand, the light harvesting chlorophyll a/b-binding proteins of PS II (the CAB proteins), while they showed a profile similar to that of Rubisco in the wild type and y3y3, progressively increased in amount during Y11y11 leaf development. We conclude that Y11y11 may be defective in the accumulation of a component required for LHC II assembly or function, while y3y3 has more global effects and may be a regulatory factor that controls the duration of senescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005824706653
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  • 103
    Electronic Resource
    Electronic Resource
    Biomass accumulation and allocation in soybean associated with genotypic differences in tolerance of nitrogen fixation to water deficits (1997)
    Springer
    Plant and soil 196 (1997), S. 101-113 
    Details
    ISSN: 1573-5036
    Keywords: drought ; Glycine max ; photosynthesis ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen fixation in soybean (Glycine max [L.] Merr.) is more sensitive to water deficits than many physiological processes and may therefore limit yield under nonirrigated conditions. Tolerance of nitrogen fixation to water deficits has been observed in the cultivar Jackson, however, the physiological basis for this is unclear. It was hypothesized that genotypes that could continue biomass production on limited soil water would prolong nitrogen fixation by continued photosynthate allocation to nodules. An initial greenhouse experiment compared biomass and N accumulation in six genotypes over an 8 d water deficit. Low stress intensity minimized genotypic expression of water-deficit tolerance; nevertheless, Jackson was clearly one of the most tolerant genotypes. In a second experiment, Jackson was compared to SCE82-303 at more severe stress levels. Biomass and N accumulation continued during water deficits for Jackson but ceased in SCE82-303. Individual nodule mass tended to increase during water deficits in Jackson and tended to decrease in SCE82-303, indicating greater allocation of photosynthate to Jackson's nodules in response to water deficits. Biomass accumulation of Jackson was contrasted with the USDA plant introduction (PI) 416937, which also has demonstrated tolerance to water deficits. For water-deficit treatments, total biomass accumulation was negligible for PI416937, but biomass accumulation continued at approximately 64% of the control treatment for Jackson. Transpirational losses for Jackson and PI416937 were approximately the same for the water-deficit treatment, indicating that Jackson had higher water use efficiency (WUE). Isotopic discrimination of 13C relative to12 C also indicated that Jackson had superior WUE during water deficits. Carbon-14 allocation in Jackson was compared to KS4895, a cultivar that was identified as sensitive to water deficits in an initial experiment. The comparison of water-deficit treatments of Jackson with KS4895 indicated that Jackson exported significantly greater amounts of14 C from labeled leaves and allocated approximately four times greater amounts of 14C per g of nodule. Results indicated that Jackson's sustained biomass production during water deficits resulted in the continued allocation of photosynthate to nodules and prolonged nitrogenase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004289609466
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  • 104
    Electronic Resource
    Electronic Resource
    Does boron play only a structural role in the growing tissues of higher plants? (1997)
    Springer
    Plant and soil 196 (1997), S. 211-215 
    Details
    ISSN: 1573-5036
    Keywords: boron ; deficiency ; function ; membrane ; mobility ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In species in which boron (B) mobility is limited, B deficiency only occurs in growing plant organs. As a consequence of the highly localized patterns of plant growth and the general immobility of B it has been extremely difficult to determine the primary function of B in plants. In species in which B is phloem mobile, the removal of B from the growth medium results in the depletion of B present in mature leaves. Thus, it is possible to develop mature leaves with increasingly severe levels of B depletion, thereby overcoming the complications of experiments based on growing tissues. Utilizing this approach we demonstrate here that B depletion of mature plum (Prunus salicina) leaves did not result in any discernible change in leaf appearance, membrane integrity or photosynthetic capacity even though B concentrations were reduced to 6-8 µg/g dwt, which is less than 30% of the reported tissue B requirement. Boron depletion, however, results in a severe disruption of plant growth and metabolism in young growing tissues. This experimental evidence and theoretical considerations suggest that the primary and possibly sole function of B, is as a structural component of growing tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004245823080
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  • 105
    Electronic Resource
    Electronic Resource
    Effect of genome and ploidy on photosynthesis of wheat (1997)
    Springer
    Euphytica 94 (1997), S. 303-309 
    Details
    ISSN: 1573-5060
    Keywords: photosynthesis ; hexaploid wheat ; A genome ; D genome ; polyploidy ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We assessed (1) the effects of addition and doses of the D genome from different sources and (2) the addition of either the A genome or the D genome on the photosynthesis of synthesized hexaploid wheats. On average, the increased doses of the D genome reduced photosynthesis, but the depression was dependent on the source of the D genome. Two accessions of Aegilops squarrosa had depressed photosynthetic rates, but not another accession of Ae. squarrosa. The D genome of cv. Thatcher did not contribute to depress photosynthetic rate. Triticum monococcum had considerably higher photosynthetic rates than Ae. squarrosa. However, addition of the A genome from T. monococcum did not increase the photosynthetic rates of hexaploids. Chlorophyll a : b ratio, functional photosystem II and the core complex of photosystem II did not account for the variation in photosynthetic rate among the genotypes studied. In our experiment, photosynthesis of polyploids was not dependent on photosynthesis rates of the donor genomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002936019332
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  • 106
    Electronic Resource
    Electronic Resource
    Oceanic picophytoplankton having a high abundance of chlorophyll b in the major light harvesting chlorophyll protein complex (1997)
    Springer
    Photosynthesis research 53 (1997), S. 121-127 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll a/b light-harvesting complex ; major LHCP ; oceanic picophytoplankton ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chl a-containing, very small unicellular, eukaryotic phytoplankton (picophytoplankton) often become the dominant organisms near the bottom of the euphotic zone in the ocean, where light is limited, not only in intensity (about 0.5% of the surface irradiance), but also in quality (dominant in blue to green wavelengths). We have isolated picophytoplankton from subsurface waters (from 75 to 150 m in depth) of the Kuroshio area near Japan. EM observations showed that a single chloroplast occupies a large part of the cytoplasm. Some of the isolates have a flagellum. The major photosynthetic pigments found in these isolates were chlorophyll a and b. The light-harvesting chlorophyll a/b complex (LHCP) was isolated from three clones of picophytoplankton, one flagellated form (NIBB8001) and two coccoid forms (94B8100A and 94B5100C) . More than 50% of the total chlorophylls were recovered in the major LHCP fraction. A common feature of the major LHCPs isolated from the three picophytoplankton clones was a high abundance of chlorophyll b: the ratios of chlorophyll a to b were about 0.8, 0.7 and 0.6 for the clones NIBB8001, 94B8100A and 94B5100C, respectively. These values were very low compared with those in chlorophyll a/b-binding LHCIIs in higher plants and in the major chlorophyll a/b-binding LHCPs in microalgae (higher than 1.0). The major LHCP apoproteins of NIBB8001 and 94B5100C contained one major polypeptide; the apparent molecular masses analyzed with SDS-PAGE were about 22 kDa and 27 kDa, respectively. The major LHCP apoprotein of 94B8100A had two major polypeptides having apparent molecular masses of about 23 and 25 kDa. None of the thylakoid proteins cross-reacted with an antibody raised against the LHC IIα apoprotein of spinach. It is suggested that the high abundance of chlorophyll b in picophytoplankton, together with a large chloroplast in a small cell, enable them to utilize the reduced light in their habitat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005857903821
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  • 107
    Electronic Resource
    Electronic Resource
    Chromophore assignment in phycoerythrocyanin from Mastigocladus laminosus (1997)
    Springer
    Photosynthesis research 54 (1997), S. 25-34 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; energy transfer ; Fischerella PCC 7603 ; photosynthesis ; phycobiliprotein ; phycoerythrocyanin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The component spectra (maxima of absorption, circular and linear dichroism) of individual chromophores have been assigned for phycoerythrocyanin (PEC) trimer, monomer(s), and its subunits (α-PEC and β-PEC) by titration with p-chloromercury-benzene-sulfonate (PCMS), linear dichroism and photochemical transformations, as well as by deconvolution using a ‘bilin’ line-shape spectrum based on the α-84 phycoviolobilin-chromophore in the α-subunit. The level ordering PVB-α-84 → PCB-β-155 → PCB-β-84 is the same irrespective of aggregation. Two different monomers (αβ) were observed. In 4 M urea, the spectra are appropriately weighted sums of the subunit spectra, whereas in the monomer obtained in 1 M KSCN, both β-chromophores are red-shifted by 4–5 nm. Formation of trimer (αβ)_3gives considerable spectral changes: (1) the absorption is narrowed, which has been rationalized by excitonic coupling between neighbouring monomers, (2) the short wavelength part in the CD spectrum is missing and (3) a fourth band (+) at 528 in the LD spectrum appears. A deconvolution of the trimeric aggregation state using only the ‘bilin’ line-shape model is not possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005877531271
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  • 108
    Electronic Resource
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    Characterisation of cytochrome c6from Chlorella fusca (1997)
    Springer
    Photosynthesis research 54 (1997), S. 107-114 
    Details
    ISSN: 1573-5079
    Keywords: CD ; Chlorella ; cytochrome c6 ; EPR ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A c-type monohaem, cytochrome c6was isolated from a soluble extract of the green alga Chlorella fusca. The isolated protein shows an apparent molecular mass of 10 kDa by SDS-PAGE, but behaves as a dimer of 20.3 kDa in gel-filtration; the isoelectric point is 3.6. The N-terminal sequence shows high identity with other green algae cytochromes c6. The mid-point redox potential is about +350 mV between pH 5 and 9. The ferric and ferrous forms, and their pH equilibria, have been studied using visible, CD and EPR spectroscopies. The visible spectrum of the reduced cytochrome c6is typical of a c-type haem protein, with maxima at 274 nm, 318 nm (δ-peak), 416 nm (γ-peak), 522 nm (β-peak), 552–553 nm (α-peak). A 690 nm band, characteristic of a haem Met-His axial coordination of the haem group, is present in the oxidized form. At high pH values (≥ 8), cytochrome c6undergoes an alkaline transition, with a pKa of 8.7. Between pH 3 and 9 the EPR spectrum is dominated by two rhombic species, with g-values at 3.32, 2.05, 1.05 and 2.96, 2.30, 1.43, which interconvert with a pKaof 4. CD spectrum of Chlorella fusca cytochrome c6shows that the proteins must be mainly built up by α-helices. Even though there are similarities between Chlorella fusca cytochrome c6and that isolated from Monoraphidium braunii, no cross-reactivity with the antibodies raised against the Chlorella fusca cytochrome has been detected for the protein from Monoraphidium braunii.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005955201482
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  • 109
    Electronic Resource
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    The effects of elevated light on Photosystem II function: A thermoluminescence study (1997)
    Springer
    Photosynthesis research 54 (1997), S. 169-183 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence quenching ; photoinhibition ; photoprotection ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used the technique of thermoluminescence (TL) to investigate high-light-induced chlorophyll fluorescence quenching phenomena in barley leaves, and have shown it to be a powerful tool in such investigations. TL measurements were taken from wild-type and chlorina f2 barley leaves which had been dark-adapted or exposed to 20 min illumination of varying irradiance or given varying periods of recovery following strong irradiance. We have found strong evidence that there is a sustained trans-thylakoid ΔpH in leaves following illumination, and that this ΔpH gives rise to quenching of chlorophyll fluorescence which has previously been identified as a slowly-relaxing component of antenna-related protective energy dissipation; we have identified a state of the PS II reaction centre resulting from high light treatments which is apparently able to perform normal charge separation and electron transport but which is ‘non-photochemically’ quenched, in that the application of a light pulse of high irradiance cannot cause the formation of a high fluorescent state; and we have provided evidence that a transient state of the PS II reaction centre is formed during recovery from such high light treatments, in which electron transport from QAto QBis apparently impaired.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005969312448
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  • 110
    Electronic Resource
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    The modification of phytosterol profiles and in vitro photosynthetic electron transport of Galium aparine L. (cleavers) treated with the fungicide, epoxiconazole (1997)
    Springer
    Plant growth regulation 22 (1997), S. 93-100 
    Details
    ISSN: 1573-5087
    Keywords: epoxiconazole ; Galium aparine L. ; photosynthesis ; phytosterols ; thylakoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Foliar application of the triazole fungicide, epoxiconazole, retarded the growth of Galium aparine L. (cleavers). GC-MS and GC analysis clearly indicated that phytosterol biosynthesis in stem and leaflet tissue was significantly affected by this treatment. For example, in leaflet tissues, 125 g ai ha-1 (field rate) caused reductions in campesterol and sitosterol of 81percnt; and 75percnt; respectively. C14-methyl phytosterols such as 14agr;-methylergost-8-enol, obtusifoliol and dihydroobtusifoliol were detected in treated tissues indicating that epoxiconazole inhibits the cytochrome P-450 dependent obtusifoliol 14agr;-demethylase. In addition, ratios of campesterol to sitosterol were reduced. Stigmasterol was not detected in control or treated tissues. Preliminary determination of photosynthetic characteristics of isolated thylakoids from treated plants indicated that electron transport and oxygen evolution were impaired by epoxiconazole and these effects were dose-related. Ten days after treatment, oxygen evolution from thylakoids (determined as electron flow from water to ferricyanide) isolated from control plants was 24.2 micro;mol mg-1 chl h-1, whilst treatment with 125 g and 250 g ai ha-1 reduced this rate to 15.2 micro;mol and 8.2 micro;mol mg-1 chl h-1 an inhibition of 37 and 67percnt; respectively. These results suggest that epoxiconazole influences thylakoid integrity and function in addition to phytosterol biosynthesis in G. aparine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005885312748
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  • 111
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    The dependance of root growth potential on light level, photosynthetic rate, and root starch content in jack pine seedlings (1997)
    Springer
    New forests 13 (1997), S. 105-119 
    Details
    ISSN: 1573-5095
    Keywords: field performance potential ; photosynthesis ; Pinus banksiana ; root initiation ; root starch ; seedling testing ; total nonstructural carbohydrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Number of new roots (root growth potential or RGP), new root length, photosynthesis, total nonstructural carbohydrate content of needles and roots, terminal bud condition, and shoot elongation were measured on jack pine container seedlings for 4 weeks at weekly intervals under greenhouse conditions of 100%, 20%, and 10% sunlight to simulate competition-induced, lower light levels in the field. Both lower light levels significantly reduced photosynthetic rate, RGP, new root length, total nonstructural carbohydrate (especially starch) content of needles and roots, speed of terminal bud flush, and shoot growth. Both light level and photosynthetic rate were positively correlated with RGP and new root length, indicating that jack pine seedlings may use current photosynthate as an energy source to support new root growth. RGP and new root length were also both negatively correlated with root starch content suggesting that jack pine seedlings may also use stored carbohydrates as a potential carbon source for root initiation and initial root growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006517820981
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  • 112
    Electronic Resource
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    The mechanism of the degradation of psaB gene product, one of the photosynthetic reaction center subunits of Photosystem I, upon photoinhibition (1997)
    Springer
    Photosynthesis research 53 (1997), S. 55-63 
    Details
    ISSN: 1573-5079
    Keywords: hydroxyl radical ; light stress ; photosynthesis ; serine protease ; protein turnover ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The psaB gene product (PsaB protein), one of the reaction center subunits of Photosystem I (PS I), was specifically degraded by light illumination of spinach thylakoid membranes. The degradation of the protein yielded N-terminal fragments of molecular mass 51 kDa and 45 kDa. The formation of the 51 kDa fragment was i) partially suppressed by the addition of phenylmethylsulfonyl fluoride or 3,4-dichloroisocoumarin, which are inhibitors of serine proteases, and ii) enhanced in the presence of hydrogen peroxide during photoinhibitory treatment, but iii) not detected following hydrogen peroxide treatment in the dark. These results suggest that the hydroxyl radical produced at the reduced iron-sulfur centers in PS I triggers the conformational change of the PS I complex, which allows access of a serine-type protease to PsaB. This results in the formation of the 51 kDa N-terminal fragment, presumably by cleavage on the loop exposed to the stromal side, between putative helices 8 and 9. On the other hand, the formation of the 45 kDa fragment, which was enhanced in the presence of methyl viologen but did not accompany the photoinhibition of PS I, was not affected by the addition of hydrogen peroxide or protease inhibitors. Another fragment of 18 kDa was identified as a C-terminal counterpart of the 45 kDa fragment. N-terminal sequence analysis of the 18 kDa fragment revealed that the cleavage occurred between Ala500 and Val501 on the loop exposed to the lumenal side, between putative helices 7 and 8 of the PsaB protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005852330671
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  • 113
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    Characteristics of photosynthetic carbon metabolism of spikelets in rice (1997)
    Springer
    Photosynthesis research 52 (1997), S. 75-82 
    Details
    ISSN: 1573-5079
    Keywords: lemma ; light-enhanced dark CO2 fixation ; palea ; panicle ; photosynthesis ; pyruvate ; Pi dikinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In lemmas and paleae of rice, the amount of pyruvate, Pi dikinase (PPDK) protein increased dramatically 6 d after anthesis and this change was consistent with that in the activity of PPDK. Since lemmas and paleae at this stage also showed high activities of the other marker enzymes of C4 pathway including phosphot enolpyruvate carboxylase (Imaizumi et al. (1990) Plant Cell Physiol 31: 835–843), photosynthetic carbon metabolism with lemmas at this stage were characterized. In a 14C pulse-12C chase study by photosynthetic CO2 fixation, about 35% and 25% of 14C fixed in lemmas were incorporated initially into 3-phosphoglycerate (3-PGA) and C4 acids, respectively. This suggests that lemmas participate mainly in C3-type photosynthetic metabolism, but that lemmas may also participate in the metabolism of C4 acids to some extent. To clarify this possibility, large amounts of 14C-labeled C4 acids were synthesized in vivo by a light-enhanced dark CO2 fixation (LED) method and the fate of 14C in C4 acids in the light was investigated. The percentage distribution of 14C in C-4 position of malate was about 90% and 83% after 10 s of photosynthetic 14CO2 fixation and 110 s of LED, respectively. Some of the 14C incorporated into C4 acids was transferred into 3-PGA and sugar phosphates. The possibility of direct fixation of CO2 by phosphot enolpyruvate carboxylase and metabolic pathway of CO2 released by decarboxylation of malate produced were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005887931498
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  • 114
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    Growth at high CO2 affects the chloroplast number but not the photosynthetic efficiency of photoautotrophicMarchantia polymorpha culture cells (1997)
    Springer
    Plant cell, tissue and organ culture 48 (1997), S. 103-110 
    Details
    ISSN: 1573-5044
    Keywords: bryophytes ; cell culture ; chlorophyll content ; LHC II ; photosynthesis ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoautotrophic suspension cells of Marchantia polymorpha were grown at gas phase CO2 concentrations of 0.4% and 2.0%. At the higher CO2 concentration the chloroplast shape appeared to be modified and the cells had about 70% more chloroplasts per cell. Differences in chlorophyll content per cell were much less pronounced, indicating a reduction in chlorophyll content per chloroplast. Also the cell size was affected by the CO2 concentration, and our data suggest that it was about 37% lower in high CO2 grown cells than in low CO2 grown cells. The capacity and the efficiency of photosynthetic oxygen evolution on a chlorophyll basis and the photosystem II chlorophyll fluorescence parameters were almost identical in both cell types. Immunodection showed that also the ratio of light harvesting complex II antenna proteins and ribulose 1,5 bisphosphate carboxylase/oxygenase were unaltered. These data indicate that the chloroplast density within photoautotrophic culture cells may be regulated independently of their photosynthetic efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005893311140
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  • 115
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    Developmental changes in carboxylase activities in in vitro cultured coconut zygotic embryos: comparison with corresponding activities in seedlings (1997)
    Springer
    Plant cell, tissue and organ culture 49 (1997), S. 227-231 
    Details
    ISSN: 1573-5044
    Keywords: carbon metabolism ; CO2 fixation ; embryo culture ; PEPC ; photosynthesis ; RubisCO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphoenolpyruvate Carboxylase (PEPC; EC: 4.1.1.31) and Ribulose 1,5-bisphosphate Carboxylase/Oxygenase (RubisCO; EC: 4.1.1.39) enzyme specific activities were measured during the in vitro development of coconut (Cocos nucifera L.) zygotic mature embryos into plantlets and compared with those of palms produced by conventional seed germination. At the time of initiation of germination, high PEPC and low RubisCO activities were measured in both cultured and conventionally germinated embryos, thus indicating an anaplerotic CO2 fixation. During both in vitro and in planta development, RubisCO progressively took over and became the main route for inorganic carbon fixation. The in vitro-grown coconut plantlets showed a faster decrease in their PEPC:RubisCO ratio than the seedlings, suggesting that an earlier transition from a heterotrophic to an autotrophic mode of carbon fixation takes place in the in vitro-derived material. Just before acclimatization, the RubisCO activity in in vitro-derived plantlets (2.83 µmol CO2h−1mg−1 TSP) was lower than that in seedlings (6.98 µmol CO2h−1mg−1 TSP) of the same age. Nevertheless, after acclimatization, RubisCO activities were comparable in both in vitro and in planta germinated material
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    URL: http://dx.doi.org/10.1023/A:1005856212846
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  • 116
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    The effect of different closure types, light, and sucrose concentrations on carbon isotope composition and growth ofGardenia jasminoides plantlets during micropropagation and subsequent acclimationex vitro (1997)
    Springer
    Plant cell, tissue and organ culture 47 (1997), S. 217-230 
    Details
    ISSN: 1573-5044
    Keywords: photoautotrophy ; photosynthesis ; shoot multiplication ; root induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth ofGardenia jasminoides Ellis plantlets and the development of photoautotrophy during two successive culture stages (shoot multiplication and root induction)in vitro was analyzed. We examined the effects of changes in growth conditions (type of tube closure, light, and sugar levels) on the development of photoautotrophy and growth during micropropagation and sought to establish whether they affected later acclimation to conditionsex vitro. During the two stagesin vitro, plantlets were grown in tubes under two different PPFD (50 and 110 µmol m−2 s−1), in media with three different sucrose concentrations (0, 1.5, and 3.0%, w/v) and with two different CO2 levels inside the tubes (controlled by either tightly closed caps or loosely sealed caps, and with an external CO2 concentration of 750 µmol mol−1). The development of photoautotrophy was assessed by determining the difference between the stable carbon isotope composition (δ13C) of sugar cane sucrose used as a heterotrophic carbon source and that of leaflets grownin vitro. Plantlets from the root-induction stage showed a more highly developed photoautotrophy than those from the shoot- multiplication stage. At both stages, utilization of closed caps was the treatment which most stimulated development of photoautotrophy in plantlets. Also, lowering PPFD or sucrose concentration induced a greater degree of photoautotrophic development, the strongest effect being observed in plantlets cultured inside loosely sealed tubes. During acclimationex vitro, plantlets taken from loosely sealed tubesin vitro performed better than those cultured inside tightly sealed tubes. The former, as well as recording a larger increase in fresh weight during this stage, also showed more negative δ13C in the newly developed leaves, which would seem to indicate a better water status during acclimation. Present results validate the usefulness of δ13C analysis of leaflets as a simple technique in assessing the development of photoautotrophy during culturein vitro. In addition, δ13C analysis can be extended to evaluate growth conditions during acclimation toex vitro conditions.
