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  • photosynthesis  (95)
  • Springer  (95)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • 1995-1999  (43)
  • 1990-1994  (52)
  • 1935-1939
  • 1999  (43)
  • 1994  (52)
Collection
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  • Springer  (95)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (1)
Years
  • 1995-1999  (43)
  • 1990-1994  (52)
  • 1935-1939
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effect of nickel on certain physiological and biochemical behaviors of an acid tolerantChlorella vulgaris (1994)
    Springer
    BioMetals 7 (1994), S. 193-200 
    Details
    ISSN: 1572-8773
    Keywords: Chorella vulgaris ; acid tolerance ; ATPase ; nickel toxicity ; nutrient uptake ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract This study concerns the inhibitory effects of acid pH and nickel on growth, nutrient (NO3 - and NH4 +) uptake, carbon fixation, O2 evolution, electron transport chain and enzyme (nitrate reductase and ATPase) activities of acid tolerant and wild-type strains of Chlorella vulgaris. Though a general reduction in all these variables was noticed with decreasing pH, the tolerant strain was found to be metabolically more active than the wild-type. A reduced cation (NH4 +, Na+, K+ and Ca2+) uptake, coupled with a facilitated influx of anions (NH4 +, PO4 3- and HCO3 -), suggested the development of a positive membrane potential in acid tolerant Chlorella. Nevertheless, a tremendous increase in ATPase activity at decreasing pH revealed the involvement of superactive ATPase in exporting H+ ions and keeping the internal pH neutral. A difference in Na+ and K+ efflux of the two strains at decreasing pH suggests there is a difference in membrane permeability. The low toxicity of Ni in the acid tolerant strain may be due to the low Ni uptake brought about by a change in membrane potential as well as in permeability. Hence, the development of superactive ATPase and a change in both membrane potential and permeability not only offers protection against acidity, but also co-tolerance to metals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00140491
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  • 2
    Electronic Resource
    Electronic Resource
    Gas exchange characteristics of the tropical mangrove, Pelliciera rhizophoreae (1999)
    Springer
    Mangroves and salt marshes 3 (1999), S. 147-153 
    Details
    ISSN: 1572-977X
    Keywords: conductance ; gas exchange ; mangrove ; photorespiration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic characteristics were investigated in the geographically isolated and restricted mangrove species, P.rhizophoreae. Gas exchange measurements were made on two to seven years old hydroponically grown plants maintained in 10%, 50% and 100% seawater. CO2 exchange in the 50% and 100% seawater treatments was reduced by 10% and 26%, respectively, compared to the 10% seawater treatment. CO2 response curves indicated that carboxylation efficiency was greater in 10% than in 50% seawater, while stomatal limitation increased from 11% to 16% as salinity increased from 10% to 50% seawater. Carbon losses via photorespiration (31% and 41%) and CO2 compensation point (67 and 81 μ11−1) were greater in 50% than in the 10% seawater treatment. Maximal CO2 exchange occurred at 30 °C with no differences among the salinity treatments. The results indicate that P. rhizophoreae exhibits many gas exchange characteristics previously reported for other mangroves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009943408779
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  • 3
    Electronic Resource
    Electronic Resource
    Modification of carbonic anhydrase activity by antisense and over-expression constructs in transgenic tobacco (1994)
    Springer
    Plant molecular biology 25 (1994), S. 377-385 
    Details
    ISSN: 1573-5028
    Keywords: carbonic anhydrase ; antisense ; over-expression ; tobacco ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity and location of carbonic anhydrase has been modified by transformation of tobacco with antisense and over-expression constructs. Antisense expression resulted in the inhibition of up to 99% of carbonic anhydrase activity but had no significant impact on net CO2 assimilation. Stomatal conductance and susceptibility to water stress appeared to increase in response to the decline in carbonic anhydrase activity. An over-expression construct designed to increase cytosolic carbonic anhydrase abundance resulted in a significant increase in net activity, a small increase in stomatal conductance but little impact on CO2 assimilation. Chloroplastic carbonic anhydrase activity was enhanced by the expression of an additional construct which targeted the polypeptide to the organelle. The increase in chloroplastic carbonic anhydrase appeared to be accompanied by a concomitant increase in Rubisco activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043867
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  • 4
    Electronic Resource
    Electronic Resource
    Over-production of the D1 protein of photosystem II reaction centre in the cyanobacterium Synechococcus sp. PCC 7942 (1994)
    Springer
    Plant molecular biology 26 (1994), S. 709-721 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; photosynthesis ; protein turnover ; psbA ; tac promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unicellular cyanobacterium Synechococcus sp. PCC 7942 has three psbA genes encoding two different forms of the photosystem II reaction centre protein D1 (D1:1 and D1:2). The level of expression of these psbA genes and the synthesis of D1:1 and D1:2 are strongly regulated under varying light conditions. In order to better understand the regulatory mechanisms underlying these processes, we have constructed a strain of Synechococcus sp. PCC 7942 capable of over-producing psbA mRNA and D1 protein. In this study, we describe the over-expression of D1:1 using a tac-hybrid promoter in front of the psbAI gene in combination with lacI Q repressor system. Over-production of D1:1 was induced by growing cells for 12 h at 50 μmol photons m-2 s-1 in the presence of 40 or 80 μg/ml IPTG. The amount of psbAI mRNA and that of D1:1 protein in cells grown with IPTG was three times and two times higher, respectively. A higher concentration of IPTG (i.e., 150 μg/ml) did not further increase the production of the psbAI message or D1:1. The over-production of D1:1 caused a decrease in the level of D1:2 synthesised, resulting in most PSII reaction centres containing D1:1. However, the over-production of D1:1 had no effect on the pigment composition (chlorophyll a or phycocyanin/number of cells) or the light-saturated rate of photosynthesis. This and the fact that the total amounts of D1 and D2 proteins were not affected by IPTG suggest that the number of PSII centres within the membranes remained unchanged. From these results, we conclude that expression of psbAI can be regulated by using the tac promoter and lacI Q system. However, the accumulation of D1:1 protein into the membrane is regulated by the number of PSII centres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00013756
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  • 5
    Electronic Resource
    Electronic Resource
    Estimation of phytoplankton photosynthesis and nutrient limitation in the Eastern Scheldt estuary using variable fluorescence (1999)
    Springer
    Aquatic ecology 33 (1999), S. 101-104 
    Details
    ISSN: 1573-5125