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    URL: http://dx.doi.org/10.1007/BF02318976
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    Activation and deactivation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in three marine microalgae (1997)
    Springer
    Photosynthesis research 51 (1997), S. 93-106 
    Details
    ISSN: 1573-5079
    Keywords: activation ; deactivation ; induction ; irradiance ; kinetics ; photosynthesis ; phytoplankton ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was examined in three marine microalgae: the chlorophyte t Dunaliella tertiolecta and the chromophytes t Pavlova lutheri and t Thalassiosira pseudonana. The three species differed in the sensitivity of Rubisco activity in crude extracts to magnesium ion concentration, the presence of protease inhibitors, the duration of the incubation on activity, and the potential for full activation of Rubisco with 20 mM magnesium chloride and 20 mM bicarbonate t in vitro. t D. tertiolecta had responses that were similar to those described in vascular plants: regulation of initial activity on a gradient of irradiances; maximum initial activities that were 80– 90% of light-saturated photosynthesis; total activities that exceeded light-saturated photosynthesis by 30–100%; and deactivation of Rubisco in darkness. Both initial and total activity declined in darkness and increased on a return to growth irradiance. First-order time constants were about 9 min for deactivation and 3 min for reactivation of initial activity. The decline in total activity after a transition into darkness could not be reversed t in vitro but could be reversed by exposing t D. tertiolecta to light, a characteristic of regulation by CA1P. The responses of t T. pseudonana were qualitatively similar, except that recovery of initial activity was low and could only account for 30–40% of light-saturated photosynthesis. Rubisco from t T. pseudonana exposed to low irradiance could be activated t in vitro but at growth irradiance and higher, total activity was lower than initial activity. The time constants for deactivation and reactivation of initial activity after reciprocal switches between growth irradiance and darkness were 12–18 min and 3 min in t T. pseudonana. t P. lutheri showed no regulation of Rubisco activity in response to changes in irradiance or light-dark transitions. This may have been an artifact of the conditions chosen to measure activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005755621305
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    Can photosynthesis respond to short-term fluctuations in atmospheric carbon dioxide? (1997)
    Springer
    Photosynthesis research 51 (1997), S. 179-184 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; FACE ; global change ; photosynthesis ; Photosystem II ; quantum yield ; quenching analysis ; rising CO2 concentration ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rapid and irregular variations of atmospheric CO2 concentrations (ca) occur in nature but are often very much more pronounced and frequent when artificially enriching CO2 concentrations in simulating the future atmosphere. Therefore, there is the danger that plant responses at elevated CO2 in fumigation experiments might reflect the increased frequency and amplitude of fluctuation in concentration as well as the increase in average concentration. Tests were conducted to determine whether the photosynthetic process could sense such fluctuations in ca. Instantaneous chlorophyll fluorescence (Ft) was monitored for wheat leaves (Triticum aestivum cv. Hereward) exposed to ca oscillating symmetrically by 225 μmol mol-1 about a ca set point concentration of 575 or 650 μmol mol-1. No Ft response was detected to half-cycle step changes in ca lasting less than two seconds, but at half-cycles of two seconds or longer, the response of Ft was pronounced. In order to determine the in vivo linear electron transport rate (J) the O2 concentration was maintained at 21 mmol mol-1 to eliminate photorespiration. J which is directly proportional to the rate of CO2 uptake under these conditions, was not significantly changed at half-cycles of 30 s or less but was decreased by half-cycles of 60 s or longer. It was inferred that if duration of an oscillation is less than 1 minute and is symmetrical with respect to mean CO2 concentration, then there is no effect on current carbon uptake, but oscillations of 1 minute or more decrease photosynthetic CO2 uptake in wheat.
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    URL: http://dx.doi.org/10.1023/A:1005804203928
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    Increases in the fluorescence Fo level and reversible inhibition of Photosystem II reaction center by high-temperature treatments in higher plants (1997)
    Springer
    Photosynthesis research 52 (1997), S. 57-64 
    Details
    ISSN: 1573-5079
    Keywords: Fm ; high-temperature stress ; pheophytin a ; photosynthesis ; Qa ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of high temperatures on the fluorescence Fm (maximum fluorescence) and Fo (dark level fluorescence) levels were studied and compared with those of the photochemical reactions of PS II. These comparisons were performed during and after the high temperature treatments. The following results were obtained; (1) increases in the Fo level at high temperatures were partly reversible, (2) the Fm level in the presence of dithionite in spinach chloroplasts decreased at high temperatures and also showed a partial reversibility, (3) photoreductions of pheophytin a and Qa were reversibly inhibited at high temperatures parallel to the decrease in the difference between the Fm and Fo levels, and (4) the decrease in the fluorescence Fm level seemed to be related to denaturation of chlorophyll-proteins. All the data suggested that, as well as the separation of light-harvesting chlorophyll a/t b protein complexes of PS II from the PS II core complexes, partly reversible inactivation of the PS II reaction center at high temperatures is the cause of the increase in the Fo level.
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    URL: http://dx.doi.org/10.1023/A:1005884717655
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    A method for measuring whole plant photosynthesis in Arabidopsis thaliana (1997)
    Springer
    Photosynthesis research 52 (1997), S. 263-269 
    Details
    ISSN: 1573-5079
    Keywords: Arabidopsis ; chlorophyll fluorescence ; gas exchange ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurement of photosynthesis of intact leaves of Arabidopsis thaliana has been prohibitive due to the small leaf size and prostrate growth habit. Because of the widespread use of Arabidopsis for plant science research it is important to have a procedure for accurate, nondestructive measurement of its photosynthesis. We developed and tested a method for analysis of photosynthesis in whole plants of Arabidopsis. Net carbon assimilation and stomatal conductance were measured with an open gas exchange system and photosynthetic oxygen evolution was determined from chlorophyll fluorescence parameters. Individual plants were grown in 50 cubic centimeter tubes that were attached with an air tight seal to an enclosed gas exchange chamber for measurement of carbon dioxide and water exchange by the whole plant. Chlorophyll fluorescence from intact leaves was simultaneously measured with a pulse modulated fluorometer. Photosynthetic CO2 assimilation and stomatal conductance rates were calculated with established gas exchange procedures and O2 evolution was determined from chlorophyll fluorescence measurement of Photosystem II yield. Carbon assimilation and oxygen evolution in response to light intensity and ambient CO2 concentration was measured and is presented here to demonstrate the potential use of this method for investigation of photosynthesis of Arabidopsis plants in controlled environment conditions.
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    URL: http://dx.doi.org/10.1023/A:1005834327441
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    Multiple strategies for a high light existence in a tropical marine macroalga (1997)
    Springer
    Photosynthesis research 53 (1997), S. 149-159 
    Details
    ISSN: 1573-5079
    Keywords: Chlorodesmis fastigiata ; D1 protein ; fluorescence ; macroalgae ; photoinhibition ; photosynthesis ; Photosystem II heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acclimation to high light conditions on the top of coral reefs was examined in the coenocytic, filamentous green macroalga Chlorodesmis fastigiata (C. Ag.) Ducker. Despite having a pool of violaxanthin, high light does not induce formation of zeaxanthin in this macroalga. Exposure to 11 and 33% of surface irradiance resulted in parallel, reversible declines in Fv/Fmand in the number of functional PSII centers. The quantum requirement for PSII inactivation was calculated to be approx. 2×107photons. Recovery of PSII activity after low photon exposures did not depend on protein synthesis, unlike at higher photon exposures, where recovery was inhibited by 50% in the presence of lincomycin. Accumulation of inactive, quenching PSII centers is proposed as a mechanism of energy dissipation; only some of these centers require protein synthesis for reactivation. In natural-sized populations, midday photoinhibition was greater in filament tips than in bases, but the number of inactive PSII centers within entire filaments did not significantly change over the course of the day. It is proposed that the higher chlorophyll concentration in the tips provides protective shading to chloroplasts in lower regions, and that cytoplasmic streaming of chloroplasts within this siphonous alga limits the cumulative exposure to high light, thereby providing another level of protection from high light stress.
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    URL: http://dx.doi.org/10.1023/A:1005820203585
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    Mutation in a novel gene required for photomixotrophic growth leads to enhanced photoautotrophic growth of Synechocystis sp. PCC 6803 (1997)
    Springer
    Photosynthesis research 53 (1997), S. 243-252 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; evolution ; glucose-sensitivity ; photoacclimation ; photosynthesis ; polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the glucose-tolerant strain of Synechocystis sp. PCC 6803, we found two types of cells with distinct growth properties. Under photoautotrophic conditions at any light intensity, one type gave larger colonies (designated WL) than the other (designated WS). Notably, the WL cells produced much larger colonies than the WS cells at higher light intensity. In contrast, growth of the WL cells was severely suppressed under mixotrophic conditions with glucose and light, while the WS cells grew normally. A gene which could complement the WL phenotype was obtained from a wild-type genomic library. The gene, designated pmgA, coded for a 23 kDa polypeptide of 204 amino acid residues with no apparent homology to known genes. In the WL genome, the base substitution of T for C at position 193 of pmgA caused replacement of Leu with Phe at position 65 of the product. The phenotype of pmgA disruption mutants was similar to that of the WL cells, indicating that the WS cells expressed a functional pmgA product. By direct sequencing of polymerase chain reaction-amplified pmgA from genomic DNA, it was revealed as an example of microevolution that WL had expelled WS from the photoautotrophic culture of wild-type in our laboratory for a year or so. Mixed culture in liquid also demonstrated that the WL cells increased gradually under photoautotrophic conditions, while they decreased rapidly under photomixotrophic conditions. These results suggest that pmgA product is essential for photomixotrophic growth, whereas it represses photoautotrophic growth. To our knowledge, the WL cells and pmgA-disrupted mutants are the first in cyanobacteria, which shows much improved photosynthetic growth than wild-type especially at high light intensity.
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    URL: http://dx.doi.org/10.1023/A:1005879905365
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    Foliar CO2photoassimilation and chloroplast linear electron transport rates in nitrogen-sufficient and nitrogen-limited soybean plants (1997)
    Springer
    Photosynthesis research 54 (1997), S. 209-217 
    Details
    ISSN: 1573-5079
    Keywords: ferredoxin, NADP photoreduction ; nitrogen limitation ; non cyclic electron transport ; photosynthesis ; Photosystem 1 and 2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaflets of soybean plants which are moderately inorganic nitrogen (N)-limited exhibit either no difference in the rate of net photosynthesis or as much as a 15–23% lower net photosynthesis rate per unit area than leaflets of N-sufficient plants [Robinson JM (1996) Photosynth Res 50: 133–148; Robinson JM (1997a) Int J Plant Sci 158: 32–43]. However, mature leaflets of N-limited soybean plants have a higher CO2photoassimilation rate per unit chlorophyll than leaflets of N-sufficient soybean plants at both moderate light intensity (≈500 µmol m-2s-1) and saturating light intensity (≈1200 µmol m-2s-1) [Robinson JM (1996) Photosynth Res 50: 133–148]. This study was undertaken to determine whether chloroplast thylakoids isolated from the leaflets of nitrogen-limited soybean plants displayed similar or higher linear electron transport rates (H2O → ferredoxin → NADP) per unit chlorophyll than thylakoids isolated from leaflets of N-sufficient plants. Chlorophyll concentration in reaction mixtures containing chloroplast thylakoids prepared from leaflets of N-limited plants was manipulated so that it was similar to the chlorophyll concentration in reaction mixtures of thylakoids prepared from leaflets of N-sufficient plants. Measurements of ferredoxin dependent, NADP dependent, O2photo-evolution in thylakoid isolates were carried out in saturating light (≈1500 µmol m-2s-1) and with $$NH_4^ + $$ (an uncoupler) in the chloroplast reaction mixtures. Chloroplast thylakoids isolated from N-limited soybean plant leaflets routinely had a 1.5 to 1.7 times higher rate of uncoupled, whole chain electron transport per unit chlorophyll in saturating light than did chloroplast thylakoids isolated from leaflets of N-sufficient plants. The results suggest that the photosystems and photosynthetic electron transport chain components are more active per unit Chl in leaflet chloroplast thylakoids of N-limited soybean plants than in thylakoids of N-sufficient plants.
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    URL: http://dx.doi.org/10.1023/A:1005995718710
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    Analysis of the chloroplast protein complexes by blue-native polyacrylamide gel electrophoresis (BN-PAGE) (1997)
    Springer
    Photosynthesis research 53 (1997), S. 35-44 
    Details
    ISSN: 1573-5079
    Keywords: b 6 f complex ; chloroplast ATP synthase ; light-harvesting complexes ; photosynthesis ; photosystems ; ribulose-bisphosphate carboxylase/oxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blue-native polyacrylamide gel electrophoresis (BN-PAGE) is a powerful procedure for the separation and characterization of the protein complexes from mitochondria. Membrane proteins are solubilized in the presence of aminocaproic acid and n-dodecylmaltoside and Coomassie-dyes are utilized before electrophoresis to introduce a charge shift on proteins. Here, we report a modification of the procedure for the analysis of chloroplast protein complexes. The two photosystems, the light-harvesting complexes, the ATP synthase, the cytochrome b 6 f complex and the ribulose-bisphosphate carboxylase/oxygenase are well resolved. Analysis of the protein complexes on a second gel dimension under denaturing conditions allows separation of more than 50 different proteins which are part of chloroplast multi-subunit enzymes. The resolution capacity of the blue-native gels is very high if compared to 'native green gel systems' published previously. N-terminal amino acid sequences of single subunits can be directly determined by cyclic Edman degradation as demonstrated for eight proteins. Analysis of chloroplast protein complexes by blue-native gel electrophoresis will allow the generation of 'protein maps' from different species, tissues and developmental stages or from mutant organelles. Further applications of blue-native gel electrophoresis are discussed.
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    URL: http://dx.doi.org/10.1023/A:1005882406718
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    Determination of the quenching efficiency of the oxidized primary donor of Photosystem I, P700+: Implications for the trapping mechanism (1997)
    Springer
    Photosynthesis research 54 (1997), S. 237-240 
    Details
    ISSN: 1573-5079
    Keywords: fluorescence induction ; fluorescence yield ; photosynthesis ; P700 ; internal conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005981016835
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    Responses of Rubisco activation and deactivation rates to variations in growth-light conditions (1997)
    Springer
    Photosynthesis research 52 (1997), S. 117-125 
    Details
    ISSN: 1573-5079
    Keywords: gas exchange ; light acclimation ; photosynthesis ; sunflecks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Basil (Ocimum basilicum) and impatiens (Impatiens wallerana) were grown in sun, shade, or fluctuating light (15 min sun, 15 min shade) to examine the effects of growth-light conditions on the rates of light-induced Rubisco activation and deactivation. Rubisco activation and deactivation rates were determined from gas-exchange measurements of photosynthesis following a step increase in PFD. Rubisco deactivation rates were also determined from biochemical analyses of leaf extracts. There were no significant differences in Rubisco activation rate among the growth conditions or between the two species. However, there were significant differences in Rubisco deactivation rate among the growth conditions in basil and between the two species. In basil, Rubisco deactivated more slowly following a decrease in PFD in sun- and fluctuating-light grown plants than in shade grown plants. Slower rates of Rubisco deactivation during periods at low PFD resulted in higher activation states at the onset of increased PFD. Thus, the contribution of Rubisco activation to the induction process was less for basil plants grown under sun and fluctuating light than for those grown under shade. Impatiens deactivated Rubisco more rapidly than in basil, but there was no substantial effect of the three growth-light conditions on Rubisco deactivation rates in impatiens.