    Keywords: chlorophyll fluorescence ; nutrient limitation ; phytoplankton ; photosynthesis ; quantum efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009900124650
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  • 6
    Electronic Resource
    Electronic Resource
    Fortnightly light and temperature variability in estuarine intertidal sediments and implications for microphytobenthos primary productivity (1999)
    Springer
    Aquatic ecology 33 (1999), S. 235-241 
    Details
    ISSN: 1573-5125
    Keywords: intertidal areas ; photosynthetically active radiation ; photosynthesis ; Tagus estuary ; tides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetically active radiation (PAR) and temperature were measured continuously at the surface of estuarine intertidal sediments in the Tagus estuary, Portugal, along two spring-neap tidal cycles. PAR and temperature were strongly conditioned by the periodic tidal inundation, with large and abrupt variations occurring during flooding and ebbing. PAR levels reaching the sediment surface decreased very rapidly to zero or very low values during most of the daytime immersion. Inundation during high tide had the general effect of attenuating the amplitude of daily temperature fluctuation, with the incoming water usually warmer than the sediment during the night or early morning and cooler during the day. The daily progression of tidal emersion resulted in a clear fortnightly variation in total daily PAR reaching the sediment surface, while both daily mean temperature and mean temperature of diurnal low tide periods failed to exhibit a well-defined fortnightly periodicity. The obtained results indicate that the estuarine intertidal environment is dominated, at sub-seasonal time scales, by fortnightly periodicity in irradiance and temperature conditions favourable for benthic photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009989229098
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  • 7
    Electronic Resource
    Electronic Resource
    Improvement of microalgal photosynthetic productivity by reducing the content of light harvesting pigment (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 195-201 
    Details
    ISSN: 1573-5176
    Keywords: dense algal suspension ; light-harvesting pigment ; photosynthesis ; productivity ; cyanobacterium ; Synechocystis PCC 6714
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microalgal productivity was examined using both a wild type and a phycocyanin-deficient mutant of Synechocystis PCC 6714 (PD-1). The culture was conducted at various light intensities under low and high cell densities in a continuous culture system. At low light intensity, photosynthetic productivity was almost the same for both low and high cell densities. However, at higher light intensities photosynthetic productivity was higher in mutant PD-1 than in the wild type. At 2000 μmol photon m−2 s−1 the productivity was 50% higher in mutant PD-1. This result is consistent with our first report (Nakajima & Ueda, 1997), which showed that photosynthetic productivity can be improved by reducing the light harvesting pigment content in high cell density cultures at high light intensities. It is concluded that the technology for reducing LHP content is a useful method for improving photosynthetic productivity in algal mass production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008015224029
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  • 8
    Electronic Resource
    Electronic Resource
    Iron deprivation in cyanobacteria (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 199-210 
    Details
    ISSN: 1573-5176
    Keywords: cyanobacteria ; iron deficiency ; photosynthesis ; siderophores ; flavodoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Iron is an essential component of electron transport in almost all living organisms. It is particularly important to phototrophs like cyanobacteria because 22–23 irons are required for a complete functional photosynthetic apparatus. Since the low solubility of Fe+++ above neutral pH in oxic ecosystems severely limits the biological availability of iron to aquatic microorganisms, cyanobacteria and other microbes have developed a number of responses to cope with iron deficiency. Cyanobacterial responses to iron stress include the synthesis of an efficient, siderophore-based system to scavenge iron and the substitution of ferredoxin with flavodoxin. An additional response in cyanobacteria involves the alteration of the light-harvesting apparatus that includes the appearance of a new, iron-stress-induced, photosystem II, chlorophyll-binding protein. Although cytochromec-553 has a potential non-iron-containing replacement in plastocyanin, a copper-containing protein, iron stress appears to favor the utilization of cytochromec-553 because siderophores also bind copper and form a complex that is excluded from the cell. This paper is intended primarily as a review of molecular and physiological responses of actively growing cyanobacterial cultures to conditions of iron stress, where iron is present but essentially insoluble, and to differentiate these responses from iron starvation, where the amount of iron in the system is not sufficient for cell growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186073
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  • 9
    Electronic Resource
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    Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 157-163 
    Details
    ISSN: 1573-5176
    Keywords: Euglena gracilis ; photosynthesis ; waste water ; pulp and paper industry ; ultraviolet-B radiation (280–320 nm) ; pentachlorophenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008032211771
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  • 10
    Electronic Resource
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    Use of chlorophyll fluorescence to estimate the effect of photoinhibition in outdoor cultures ofSpirulina platensis (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 31-34 
    Details
    ISSN: 1573-5176
    Keywords: fluorescence ; photoinhibition ; photosynthesis ; Spirulina ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll fluorescence measurements were used to evaluate the effect of temperature on photoinhibition inSpirulina platensis cultures grown in tubular reactors outdoors. Cultures grown at 35 °C during the day time showed a lower reduction in the Fv/Fm ratio as compared to cultures grown at 25 °C. It is demonstrated that the lower temperature photoinhibited cells can undergo a complete recovery once transferred to low light and higher temperature. This recovery does not take place when 100 µg ml-1 chloramphenicol is added to cells. The recovery is light dependent and cells incubated in the dark at low temperature do not show a recovery in the Fv/Fm ratio. The data presented strongly support the hypothesis that photoinhibition takes place in outdoorSpirulina cultures. At the same time it is demonstrated that fluorescence measurements can be used as a fast reliable indication for photoinhibition in outdoor algal cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185901
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  • 11
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    Use of macroalgae for marine biomass production and CO2 remediation: a review (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 45-60 
    Details
    ISSN: 1573-5176