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    URL: http://dx.doi.org/10.1023/A:1005847500471
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    Recovery of net CO2 assimilation after heat stress is correlated with recovery of oxygen-evolving-complex proteins in Zea mays L. (1997)
    Springer
    Photosynthetica 34 (1997), S. 13-20 
    Details
    ISSN: 1573-9058
    Keywords: D1 protein ; internal CO2 concentration ; maize ; oxygen evolution ; phosphoenolpyruvate carboxylase ; photosynthesis ; photosystem 2 ; ribulose-1,5-bisphophate carboxylase/oxygenase ; stomatal conductance ; thermotolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem 2 (PS2) in general, and the oxygen-evolving complex (OEC) in particular, is one of the most thermolabile components of photosynthesis. We examined the effects of heat stress on net photosynthetic rate (PN) and content of several stromal and thylakoid-membrane proteins (including OEC proteins) in maize (Zea mays L.) in order to determine if decreases in PN during, and especially after, heat stress were correlated with decreases in the content of OEC proteins. The PN decreased with heat stress in maize, and post-heat stress recovery of PN required 4 d following the second of two heat-shocks. The decrease in PN was not the result of stomatal closure. Cellular levels of the 33, 23, and 16 kDa OEC proteins decreased with heat stress, and the decreases were greatest and most closely correlated with decreases in PN for OEC16. Following the second heat stress, full recovery of OEC levels (especially OEC16 and 33) coincided with full recovery of PN, more so than with other photosynthetic proteins examined. For example, decreases in levels of the 32-kDa QB-binding protein of the PS2 reaction center (D1), ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit, and phosphoenolpyruvate carboxylase were generally smaller than for the OEC proteins and full recovery of these proteins occurred at least 2 d prior to full recovery of photosynthesis. These results are consistent with previous fluorescence and in vitro studies by others in suggesting that heat-relaed effects on PS2 and the OEC are an important limitation to Pn during heat stress. Additionally, these results suggest that heat-related decreases in the content of OEC proteins may limit post-heat stress recovery of carbon fixation.
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    URL: http://dx.doi.org/10.1023/A:1006899314677
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    Effect of cytokinins on the photosynthetic apparatus in water-stressed and rehydrated bean plants (1997)
    Springer
    Photosynthetica 34 (1997), S. 563-567 
    Details
    ISSN: 1573-9058
    Keywords: oxygen flash yields ; photochemical activity ; photosynthesis ; photosystem 2 ; thermoluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of the cytokinins 6-benzylaminopurine (BAP) and N-2-chloro-4-pyridyl-N′-phenylurea (4-PU-30) on the photochemical activity, oxygen flash yields, and thermoluminescence in bean plants under a water stress were studied. The cytokinins increased the photochemical (Hill reaction) activity and thermoluminescence "B"-band in control as well as in stressed and rehydrated plants, while the oxygen flash yields were affected only in the stressed and rehydrated plants.
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    URL: http://dx.doi.org/10.1023/A:1006821730974
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    Effect of fruiting and drought or flooding on carbon balance of apple trees (1997)
    Springer
    Photosynthetica 33 (1997), S. 269-275 
    Details
    ISSN: 1573-9058
    Keywords: Malus domestica ; open-top cuvettes ; photosynthesis ; respiration ; water stress ; water use efficiency ; xylem water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of fruiting or deblossomed trees to water stress such as drought or flooding was investigated in six semi open-top cuvettes each containing one apple (Malus domestica Borkh. cv. Golden Delicious) tree. Xylem water potentials of leaves dropped from -1.2 to -4.1 MPa within 7 d of drought, the effect being enhanced by fruiting. Apple trees without fruits showed smaller reductions in net photosynthetic rate (P N ) and dark respiration rate (R D ) after 2 d of drought and hence more positive carbon balances relative to fruiting trees. Flooding for 4 d had a more pronounced effect on P N than on transpiration, resulting in a reduced water use efficiency (WUE). This reduction in WUE was greater in the non-fruiting trees. Flooding reduced P N of the whole apple canopies irrespective of fruiting; aple trees without fruits increased R D resulting in a less positive carbon balance relative to fruiting trees. Fruiting increased the sensitivity to drought of apple trees (R D and P N ), but decreased their sensitivity to flooding (R D and WUE), suggesting different adaptation mechanisms for the two forms of water stress.
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    URL: http://dx.doi.org/10.1023/A:1022172515878
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    Picosecond fluorescence decay studies on water-stressed pea leaves: energy transfer and quenching processes in photosystem 2 (1997)
    Springer
    Photosynthetica 34 (1997), S. 97-106 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll ; DCMU ; exciton-radical pair equilibrium model ; NH2OH ; photosynthesis ; Pisum ; quinones ; relative air humidity ; wilting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Detached leaves of pea (Pisum sativum) were submitted to water stress at different relative air humidities. The photosynthetic activity of photosystem 2 (PS2) was monitored by time-resolved picosecond chlorophyll (Chl) fluorescence spectroscopy. In the first days the well-known fast Chl fluorescence decay was observed which indicated high PS2 activity. After a few days the average fluorescence decay time τm reached a maximum, depending on the wilting conditions, but always at a relative loss of leaf mass of 80%. After this maximum, τm decreased within a few hours, the fluorescence decay became similar to that one of an intact leaf, but an additional fluorescence decay component with a lifetime of 3.6 ns appeared. At first the primary quinone QA was reduced due to inhibition of the electron transfer to the secondary quinone QB. Simultaneously, water deficiency caused an electron lack at the oxidizing site of PS2. This disabled the primary electron donor of PS2, tyrosine Z, from reducing the oxidized reaction centre of PS2 (P680+). Thus a recombination of P680+-pheophytin-QA- took place, and the energy was lost as heat. With further water stress, QA was decoupled from PS2. The new fluorescence decay component could therefore be assigned to energetically decoupled antenna complexes.
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    Short-term effects of aluminium at alkaline pH on the structure and function of the photosynthetic apparatus (1997)
    Springer
    Photosynthetica 34 (1997), S. 169-177 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll fluorescence ; chloroplast ultrastructure ; photosynthesis ; photosystem 2 ; Thinopyrum bessarabicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 24 h exposure of the salt-tolerant grass Thinopyrum bessarabicum (Savul. and Rayss) A. Love seedlings to 1 mM aluminium (Al) in nutrient solution at pH of 9.0 resulted in a significant reduction of the biomass. In control samples the mesophyll chloroplasts exhibited the usual lens shape with most grana arranged in straight or slightly curving lines, and only 6.5 % of the grana were out of order. In Al-treated plants the mesophyll chloroplasts displayed a slightly distorted shape and distended size with most grana arranged in bow-like lines, while in the central region of the organelle as many as 26.7 % of the grana were independent and out of order in relation to the long axis. The morphological changes in the chloroplast shape and grana arrangement were probably due to swelling and distension of the chloroplasts in consequence to the altered membrane permeability. The initial in vivo chlorophyll (Chl) fluorescence FO, as well as the intermediate FI and peak fluorescence FP were increased under the Al stress: this indicated a destruction of photosystem (PS) 2 reaction centres and increased reduction of QA. The (FI-FO)/(FP-FO) ratio exhibited a significant increase indicating higher proportion of PS2 centres unable to reduce QB. Changes in the chloroplast ultrastructure seemed to be the reason of photosynthetic electron transport inhibition. Yet all these changes in the photosynthetic performance and chloroplast ultrastructure were considered as indirect effects of Al treatment since Al concentration in the leaves was undetectable. Disturbances in the chloroplast ultrastructure could be caused by a reduced uptake and/or transport of other nutrients.
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    URL: http://dx.doi.org/10.1023/A:1006880205108
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    Planting density effects on assimilation and partitioning of photosynthates during grain filling in the late-sown wheat (1997)
    Springer
    Photosynthetica 33 (1997), S. 199-204 
    Details
    ISSN: 1573-9058
    Keywords: photosynthates ; 14CO2 ; ear ; leaf insertion ; photosynthesis ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaf blades of the late-sown winter wheat produced the major portion, i.e., more than 60 %, of the total 14C-photosynthates at grain filling, but ear (rachis and glumes) only about 15 %, sheaths about 11 %, and stem internodes about 11 %. The change of plant density in this experiment had little influence on the 14CO2-photoassimilation of the ear (rachis and glumes), flag leaf lamina, sheaths and stem internodes, but markedly affected photosynthesis of the second, the third and lower leaves. The photosynthetic rate [expressed as specific radioactivity, s-1 kg-1(d.m.)] and the amount of 14CO2 photosynthates decreased significantly in the second, the third and other lower leaves at a high plant density. Upon grain-filling of the late-sown wheat, the grain was the major importer of photosynthates. Yet partitioning to the stem internodes depended on the plant density. Stem was the importer of photosynthates at a low plant density, but the exporter at a high plant density. In plants at a low plant density a fairly large proportion of photosynthates was distributed into the roots. The middle and lower above-ground parts of the late-sown wheat at a high plant density decreased or lost their function early. As a result, the plant senesced earlier. However, the grain setting, filling and yielding were restricted. An appropriately low plant density was suitable for prolonging the function of the middle and lower organs, delaying the senescence of plant, increasing the source supply for grain filling, and improving the grain yield.
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    URL: http://dx.doi.org/10.1023/A:1022156112243
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    Phosphate uptake by phosphorus-starved cells of the cyanobacterium Phormidium laminosum (1997)
    Springer
    World journal of microbiology and biotechnology 13 (1997), S. 699-705 
    Details
    ISSN: 1573-0972
    Keywords: Phormidium laminosum ; phosphate uptake ; phosphorus-starved ; photosynthesis ; vanadate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Phosphorus(P)-starved cells of the cyanobacterium Phormidium laminosum have been investigated in relation to their phosphate uptake characteristics. P-deficient cells showed much higher phosphate uptake rates from ultrapure water supplemented with this anion than P-sufficient ones. After 9 days of starvation in P-free medium, the total cellular P content of P-deficient cells was approximately five times lower than that of cells grown in the presence of phosphate. Phosphate uptake by P-deficient cells occurred in both light and dark under aerobic conditions. In anaerobiosis, light was required for uptake, suggesting that the necessary energy could be derived from the respiratory electron transport chain. Phosphate uptake in P-deficient cells was sensitive to vanadate, suggesting the involvement of a plasma membrane ATPase.
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    URL: http://dx.doi.org/10.1023/A:1018583224294
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    Ultrastructural changes in gametophytes of Acrostichum aureum L. cultured in different sodium chloride concentrations (1997)
    Springer
    Biologia plantarum 39 (1997), S. 607-614 
    Details
    ISSN: 1573-8264
    Keywords: chloroplasts ; fern ; mitochondria ; photosynthesis ; respiration ; salt stress ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gametophytes cultured in solutions containing 0.0 to 0.7 % NaCl exhibited no change in ultra structural organization of chloroplasts. In 1.0% NaCl-grown gametophytes, there were thinner granal stacks, relatively larger spaces between granal thylakoidal membranes and larger plastoglobuli in the chloroplasts. These changes were accompanied by a decrease in photosynthesis. Cup shape, horseshoe shape, ring shape, and amoeboid mitochondria were observed in gametophytes grown in 0.0 to 0.7% NaCl. Only round mitochondria were observed in the gametophytes grown in 1.0 % NaCl. Mitochondria seemed to be more resistant to salt stress compared to chloroplasts. There was no direct relationship between changes in respiration rate and changes in mitochondrial shape among gametophytes grown in different NaCl concentrations.
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    URL: http://dx.doi.org/10.1023/A:1000939017348
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    Control of PAR-saturated CO2 exchange rate in some C3 and CAM plants (1997)
    Springer
    Biologia plantarum 40 (1997), S. 91-101 
    Details
    ISSN: 1573-8264
    Keywords: CER ; leaf thickness ; photosynthesis ; photosynthetic N-use efficiency succulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We measured PAR-saturated CO2 exchange rate (CER), and leaf N, P and chlorophyll (Chl) concentrations in 21 plant species, selected to encompass as broad a range in specific leaf area (SLA) as possible, and encompassing non-succulent C3 as well as succulent CAM plants. We worked with plants growing under uniform conditions in the facilities of a biological research station to ensure that any correlations found were due to inherent, genetically controlled, relationships between the measured parameters and not due to variations in resource availability in different habitats. We found CER to be strongly correlated to SLA, leaf N concentration and Chl concentration. CER increased much faster with increasing leaf N concentration (CER ≈ N3.1) than with increasing SLA (CER ≈ SLA1.2). CER also increased much faster with leaf N concentration than with increasing Chl concentration (CER ≈ Chl1.3), indicating the photosynthetic N-use efficiency (NUE) to be higher for plants with high N concentration than for plants with low N concentration (NUE ≈ N2.1). Analysis of covariance showed that these relationships exist even when comparing plants of widely different growth forms - succulent or non-succulent, and of different photosynthetic pathways, as the C3 and CAM plants compared here. Testing against scaling coefficients calculated using dimensional analysis, showed that the scaling of N, Chl and CER against SLA was not merely a result of diluting N and Chl with carbon in thicker leaves but that SLA, probably through influencing light absorptio and/or CO2 diffusion pathway, played an independent role in controlling CER.
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    URL: http://dx.doi.org/10.1023/A:1000900718932
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    Over-production of the D1:2 protein makes Synechococcus cells more tolerant to photoinhibition of photosystem II (1996)
    Springer
    Plant molecular biology 30 (1996), S. 467-478 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; photosynthesis ; protein turnover ; psbA ; tac promoter ; D1 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Over-expression of the psbAIII gene encoding for the D1 protein (form II; D1:2) of the photosystem II reaction centre in the Synechococcus sp. PCC 7942 was studied using a tac promoter and the lacI Q system. Over-expression was induced with 40 μg/ml IPTG in the growth medium for either 6 or 12 h at growth irradiance (50 μmol photons m-2 s-1). This treatment doubled the amount of psbAII/III mRNA and the D1:2 protein in membranes but decreased the amount of psbAI messages and the D1:1 protein. The total amount of both heterodimeric reaction centre proteins, D1 and D2, remained constant under growth light conditions, indicating that the number of PSII centres in the membranes was not affected, only the form of the D1 protein was changed from D1:1 to D1:2 in most centres. When the cells were photoinhibited either at 500 or 1000 μmol photons m-2 s-1, in the presence or absence of the protein synthesis inhibitor lincomycin, the D1:2 protein remained at a higher level in cells in which over-expression had been induced by IPTG. These cells were also less prone to photoinhibition of PSII. It is suggested that the tolerance of cells to photoinhibition increases when most PSII reaction centres contain the D1:2 protein at the beginning of high irradiance. This tolerance is further strengthened by maintaining psbAIII gene over-expression during the photoinhibitory treatment.
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    URL: http://dx.doi.org/10.1007/BF00049325
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    Effects of altered phosphoenolpyruvate carboxylase activities on transgenic C3 plant Solanum tuberosum (1996)
    Springer
    Plant molecular biology 32 (1996), S. 831-848 
    Details
    ISSN: 1573-5028
    Keywords: antisense ; Corynebacterium glutamicum ; Escherichia coli ; Flaveria trinervia ; overexpression ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphoenolpyruvate carboxylase (PEPC) genes from Corynebacterium glutamicum (cppc), Escherichia coli (eppc) or Flaveria trinervia (fppc) were transferred to Solanum tuberosum. Plant regenerants producing foreign PEPC were identified by Western blot analysis. Maximum PEPC activities measured in eppc and fppc plants grown in the greenhouse were doubled compared to control plants. For cppc a transgenic plant line could be selected which exhibited a fourfold increase in PEPC activity. In the presence of acetyl-CoA, a known activator of the procaryotic PEPC, a sixfold higher activity level was observed. In cppc plants grown in axenic culture PEPC activities were even higher. There was a 6-fold or 12-fold increase in the PEPC activities compared to the controls measured in the absence or presence of acetyl-CoA, respectively. Comparable results were obtained by transient expression in Nicotiana tabacum protoplasts. PEPC of C. glutamicum (PEPC C.g.) in S. tuberosum leaf extracts displays its characteristic K m(PEP) value. Plant growth was examined with plants showing high expression of PEPC and, moreover, with a plant cell line expressing and antisense S. tuberosum (anti-sppc) gene. In axenic culture the growth rate of a cppc plant cell line was appreciably diminished, whereas growth rates of an anti-sppc line were similar or slightly higher than in controls. Malate levels were increased in cppc plants and decreased in antisense plants. There were no significant differences in photosynthetic electron transport or steady state CO2 assimilation between control plants and transformants overexpressing PEPC C.g. or anti-sppc plants. However, a prolonged dark treatment resulted in a delayed induction of photosynthetic electron transport in plants with less PEPC. Rates of CO2 release in the dark determined after a 45 min illumination period at a high proton flux density were considerably enhanced in cppc plants and slightly diminished in anti-sppc plants. When CO2 assimilation rates were corrected for estimated rates of mitochondrial respiration in the light, the electron requirement for CO2 assimilation determined in low CO2 was slightly lower in transformants with higher PEPC, whereas transformants with decreased PEPC exhibited an appreciably elevated electron requirement. The CO2 compensation point remained unchanged in plants (cppc) with high PEPC activity, but might be increased in an antisense plant cell line. Stomatal opening was delayed in antisense plants, but was accelerated in plants overexpressing PEPC C.g. compared to the controls.
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    URL: http://dx.doi.org/10.1007/BF00020481
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    Random chemical mutagenesis of a specific psbDI region coding for a lumenal loop of the D2 protein of photosystem II in Synechocystis sp. PCC 6803 (1996)
    Springer
    Plant molecular biology 30 (1996), S. 243-254 
    Details
    ISSN: 1573-5028
    Keywords: Cyanobacteria ; photosynthesis ; random mutagenesis ; sodium bisulfite ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To identify amino acid residues of the D2 protein that are critical for functional photosystem II (PS II), sodium bisulfite was utilized for in vitro random mutagenesis of the psbDI gene from Synechocystis sp. PCC 6803. Sodium bisulfite reacts specifically with cytosine in single-stranded regions of DNA and does not attack double-stranded DNA. Using a hybrid plasmid that was single-stranded in the region to be mutagenized and that was double-stranded elsewhere, mutations were targeted to a specific psbDI region coding for the lumenal A-B loop of the D2 protein. Several mutants were isolated with a total of 15 different amino acid changes in the loop. The majority of these mutations did not result in a loss of photoautotrophic growth or in significantly altered PS II function. However, mutation of Glu-69 to Lys, Ser-79 to Phe, and Ser-88 to Phe were found to influence photosystem II activity; the importance of the latter two residues for proper PS II function was unexpected. Cells carrying the double mutation S79F/S88F in D2 did not grow photoautotrophically and had no functionally active PS II centers. The single mutant S79F was also incapable of photoautrophic growth, but displayed reasonably stable oxygen evolution, while PS II function in the single mutant S88F appeared to be close to normal. Because of the more pronounced phenotype of the S79F/S88F strain as compared to the single mutants, both Ser residues appear to affect stable assembly and function of the PS II complex. The mechanism by which the S79F mutant loses photoautotrophic growth remains to be established. However, these results show the potential of targeted random mutagenesis to identify functionally important residues in selected regions of proteins.
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    URL: http://dx.doi.org/10.1007/BF00020111
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    Drought-dependent responses of photosynthesis, transpiration and water use efficiency of Japanese cypress and Japanese red pine seedlings (1996)
    Springer
    Journal of forest research 1 (1996), S. 73-78 
    Details
    ISSN: 1610-7403
    Keywords: Chamaecyparis obtusa Endl. ; photosynthesis ; Pinus densiflora Sieb. et Zucc. ; stomatal conductance ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to investigate the potential for modifying drought tolerance of Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese red pine (Pinus densiflora Sieb. et Zucc.). Three-year-old seedlings were controlled for five-months at three different soil water potentials ({ie73-1}). Japanese cypress exposed to high {ie73-2} was able to maintain higher photosynthesis (Phn), transpiration (Tr) and stomatal conductance to H2O (gH2O) in comparison to low {ie73-3} pretreatments, however, there was no significant difference in Phn for Japanese red pine. Soil water potential at the threshold from the maximum to limited Phn was higher in high {ie73-4} pretreatments than in low {ie73-5} pretreatments. Net photosynthesis, Tr and gH2O decreased more rapidly in high {ie73-6} pretreatments than in low {ie73-7} pretreatments. Transpiration decreased more significantly than Phn, thus, resulted in increased water use efficiency. All these factors are likely to result in significant improvements in the drought tolerance. Japanese red pine seems more drought-tolerant than Japanese cypress. Japanese cypress is suitable to soil of −0.05 MPa water potential, and Japanese red pine is suitable to −0.16 MPa and even dryer soils.