    Keywords: biofilter ; biofuels ; CO2 ; macroalgae ; marine biomass ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Biomass production from macroalgae has been viewed as important mainly because of the need for pollution abatement. Environmental considerations will increasingly determine product and process acceptability and drive the next generation of economic opportunity. Some countries, including Japan, are actively promoting "green" technologies that will be in demand worldwide in the coming decades. Should an international agreement on CO2-reduction be ratified, its effective use for energy production would be of high priority. This report shows that macroalgae have great potential for biomass production and CO2 bioremediation. Macroalgae have high productivity, as great or greater than the most productive land plants, and do not compete with terrestrial crops for farm land. The review focuses on recent data on productivity, photosynthesis, nutrient dynamics, optimization and economics. Biomass from macroalgae promises to provide environmentally and economically feasible alternatives to fossil fuels. Nevertheless, the techniques and technologies for growing macroalgae on a large-scale and for converting feedstocks to energy carriers must be more fully developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185904
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  • 12
    Electronic Resource
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    Photosynthetic inorganic carbon utilization and growth of Porphyra linearis (Rhodophyta) (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 447-453 
    Details
    ISSN: 1573-5176
    Keywords: algal growth ; Porphyra ; inorganic carbon (Ci) ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic (oxygen evolution) and growth (biomass increase) responses to ambient pH and inorganic carbon (Ci) supply were determined for Porphyralinearis grown in 0.5 L glass cylinders in the laboratory, or in 40 L fibreglass outdoor tanks with running seawater. While net photosynthetic rates were uniform at pH 6.0–8.0, dropping only at pH 8.7, growth rates were significantly affected by pH levels other than that of seawater (c. pH 8.3). In glass cylinders, weekly growth rates averaged 76% at external pH 8.0, 13% at pH 8.7 and 26% at pH 7.0. Photosynthetic O2 evolution on a daily basis(i.e. total O2 evolved during day time less total O2 consumed during night time) was similar to the growth responses at all experimental pH levels, apparently due to high dark respiration rates measured at acidic pH. Weekly growth rates averaged 53% in algae grown in fibreglass tanks aerated with regular air (360 mg L-1 CO2) and 28% in algae grown in tanks aerated with CO2-enriched air (750 mg L-1 CO2). The pH of the seawater medium in which P. linear is was grown increased slightly during the day and only rarely reached 9.0. The pH at the boundary layer of algae submerged in seawater increased in response to light reaching, about pH 8.9 within minutes, or remained unchanged for algae submerged in a CO2-free artificial sea water medium. Photosynthesis of P. linearissaturated at Ci concentrations of seawater (K0.5560 μM at pH 8.2) and showed low photosynthetic affinity for CO2(K0.5 61 μM) at pH 6.0. It is therefore concluded that P. linearisuses primarily CO2 with HCO3 - being an alternative source of Ci for photosynthesis. Its fast growth could be related to the enzyme carbonic anhydrase whose activity was detected intra- and extracellularly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008122306268
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  • 13
    Electronic Resource
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    Effects of different levels of CO2 on photosynthesis and cell components of the red alga Porphyra leucosticta (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 455-461 
    Details
    ISSN: 1573-5176
    Keywords: CO2 ; inorganic carbon ; macroalgae ; photosynthesis ; PAM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis and cell composition of Porphyraleucosticta discs grown at low (〈 0.0001% in air), current (control) and high (1% CO2 in air)inorganic carbon (Ci) concentrations were analyzed. Carbohydrate content in discs grown at high Ci increased (15.1 mg g-1 FW) with respect to the control (6.4 mg g FW-1), whereas soluble protein content decreased to one-third (5.6 to2.1 mg g-1 FW). Carbohydrate content was unaffected and soluble protein slightly increased in discs grown at low Ci. As a consequence of these changes, a lower C/N molar ratio (8.6) was found in the discs grown at low compared to high Ci(12.4). Nitrate reductase activity increased at high Ci from 0.3 ± 0.2 to 1.7 ± 0.4 μmolNO2 - g-1 FW h-1indicating that reduction and assimilation of nitrate were uncoupled. The response of photosynthesis to increasing irradiance, estimated from O2evolution vs. irradiance curves, was affected by the treatments. Maximum quantum yield (Φ O2°) and effective quantum yield (Φ O2) at 150 μmol photon m-2s-1 decreased by 20% and 50%, respectively, at low Ci. These differences could be due to changes in photosynthetic electron flow between PSII and PSI. Treatments also produced changes in maximal (Fv/Fm) and effective (ΔF/Fm′)quantum yield for photosystem II charge separation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008194223558
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  • 14
    Electronic Resource
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    What kind of lamp for the cultivation of algae? (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 309-313 
    Details
    ISSN: 1573-5176
    Keywords: light source ; emission spectrum ; photosynthesis ; algae ; absorption ; efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for quantitative evaluation of light sources from the point of their suitability for algal cultivation is described. Two parameters are used for the evaluation: (1) amount of photons emitted in the spectral region absorbed by algae per consumed unit of electrical energy; (2) fraction of photons intercept by the algae that got effectively transformed into chemical energy. The value of parameter (2) depends on the emission spectrum of the light source, the absorption spectrum of the algae, quantum capacity of the algae and on conditions of cultivation. The method permits the assessment of the differences in algal productivity under light of various light sources with respect to other recent methods for comparison.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181944
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  • 15
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    A preliminary comparison of the mariculture potential of Porphyra purpurea and Porphyra umbilicalis (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 473-477 
    Details
    ISSN: 1573-5176
    Keywords: aquaculture ; light ; photosynthesis ; Porphyra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Due to their rapid growth and nutrient assimilation,Porphyra spp. are good candidates for bioremediation and polyculture. The production potential of two strains of P. purpurea and P. umbilicalis from north-east USA was evaluated by measuring rates of photosynthesis (as O2evolution) of material grown at 20 °C. Photosynthetic rates of P. umbilicalis were 80%higher than P. purpurea over the temperature range 5–20 °C, at both sub-saturating andsaturating irradiances (37 and 289 μmol photonm-2 s-1). Porphyra umbilicalis was more efficient at low irradiances (higher α) and had a higher Pmax (23.0 vs 15.6 μmolO2 g-1 DW min-1) than P.purpurea, suggesting that P. umbilicalis is a better choice for mass culture, where self-shading maybe severe.
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    URL: http://dx.doi.org/10.1023/A:1008102426752
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  • 16
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    Dried field populations of Nostoc flagelliforme (Cyanophyceae) require exogenous nutrients for their photosynthetic recovery (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 535-541 
    Details
    ISSN: 1573-5176
    Keywords: cyanobacterium ; Nostoc flagelliforme ; nutrients ; photosynthesis ; potassium ; re-hydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nutrients on the photosynthetic recovery of Nostoc flagelliforme during re-hydration were investigated in order to see if their addition was necessary. Net photosynthesis was negligible in distilled water without nutrient-enrichment. Addition of K+ resulted in significant enhancement of net photosynthesis, whereas other nutrients (Fe3+, Mg2+, Na+, NO3 -, PO4 3-, Cl-) and trace-metals (A5) showed little effect. The recovered net photosynthetic activity increased with the increased K+, and reached the maximum at concentrations above 230 μM. Desiccation and re-hydration did not affect the dependence of photosynthetic recovery on K+. It was concluded that dried field populations of N. flagelliforme require exogenous addition of potassium for photosynthetic recovery and that growth may be potassium-limited in nature.
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    URL: http://dx.doi.org/10.1023/A:1008146722229
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  • 17
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    Turbulence in mass algal cultures and the role of light/dark fluctuations (1994)
    Springer
    Journal of applied phycology 6 (1994), S. 331-335 
    Details
    ISSN: 1573-5176
    Keywords: turbulence ; photosynthesis ; Chlorella ; light/dark cycles ; mass transfer rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In mass algal cultures, some form of agitation is usually provided; among other effects, this moves the organisms though an optically dense profile and provides mixing. During this transport, medium frequency fluctuations in the light energy supply are perceived by the algae, which are of the order of 1 Hz and less. It has been suggested that turbulence with the resultant light/dark cycles of medium frequency enhances productivity. However, turbulence has two major influences in a well mixed system: it facilitates fluctuating light regimes and increases the transfer rates between the growth medium and the cultured organism. An estimation of productivity as oxygen liberation was measured under laminar and turbulent flow rates, and varying light/dark ratios. Increased turbulence, which increased exchange rates of nutrients and metabolites between the cells and their growth medium, together with increased light/dark frequencies, increased productivity and photosynthetic efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181947
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  • 18
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    Partial Pressure of Carbon Dioxide in Coral Reef Lagoon Waters: Comparative Study of Atolls and Barrier Reefs in the Indo-Pacific Oceans (1999)
    Springer
    Journal of oceanography 55 (1999), S. 731-745 
    Details
    ISSN: 1573-868X
    Keywords: Carbon dioxide ; coral reefs ; atoll ; lagoon ; photosynthesis ; calcification ; total alkalinity ; partial pressure ; topography ; residence time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Factors controlling the CO2 system parameters, including the partial pressure of CO2 (PCO2) in coral reef waters, were investigated in three mid-oceanic reefs of the Indo-Pacific region. Surface water PCO2 in the lagoons of Majuro Atoll and Palau barrier reef in the Pacific were 25 µatm and 48 µatm higher than those of the offshore waters, respectively, while South Male Atoll lagoon of the Maldives in the Indian Ocean exhibited relatively small difference in PCO2 compared to the offshore water. Observations from Majuro Atoll and Palau barrier reef are consistent with the view that calcium carbonate production predominates in coral reefs. On the other hand, results from South Male Atoll can be attributed to the thorough flushing of the lagoon, which is connected to the open ocean by numerous deep channels. The offshore-lagoon PCO2 difference depends on system-level net organic-to-inorganic carbon production ratio while reef topography, especially residence time of the lagoon, has a secondary effect on the magnitude of the offshore-lagoon difference. A potential for releasing CO2 might be more evident in an enclosed atoll where the reef water has a longer residence time. Oceanic atoll and barrier reef lagoons, which are in the terminal stage of evolutionary history of oceanic volcanic islands, have the potential to release CO2 to the atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007872314591
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  • 19
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    Auxiliary Photosynthetic Functions of Arabidopsis thaliana—Studies in vitro and in vivo (1999)
    Springer
    Bioscience reports 19 (1999), S. 499-509 
    Details
    ISSN: 1573-4935
    Keywords: Arabidopsis ; auxiliary enzymes ; light stress ; photosynthesis ; protein phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An improved cultivation system for Arabidopsis thaliana was developed, allowing advanced biochemical studies in vitro and in vivo of this important model plant. Highly functional Arabidopsis thylakoids were isolated and used to study both basic and regulatory photosynthetic functions with the aim to create a platform for the characterization of mutants deficient in auxiliary proteins. Light-induced proteolytic degradation of the D1 protein could be followed and shown to be a subsequent event to photoinactivation of electron transport. The phosphorylation and dephosphorylation of thylakoid proteins resembled that seen in spinach leaves although phospho-CP43 revealed an unusual regulatory behavior.