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    URL: http://dx.doi.org/10.1007/BF02348307
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    Simultaneous measurements of quantum yield and CO2 uptake for the assessment of non-assimilative electron flow in tree leaves (1996)
    Springer
    Journal of forest research 1 (1996), S. 79-85 
    Details
    ISSN: 1610-7403
    Keywords: chlorophyll fluorescence ; electron transport ; photorespiration ; photosynthesis ; quantum yield ; tree
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using attached and detached leaves ofAcer palmatum Thunb. andRhaphiolepsis umbellata Makino, pulse-modulated chlorophyll fluorescence and CO2 exchange were measured. Quantum yield of photosynthesis was determined from the fluorescence parameter(Fm′−Fs)/Fm′, where (Fm′−Fs) was defined as the difference between steady state chlorophyll fluorescence (Fs) and maximum fluorescence (Fm′) elicited by a saturating light pulse. The rate of electron transport through photosystem II (total electron flow) was calculated from the product of quantum yield andA (PFD), whereA is the rate of absorbed photons as given by leaf absorptance, and PFD is the photon flux density at the leaf surface. The rate of electron transport dependant on CO2 uptake (assimilative electron flow) was calculated from the gross photosynthetic rate in a leaf. The difference between the rates of total and assimilative electron transport was denoted as the rate of non-assimilative electron transport which depends on photorespiration and oxygen reduction. Available data provided quantitative information on the rate of non-assimilative electron flow in intact leaves. When leaf photosynthesis ofA. palmatum was measured under sunlight, the rates of total and assimilative electron transport were determined to be approximately 900 and 150 μmol equiv. e/mg Chl·h, respectively. The difference (750 μmol equiv. e/mg Chl·h) was attributed to the activity of non-assimilative electron flow. The ratio of total to assimilative electron flow was found to increase gradually with rising in irradiance. The results suggest that non-assimilative electron flow occurred at much higher rate than assimilative electron flow at high irradiance. Implications of the results are briefly discussed in relation to photosynthesis limitation in tree leaves.
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    URL: http://dx.doi.org/10.1007/BF02348308
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    Molecular genetics of the cyanobacteriumSynechocystis sp. PCC 6803: Principles and possible biotechnology applications (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 263-273 
    Details
    ISSN: 1573-5176
    Keywords: molecular biology ; mutagenesis ; photosynthesis ; protein engineering ; respiration ; thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacteriumSynechocystis sp. PCC 6803 is readily amenable to targeted mutagenesis: Foreign DNA is taken up spontaneously, and after uptake DNA can be integrated into the organism's genome by homologous recombination. Using appropriate DNA constructs for transformation, specific genes in the organism can be interrupted, deleted, or replaced by modified gene copies. The organism can grow under a number of different conditions, ranging from photoautotrophic to fully heterotrophic modes, making genetic modifications that alter fundamental processes such as photosynthesis and/or respiration feasible. For example, deletion of photosystem I leads to an obligate (photo)heterotrophic strain in which photosystem II-generated electrons appear to be consumed by respiratory processes, whereas deletion of photosystem II leads to an obligate (photo)heterotrophic strain in which cyclic electron flow around photosystem I appears to remain active. A major advantage ofSynechocystis sp. PCC 6803 is that its entire genome has been sequenced (by S. Tabata and co-workers), opening many avenues to address basic and applied research problems. For example, genes can be introduced, modified or deleted, and hypotheses regarding the function of an open reading frame can be tested by deletion of this open reading frame. Methods to modify genes are numerous. In addition to site-directed mutagenesis, novel molecular genetic approaches including ‘targeted random mutagenesis’, combinatorial mutagenesis and introduction of hybrid genes have come of age and have proven to be very powerful tools in protein engineering. These approaches have been utilized primarily in this strain to study photosynthesis, but applications of this technology, including pathway engineering, alterations of substrate specificity of enzymes and introduction of tolerance to a variety of stresses, are equally feasible in relation to more applied aims. For optimal utilization of the potential of theSynechocystis sp. PCC 6803 system, however, an increased emphasis toward understanding the biochemistry and molecular physiology of cyanobacteria will also be critically important.
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    URL: http://dx.doi.org/10.1007/BF02178569
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    In situ monitoring of chlorophyll fluorescence to assess the synergistic effect of low temperature and high irradiance stresses inSpirulina cultures grown outdoors in photobioreactors (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 283-291 
    Details
    ISSN: 1573-5176
    Keywords: fluorescence ; photoinhibition ; photosynthesis ; Spirulina ; photobioreactor ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chlorophyll fluorescence technique was applied to anin situ study on the effects of low temperature and high light stresses onSpirulina cultures grown outdoors in controlled tubular photobioreactors at high (1.1 g L−1) and low (0.44 g L−1) biomass concentrations. Diurnal changes in PSII photochemistry (F v/F m) after 15 min of darkness, or in the light (dF/F′ m), and non-photochemical (qN) quenching were measured using a portable, pulse-amplitude-modulated fluorometer. The depression of theF v/F m ratio ofSpirulina cultures grown outdoors at 25°C (i.e. 10°C below optimum for growth) and 0.44 g L−1, reached 30% at the middle of the day. At the same time of the day thedF/F′ m ratio showed a reduction of up to 52%. The depression of bothF v/F m anddF/F′ m was lower in the cultures grown at 1.1 g L−1. Photoinhibition reduced the daily productivity of the culture grown at 0.44 g L−1 and 25°C by 33% with respect to that grown at 35°C. Changes in the growth yields of the cultures grown under different temperatures and growth rates correlate well with analogous changes in photon yield (dF/F′ m). Simple measurements of photochemical yield (F v/F m) can be used to test the physiological status ofSpirulina cultures. The results indicate that the saturating pulse fluorescence technique, when usedin situ, is a powerful tool for assessment of the photosynthetic characteristics of outdoor cultures ofSpirulina.
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    URL: http://dx.doi.org/10.1007/BF02178571
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    Selective effect of the herbicide DCMU on unicellular algae — a potential tool to maintain monoalgal mass culture ofNannochloropsis (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 415-419 
    Details
    ISSN: 1573-5176
    Keywords: herbicide ; DCMU ; photosynthesis ; monoalgal culture ; Chaetoceros ; Dunaliella ; Nannochloropsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The selective effect of DCMU on photosynthetic activity and growth rate was examined in several marine unicellular algae:Nannochloropsis sp. (Eustigmatohyceae),Dunaliella salina (Chlorophyceae)Isochrysis galbana (Prymnesiophyceae) andChaetoceros sp. (Bacillariophyceae). DCMU at 10−7 M caused an immediate decrease in the photosynthetic rate ofDunaliella andIsochrysis (about 50% inhibition), whereas 10−6 M imposed 80% inhibition in the photosynthetic rate ofChaetoceros. InNannochloropsis the rate was affected only when DCMU concentration exceeded 10−6M. Cellular growth rate of all studied algae was affected by DCMU in a similar manner to photosynthesis. The differential effect of DCMU was further examined in mixed cultures in whichNannochloropsis was cultivated together with an additional species simulating a contamination situation of aNannochloropsis culture. When DCMU was added at concentrations higher than 10−7 M, the growth of the competing algae significantly decreased, whileNannochloropsis maintained a relatively high growth rate. Consequently, after a growth period of 4 to 7 days a clear domination ofNannochloropsis was observed. These results demonstrate that DCMU and probably other herbicides of similar characteristics can be used effectively as a selective tool to suppress contaminating unicellular algae in open ponds in order to maintain a monoculture ofNannochloropsis.
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    URL: http://dx.doi.org/10.1007/BF02178586
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    Role of light and photosynthesis on the acclimation process of the cyanobacteriumSpirulina platensis to salinity stress (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 119-124 
    Details
    ISSN: 1573-5176
    Keywords: Spirulina platensis ; cyanobacterium ; NaCl ; photoinhibition ; photosynthesis ; photosystem II ; salt stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response ofSpirulina platensis cells to salinity stress was studied. Once adapted to the higher osmoticum, photosynthetic parameters such as the maximum rate of photosynthesis under saturating irradiance (Pmax) and the initial slope of the P-I curve (α) are reduced by 15% and 25% in 0.5 M NaCl grown cells, respectively. Salt-adapted cells have a modified biochemical composition; reduced protein and chlorophyll content, and an increased level of carbohydrates. The reduction in the photosynthetic capacity of the salt-adaptedSpirulina cells reflects a lower ability to utilize light energy and results in an increase in the susceptibility of the stressed cells to photoinhibition. This conclusion is supported by the finding that cultures exposed to salt stress show not only a decrease in growth rate (μ), but lose the ability to respond to increased irradiance with an increase in growth. The use of variable fluorescence as a fast and reliable measurement to follow the changes in PSII of salt-stressesSpirulina cells enables following the early events of salinity shock. It indicates that as soon as the cells are exposed to salt, a protection mechanism is induced. This mechanism does not require any protein synthesis and may take place even in the dark, though at somewhat reduced effectiveness. The significance of the result in providing a better understanding of the interaction between two environmental stresses — light and salinity — and their application in the outdoor mass cultivation ofSpirulina are discussed.
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    Light acclimation and photoinhibition in threeSpirulina platensis (cyanobacteria) isolates (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 35-40 
    Details
    ISSN: 1573-5176
    Keywords: cyanobacteria ; light intensity ; photoinhibition ; photosynthesis ; recovery ; Spirulina platensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three isolates ofSpirulina platensis (Norst) Geitler marked BP, P4P and Z19/2 were compared with respect to their response and acclimation capability to high photon flux densities (HPFD). Cultures exposed to HPFD (1500–3500 μmol photon m−2 s−1) exhibited a marked decrease in light-dependent O2 evolution rate. P4P was more sensitive to HPFD than the two other isolates. All three isolates recovered from photoinhibition when placed under low PFD. The BP isolate was able to recover also in the dark but to a lower extent and at a lower rate, while no recovery was observed in the other two isolates under dark conditions. No recovery was observed when protein synthesis was inhibited using chloramphenicol. Cultures grown at 200 μmol photon m−2 s−1 differed from cultures grown at 120 μmol photon m 2 s-1 by their lower maximal photosynthetic rate (P max ) and higher light saturation (I k ) value, while being more resistant to HPFD stress. The ability ofSpirulina isolates to acclimate and withstand HPFD may provide useful information for the selection of strains useful for outdoor mass cultivation.
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    URL: http://dx.doi.org/10.1007/BF02186220
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    New method for toxicity assessment in marine and brackish environments using the macroalga Gracilaria tenuistipitata (Gracilariales, Rhodophyta) (1996)
    Springer
    Hydrobiologia 326-327 (1996), S. 317-325 
    Details
    ISSN: 1573-5117
    Keywords: biotest ; brackish ; Gracilaria ; growth inhibition ; marine ; photosynthesis ; Rhodophyta ; seaweed ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A growth inhibition test method was developed using the macroalga Gracilaria tenuistipitata as the test organism. This alga was chosen because of its high laboratory growth rates, commonly 30–40% d−1, which are reached in salinities between 5 and 40‰, and its epiphyte resistance. The toxicity of a number of substances, including heavy metals, herbicides and complex wastewaters towards the alga was assayed. Anti-fouling paints were tested with a modification of the method. EC50 values for heavy metals varied between 0.05 and 17 mg l−1 and for herbicides between 0.002 and 0.02 mg l−l. The sensitivity to the toxicant was generally higher at low salinity. Omitting nitrogen and phosphorus additions to the test medium increased the sensitivity and a semi-static performance was possible with maintained or increased sensitivity. Preliminary tests done with a computerised photosynthesis inhibition method produced promising results. In conclusion, this is a simple, sensitive and reproducible test method for assessing the toxicity of substances, wastewaters and anti-fouling paints in brackish and marine environments.
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    URL: http://dx.doi.org/10.1007/BF00047825
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    Control of Photosystem II in spinach leaves by continuous light and by light pulses given in the dark (1996)
    Springer
    Photosynthesis research 50 (1996), S. 181-191 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; energy dissipation ; light scattering ; photosynthesis ; state transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The light-induced induction of components of non-photochemical quenching of chlorophyll fluorescence which are distinguished by different rates of dark relaxation (qNf, rapidly relaxing and qNs, slowly relaxing or not relaxing at all in the presence brief saturating light pulses which interrupt darkness at low frequencies) was studied in leaves of spinach. After dark adaptation of the leaves, a fast relaxing component developed in low light only after a lag phase. Quenching increased towards a maximum with increasing photon flux density. This ‘fast’ component of quenching was identified as energy-dependent quenching qE. It required formation of an appreciable transthylakoid ΔpH and was insignificant when darkened spinach leaves received 1 s pulses of light every 30 s even though zeaxanthin was formed from violaxanthin under these conditions. Another quenching component termed qNs developed in low light without a lag phase. It was not dependent on a transthylakoid pH gradient, decayed exponentially with a long half time of relaxation and was about 20% of total quenching irrespective of light intensity. When darkened leaves were flashed at frequencies higher than 0.004 Hz with 1 s light pulses, this quenching also appeared. Its extent was very considerable, and it did not require formation of zeaxanthin. Relaxation was accelerated by far-red light, and this acceleration was abolished by NaF. We suggest that qNs is the result of a so-called state transition, in which LHC II moves after its phosphorylation from fluorescent PS II to nonfluorescent PS I. This state transition was capable of decreasing in darkened leaves the potential maximum quantum efficiency of electron flow through Photosystem II by about 20%.
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    URL: http://dx.doi.org/10.1007/BF00014888
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    Cobalt induced changes in photosystem activity in Synechocystis PCC 6803: Alterations in energy distribution and stoichiometry (1996)
    Springer
    Photosynthesis research 50 (1996), S. 243-256 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; electron transport ; fluorescence ; photosynthesis ; spillover ; state changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adaptive responses to excess (supraoptimal) level of cobalt supplied to the growth medium were studied in the cyanobacterium Synechocystis PCC 6803. Growth of cells in the medium containing 10 μM CoCl2 led to a large stimulation (50%) in O2-evolution and an overall increase (∼30%) in the photosynthetic electron transport rates. Analysis of variable Chl a fluorescence yield of PS II and immuno-detection of Photosystem II (PS II) reaction-center protein D1, showed a small increase (15–20%) in the number of PS II units in cobalt-grown cells. Cobalt-grown cells, therefore, had a slightly elevated PS II/PS I ratio compared to control. We observed alteration in the extent of energy distribution between the two photosystems in the eobalt grown cells. Energy was preferentially distributed in favour of PS II accompanied by a reduction in the extent of energy transfer from PS II to PS I in cobalt-grown cells. These cells also showed a smaller PS I absorption cross-section and a smaller size of intersystem electron pool than the control cells. Thus, our results suggest that supplementation of 10 μM CoCl2, to the normal growth medium causes multiple changes involving small increase in PS II to PS I ratio, enhanced funneling of energy to PS II and an increase in PS I electron transport, decrease PS I cross section and reduction in intersystem pool size. The cumulative effects of these alterations cause stimulation in electron transport and O2 evolution.
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    URL: http://dx.doi.org/10.1007/BF00033123
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    Responses of three bottomland species with different flood tolerance capabilities to various flooding regimes (1996)
    Springer
    Wetlands ecology and management 4 (1996), S. 245-256 
    Details
    ISSN: 1572-9834
    Keywords: Anaerobiosis ; baldcypress ; cherrybark oak ; nuttall oak ; photosynthesis ; productivity ; soil redox potential ; stomatal conductance ; waterlogging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seedlings of baldcypress (Taxodium distichum), nuttall oak (Quercus nuttalli), and cherrybark oak (Quercus falcata var.pagodaefolia) were subjected to four flooding treatments: control, continuously flooded, intermittently flooded, and partially flooded for 70 days in a greenhouse. The treatments imposed various durations and intensities of soil redox potential (Eh) conditions representing a range encountered by plants in their habitats. Morphological changes and gas exchange responses to the treatments differed among the study species. Rapid development of adventitious root and hypertrophied lenticels were observed in baldcypress and nuttall oak under all flooded treatments. Cherrybark oak had the highest percentage reduction in net photosynthesis ranging from 65–87%, whereas reductions in nuttall oak ranged between 35–68% and in baldcypress between 6–21% in response to various treatments. Recovery of gas exchange was noted in baldcypress but no significant recovery was found in oaks. The recovery in baldcypress contributed to the continued growth and biomass accumulation under various treatments. Little evidence of consistent changes in biomass allocation patterns in response to the treatments was found in baldcypress but total biomass decreased significantly under the continuously flooded treatment. In oaks, total biomass decreased significantly in all flooded treatments. The present findings demonstrated that physiological functions are adversely affected by low soil Eh conditions and the extent of such effects are dependent on the intensity and duration of soil reduction as well as the species' capability to respond to such conditions rapidly. Management plans concerned with regeneration of bottomland forested ecosystems should consider the species flood response capabilities at seedling stages as well as the timing, durations, and intensities of soil reduction at the specific site.
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    URL: http://dx.doi.org/10.1007/BF02150538
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    Measurement and modelling of photosynthetic response of pearl millet to soil phosphorus addition (1996)
    Springer
    Plant and soil 184 (1996), S. 67-73 
    Details
    ISSN: 1573-5036
    Keywords: pearl millet ; Pennisetum glaucum (L.) R. Br. ; phosphorus ; photosynthesis ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract There have been no studies of the effects of soil P deficiency on pearl millet (Pennisetum glaucum (L.) R. Br.) photosynthesis, despite the fact that P deficiency is the major constraint to pearl millet production in most regions of West Africa. Because current photosynthesis-based crop simulation models do not explicitly take into account P deficiency effects on leaf photosynthesis, they cannot predict millet growth without extensive calibration. We studied the effects of soil addition on leaf P content, photosynthetic rate (A), and whole-plant dry matter production (DM) of non-water-stressed, 28 d pearl millet plants grown in pots containing 6.00 kg of a P-deficient soil. As soil P addition increased from 0 to 155.2 mg P kg−1 soil, leaf P content increased from 0.65 to 7.0 g kg−1. Both A and DM had maximal values near 51.7 mg P kg−1 soil, which corresponded to a leaf P content of 3.2 g kg−1. Within this range of soil P addition, the slope of A plotted against stomatal conductance (gs) tripled, and mean leaf internal CO2 concentration ([CO2]i) decreased from 260 to 92 μL L−1, thus indicating that P deficiency limited A through metabolic dysfunction rather than stomatal regulation. Light response curves of A, which changed markedly with P leaf content, were modelled as a single substrate, Michaelis-Menten reaction, using quantum flux as the substrate for each level of soil P addition. An Eadie-Hofstee plot of light response data revealed that both KM, which is mathematically equivalent to quantum efficiency, and Vmax, which is the light-saturated rate of photosynthesis, increased sharply from leaf P contents of 0.6 to 3 g kg−1, with peak values between 4 and 5 g P kg−1. Polynomial equations relating KM and Vmax, to leaf P content offered a simple and attractive way of modelling photosynthetic light response for plants of different P status, but this approach is somewhat complicated by the decrease of leaf P content with ontogeny.