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    URL: http://dx.doi.org/10.1023/A:1020280710067
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    Genetic variation in pigeon pea (Cajanus cajan (L.) Mill sp.) in response to successive cycles of water stress (1994)
    Springer
    Plant and soil 158 (1994), S. 193-201 
    Details
    ISSN: 1573-5036
    Keywords: photosynthesis ; osmotic adjustment ; stomatal conductance ; relative water content ; water potential ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four pigeon pea [Cajanus cajan (L.) Mill sp.] cultivars were studied during two cycles of development of water stress and recovery. During these two cycles the genetic variation in vegetative development, leaf water potential, relative water content, photosynthesis, and stomatal conductance was followed. Plants were grown in a greenhouse and irrigated every seventh day. On two occasions (30 days and 80 days from sowing) water was withheld for 13 days in one group of plants and 16 days in another. Control plants were irrigated as usual. The four cultivars differed in their response to drought, with ICPL 215 being the most tolerant cultivar. In the plants exposed to the 13-day water stress, the first stress cycle resulted in preconditioning of plants such that higher values for carbon dioxide exchange rate and relative water content were observed in the second stress cycle. The longer stress period (16 days) resulted in some damage to the photosynthetic capacity and in a slow recovery rate in both cycles. During the second drought cycle the plants retained a water content above the critical value, possibly due to osmotic adjustment. It seems that water status parameters, especially relative water content, may serve as indicators of drought tolerance in pigeon pea varieties and may be useful in breeding programs for cultivation of pigeon pea under semiarid conditions.
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    URL: http://dx.doi.org/10.1007/BF00009494
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    Partitioning of P and the activity of root acid phosphatase in white clover (Trifolium repens L.) are modified by increased atmospheric CO2 and P fertilisation (1999)
    Springer
    Plant and soil 210 (1999), S. 159-166 
    Details
    ISSN: 1573-5036
    Keywords: elevated CO2 ; leaf transpiration ; nonstructural carbohydrate ; P nutrition ; photosynthesis ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growth response of white clover (Trifolium repens L.) to the expected increase in atmospheric partial pressure of CO2 (pCO2) may depend on P availability. A decrease in the rate of transpiration due to increased pCO2 may reduce the amount of P transported to the shoot, thereby causing a change in the partitioning of P between the root and shoot. To test these hypotheses, four concentrations of P in the nutrient solution, combined with two pCO2 treatments, were applied to nodulated white clover plants. Compared to ambient pCO2 (35 Pa), twice ambient pCO2 (70 Pa) reduced the rate of transpiration but did not impair the total P uptake per plant. However, at twice ambient pCO2 and a moderate to high supply of P, concentrations of structural P and soluble P (Pi) were lower in the leaves and higher in the roots. The activity of root acid phosphatase was lower at twice ambient pCO2 than at ambient pCO2; it depended on the Pi concentration in the roots. At the highest P concentration, twice ambient pCO2 stimulated photosynthesis and the growth rate of the plant without affecting the concentration of nonstructural carbohydrates in the leaves. However, at the lower P concentrations, plants at twice ambient pCO2 lost their stimulation of photosynthesis in the afternoon, they accumulated nonstructural carbohydrates in the leaves and their growth rate was not stimulated; indicating C-sink limitation of growth. P nutrition will be crucial to the growth of white clover under the expected future conditions of increased pCO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004625801141
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    Effects of phosphorus nutrition on tiller emergence in wheat (1999)
    Springer
    Plant and soil 209 (1999), S. 283-295 
    Details
    ISSN: 1573-5036
    Keywords: leaf emergence ; phosphorus ; photosynthesis ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency limits the yield of wheat, particularly by reducing the number of ears per unit of area because of a poor tiller emergence. The objectives of this work were to (i) determine whether tiller emergence under low phosphorus availability is a function of the availability of assimilates for growth or a direct result of low P availability, (ii) attempt to establish a quantitative relation between an index of the availability of P in the plant and the effects of P deficiency on tiller emergence, and (iii) to provide a better understanding of the mechanisms involved in tiller emergence in field-grown wheat. Wheat (Triticum aestivum L., cv. INTA Oasis), was grown in the field under drip irrigation on a typic Argiudol, low in P (5.5 μg P g-1 soil Bray & Kurtz I) in Balcarce, Argentina. Treatments consisted of the combination of three levels of P fertilization 0, 60 and 200 kg P2O5 ha-1, and two levels of assimilate availability, a control (non-shaded) and 65% of reduction in incident irradiance from seedling emergence until the end of tillering (shaded). Phosphorus treatments significantly modified the pattern of growth and development of the plants. Shading reduced the growth and concentration of water-soluble carbohydrates in leaves and stems. Leaf photosynthetic rate at saturating irradiance was reduced by P deficiency, but was not affected by shading. At shoot P concentrations less than 4.2 g P kg-1 the heterogeneity in the plant population increased with respect to the number of plants bearing a certain tiller. At a shoot P concentration of 1.7 g P kg-1 tillering ceased completely. Phosphorus deficiency directly altered the normal pattern of tiller emergence by slowing the emergence of leaves on the main stem (i.e. increasing the phyllochron), and by reducing the maximum rate of tiller emergence for each tiller.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004690404870
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    Model studies of chlorophyll fluorescence reabsorption at chloroplast level under different exciting conditions (1994)
    Springer
    Photosynthesis research 40 (1994), S. 67-74 
    Details
    ISSN: 1573-5079
    Keywords: light conditions ; theoretical model ; barley leaf ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A theoretical model is presented describing the distortion of chlorophyll fluorescence spectra of a chloroplast or a group of chloroplasts by the effect of fluorescence reabsorption. Model calculations using the experimental data show that the primary reabsorption effect occurs already within one chloroplast and the spectral distortion depends significantly on the excitation regime of the chloroplast. A theoretical dependence of the distortion function, defined as a change in the F(685)/F(735) fluorescence band ratio, on the mean chlorophyll concentration in a chloroplast is predicted for different light excitation regimes. The distortion of measured chlorophyll fluorescence spectra at 77 K of chloroplast suspension adsorbed on filter papers of two strongly different diffusive reflectivities and at different mean chlorophyll concentrations are discussed with the help of the presented theory.