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    URL: http://dx.doi.org/10.1007/BF00029275
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    Abscisic acid concentrations are correlated with leaf area reductions in two salt-stressed rapid-cycling Brassica species (1996)
    Springer
    Plant and soil 179 (1996), S. 25-33 
    Details
    ISSN: 1573-5036
    Keywords: abscisic acid ; Brassica napus ; Brassica carinata ; callus ; photosynthesis ; plant growth ; salinity ; salt tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The greater sensitivity of B. carinata to salinity in comparison to B. napus has been linked to a greater reduction in net assimilation rate. Apparently this is not due to ion toxicity; the cause is unknown. In this report, we test the hypothesis that increases in abscisic acid (ABA) are involved in the reduction of growth by salinity. Salinity (8 dS m−1) caused an increase of ABA concentrations in the shoot, root and callus of both species. ABA concentrations were lower in the salt-tolerant species, B. napus, than the salt-sensitive species, B. carinata, both in the whole plant and callus. Leaf expansion for both species was equally sensitive to ABA; salt stress did not significantly alter sensitivity to applied ABA. The growth inhibition increased in a hyperbolic manner with an increase in endogenous ABA concentration. These results indicate that ABA in salt-stressed plants may play a role in the inhibition of growth. The photosynthesis of salt-sensitive species, B. carinata, was also decreased by salinity, corresponding to the reduction in growth. The decreased photosynthesis does not appear to be the cause of the growth reduction, because photosynthesis was not inhibited by short-term exposure to salinity and photosynthesis was poorly correlated with endogenous ABA concentrations.
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    URL: http://dx.doi.org/10.1007/BF00011639
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    Chlorophyll fluorescence as an indicator of frost hardiness in white spruce seedlings from different latitudes (1996)
    Springer
    New forests 11 (1996), S. 233-253 
    Details
    ISSN: 1573-5095
    Keywords: variable chlorophyll fluorescence ; frost hardiness ; freezing damage ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study examined the utility of variable chlorophyll fluorescence (Fvar) to detect freezing damage in white spruce seedlings of four seedlots. Logistic regression analysis done for freezing tests in September showed that visible needle damage from freezing could be estimated by the Fvar attributes Fo/IABS(r2=0.94), Fp(r2=0.98), Fv/Fm (r2=0.99), and F1(r2=0.86). The regression curves indicated that for all four fluorescence attributes, inflection points occurred between 10 and 20% visible needle damage. The lack of a relationship between fluorescence attributes and visible seedling needle damage in October through December is because the minimum temperature (−18 and −24°C respectively) applied was insufficient to cause needle damage. Freezing-induced changes to Fvar attributes can be detected which also result in photosynthetic rate decreases when no visible needle damage, and even electrolyte conductivity changes are evident. Fvar attribute differences due to freezing can be resolved to the seedlot level. The Fvar curve feature manifested 5 seconds after dark-adapted seedlings have been exposed to light (F5s) will estimate (r2=0.76) photosynthetic rate after freezing.
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    URL: http://dx.doi.org/10.1007/BF00036784
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    Thermoluminescence investigations on the site of action of o-phthalaldehyde in photosynthetic electron transport (1996)
    Springer
    Photosynthesis research 48 (1996), S. 213-220 
    Details
    ISSN: 1573-5079
    Keywords: Arnold ; chemical modification ; electron transfers ; oxygen evolution ; o-phthalaldehyde ; photosynthesis ; photosystems ; thermoluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glow curves from spinach leaf discs infiltrated with o-phthalaldehyde (OPA) show significant similarity to those obtained by DCMU treatment which is known to block the electron flow from QA, the stable acceptor of Photosystem II (PS II). In both the cases, the thermoluminescence (TL) peak II (Q band) was intensified significantly, whereas peaks III and IV (B band) were suppressed. Total TL yield of the glow curve remained constant even when the leaf discs were infiltrated with high concentrations of OPA (4 mM) or with DCMU (100 μM), indicating that even at these high concentrations no significant change in the number of species undergoing charge recombination in PS II occurred. However, studies with thylakoids revealed significant differences in the action of OPA and DCMU on PS II. Although OPA, at a certain concentration and time of incubation, reduced the B band intensity by about 50–70%, and completely abolished the detectable oxygen evolution, it still retained the TL flash yield pattern, and, thus, S state turnover. OPA is known to inhibit the oxidoreductase activity of in vitro Cyt b6/f (Bhagwat et al. (1993) Arch Biochem Biophys 304: 38–44). However, in the OPA treated thylakoids the extent of inhibition of O2 evolution was not reduced even in the presence of oxidized tetramethyl-p-phenylenediamine which accepts electrons from plastoquinol and feeds then directly to Photosystem I. This suggests that OPA inhibition is at a site prior to plastoquinone pool in the electron transport chain, in agreement with it being between QA and QB. However, an unusual feature of OPA inhibition is that even though all oxygen evolution was completely suppressed, a significant fraction of PS II centers were functional and turned over with the same periodicity of four in the absence of any added electron donor, an observation which appears to be similar to that reported by Wydrzynski (Wydrzynski et al. (1985) Biochim Biophys Acta 809: 125–136) with lauroylcholine chloride, a lipid analogue compound. The detailed chemistry of OPA inhibition remains to be studied. Since we dedicate this paper to William A. Arnold, discoverer of delayed light and TL in photosynthesis, we have also included in the Introduction, a brief history of how TL work was initiated at BARC (Bombay, India).
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    URL: http://dx.doi.org/10.1007/BF00041011
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    Influence of photoheterotrophy on the expression of chlorophyll a/b-binding proteins in the green alga Pyrobotrys stellata (1996)
    Springer
    Photosynthesis research 49 (1996), S. 49-56 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll a/b-binding (CAB) protein ; cyclic electron flow ; gene-expression ; light-harvesing complex (LHC) ; photosynthesis ; Pyrobotrys (Chlamydobotrys) stellata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two genes (lhca5 and lhcb1) from the unicellular, green alga Pyrobotrys (formerly Chlamydobotrys) stellata were isolated, coding for Chlorophyll a/b-binding proteins that putatively represent constituents of the light-harvesting complexes connected with Photosystem I and Photosystem II, respectively. Expression of both genes on the mRNA-level is markedly inhibited by CO2-depletion. The lhca5 transcript-level was reduced to about 25%, and the lhcb1-expression was completely blocked 9 h after removal of CO2 from the growth medium. Simultaneous addition of acetate, which can substitute for CO2 as a carbon source during photoheterotrophic growth of P. stellata, did not compensate for the diminishing effect of CO2-depletion on lhcb1. However, the amount of lhca5 transcript was comparable to that during photoautotrophic growth. These results are interpreted in terms of the specific metabolic demands of photoheterotrophic growth in P. stellata. Cyclic electron-transfer along Photosystem I must be sustained for ATP-production. Linear electron transport fed by Photosystem II and concomitant production of NADPH for CO2-reduction is no longer required. The sequences reported in this article have been deposited at the EMBL data library under the accession numbers X69434 (CSCAB1) and X71965 (CSCAB2MR).
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    URL: http://dx.doi.org/10.1007/BF00029427
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    Characterization of the csmD and csmE genes from Chlorobium tepidum. The CsmA, CsmC, CsmD, and CsmE proteins are components of the chlorosome envelope (1996)
    Springer
    Photosynthesis research 50 (1996), S. 41-59 
    Details
    ISSN: 1573-5079
    Keywords: green sulfur bacterium ; Chlorobium tepidum ; chlorosomes ; DNA sequence ; protein overproduction ; primer extension mapping ; light-harvesting antenna ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The csmD and csmE genes, encoding two proteins of the chlorosome envelope, have been cloned and sequenced from the green sulfur bacterium Chlorobium tepidum. The csmD gene predicts a hydrophobic protein of 113 amino acids with a molecular mass of 11.1 kDa. The csmE gene was identified immediately upstream from csmD; the csmE gene predicts a protein of 82 amino acids (9.0 kDa) which is 49% identical to CsmA (Chung et al. (1994) Photosynthesis Res 41: 261–275). The CsmE protein is post-translationally processed, most likely in a manner similar to CsmA. The csmE and csmD genes are cotranscribed as a dicistronic mRNA but can also be cotranscribed with an open reading frame upstream from csmE that predicts a protein with sequence similarity to the CheY and SpoOF subclass of regulatory proteins. The CsmA, CsmC, CsmD, and CsmE proteins were overproduced in Escherichia coli, purified, and used to raise polyclonal antibodies in rabbits. Protease susceptibility mapping and agglutination experiments using these antibodies indicate that all four proteins are exposed at the surface of isolated chlorosomes and hence are probably components of the chlorosome envelope. Additionally, antigalactose antibodies were used to confirm that the galactosyl moiety of monogalactosyl diglycerol is exposed at the chlorosome surface; this is consistent with the notion that these lipids are components of the chlorosome envelope.
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    URL: http://dx.doi.org/10.1007/BF00018220
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    Carbohydrate and carbon metabolite accumulation responses in leaves of ozone tolerant and ozone susceptible spinach plants after acute ozone exposure (1996)
    Springer
    Photosynthesis research 50 (1996), S. 103-115 
    Details
    ISSN: 1573-5079
    Keywords: glucose ; hexose phosphates ; ozone ; photosynthesis ; respiratory substrates ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to determine whether exposure of plants to ozone (O3) increased the foliar levels of glucose, glucose sources, e.g., sucrose and starch, and glucose-6-phosphate (G6P), because in leaf cells, glucose is the precursor of the antioxidant, L-ascorbate, and glucose-6-phosphate is a source of NADPH needed to support antioxidant capacity. A further objective was to establish whether the response of increased levels of glucose, sucrose, starch and G6P in leaves could be correlated with a greater degree of plant tolerance to O3. Four commercially available Spinacia oleracea varieties were screened for tolerance or susceptibility to detrimental effects of O3 employing one 6.5 hour acute exposure to 25O nL O3 L-1 air during the light. One day after the termination of ozonation (29 d post emergence), leaves of the plants were monitored both for damage and for gas exchange characteristics. Cultivar Winter Bloomsdale (cv Winter) leaves were least damaged on a quantitative grading scale. The leaves of cv Nordic, the most susceptible, were approximately 2.5 times more damaged. Photosynthesis (Pn) rates in the ozonated mature leaves of cv Winter were 48.9% less, and in cv Nordic, 66.2% less than in comparable leaves of their non-ozonated controls. Stomatal conductance of leaves of ozonated plants was found not to be a factor in the lower Pn rates in the ozonated plants. At some time points in the light, leaves of ozonated cv Winter plants had significantly higher levels of glucose, sucrose, starch, G6P, G1P, pyruvate and malate than did leaves of ozonated cv Nordic plants. It was concluded that leaves of cv Winter displayed a higher tolerance to ozone mediated stress than those of cv Nordic, in part because they had higher levels of glucose and G6P that could be mobilized during diminished photosynthesis to generate antioxidants (e.g., ascorbate) and reductants (e.g., NADPH). Elevated levels of both pyruvate and malate in the leaves of ozonated cv Winter suggested an increased availability of respiratory substrates to support higher respiratory capacity needed for repair, growth, and maintenance.
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    URL: http://dx.doi.org/10.1007/BF00014882
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    Photosynthetic plasticity in Potamogeton pectinatus L. from Argentina: strategies to survive adverse light conditions (1996)
    Springer
    Hydrobiologia 340 (1996), S. 1-5 
    Details
    ISSN: 1573-5117
    Keywords: light climate manipulation ; Potamogeton pectinatus ; photosynthesis ; turbidity ; weed management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Argentine Potamogeton pectinatus L. was grown in The Netherlands under laboratory conditions at four light intensities (50, 100, 150 and 200 µE m−2 s−1), and photosynthetic performance was evaluated after about 1, 2 and 3 months of growth. At these moments, chlorophyll-a and -b and tissue N and P content were also determined. During the growing period, plant lengths and number of secondary shoots were measured. In the field in Argentina, photosynthetic performance of P. pectinatus was also measured at different light intensities created by artificial shading at various times during the growing season. Field and laboratory photosynthetic results were in good agreement. P. pectinatus showed a significant plasticityin its photosynthesis, rather than in morphology. A fairly constant maximum photosynthetic rate with reduced light enabled the plants to maintain netproduction rates rather unaffected at low light intensities. Still, it can be predicted that increasing turbidity from 1–2 m−1 at present to 3 m−1 could lead to a strongly light-limited growth which should reduce the present weed problem considerably. Such a turbidity increase might be achieved by the introduction of a fairly dense bottom-feeding fish population like Common carp (Cyprinus carpio L.).
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    URL: http://dx.doi.org/10.1007/BF00012725
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    Mepiquat chloride (PIX)-induced changes in photosynthesis and growth of cotton (1996)
    Springer
    Plant growth regulation 20 (1996), S. 179-183 
    Details
    ISSN: 1573-5087
    Keywords: cotton ; growth ; mepiquat chloride ; photosynthesis ; PIX ; RuBP carboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mepiquat chloride (N, N-dimethylpiperidinium chloride), well known as PIX, is a potential systemic plant growth regulator. The effects of PIX on plant height, stem elongation, leaf area, net photosynthetic rates, chlorophyll content, sucrose and starch levels, and RuBP carboxylase activity in cotton (Gossypium hirsutum L. cv. DES 119) plants were measured. PIX was sprayed (0, 7.65, 15.3, 30.6 or 61.2 g active ingredient ha−1) on the plants at first square (25 days after emergence) and measurements were made at frequent intervals. Plant height was clearly reduced by PIX. The total length of vegetative branches and fruiting branches was 40% and 50% less than the control. Total leaf area in PIX treated plants was 16% less than the control. Net photosynthetic rates were 25% less in PIX-treated leaves. PIX treated leaves had more chlorophyll content. The activity of RuBP carboxylase was decreased in PIX treated plants. Starch accumulation was noticed in PIX treated leaves while sucrose content was not changed. The data reported here suggest that reduced growth responses induced by PIX results in partial loss of photosynthetic capacity in cotton at least up to 20 days after application of the growth regulator.
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    URL: http://dx.doi.org/10.1007/BF00043305
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    Development of photoautotrophy and photoinhibition of Gardenia jasminoides plantlets during micropropagation (1996)
    Springer
    Plant cell, tissue and organ culture 45 (1996), S. 1-16 
    Details
    ISSN: 1573-5044
    Keywords: chlorophyll fluorescence ; leaf anatomy ; photosynthesis ; root induction ; shoot multiplication ; stable carbon isotope composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper reports on the fast fluorescence responses of Gardenia jasminoides Ellis plantlets, at two successive stages (shoot multiplication and root induction) of culture in vitro. We test whether plantlets in vitro suffer photoinhibition during culture and whether the degree of photoautotrophy of these mixotrophic plantlets has any effect on the extent of photoinhibitory impairment. In this regard the effects of different sucrose levels in the medium and PPFD during growth on the development of photoautotrophy and the extent of photoinhibition were evaluated. Plantlets were grown under low, intermediate, and high (50, 100, and 300 μmol m-2 s-1) PPFD, and at 3 different sucrose concentrations (0.5, 1.5, and 3.0%, w/v) in the medium, during shoot multiplication. During root induction the same growth conditions were assayed except for the high PPFD. The development of photoautotrophy was assessed via the difference between the stable carbon isotope composition of sucrose used as heterotrophic carbon source and that of leaflets grown in vitro. Plantlets from root induction showed more developed photoautotrophy than those from shoot multiplication. For both stages the low-sucrose medium stimulated the photoautotrophy of plantlets in vitro. In addition, intermediate PPFD induced photoautotrophy during shoot multiplication. For plantlets of both culture stages at the lowest PPFD no photoinhibition occurred irrespective of the sucrose concentration in media. However, during the shoot multiplication stage chlorophyll fluorescence measurements showed a decrease in F v /F m and in t 1/2 as growing PPFD increased, indicating photoinhibitory damage. The decline of F v /F m was caused mostly by an increase in F o , indicating the inactivation of PSII reaction centers. However plantlets growing under low sucrose showed reduced susceptibility to photoinhibition. During root induction, only plantlets cultured with high sucrose showed a decrease in F v /F m as PPFD increased, although t 1/2 remained unchanged. In this case, the decline of F v /F m was mostly due to a decrease in F m , which indicates increased photoprotection rather than occurrence of photodamage. Therefore, growth in low-sucrose media had a protective effect on the resistance of PSII to light stress. In addition, plantlets were more resistant to photoinhibition during root induction than during shoot multiplication. Results suggest that increased photoautotrophy of plantlets reduces susceptibility to photoinhibition during gardenia culture in vitro.
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    URL: http://dx.doi.org/10.1007/BF00043422
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    Photosynthesis in leaves and siliques of winter oilseed rape (Brassica napus L.) (1996)
    Springer
    Plant and soil 186 (1996), S. 227-236 
    Details
    ISSN: 1573-5036
    Keywords: Brassica napus ; canola ; oilseed rape ; nitrogen nutrition ; irrigation ; photosynthesis ; photosynthetic nitrogen use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The rate of photosynthesis and its relation to tissue nitrogen content was studied in leaves and siliques of winter oilseed rape (Brassica napus L.) growing under field conditions including three rates of nitrogen application (0, 100 or 200 kg N ha-1) and two levels of irrigation (rainfed or irrigated at a deficit of 20 mm). The predominant effect of increasing N application under conditions without water deficiency was enhanced expansion of photosynthetically active leaf and silique surfaces, while the rate of photosynthesis per unit leaf or silique surface area was similar in the different N treatments. Thus, oilseed rape did not increase N investment in leaf area expansion before a decline in photosynthetic rate per unit leaf area due to N deficiency could be avoided. Much less photosynthetically active radiation penetrated into high-N canopies than into low-N canopies. The specific leaf area increased markedly in low light conditions, causing leaves in shade to be less dense than leaves exposed to ample light. In both leaves and siliques the photosynthetic rate per unit surface area responded linearly to increasing N content up to about 2 g m-2, thus showing a constant rate of net CO2 assimilation per unit increment in N (constant photosynthetic N use efficiency). At higher tissue N contents, photosynthetic rate responded less to changes in N status. Expressed per unit N, light saturated photosynthetic rate was three times higher in leaves than in silique valves, indicating a more efficient photosynthetic N utilization in leaves than in siliques. Nevertheless, from about two weeks after completion of flowering and onwards total net CO2 fixation in silique valves exceeded that in leaves because siliques received much higher radiation intensities than leaves and because the leaf area declined rapidly during the reproductive phase of growth. Water deficiency in late vegetative and early reproductive growth stages reduced the photosynthetic rate in leaves and, in particular, siliques of medium- and high-N plants, but not of low-N plants.
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    URL: http://dx.doi.org/10.1007/BF02415518
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    Antenna organization in purple bacteria investigated by means of fluorescence induction curves (1996)
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    Photosynthesis research 47 (1996), S. 175-185 
    Details
    ISSN: 1573-5079
    Keywords: connectivity ; lake model ; photosynthesis ; Rs. rubrum ; Rps. viridis ; Rb. capsulatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluorescence induction curves of purple bacteria (Rs. rubrum, Rps. viridis and Rb. capsulatus) were measured in the sub-millisecond time range employing a xenon flash technique. The induction curves of all three species displayed a sigmoidal shape. Analysis of the curves showed that none of the species examined had an antenna organization of a lake (i.e. unrestricted energy transfer between photosynthetic units). The apparent time constants of inter-unit exciton transfer were estimated to be approximately 24 ps in the case of LHC 1-containing species (Rs. rubrum and Rps. viridis) and 40 ps in the case of the LHC 2-containing species Rb. capsulatus. This result demonstrates that LHC 2 (B800–850) acts as a sort of insulator between photosynthetic units. Assuming a coordination number of 6 in the LHC 1-containing species the mean single step energy transfer time between adjacent LHC 1 can be estimated to be 4–5 ps. This is not perfectly compatible with the much faster Förster transfer rate of 〈1ps that follows from the minimal chromophore-chromophore distances estimated from digital image processing of micrographs from stained membranes. It thus may be concluded that the photosynthetic units (reaction center plus LHC 1) are loosely arranged in the photosynthetic membrane, like in the fluid-mosaic-membrane model, rather than in a hexagonally crystalline configuration.