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    URL: http://dx.doi.org/10.1007/BF00019046
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  • 24
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    UV-B damage and protection at the molecular level in plants (1994)
    Springer
    Photosynthesis research 39 (1994), S. 475-489 
    Details
    ISSN: 1573-5079
    Keywords: DNA repair ; flavonoids ; gene expression ; oxidative stress ; photosynthesis ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Influx of solar UV-B radiation (280–320 nm) will probably increase in the future due to depletion of stratospheric ozone. In plants, there are several targets for the deleterious UV-B radiation, especially the chloroplast. This review summarizes the early effects and responses of low doses of UV-B at the molecular level. The DNA molecules of the plant cells are damaged by UV due to the formation of different photoproducts, such as pyrimidine dimers, which in turn can be combatted by specialized photoreactivating enzyme systems. In the chloroplast, the integrity of the thylakoid membrane seems to be much more sensitive than the activities of the photosynthetic components bound within. However, the decrease of mRNA transcripts for the photosynthetic complexes and other chloroplast proteins are among very early events of UV-B damage, as well as protein synthesis. Other genes, encoding defence-related enzymes, e.g., of the flavonoid biosynthetic pathway, are rapidly up-regulated after commencement of UV-B exposure. Some of the cis-acting nucleotide elements and trans-acting protein factors needed to regulate the UV-induced expression of the parsley chalcone synthase gene are known.
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    URL: http://dx.doi.org/10.1007/BF00014600
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    Photosynthetic electrogenic events in native membranes ofChloroflexus aurantiacus. Flash-induced charge displacements within the reaction center-cytochromec 554 complex (1994)
    Springer
    Photosynthesis research 41 (1994), S. 135-143 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; electrometry ; membrane potential ; electron transfer ; charge displacement ; electrostatic ; Chloroflexus aurantiacus ; Rhodopseudomonas viridis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The thermophilic phototrophChloroflexus aurantiacus possesses a photosynthetic reaction center (RC) containing a pair of menaquinones as primary (QA) and secondary (QB) electron acceptors and a bacteriochlorophyll dimer (P) as a primary donor. A tetraheme cytochromec 554 with two high(H)- and two low(L)-potential hemes operates as an immediate electron donor for P. The following equilibrium Em,7 values were determined by ESR for the hemes in whole membrane preparations: 280 mV (H1), 150 mV (H2), 95 mV (L1) and 0 mV (L2) (Van Vliet et al. (1991) Eur. J. Biochem. 199: 317–323). Partial electrogenic reactions induced by a laser flash inChl. aurantiacus chromatophores adsorbed to a phospholipid-impregnated collodion film were studied electrometrically at pH 8.3. The photoelectric response included a fast phase of ΔΨ generation (τ 〈 10 ns, phase A). It was ascribed to the charge separation between P+ and QA − as its amplitude decreased both at high and low Eh values (Em,high=360±10 mV, estimated Em,low∼\s-160 mV) in good agreement with Em values for P/P+ and QA/QA − redox couples. A slower kinetic component appeared upon reduction of the cytochromec 554 hemes (phase C). With H1 reduced before the flash the amplitude of phase C was equal to 15–20% of that of phase A and its rise time was 1.2–1.3 μs: we attribute this phase to the electrogenic electron transfer from H1 to P+. Pre-reduction of H2 decreased the τ value to about 700–800 ns and increased the amplitude of phase C to 30–35% of that of phase A. Pre-reduction of L1 further accelerated phase C (up to τ of 500 ns) and induced a reverse electrogenic phase with τ of 12 μs and amplitude equal to 10% of phase A. Upon pre-reduction of L2 the rise time of phase C was decreased to about 300 ns and its amplitude decreased by 30%. The acceleration in the onset of phase C is explained by the acceleration of the rate-limiting H1 ⇒ P electrogenic reaction after reduction of the other hemes due to their electrostatic influence; a P-H1-(L1-L2)-H2 alignment of redox centers with an approximately rhombic arrangement of the cytochromec 554 hemes is proposed. The observed reverse phase is ascribed to the post-flash charge redistribution between the hemes. Redox titration of the amplitude of phase C yielded the Em,8.3 values of H1, H2 and L2 hemes: 340±10 mV for H1, 160±20 mV for H2 and −40±40 mV for L2.
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    URL: http://dx.doi.org/10.1007/BF02184153
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    Pigment interactions in chlorosomes of various green bacteria (1994)
    Springer
    Photosynthesis research 41 (1994), S. 175-180 
    Details
    ISSN: 1573-5079
    Keywords: Chlorobium ; Chloroflexus ; chlorophyll ; light-harvesting ; photosynthesis ; resonance Raman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Resonance Raman experiments were performed on different green bacteria. With blue excitation, i.e. under Soret resonance or preresonance conditions, resonance Raman contributions were essentially arising from the chlorosome pigments. By comparing these spectra and those of isolated chlorosomes, it is possible to evaluate how the latter retain their native structure during the isolation procedures. The structure of bacteriochlorophyll oligomers in chlorosomes was interspecifically compared, in bacteriochlorophyllc- and bacteriochlorophylle- synthesising bacteria. It appears that interactions assumed by the 9-keto carbonyl group are identical inChlorobium limicola, Chlorobium tepidum, andChlorobium phaeobacteroides. In the latter strain, the 3-formyl carbonyl group of bacteriochlorophylle is kept free from intermolecular interactions. By contrast, resonance Raman spectra unambiguously indicate that the structure of bacteriochlorophyll oligomers is slightly different in chlorosomes fromChloroflexus auranticus, either isolated or in the whole bacteria.