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    Reaction center and antenna processes in photosynthesis at low temperature (1996)
    Springer
    Photosynthesis research 48 (1996), S. 99-106 
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    ISSN: 1573-5079
    Keywords: electron transfer ; energy transfer ; low temperature ; photosynthesis ; spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Around 1960 experiments of Arnold and Clayton, Chance and Nishimura and Calvin and coworkers demonstrated that the primary photosynthetic electron transfer processes are not abolished by cooling to cryogenic temperatures. After a brief historical introduction, this review discusses some aspects of electron transfer in bacterial reaction centers and of optical spectroscopy of photosynthetic systems with emphasis on low-temperature experiments.
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    Competition between annihilation and trapping leads to strongly reduced yields of photochemistry under ps-flash excitation (1996)
    Springer
    Photosynthesis research 48 (1996), S. 255-262 
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    ISSN: 1573-5079
    Keywords: photochemical yield ; photosynthesis ; Photosystem I ; Photosystem II ; Rps. viridis ; Rs. rubrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Excitation of photosynthetic systems with short intense flashes is known to lead to exciton-exciton annihilation processes. Here we quantify the effect of competition between annihilation and trapping for Photosystem II, Photosystem I (thylakoids from peas and membranes from the cyanobacterium Synechocystis sp.), as well as for the purple bacterium Rhodospirillum rubrum. In none of the cases it was possible to reach complete product saturation (i.e. closure of reaction centers) even with an excitation energy exceeding 10 hits per photosynthetic unit. The parameter α introduced by Deprez et al. ((1990) Biochim. Biophys. Acta 1015: 295–303) describing the competition between exciton-exciton annihilation and trapping was calculated to range between ≈4.5 (PS II) and ≈6 (Rs. rubrum). The rate constants for bimolecular exciton-exciton annihilation ranged between (42 ps)-1 and (2.5 ps)-1 for PS II and PS I-membranes of Synechocystis, respectively. The data are interpreted in terms of hopping times (i.e. mean residence time of the excited state on a chromophore) according to random walk in isoenergetic antenna.
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    Halcyon days with Bill Arnold (1996)
    Springer
    Photosynthesis research 48 (1996), S. 11-18 
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    ISSN: 1573-5079
    Keywords: aging ; delayed light production ; firefly ATP assay ; plant luminescence ; loss of rDNA ; luminous bacteria ; neuronal memory storage and pulse pattern coding ; organic mass spectroscopy ; plant luminescence ; photosynthetic ATP production ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The circumstances that led to the discovery that plants luminesce after they are illuminated are described, as are other discoveries that would not have been possible were it not for the fortuitous association I had with my dear and most admirable friend, W.A. Arnold, to whom this special issue is dedicated.
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    Acclimation of photosynthesis to elevated CO2 through feedback regulation of gene expression: Climate of opinion (1996)
    Springer
    Photosynthesis research 48 (1996), S. 353-365 
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    ISSN: 1573-5079
    Keywords: catabolite repression ; glucose sensing ; high CO2 acclimation ; Lycopersicon esculentum ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although down-regulation of photosynthesis in higher C3 plants exposed to long-term elevated CO2 has been recognized in plants with low sink activity or poor nutrient status, the underlying molecular mechanisms remain unclear. This review covers aspects of rising CO2 on plant productivity in general, and then focuses on photosynthesis, biochemistry (stroma and thylakoid proteins, Rubisco activities and metabolites), and gene expression in tomato plants grown under ambient or elevated CO2. Taking into account these data and the recent discovery that glucose triggers repression of photosynthetic gene transcription, a molecular mechanism is proposed for feedback regulation of photosynthesis under high CO2. Different living organisms such as bacteria, yeast, and mammals have been investigated for the sensing mechanisms of the carbohydrate status of their cells, and this information is used together with some recent data obtained for plants to propose how hexose levels might be sensed in higher plant cells.
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    Kinetic and functional characterization of a membrane-bound NAD(P)H dehydrogenase located in the chloroplasts of Pleurochloris meiringensis (Xanthophyceae) (1996)
    Springer
    Photosynthesis research 49 (1996), S. 183-193 
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    ISSN: 1573-5079
    Keywords: algae ; chlororespiration ; NAD(P)H: plastoquinone oxidoreductase ; photosynthesis ; chloroplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using isolated chloroplasts or purified thylakoids from photoautotrophically grown cells of the chromophytic alga Pleurochloris meiringensis (Xanthophyceae) we were able to demonstrate a membrane bound NAD(P)H dehydrogenase activity. NAD(P)H oxidation was detectable with menadione, coenzyme Q0, decylplastoquinone and decylubiquinone as acceptors in an in vitro assay. K m-values for both pyridine nucleotides were in the μmolar range (K m[NADH]=9.8 μM, K m[NADPH]=3.2 μM calculated according to Lineweaver-Burk). NADH oxidation was optimal at pH 9 while pH dependence of NADPH oxidation showed a main peak at 9.8 and a smaller optimum at pH 7.5–8. NADH oxidation could be completely inhibited with rotenone, an inhibitor of mitochondrial complex I dehydrogenase, while NADPH oxidation revealed the typical inhibition pattern upon addition of oxidized pyridine nucleotides reported for ferredoxin: NADP+ reductase. Partly-denaturing gel electrophoresis followed by NAD(P)H dehydrogenase activity staining showed that NADPH and NADH oxidizing proteins had different electrophoretic mobilities. As revealed by denaturing electrophoresis, the NADH oxidizing enzyme had one main subunit of 22 kDa and two further polypeptides of 29 and 44 kDa, whereas separation of the NADPH depending protein yielded five bands of different molecular weight. Measurement of oxygen consumption due to PS I mediated methylviologen reduction upon complete inhibition of PS II showed that the NAD(P)H dehydrogenase is able to catalyze an input of electrons from NADH to the photosynthetic electron transport chain in case of an oxidized plastoquinone-pool. We suggest ferredoxin: NADP+ reductase to be the main NADPH oxidizing activity while a thylakoidal NAD(P)H: plastoquinone oxidoreductase involved in the chlororespiratory pathway in the dark acts mainly as an NADH oxidizing enzyme.
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    The role of chromophore coupling in tuning the spectral properties of peripheral light-harvesting protein of purple bacteria (1996)
    Springer
    Photosynthesis research 50 (1996), S. 5-10 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; antenna complex ; LH2 ; bacteriochlorophyll
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The publication of a structure for the peripheral light-harvesting complex of a purple photosynthetic bacterium (McDermott et al. (1995), Nature 374: 517–521) provides a framework within which we can begin to understand various functional aspects of these complexes, in particular the relationship between the structure and the red-shift of the bacteriochlorophyll Qy transition. In this article we describe calculations of some of the spectral properties expected for an array of chromophores with the observed geometry. We report the stability of the calculated absorption spectrum to minor structural alterations, and deduce that the observed red shift of the 850 nm Qy transition in the B800–850 antenna complexes is about equally attributable to chromophore-chromophore and chromophore-protein interactions, while chromophore-chromophore interactions predominate in generating the red-shift of the 820 nm Qy transition in B800–820 type peripheral liggt-harvesting complexes. Finally we suggest that the red shift in the absorbance of the monomeric Bchl a found in antenna complexes to 800 nm, from 770 nm as observed in most solvents, is largely attributable to a hydrogen bond with the 2-acetyl group of this chromophore.
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    A comparative flash-photolysis study of electron transfer from pea and spinach plastocyanins to spinach Photosystem 1. A reaction involving a rate-limiting conformational change (1996)
    Springer
    Photosynthesis research 50 (1996), S. 11-21 
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    ISSN: 1573-5079
    Keywords: blue copper protein ; gated electron transfer ; photosynthesis ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two mutants of plastocyanin have been constructed by site-directed mutagenesis in spinach and pea to elucidate the binding and electron transfer properties between plastocyanin and spinach Photosystem 1. The conserved, surface-exposed Tyr-83 has been replaced by phenylalanine and leucine in plastocyanin from both species and the proteins have been expressed in Escherichia coli. The reaction mechanism of electron transfer from plastocyanins to photooxidized P700 in Photosystem 1 has been studied by laser-flash absorption spectroscopy. The experimental data were interpreted with a model involving a rate-limiting conformational change, preceding the intracomplex electron transfer. The pea proteins show an overall facilitated reaction with spinach Photosystem 1, compared to spinach plastocyanins. The changes are small but significant, indicating a more efficient electron transfer within the transient complex. In addition, for the spinach leucine mutant, the equilibrium within the plastocyanin-Photosystem 1 complex is more displaced towards the active conformation than for the corresponding wild-type. Absorption spectra, EPR and reduction potentials for the mutants are similar to those of the corresponding wild-type, although small shifts are observed in the spectra of the Tyr83Leu proteins. Based on these results, it is suggested that Photosystem 1 from spinach is capable of using both pea and spinach plastocyanin as an efficient electron donor and that the former even can stimulate the Photosystem 1 reduction. The origin of the stimulation is discussed in terms of differences in surface-exposed residues. Since the effects of the mutations are small, it can be concluded that electron transfer to Photosystem 1 does not occur via Tyr-83.
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    The relationship of intercompartmental excitation transfer rate constants to those of an underlying physical model (1996)
    Springer
    Photosynthesis research 50 (1996), S. 117-131 
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    ISSN: 1573-5079
    Keywords: compartment theory ; electronic excitation transport ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In studies on photosynthetic systems it is common practice to interpret the results of time-resolved fluorescence experiments on the basis of compartmental, or target, models. Each compartment represents a group of molecules with similar fluorescence characteristics. In cases of practical interest, the members of each compartment are spatially contiguous and make up part of an overall energy-transferring system. Since a rate constant describing the overall transfer between compartments is not that of any pair of molecules in the system, this question naturally rises: what do we learn about the microscopic structure from these data? In this note we introduce ‘compartment melting’, a smooth mathematical connection between the compartmental and microscopic levels. We then show, on the basis of model calculations on finite lattices in one, two, and three dimensions, that average microscopic rates at the interfaces between compartments may be estimated from observed intercompartmental rates. The estimate involves a modest number of structural assumptions about the system. As examples of the method, which is applicable mainly to systems containing homogeneous pigment pools, some recent chlorophyll-protein antenna studies are analyzed.
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    Leaflet photosynthesis rate and carbon metabolite accumulation patterns in nitrogen-limited, vegetative soybean plants (1996)
    Springer
    Photosynthesis research 50 (1996), S. 133-148 
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    ISSN: 1573-5079
    Keywords: anaplerotic carbon metabolites ; dark respiration ; hexose phosphates ; nitrogen-limitation ; orthophosphate ; photosynthesis ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Prolonged inorganic nitrogen (NO3 −+NH4 +) limitation of non-N2-fixing soybean plants affected leaflet photosynthesis rates, photosynthate accumulation rates and levels, and anaplerotic carbon metabolite levels. Leaflets of nitrogen-limited (N-Lim), 27–31-day-old plants displayed ≈ 15 to 23% lower photosynthesis rates than leaflets of nitrogen-sufficient (N-Suff) plants. In contrast, N-Lim plant leaflets displayed higher sucrose and starch levels and rates of accumulation, as well as higher levels of carbon metabolites associated with sucrose and starch synthesis, e. g., glycerate-3-phosphate and glucose phosphates, than N-Suff plant leaflets. Concurrently, levels of soluble protein, chlorophyll, and anaplerotic metabolites, e.g., malate and phosphoenolpyruvate, were lower in leaflets of N-Lim plants than N-Suff plants, suggesting that the enzymes of the anaplerotic carbon metabolite pathway were lower in activity in N-Lim plant leaflets. Malate net accumulation rates in the earliest part of the illumination period were lower in N-Lim than in N-Suff plant leaflets; however, by the midday period, malate accumulation rate in N-Lim plant leaflets exceeded that in leaflets of N-Suff plants. Further, soluble protein accumulation rates in leaflets of N-Suff and N-Lim plants were similar, and the rate of dark respiration, measured in the early part of the dark period, was higher in N-Lim plant leaflets than in N-Suff plant leaflets. It was concluded that during prolonged N-limitation, foliar metabolite conditions favored the channelling of a large proportion of the carbon assimilate into sucrose and starch, while assimilate flow through the anaplerotic pathway was diminished. However, in some daytime periods, there was a normal level of carbon assimilate channelled through the anaplerotic pathway for ultimate use in amino acid and protein synthesis.
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    The mechanism of Rubisco activase: Insights from studies of the properties and structure of the enzyme (1996)
    Springer
    Photosynthesis research 47 (1996), S. 1-11 
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    ISSN: 1573-5079
    Keywords: chaperone chloroplast ; enzyme regulation ; photosynthesis ; protein-protein interaction ; ribulose-1,5-bisphosphate carboxylase/oxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rubisco, the primary carboxylating enzyme in photosynthesis, must be activated to catalyze CO2 fixation. The concept of an ‘activase’, a specific protein for activating Rubisco, was first introduced in 1985 based largely on biochemical and genetic studies of a high CO2-requiring mutant of Arabidopsis (Salvucci et al. (1985) Photosynth Res 7: 193–201). Over the past ten years, details about the occurrence, structure, and properties of Rubisco activase have been elucidated. However, the mechanism of action of Rubisco activase remains elusive. This review discusses the need for and function of Rubisco activase and summarizes information about the properties and structure of Rubisco activase. The information is evaluated in the context of the mechanism of Rubisco activase.
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    Measurement of chlorophyll fluorescence within leaves using a modified PAM Fluorometer with a fiber-optic microprobe (1996)
    Springer
    Photosynthesis research 47 (1996), S. 103-109 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; quenching analysis ; photosynthesis ; quantum yield ; photoinhibition ; fiber-optic microsensor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By using a fiber-optic microprobe in combination with a modified PAM Fluorometer, chlorophyll fluorescence yield was measured within leaves with spatial resolution of approximately 20 μm. The new system employs a miniature photomultiplier for detection of the pulse-modulated fluorescence signal received by the 20 μm fiber tip. The obtained signal/noise ratio qualifies for recordings of fluorescence induction kinetics (Kautsky effect), fluorescence quenching by the saturation pulse method and determination of quantum yield of energy conversion at Photosystem II at different sites within a leaf. Examples of the system performance and of practical applications are given. It is demonstrated that the fluorescence rise kinetics are distinctly faster when chloroplasts within the spongy mesophyll are illuminated as compared to palisade chloroplasts. Photoinhibition is shown to affect primarily the quantum yield of the palisade chloroplasts when excessive illumination is applied from the adaxial leaf side. The new system is envisaged to be used in combination with light measurements within leaves for an assessment of the specific contributions of different leaf regions to overall photosynthetic activity and for an integrative modelling of leaf photosynthesis.
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    Characterisation of a H2O2-oxidisable cytochrome b-559 in intact chloroplasts with a new type of LED Array Spectrophotometer (1996)
    Springer
    Photosynthesis research 47 (1996), S. 187-197 
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    ISSN: 1573-5079
    Keywords: cyt b-559 ; photosynthesis ; heat stress ; light stress ; hydrogen peroxide ; ascorbate peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytochrome (cyt) b-559 absorbance changes in intact chloroplasts were deconvoluted using a previously described LED-Array-Spectrophotometer (Klughammer et al. (1990), Photosynth Res 25: 317–327). When intact chloroplasts were isolated in the presence of ascorbate, approx. 15% of the total cyt b-559 could be transiently oxidised by 200 μM H2O2 in the dark. This fraction displays low-potential properties, as it can be also oxidised by menadione in the presence of 5 mM ascorbate. Heat pretreatment increased the size of this fraction by a factor of 3–4. Low concentrations of cyanide (in the μM range) prolonged the oxidation time while high concentrations suppressed the oxidation (I50=1.5 mM KCN). The former KCN-effect relates to inhibition of ascorbate dependent H2O2-reduction which is catalysed by ascorbate peroxidase, whereas the latter effect reflects competition between H2O2 and CN− for the same binding site at the cytochrome heme. In the light, much lower concentrations of H2O2 were required to obtain oxidation, the amplitude depending on light intensity and on the concentration of the added H2O2, but never exceeding approx. 15% of the total cyt b-559. In the light, but not in the dark, H2O2 also induced the transient oxidation of a cyt f fraction similar in size to the H2O2-oxidisable cyt b-559 fraction. In this case, H2O2 serves as an acceptor of Photosystem I in conjunction with the ascorbate peroxidase detoxification system. Light can also induce oxidation of a 15% cyt b-559 fraction without H2O2-addition, if nitrite is present as electron acceptor and the chloroplasts are depleted of ascorbate. It is concluded that light-induced cyt b-559 oxidation in vivo is likely to be restricted to the H2O2-oxidisable cyt b-559 LP fraction and is normally counteracted by ascorbate.
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    Evidence of singlet oxygen evolution by whole living cells of Chlamydomonas reinhardtii (1996)
    Springer
    Photosynthesis research 47 (1996), S. 99-102 
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    ISSN: 1573-5079
    Keywords: Chlamydomonas ; photosynthesis ; singlet oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The oxygen evolved by Chlamydomonas reinhardtii in the light is measured simultaneously with a Clark electrode and with the nitrosodimethylaniline-imidazole colorimetric method which is specific for singlet oxygen. Experiments with wild-type and FuD7 mutant cells (unable to synthesize the D1 protein of Photosystem II), with dichlorophenyldimethylurea (which blocks electron transfer from Photosystem II to Photosystem I) and with dibromothymoquinone (which diverts electrons from their normal path between the two photosystems), as well as with hydroxylamine (an inactivator of the water-splitting part of Photosystem II and a competitor of water for electron donation to it), all point to the dependence of detected singlet oxygen on photolysis of water by Photosystem II.
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    Two forms of the Photosystem II D1 protein alter energy dissipation and state transitions in the cyanobacterium Synechococcus sp. PCC 7942 (1996)
    Springer
    Photosynthesis research 47 (1996), S. 131-144 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; electron transport ; light-acclimation ; light-harvesting ; photosynthesis ; quenching analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Synechococcus sp. PCC 7942 (Anacystis nidulans R2) contains two forms of the Photosystem II reaction centre protein D1, which differ in 25 of 360 amino acids. D1: 1 predominates under low light but is transiently replaced by D1:2 upon shifts to higher light. Mutant cells containing only D1:1 have lower photochemical energy capture efficiency and decreased resistance to photoinhibition, compared to cells containing D1:2. We show that when dark-adapted or under low to moderate light, cells with D1:1 have higher non-photochemical quenching of PS II fluorescence (higher qN) than do cells with D1:2. This is reflected in the 77 K chlorophyll emission spectra, with lower Photosystem II fluorescence at 697–698 nm in cells containing D1:1 than in cells with D1:2. This difference in quenching of Photosystem II fluorescence occurs upon excitation of both chlorophyll at 435 nm and phycobilisomes at 570 nm. Measurement of time-resolved room temperature fluorescence shows that Photosystem II fluorescence related to charge stabilization is quenched more rapidly in cells containing D1:1 than in those with D1:2. Cells containing D1:1 appear generally shifted towards State II, with PS II down-regulated, while cells with D1:2 tend towards State I. In these cyanobacteria electron transport away from PS II remains non-saturated even under photoinhibitory levels of light. Therefore, the higher activity of D1:2 Photosystem II centres may allow more rapid photochemical dissipation of excess energy into the electron transport chain. D1:1 confers capacity for extreme State II which may be of benefit under low and variable light.
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    Self quenching of chlorosome chlorophylls in water and hexanol-saturated water (1996)
    Springer
    Photosynthesis research 47 (1996), S. 207-218 
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    ISSN: 1573-5079
    Keywords: aggregate ; antenna ; atomic force microscopy ; bacteriochlorophyllc ; chlorosome ; concentration quenching ; energy transfer ; green bacteria ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The optical properties of a methyl ester homolog of bacteriochlorophylld (BChld M ) and bacteriochlorophyllc (BChlc) in H2O, hexanol-saturated H2O and methanol were studied by absorption, fluorescence emission, and circular dichroism (CD). In H2O, BChld M spontaneously forms an aggregate similar to that formed in hexane, with absorption maximum at 730 nm and fluorescence emission at 748 nm. For the pigment sample in hexanol-saturated H2O, while the absorption peaks at 661 nm, only slightly red-shifted compared to the monomer, the fluorescence emission is highly quenched. When diluted 2–3 fold with H2O, the absorption returns to around 720 nm, characteristic of an aggregate. The CD spectrum of the H2O aggregate exhibits a derivative-shaped feature with positive and negative peaks, while the amplitude is lower than that of chlorosomes. The Fourier transform infrared spectra of BChld M aggregates in H2O and hexane were measured. A 1644 cm−1 band, indicative of a bonded 131-keto group, is detected for both samples. A marker band for 5-coordinated Mg was observed at 1611 cm−1 for the two samples as well. To study the kinetic behavior of the samples, both single-photon counting (SPC) fluorescence and transient absorption difference spectroscopic measurements were performed. For BChld M in hexanol-saturated H2O, a fast decay component with a lifetime of 10 to 14 ps was detected using the two different techniques. The fast decay could be explained by the concentration quenching phenomenon due to a high local pigment concentration. For the pigment sample in H2O, SPC gave a 16 ps component, whereas global analysis of transient absorption data generated two fast components: 3.5 and 26 ps. The difference may arise from the different excitation intensities. With a much higher excitation in the latter measurements, other quenching processes, e.g. annihilation, might be introduced, giving the 3.5 ps component. Finally, atomic force microscopy was used to examine the ultrastructure of BChld M in H2O and hexanol-saturated H2O. Pigment clusters with diameters ranging from 15 to 45 nm were observed in both samples.
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    Chromatic regulation inChlamydomonas reinhardtii alters photosystem stoichiometry and improves the quantum efficiency of photosynthesis (1996)
    Springer
    Photosynthesis research 47 (1996), S. 253-265 
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    ISSN: 1573-5079
    Keywords: Chlamydomonas reinhardtii ; chromatic acclimation ; photosynthesis ; photosystem stoichiometry ; quantum yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The work addressed the adjustment of the photosystem ratio in the green algaChlamydomonas reinhardtii. It is shown that green algae, much like cyanophytes and higher plants, adjust and optimize the ratio of the two photosystems in chloroplasts in response to the quality of irradiance during growth. Such adjustments are compensation reactions and helpC. reinhardtii to retain a quantum efficiency of oxygen evolution near the theoretical maximum. Results show variable amounts of PS I and a fairly constant amount of PS II in chloroplasts and suggest that photosystem stoichiometry adjustments, occurring in response to the quality of irradiance during plant growth, are mainly an adjustment in the concentration of PS I. The work delineates chromatic effects on chlorophyll accumulation in the chloroplast ofC. reinhardtii from those pertaining to the regulation of the PS I/PS II ratio. The detection of the operation of a molecular feedback mechanism for the PS I/PS II ratio adjustment in green algae strengthens the notion of the highly conserved nature of this mechanism among probably all oxygen evolving photosynthetic organisms. Findings in this work are expected to serve as the basis of future biochemical and mutagenesis experiments for the elucidation of the photosystem ratio adjustment in oxygenic photosynthesis.
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    URL: http://dx.doi.org/10.1007/BF02184286
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    On the relation between absorption and fluorescence emission spectra of photosystems: Derivation of a Stepanov relation for pigment culsters (1996)
    Springer
    Photosynthesis research 48 (1996), S. 139-145 
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    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; energy transfer ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stepanov (1957a, Soviet Physics-Doklady 2: 81–84) obtained an equation which relates the absorption spectrum and the fluorescence emission spectrum of a single dye molecule. Here, a similar equation is derived for a cluster of interacting pigments, e.g. the antenna pigments of a photosystem. This relation can be used to assess the possibility of occurrence of rapid exciton equilibration (Dau and Sauer, 1996, Biochim. Biophys. Acta, 1273: 175–190). The excited state potential of a pigment cluster is discussed and compared to the excited state potential of a single pigment.
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    Chimaeric CP47 mutants of the cyanobacterium Synechocystis sp. PCC 6803 carrying spinach sequences: Construction and function (1996)
    Springer
    Photosynthesis research 48 (1996), S. 147-162 
    Details
    ISSN: 1573-5079
    Keywords: gene replacement ; Photosystem II ; photosynthesis ; thylakoid membranes ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimaeric mutants of the cyanobacterium Synechocystis sp. PCC 6803 have been generated carrying part or all of the spinach psbB gene, encoding CP47 (one of the chlorophyll-binding core antenna proteins in Photosystem II). The mutant in which the entire psbB gene had been replaced by the homologous gene from spinach was an obligate photoheterotroph and lacked Photosystem II complexes in its thylakoid membranes. However, this strain could be transformed with plasmids carrying selected regions of Synechocystis psbB to give rise to photoautotrophs with a chimaeric spinach/cyanobacterial CP47 protein. This process involved heterologous recombination in the cyanobacterium between psbB sequences from spinach and Synechocystis 6803; which was found to be reasonably effective in Synechocystis. Also other approaches were used that can produce a broad spectrum of chimaeric mutants in a single experiment. Functional characterization of the chimaeric photoautotrophic mutants indicated that if a decrease in the photoautotrophic growth rates was observed, this was correlated with a decrease in the number of Photosystem II reaction centers (on a chlorophyll basis) in the thylakoid membrane and with a decrease in oxygen evolution rates. Remaining Photosystem II reaction centers in these chimaeric mutants appeared to function rather normally, but thermoluminescence and chlorophyll a fluorescence measurements provided evidence for a destabilization of QB −. This illustrates the sensitivity of the functional properties of the PS II reaction center to mild perturbations in a neighboring protein.
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    URL: http://dx.doi.org/10.1007/BF00041005
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    Excitation energy transfer in the green photosynthetic bacterium Chloroflexus aurantiacus: A specific effect of 1-hexanol on the optical properties of baseplate and energy transfer processes (1996)
    Springer
    Photosynthesis research 48 (1996), S. 263-270 
    Details
    ISSN: 1573-5079
    Keywords: Chloroflexus aurantiacus ; chlorophyll ; chlorosome ; energy transfer ; green bacteria ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of 1-hexanol on spectral properties and the processes of energy transfer of the green gliding photosynthetic bacterium Chloroflexus aurantiacus was investigated with reference to the baseplate region. On addition of 1-hexanol to a cell suspension in a concentration of one-fourth saturation, a specific change in the baseplate region was induced: that is, a bleach of the 793-nm component, and an increase in absorption of the 813-nm component. This result was also confirmed by fluorescence spectra of whole cells and isolated chlorosomes. The processes of energy transfer were affected in the overall transfer efficiency but not kinetically, indicating that 1-hexanol suppressed the flux of energy flow from the baseplate to the B806-866 complexes in the cytoplasmic membranes. The fluorescence excitation spectrum suggests a specific site of interaction between bacteriochlorophyll (BChl) c with a maximum at 771 nm in the rod elements and BChl a with a maximum at 793 nm in the baseplate, which is a funnel for a fast transfer of energy to the B806-866 complexes in the membranes. The absorption spectrum of chlorosomes was resolved to components consistently on the basis, including circular dichroism and magnetic circular dichroism spectra; besides two major BChl c forms, bands corresponding to tetramer, dimer, and monomer were also discernible, which are supposed to be intermediary components for a higher order structure. A tentative model for the antenna system of C. aurantiacus is proposed.
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    URL: http://dx.doi.org/10.1007/BF00041017
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    Effects of flooding and salinity on photosynthesis and water relations of four Southeastern Coastal Plain forest species (1996)
    Springer
    Wetlands ecology and management 4 (1996), S. 31-42 
    Details
    ISSN: 1572-9834
    Keywords: baldcypress ; green ash ; flooding ; photosynthesis ; salinity ; Chinese tallow ; water relations ; water tupelo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of flooding and salinity on photosynthesis and water relations was examined for four common coastal tree species [green ash (Fraxinus pennsylvanica Marshall), water tupelo (Nyssa aquatica L.). Chinese tallow (Sapium sebiferum (L.) Roxb.), and baldcypress (Taxodium distichum (L.) Richard)]. Both chronic (as might be associated with sea level rise) and acute (similar to hurricane storm surges) exposures to these stresses were examined. Chronic freshwater flooding of green ash, water tupelo, and Chinese tallow seedlings reduced photosynthesis (A) relative to that of watered seedlings, while baldcypress was unaffected. Chinese tallow A declined with increasing length of flooding. A salinity increase of the floodwater to 2 ppt decreased A of baldcypress and water tupelo, but not A of green ash and Chinese tallow, which was already severely reduced by freshwater flooding. All seedlings of the four species died within 2 to 6 weeks when flooded with 10 ppt saltwater. Photosynthesis of all four species did not differ between 0 and 2 ppt watering. Watering with 10 ppt salinity initially reduced A of all four species, but the seedlings recovered over time. Photosynthesis was severely decreased for all species when flooded with 21 ppt salinity for 48 hours. Reduced A continued following the treatment. Photosynthesis of only green ash and water tupelo was reduced by watering with 21 ppt salinity for 48 hours. Flooding of low-lying areas with increased salinity would lead to shifts in species composition of coastal forests due to these differential tolerances.
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    URL: http://dx.doi.org/10.1007/BF01876133
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    Extraction of humic-β-glucosidase fractions from soil (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 77-82 
    Details
    ISSN: 1432-0789
    Keywords: Soil enzymes ; β-Glucosidase ; Humic/enzyme complexes ; Enzymatic extration ; Pyrophosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Humic compounds with β-glucosidase activity were extracted from soil using tetrasodium pyrophosphate as extracting solution. Mixture of soil samples with 0.01 M pyrophosphate in a ratio of 1:5 (w/v), adjustment to pH 7.0–7.3, extraction for 18 h with reciprocating agitation, and bacteriological filtration after centrifugation were the optimum conditions for extraction of the β-glucosidase complexes. Otherwise, experimental conditions for extraction indicated that the concentration and pH of pyrophosphate were the factors with the most influence on enzymatic extraction yields. The results indicated that the β-glucosidase was extracellular and associated with soil humates.
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    URL: http://dx.doi.org/10.1007/BF00307845
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    Ozone effects on dry matter partitioning and chlorophyll fluorescence during plant development of wheat (1995)
    Springer
    Water, air & soil pollution 85 (1995), S. 1461-1466 
    Details
    ISSN: 1573-2932
    Keywords: ozone ; wheat ; Triticum aestivum ; growth ; senescence ; biomass partitioning ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In closed-chamber fumigation experiments dry matter partitioning and chlorophyll fluorescence of wheat were studied, analysing the effects of ozone during different stages of plant development. Ozone causes enhanced leaf senescence, leading to a loss of green leaf area and, consequently to a decreased supply of assimilates, affecting (in increasing order of severeness) stem, ear and grain productivity because of reduced storage pools for translocation. Leaves of plants before shooting stage were most sensitive but the lack of green leaf area after ear emergence had the most pronounced effects on grain yield. Measurements of photochemical capacity showed that evidence for negative ozone effects could be found in changes of chlorophyll fluorescence parameters in leaf sections not yet showing visible ozone injury. Negative effects on photosynthesis were more distinct with increasing accumulated ozone dose, with increasing age of leaf tissue and with increasing ozone sensitivity of the cultivar. The changes in chlorophyll fluorescence are most likely to be explained by a decreased pool size of plastoquinones caused by ozone.
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    URL: http://dx.doi.org/10.1007/BF00477187
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    Novel aspects of the regulation of a cDNA (Arf1) from Chlamydomonas with high sequence identity to animal ADP-ribosylation factor 1 (1995)
    Springer
    Plant molecular biology 29 (1995), S. 567-577 
    Details
    ISSN: 1573-5028
    Keywords: Cell cycle ; circadian clock ; green alga ; GTP-binding proteins ; light regulation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ADP-ribosylation factor (ARF) is a highly conserved, low molecular mass (ca. 21 kDa) GTP-binding protein that has been implicated in vesicle trafficking and signal transduction in yeast and mammalian cells. However, little is known of ARF in plant systems. A putative ARF polypeptide was identifed in subcellular fractions of the green alga Chlamydomonas reinhardtii, based on [32P]GTP binding and immunoblot assays. A cDNA clone was isolated from Chlamydomonas (Arf1), which encodes a 20.7 kDa protein with 90% identity to human ARF1. Northern blot analyses showed that levels of Arf1 mRNA are highly regulated during 12 h/12 h light/dark (LD) cycles. A biphasic pattern of expression was observed: a transient peak of Arf1 mRNA occurred at the onset of the light period, which was followed ca. 12 h later by a more prominent peak in the early to mid-dark period. When LD-synchronized cells were shifted to continuous darkness, the dark-specific peak of Arf1 mRNA persisted, indicative of a circadian rhythm. The increase in Arf1 mRNA at the beginning of the light period, however, was shown to be light-dependent, and, moreover, dependent on photosynthesis, since it was prevented by DCMU. We conclude that the biphasic pattern of Arf1 mRNA accumulation during LD cycles is due to regulation by two different factors, light (which requires photosynthesis) and the circadian clock. Thus, these studies identify a novel pattern of expression for a GTP-binding protein gene.
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    URL: http://dx.doi.org/10.1007/BF00020985
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    Loss of chloroplast transcripts for proteins associated with photosystem II: an early event during heat-bleaching in Euglena gracilis (1995)
    Springer
    Plant molecular biology 27 (1995), S. 317-325 
    Details
    ISSN: 1573-5028
    Keywords: chloroplasts ; gene expression ; heat bleaching ; photosynthesis ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A shift in the ratio of chlorophyll (Chl) a and Chl b is an early indicator of heat bleaching in Euglena gracilis. This observation prompted us to consider whether or not changes in steady-state levels of chloroplast transcripts and in transcriptional activity could limit the synthesis of Chl a-binding proteins in bleaching plastids. We found that the mature transcripts for CP47 and CP43, the Chl a-binding apoproteins of the proximal antenna of photosystem II, decline sharply very early during bleaching. Our study also shows that transcription of psbB and psbC, the chloroplast genes encoding CP47 and CP43, remains essentially unchanged during the same interval. We conclude that posttranscriptional events, such as mRNA stability, could play a major role in initiating an irreversible loss of chloroplast function in Euglena at a moderately elevated temperature. Lack of these transcripts would eventually impair the assembly of photosystem II in thylakoids.
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    URL: http://dx.doi.org/10.1007/BF00020186
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    Characterization of the single psbA gene of Prochlorococcus marinus CCMP 1375 (Prochlorophyta) (1995)
    Springer
    Plant molecular biology 27 (1995), S. 1189-1196 
    Details
    ISSN: 1573-5028
    Keywords: Cyanobacteria ; gene copy number ; light regulation ; photosynthesis ; photosystem II reaction center ; polymerase chain reaction ; psbA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequence, copy number, expression and phylogenetic relevance of the psbA gene from the abundant marine prokaryote P. marinus CCMP 1375 was analyzed. The 7 amino acids near the C-terminus missing in higher plant and in Prochlorothrix hollandica D1 proteins are present in the derived amino acid sequence. P. marinus contains only a single psbA gene. Thus, this organism lacks the ability to adapt its photosystem II by replacement of one type of D1 by another, as several cyanobacteria do. Phylogenetic trees suggested the D1-1 iso-form from Synechococcus PCC 7942 as the next related D1 protein and place P. Marinus separately from Prochlorothrix hollandica among the cyanobacteria.
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    URL: http://dx.doi.org/10.1007/BF00020892
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    Light-dependent chlorophyll a biosynthesis upon chlL deletion in wild-type and photosystem I-less strains of the cyanobacterium Synechocystis sp. PCC 6803 (1995)
    Springer
    Plant molecular biology 29 (1995), S. 933-945 
    Details
    ISSN: 1573-5028
    Keywords: chlorophyll synthesis ; cyanobacteria ; chlorophyl-binding proteins ; photosynthesis ; thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Part of the chlL gene encoding a component involved in light-independent protochlorophyllide reduction was deleted in wild type and in a photosystem I-less strain of Synechocystis sp. PCC 6803. In resulting mutants, chlorophyll biosynthesis was fully light-dependent. When these mutants were propagated under light-activated heterotrophic growth conditions (in darkness except for 15 min of weak light a day) for several weeks, essentially no chlorophyll was detectable but protochlorophyllide accumulated. Upon return of the chlL - mutant cultures to continuous light, within the first 6 h chlorophyll was synthesized at the expense of protochlorophyllide at a rate independent of the presence of photosystem I. Chlorophyll biosynthesized during this time gave rise to a 685 nm fluorescence emission peak at 77 K in intact cells. This peak most likely originates from a component different from those known to be directly associated with photosystems II and I. Development of 695 and 725 nm peaks (indicative of intact photosystem II and photosystem I, respectively) required longer exposures to light. After 6 h of greening, the rate of chlorophyll synthesis slowed as protochlorophyllide was depleted. In the chlL - strain, greening occurred at the same rate at two different light intensities (5 and 50 μE m-2s-1), indicating that also at low light intensity the amount of light is not rate-limiting for protochlorophyllide reduction. Thus, in this system the rate of chlorophyll biosynthesis is limited neither by biosynthesis of photosystems nor by the light-dependent protochlorophyllide reduction. We suggest the presence of a chlorophyll-binding ‘chelator’ protein (with 77 K fluorescence emission at 685 nm) that binds newly synthesized chlorophyll and that provides chlorophyll for newly synthesized photosynthetic reaction centers and antennae.
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    Photosynthetic metabolism and cell-wall polysaccharide accumulation inGelidium sesquipedale (Clem.) Born. et Thur. under different light qualities (1995)
    Springer
    Journal of applied phycology 7 (1995), S. 167-174 
    Details
    ISSN: 1573-5176
    Keywords: cell-wall polysaccharides ; chlorophylla ; Gelidium sesquipedale ; internal C and N ; light quality ; photosynthesis ; phycobiliproteins ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of different light qualities on the photosynthetic rate, dark respiration, intracellular carbon and nitrogen content, and accumulation of photosynthetic pigments and cell-wall polysaccharides during short-term incubation (5 h) of the red algaGelidium sesquipedale was investigated. The same photon irradiance of 50μmol m−2 s−2 below the light saturation point of photosynthesis was applied in each case. Blue light stimulated photosynthesis, dark respiration and the accumulation of chlorophyll and biliproteins, phycoerythrin in particular. The accumulation of internal carbon and nitrogen was greater under blue light than under the other light qualities. In contrast, the percentage of cell-wall polysaccharides was higher in red light. The content of cell-wall polysaccharides decreased during the time of incubation in all light treatments except in red light. The action of a non-photosynthetic photoreceptor in the control of cell-wall polysaccharide synthesis is suggested because the accumulation of cell-wall polysaccharides was not correlated with net photosynthesis in contrast to what occurred with carbon, chlorophyll and phycoerythrin accumulation.