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    URL: http://dx.doi.org/10.1007/BF02184158
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    The formation and characterization of the in vitro polymeric aggregates of bacteriochlorophyllc homologs fromChlorobium limicola in aqueous suspension in the presence of monogalactosyl diglyceride (1994)
    Springer
    Photosynthesis research 41 (1994), S. 235-243 
    Details
    ISSN: 1573-5079
    Keywords: bacteriochlorophyll ; chlorosomeChlorobium limicola ; green bacteria ; photosynthesis ; monogalactosyl diglyceride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Artificial aggregates of bacteriochlorophyllc (BChlc) were formed in an aqueous medium in the presence of a lipid, monogalactosyl diglyceride (MGDG), and the optical properties of those aggregates were studied by absorption and circular dichroism (CD) mainly. Four BChlc homologs, ([E,E]BChlc F, [P,E]BChlc F, [E,M]BChlc F and [I,E]BChlc F), were isolated from the green photosynthetic bacteriumChlorobium limicola strain 6230. Above 0.0004%, MGDG induced a red-shift of the absorption maxima of BChlc aggregates. At 0.003% MGDG BChlc aggregates showed absorption maxima in the range of 724 to 745 (±3) nm with a shift of 12 to 24 (±3) nm depending on the homolog species. Four kinds of BChlc-MGDG aggregates showed characteristic CD spectra. [E,M]BChlc F gave rise to a CD spectrum similar to that of chlorosomes, while the other three gave spectra of opposite sign. These aggregates are sensitive to 1-hexanol treatment; in a saturating amount (0.85%) of 1-hexanol, all the homologs gave a monomer-like absorption spectrum peaking at 670nm. At an intermediate concentration (0.5%), [E,M]BChlc F showed an enhanced CD intensity, as observed in native chlorosomes. Resonance Raman spectra of the monomer-like BChlc samples indicated that the keto vibrational band at ca. 1640 cm−1 was considerably weakened by the 0.85% 1-hexanol treatment, however the 1680 cm−1 band characteristic of a free keto group did not appear. These results indicate that the artificial aggregates formed by purified BChlc homologs and MGDG are good models for studying chlorosomes structure.
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    URL: http://dx.doi.org/10.1007/BF02184164
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    Sensitivity of the relative Fpl level of chlorophyll fluorescence induction in leaves to the heat stress (1994)
    Springer
    Photosynthesis research 39 (1994), S. 201-204 
    Details
    ISSN: 1573-5079
    Keywords: automatic determination ; fluorescence parameters ; fluorometer ; induction curve ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The (Fpl-Fo)/Fv value of the fluorescence induction curve is shown to be a more suitable parameter to detect a wider range of heat stress damage to thylakoid membranes as compared to quantities t 1/2 (time of fluorescence rise from Fo to (Fo+Fm)/2 level) and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaacq% aHepaDaaaaaa!39D5!\[\overline \tau \] (the fluorescence induction time defined as the area above the induction curve normalized to Fv=1). A method for exact and automatic Fpl determination is presented. A break point in the quality and behaviour of the fluorescence induction curve of barley leaves incubated at 49°C was reached at the moment (about 240 s) when the transformation of PS II active (QB-reducing) to PS II inactive (QB-non-reducing) centres was completed. The meaning of the standard Fv and Fv/Fm parameter was then changed. The method of Fpl determination described here may help to increase the analytical value of the standard chlorophyll fluorometers.
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    URL: http://dx.doi.org/10.1007/BF00029387
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    The role of iron in phytoplankton photosynthesis, and the potential for iron-limitation of primary productivity in the sea (1994)
    Springer
    Photosynthesis research 39 (1994), S. 275-301 
    Details
    ISSN: 1573-5079
    Keywords: chlorosis ; diagnostic ; flavodoxin ; iron-limitation ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Iron supply has been suggested to influence phytoplankton biomass, growth rate and species composition, as well as primary productivity in both high and low NO3 − surface waters. Recent investigations in the equatorial Pacific suggest that no single factor regulates primary productivity. Rather, an interplay of bottom-up (i.e., ecophysiological) and top-down (i.e., ecological) factors appear to control species composition and growth rates. One goal of biological oceanography is to isolate the effects of single factors from this multiplicity of interactions, and to identify the factors with a disproportionate impact. Unfortunately, our tools, with several notable exceptions, have been largely inadequate to the task. In particular, the standard technique of nutrient addition bioassays cannot be undertaken without introducing artifacts. These so-called ‘bottle effects’ include reducing turbulence, isolating the enclosed sample from nutrient resupply and grazing, trapping the isolated sample at a fixed position within the water column and thus removing it from vertical movement through a light gradient, and exposing the sample to potentially stimulatory or inhibitory substances on the enclosure walls. The problem faced by all users of enrichment experiments is to separate the effects of controlled nutrient additions from uncontrolled changes in other environmental and ecological factors. To overcome these limitations, oceanographers have sought physiological or molecular indices to diagnose nutrient limitation in natural samples. These indices are often based on reductions in the abundance of photosynthetic and other catalysts, or on changes in the efficiency of these catalysts. Reductions in photosynthetic efficiency often accompany nutrient limitation either because of accumulation of damage, or impairment of the ability to synthesize fully functional macromolecular assemblages. Many catalysts involved in electron transfer and reductive biosyntheses contain iron, and the abundances of most of these catalysts decline under iron-limited conditions. Reductions of ferredoxin or cytochrome f content, nitrate assimilation rates, and dinitrogen fixation rates are amongst the diagnostics that have been used to infer iron limitation in some marine systems. An alternative approach to diagnosing iron-limitation uses molecules whose abundance increases in response to iron-limitation. These include cell surface iron-transport proteins, and the electron transfer protein flavodoxin which replaces the Fe-S protein ferredoxin in many Fe-deficient algae and cyanobacteria.