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    URL: http://dx.doi.org/10.1007/BF00693064
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    Diurnal gas exchange characteristics and water use efficiency of three salt-secreting mangroves at low and high salinities (1995)
    Springer
    Hydrobiologia 295 (1995), S. 13-22 
    Details
    ISSN: 1573-5117
    Keywords: gas exchange ; mangrove ; photosynthesis ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Continuous measurements of gas exchange characteristics were made on two to nine year old hydroponically grown Avicennia germinans (L.) Stearn, Aegialitis annulata R. Br. and Aegiceras corniculatum (L.) Blanco maintained at 50 or 500 mol m−3 NaCl. In Avicennia germinans and Aegialitis annulata, CO2 assimilation rates were initially higher at 500 mol m−3 NaCl and decreased gradually towards the end of the photoperiod when rates were similar to those at the lower salinity. In Aegiceras corniculatum, assimilation rates were higher at 50 mol m−3 NaCl and about 55% lower at the higher salinity. In all three species, leaf conductance and transpiration exhibited trends similar to those for CO2 assimilation. Intercellular CO2 concentrations were similar at both salinities in Avicennia germinans and Aegialitis annulata, but considerably higher at the lower salinity in Aegiceras corniculatum. Water use efficiencies (WUE), although similar between salinity treatments in Avicennia germinans and Aegialitis annulata, were greater at the higher salinity in Aegiceras corniculatum. Data obtained from CO2 response curves indicated that assimilation at high salinity in Aegiceras corniculatum was limited by conductance, and to a lesser extent, by photosynthetic capacity. In Avicennia germinans and Aegialitis annulata, assimilation was greater at the higher salinity as indicated by increase in both the initial slope and the upper plateau of the CO2 response data. Greater assimilation at high salinity in Avicennia germinans and Aegialitis annulata may be attributed to lower carbon losses via photorespiration and to efficient salt excretion and sequestration.
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    The influence of photon flux density (PFD) on short term 14C incorporation into proteins, carbohydrates and lipids in freshwater algae (1995)
    Springer
    Hydrobiologia 308 (1995), S. 51-59 
    Details
    ISSN: 1573-5117
    Keywords: photon flux density ; intracellular metabolic pools ; proteins ; carbohydrates ; lipids ; polysaccharides ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of photon flux density (PFD) on the partitioning of photosynthetically fixed 14CO2-C into major intracellular end products was investigated for three species of freshwater planktonic algae (Nitzschia palea, Monoraphidium minutum and Synechococcus elongatus belonging to three different classes. This study was designed to investigate the phenomenon of polysaccharide synthesis associated with the saturation of protein synthesis and to test if this process is common to all three phytoplankton species. Protein synthesis was saturated at low PFD in all three species of algae studied. However, fixed carbon was differentially stored, namely in lipids in Nitzschia palea (Bacillariophyceae), in polysaccharides in Monoraphidium minutum (Chlorophyceae), and in low molecular weight metabolites (LMW) in Synechococcus elongatus (Cyanophyceae). The results of this transient state study indicate that the metabolic pathways of algae can easily be controlled by different irradiance. Furthermore, it appears that the difference in the patterns of synthesis is taxonomy dependent.
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    Relationship between net photosynthesis and nitrogen in Scots pine: Seasonal variation in seedlings and shoots (1995)
    Springer
    Plant and soil 168-169 (1995), S. 263-270 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; nutrient availability ; photosynthesis ; Scots pine ; seasonal change ; site quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship between light saturated net photosynthesis (Amax) and nitrogen concentration (N) was studied in needles of both Scots pine seedlings, grown at three relative growth rates (2,6 and 8%) controlled by nutrient addition rate, and Scots pine shoots collected from four sites with different fertility. In the seedlings, Amax was measured on 14 different dates starting at the beginning of the second growing season and ending when growth of the new shoot and the secondary needles had finished. In shoots from the natural stands Amax of the previous-year shoots was measured on 6 dates throughout the growing season. Both in seedlings and shoots, the correlation between Amax and N was poor, when data from all sampling dates were taken together. However, Amax was correlated with N in most instances when the age of the needles was considered and the data were examined either at weekly intervals (seedlings) or separately for each sampling date (shoots). The slope of the Amax vs N relationship varied greatly between sampling dates. In the seedlings the correlation between Amax and N was strongest by the time when the new needles were developing. In the shoots the correlation was significant from mid June until mid August, while no correlation was found in the beginning and at the end of the growing season. Our data indicate that in pine needles the photosynthesis-nitrogen relationship is more complex than in broadleaved species. Contrary to the broadleaved species, where the correlation is independent of sampling time, in this conifer the time of the year affects the correlation and there are phases during the growing season when the correlation is poor or nonexistent.
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    Growth and carbon economy of a fast-growing and a slow-growing grass species as dependent on nitrate supply (1995)
    Springer
    Plant and soil 171 (1995), S. 217-227 
    Details
    ISSN: 1573-5036
    Keywords: carbon budget ; growth analysis ; interspecific variation ; nitrogen supply ; photosynthesis ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In previous experiments systematic differences have been found in the morphology, carbon economy and chemical composition of seedlings of inherently fast- and slow-growing plant species, grown at a non-limiting nutrient supply. In the present experiment it was investigated whether these differences persist when plants are grown at suboptimal nutrient supply rates. To this end, plants of the inherently fast-growing Holcus lanatus L. and the inherently slow-growing Deschampsia flexuosa (L.) Trin. were grown in sand at two levels of nitrate supply. Growth, photosynthesis, respiration and carbon and nitrogen content were studied over a period of 4 to 7 weeks. At low N-supply, the potentially fast-growing species still grew faster than the potentially slow-growing one. Similarly, differences in leaf area ratio (leaf area:total dry weight), specific leaf area (leaf area:leaf dry weight) and leaf weight ratio (leaf dry weight:total dry weight), as observed at high N-supply persisted at low N-availability. The only growth parameter for which a substantial Species × N-supply interaction was found was the net assimilation rate (increase in dry weight per unit leaf area and time). Rates of photosynthesis, shoot respiration and root respiration, expressed per unit leaf, shoot and root weight, respectively, were lower for the plants at low N-availability and higher for the fast-growing species. Species-specific variation in the daily carbon budget was mainly due to variation in carbon fixation. Lower values at low N were largely determined by both a lower C-gain of the leaves and a higher proportion of the daily gain spent in root respiration. Interspecific variation in C-content and dry weight:fresh weight ratio were similar at low and high N-supply. Total plant organic N decreased with decreasing N-supply, without differences between species. It is concluded that most of the parameters related to growth, C-economy and chemical composition differ between species and/or are affected by N-supply, but that differences between the two species at high N-availability persist at low N-supply.
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    URL: http://dx.doi.org/10.1007/BF00010275
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    Variation in thylakoid proteins and photosynthesis in Syrian landraces of barley (1995)
    Springer
    Euphytica 82 (1995), S. 213-220 
    Details
    ISSN: 1573-5060
    Keywords: barley landraces ; drought ; Hordeum vulgare ; leaf colour ; photosynthesis ; photosystem I and II ; thylakoid chlorophyll-proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Barley breeders at ICARDA have observed that genotypes adapted to dry regions have leaves which are lighter in colour than those of unadapted ones. We measured photosynthesis, chlorophyll content and chlorophyll a:b ratios in two sets of genotypes which had previously been observed to have either light green or dark green leaves when grown in the field. Thylakoid membranes were also extracted and the proteins analysed on SDS-PAGE gels. The light leaf colour was associated with a higher chlorophyll a:b ratio. This was a measure of a reduction in the amount of antenna chlorophyll compared to that in the core complex of PSII. Genotypes with light green leaves had consistently less chlorophyll per unit leaf area and lower photosynthetic rates per unit area than those with dark green leaves. It is suggested that these features of light green leaves may confer the ability to adapt to high levels of irradiance under drought conditions. This ability may result from a high rate of photosynthetic electron transport through each PSII reaction centre, thus reducing the risk of damage from the overexcitation of these centres.
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    Photosynthetic energy storage in aquatic leaves measured by photothermal deflection (1995)
    Springer
    Photosynthesis research 45 (1995), S. 157-168 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast movement ; photosynthesis ; photothermal deflection spectroscopy ; Vallisneria americana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a study of photosynthetic energy storage efficiency (ES), the adaxial surface of the leaves of Vallisneria americana exhibited the highest ES values (22%) of the four aquatic plants examined. V. americana leaves have a dispersed structure and it was possible to measure the energy storage properties of the epidermal cells independently of the rest of the leaf. The abaxial epidermis had a higher value of ES at zero light fluence than the adaxial epidermis but ES in the abaxial epidermis declined much more rapidly with light fluence. Thus the abaxial epidermis is more suited to lower light fluences than the adaxial epidermis. ES declined as the pH rose from 4.0 to 8.0 at a constant dissolved inorganic carbon concentration. This paralleled the change from carbon dioxide to bicarbonate and suggests that these leaves utilise CO2 more efficiently than bicarbonate. ES increased by about 50% at pH 8.0 as leaf sections further from the leaf tip were examined which demonstrates that the older epidermal cells are less well able to use bicarbonate. Exposure to 30 min of a saturating light fluence caused the epidermal chloroplasts to move from the periclinal walls to the anticlinal walls. This decreased the photothermal signal by increasing the thermal diffusion distance and lowering the light fluence due to greater chloroplast shading. The latter effect increased ES. It appears that chloroplast movement could assist the epidermis to survive harmful light fluences.
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    Effects of calcium deficiency on Coffea arabica. Nutrient changes and correlation of calcium levels with some photosynthetic parameters (1995)
    Springer
    Plant and soil 172 (1995), S. 87-96 
    Details
    ISSN: 1573-5036
    Keywords: calcium ; Coffea arabica ; fluorescence analysis ; nutrient relations ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Calcium deficiency was induced in hydroponically grown 1.5-years-old coffee plants with 12–14 pairs of leaves. Calcium was given in the form of Ca(NO3)2: 5, 2.5, 0.1, 0.01 and 0 mM. After 71 days of Ca-treatment root and shoot as well as total biomass were decreased by severe Ca-deficiency. However, a stronger decrease was observed for shoot growth as revealed by the increase in the root/shoot ratio. New leaves were affected showing decreases in the total leaf area and in Leaf Area Duration (LAD). After 91 days of deficiency, leaf protein concentration decreased (by about 45%) in the top leaves while nitrate reductase activity (NRA) and NO3 content showed no significant changes. Total nitrogen and mineral concentrations (P, K, Ca, Mg and Na) were also determined in leaves and roots. With the decrease in calcium concentration in Ca-deficiency conditions, we observed concomitant increases in the concentrations of K+, Mg2+ and Na+ in leaves (maximal changes of 32% for K+, 96% for Mg2+ and 438% for Na+) and in roots (108% for K+, 86% for Mg2+ and 38% for Na+). Accordingly, the ratio between elements changed, including the ratio N/P, showing a non-equilibrium in the balance of nutrients. Significant correlations were obtained between Ca2+ concentration and some photosynthetic parameters. Ca-deficiency conditions would increase the loss of energy as expressed by the rise in aE and decrease the photochemical efficiency, which confirms the importance of this element in the stabilization of chlorophyll and in the maintenance of good photochemical efficiency at PS II level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020862
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  • 196
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    Effects of calcium on growth and leaf ion concentrations of Gossypium hirsutum grown in saline hydroponic culture (1995)
    Springer
    Plant and soil 176 (1995), S. 219-227 
    Details
    ISSN: 1573-5036
    Keywords: calcium ; chloride ; cotton ; photosynthesis ; potassium ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The optimum Ca2+ concentration for growth of cotton (Gossypium hirsutum cv. Acala SJ-2) was in the range 1 to 15 mol m−3 for plants growing in hydroponic culture with 100–150 mol m−3 NaCl. Most saline (but not sodic) soils contain higher Ca2+ concentrations. CaCl2 was inhibitory to the growth of cotton above 20–50 mol m−3. Increasing concentrations of Ca2+ in the range 0–2 mol m−2 drastically reduced Na+ accumulation in the leaves. As CaCl2 concentrations were increased above the optimum for growth there was a further reduction in leaf Na+ accumulation, but this was more than offset by increased leaf Ca2+ and Cl− concentrations. Leaf K+ concentrations were not much affected by changes in external CaCl2 concentrations. The response of Mg2+ varied from an increase to a decrease with increasing external CaCl2 and was influenced by nutritional status. There was no evidence that high Ca2+ caused a deficiency of Mg2+ in cotton. Except for Cl−, whose concentrations tended to decrease initially and then increase as the CaCl2 concentration increased, the anions were largely unaffected by changes in external CaCl2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011785
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  • 197
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    Seasonal development of the photosynthetic performance of Norway spruce (Picea abies [L.] Karst.) under magnesium deficiency (1995)
    Springer
    Plant and soil 168-169 (1995), S. 255-261 
    Details
    ISSN: 1573-5036
    Keywords: magnesium deficiency ; Norway spruce ; photosynthesis ; Picea abies (L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to investigate the influence of different magnesium nutrition on photosynthesis, one hundred 6-year-old spruce trees derived from one clone were planted in October 1990 into a special out-door experimental construction, where they were cultivated in sand culture with an optimal supply of nutrients, except magnesium, via circulating nutrient solutions. Magnesium was added to the nutrient solutions in three different concentrations, varying from optimal to severe deficient supplies. During the first vegetative period in 1991, photosynthetic performance and carboxylation efficiency were measured under saturating light, controlled CO2 conditions, optimal temperature and humidity, using a minicuvette system. During summer, the trees under moderate magnesium deficiency developed tip yellowing symptoms on older needles, while the youngest needles remained green with unchanged chlorophyll contents. Trees under severe magnesium deficiency showed yellowing symptoms on all needle age classes combined with decreased chlorophyll contents in the youngest needles as well. In comparison with the controls, the photosynthetic performance of the 1-year-old needles was significantly lower in both deficiency treatments. The same was observed in the youngest needles of the trees under severe deficiency. Trees under moderate deficiency treatment decreased in photosynthetic performance during the summer without reduction of chlorophyll contents. The reduction of photosynthetic rates corresponded to a decrease in carboxylation efficiency, which is taken as a measure of the activity of the enzyme ribulose-1,5-bisphosphate carboxylase. This reduction, together with the observed increase of carbohydrate contents in needles of trees growing under magnesium deficiency, led to the assumption that the photosynthetic carbonfixation is reduced as a consequence of the accumulation of carbohydrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029336
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  • 198
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    Effect of ammonium and nitrate on net photosynthesis, flower formation, growth and yield of eggplants (Solanum melongena L.) (1995)
    Springer
    Plant and soil 171 (1995), S. 267-274 
    Details
    ISSN: 1573-5036
    Keywords: ammonium toxicity ; buffered nutrient solution ; eggplant ; flowers ; fruit yield ; nitrate ; photosynthesis ; Solanum melongena ; starch ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eggplants (Solanum melongena L. cv. Bonica) were grown in a glasshouse during summer under natural light with one unbranched shoot or one shoot with 3 to 4 branches and with or without fruit in quartz sand buffered and not buffered with 0.5% CaCO3 (w : v), respectively. Nutrient solutions supplied contained nitrate or ammonium as the sole nitrogen source. Compared with nutrient solutions containing nitrate (10 mM), solutions containing ammonium (10 mM) caused a decrease in net photosynthesis of eggplants during early stages of vegetative growth when grown in quartz sand not buffered with CaCO3. The decrease was not observed before leaves showed interveinal chlorosis. In contrast, net photosynthesis after bloom at first increased more rapidly in eggplants supplied with ammonium than with nitrate nitrogen. However, even in this case, net photosynthesis decreased four weeks later when ammonium nutrition was continued. The decrease was accompanied by epinasty and interveinal chlorosis on the lower leaves and later by severe wilting, leaf drop, stem lesions, and hampered growth of stems, roots, and fruits. These symptoms appeared later on plants not bearing fruits than on plants bearing fruits. If nutrient solutions containing increasing concentrations of ammonium (0.5–30 mM) were supplied after the time of first fruit ripening, shoot growth and set of later flowers and fruits were promoted. In contrast, vegetative growth and reproduction was only slightly affected by increasing the concentration of nitrate in the nutrient solutions. In quartz sand buffered with CaCO3 ammonium nutrition caused deleterious effects only under low light conditions (shade) and on young plants during rapid fruit growth. If eggplants were supplied with ammonium nitrogen before bloom, vegetative growth was promoted, and set of flowers and fruit occurred earlier than on plants supplied with nitrate. Furthermore, the number of flowers and fruit yield increased. These effects of ammonium nutrition were more pronounced when plants were grown with branched shoots than with unbranched shoots. The results indicate that vegetative and reproductive growth of eggplants may be manipulated without causing injury to the plants by supplying ammonium nitrogen as long as the age of the plants, carbohydrate reserves of the roots, quantity of ammonium nitrogen supplied, and pH of the growth medium are favourable. T W Rufty Section editor
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010281
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    Function and organization of Photosystem I polypeptides (1995)
    Springer
    Photosynthesis research 44 (1995), S. 23-40 
    Details
    ISSN: 1573-5079
    Keywords: chloroplasts ; cyanobacteria ; ferredoxin ; photosynthesis ; plastocyanin ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem I functions as a plastocyanin:ferredoxin oxidoreductase in the thylakoid membranes of chloroplasts and cyanobacteria. The PS I complex contains the photosynthetic pigments, the reaction center P700, and five electron transfer centers (A0, A1, FX, FA, and FB) that are bound to the PsaA, PsaB, and PsaC proteins. In addition, PS I complex contains at least eight other polypeptides that are accessory in their functions. Recent use of cyanobacterial molecular genetics has revealed functions of the accessory subunits of PS I. Site-directed mutagenesis is now being used to explore structure-function relations in PS I. The overall architecture of PSI complex has been revealed by X-ray crystallography, electron microscopy, and biochemical methods. The information obtained by different techniques can be used to propose a model for the organization of PS I. Spectroscopic and molecular genetic techniques have deciphered interaction of PS I proteins with the soluble electron transfer partners. This review focuses on the recent structural, biochemical and molecular genetic studies that decipher topology and functions of PS I proteins, and their interactions with soluble electron carriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018294
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  • 200
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    Isolation of membrane bound light-harvesting-complexes from the dinoflagellates Heterocapsa pygmaea and Prorocentrum minimum (1995)
    Springer
    Photosynthesis research 44 (1995), S. 127-138 
    Details
    ISSN: 1573-5079
    Keywords: diadinoxanthin ; dinoflagellate ; light-harvesting-complex ; peridinin ; photoacclimation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated Chl a-Chl c-carotenoid binding proteins from the dinoflagellates Prorocentrum minimum and Heterocapsa pygmaea grown under high (500 μmol m−2 s−1, HL) and low (35 μmol m−2 s−1, LL) light conditions. We compared various isolation procedures of membrane bound light harvesting complexes (LHCs) and assayed the functionality of the solubilized proteins by determining the energy transfer efficiency from the accessory pigments to Chl a by means of fluorescence excitation spectra. The identity of the newly isolated protein-complexes were confirmed by immunological cross-reactions with antibodies raised against the previously described membrane bound Chl a-c proteins (Boczar et al. (1980) FEBS Lett 120: 243–247). Spectroscopic analysis demonstrated the relatedness of these proteins with the recently described Chl-a-c 2-peridinin (ACP) binding protein (Hiller et al. (1993) Photochem Photobiol 57: 125–131; Iglesias Prieto et al. (1993) Phil Trans R Soc London B 338: 381–392). The water-soluble peridinin-Chl a binding-protein (PCP) was not detectable in P. minimum. Two functional forms of ACP with different pigmentation were isolated. A variant of ACP which was isolated from high-light grown cells, that specifically binds increased amounts of diadinoxanthin was compared to the previously described ACPs that bind proportionately more peridinin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018303
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