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    URL: http://dx.doi.org/10.1007/BF00014588
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    Molecular topology of the Photosystem II chlorophyll a binding protein, CP 43: Topology of a thylakoid membrane protein (1994)
    Springer
    Photosynthesis research 40 (1994), S. 11-19 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; membrane protein ; protein structure ; light harvesting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used antibodies generated against synthetic peptides to determine the topology of the 43 kD chlorophyll a binding protein (CP 43) of Photosystem II. Based on the pattern of proteolytic fragments detected (on western blots) by peptide specific antibodies, a six transmembrane span topological model, with the amino and carboxyl termini located on the stromal membrane surface, is predicted. This structure is similar to that predicted for CP 47, a PS II chlorophyll a binding protein (Bricker T (1990) Photosynth Res 24: 1–13). The model is discussed in reference to the possible location of chlorophyll binding sites.
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    Rubisco activase transcript (rca) abundance increases when the marine unicellular green alga Chlorococcum littorale is grown under high-CO2 stress (1999)
    Springer
    Plant molecular biology 41 (1999), S. 627-635 
    Details
    ISSN: 1573-5028
    Keywords: green algae ; high-CO2 stress ; photosynthesis ; regulation ; Rubisco activase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract cDNA and the corresponding genomic DNA region encoding Rubisco activase were isolated from the unicellular green alga Chlorococcum littorale. The deduced amino acid sequence encoded by the cDNA was 403 amino acids long and exhibited important homology with those of other known Rubisco activases. Its N-terminal sequence was similar to the chloroplastic transit peptides in Chlamydomonas reinhardtii. The mature protein had a predicted molecular mass of 42 kDa. Five introns were located inside the genomic gene encoding Rubisco activase (rca). Genomic Southern blots indicated that two copies of the rca gene were present in the genome of C. littorale. The level of rca messenger RNA increased when cells of C. littorale were subjected to high-CO2 stress (i.e. grown under at least 20% CO2). Hsp70 heat-shock protein was also induced under high-CO2 conditions and, as expected, was also induced at 35 °C. The rca gene, in contrast, was not induced at 35 °C, indicating that this gene was induced in response to the high CO2 concentration and not to general stress. A search of the promoter-binding proteins by a gel retardation assay showed that, under the high-CO2 conditions, a protein(s) which was probably an activator of the rca transcription was synthesized.
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    URL: http://dx.doi.org/10.1023/A:1006371905597
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    The Wageningen Rhizolab — a facility to study soil-root-shoot-atmosphere interactions in crops (1994)
    Springer
    Plant and soil 161 (1994), S. 275-287 
    Details
    ISSN: 1573-5036
    Keywords: crop growth ; gas exchange ; minirhizotrons ; nutrients ; photosynthesis ; respiration ; rhizotron ; root observation ; root growth ; water balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A research facility is described for the integrated study of soil-root-shoot-atmosphere relationships in crops. The Wageningen Rhizolab has been in use since 1990, and consists of two rows, each with eight below-ground compartments aligned along a corridor. A rain shelter automatically covers the experimental area at the start of rainfall. Compartments are 125 cm × 125 cm and 200 cm deep. Each compartment has a separate drip irrigation system. Crop canopy photosynthesis, respiration, and transpiration can be measured simultaneously and continuously on four out of eight compartments at a time. Each compartment can be filled with a selected soil material (repacked soil) and is accessible from the corridor over its full depth. Multiple sensors for measuring soil moisture status, electrical conductivity, temperature, soil respiration, trace gases and oxygen are installed in spatial patterns in accordance with the requirements of the experiments. Sensors are connected to control and data-acquisition devices. Likewise, provisions have been made to sample manually the soil solution and soil atmosphere. Root observation tubes (minirhizotrons) are installed horizontally at depth intervals ranging from 5 cm (upper soil layers) to 25 cm (below 1 m). The facility is at present in use to study growth and development of vegetation (crops) in relation to drought, nutrient status, soil-borne diseases, and underground root competition. One important application is the study of elevated CO2 concentration and climate change and the way they affect crops and their carbon economy. Growth and development of field grown vegetables and winter cover crops are also evaluated. The common aspect of those studies is to gain a better understanding of crop growth under varying environmental conditions, and to collect datasets that may help to improve mechanistic crop growth simulation models that can address suboptimal growth conditions.
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    URL: http://dx.doi.org/10.1007/BF00046399
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    Phycoerythrins of the oxyphotobacterium Prochlorococcus marinus are associated to the thylakoid membrane and are encoded by a single large gene cluster (1999)
    Springer
    Plant molecular biology 40 (1999), S. 507-521 
    Details
    ISSN: 1573-5028
    Keywords: cyanobacteria ; immunogold labelling ; light-harvesting complexes ; photosynthesis ; phycobilins ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An intrinsic divinyl-chlorophyll a/b antenna and a particular form of phycobiliprotein, phycoerythrin (PE) III, coexist in the marine oxyphotobacterium Prochlorococcus marinus CCMP 1375. The genomic region including the cpeB/A operon of P. marinus was analysed. It encompasses 10 153 nucleotides that encode three structural phycobiliproteins and at least three (possibly five) different polypeptides analogous to cyanobacterial or red algal proteins involved either in the linkage of subunits or the synthesis and attachment of chromophoric groups. This gene cluster is part of the chromosome and is located within a distance of less than 110 kb from a previously characterized region containing the genes aspA-psbA-aroC. Whereas the Prochlorococcus phycobiliproteins are characterized by distinct deletions and amino acid replacements with regard to analogous proteins from other organisms, the gene arrangement resembles the organization of phycobiliprotein genes in some other cyanobacteria, in particular marine Synechococcus strains. The expression of two of the Prochlorococcus polypeptides as recombinant proteins in Escherichia coli allowed the production of individual homologous antisera to the Prochlorococcus α and β PE subunits. Experiments using these sera show that the Prochlorococcus PEs are specifically associated to the thylakoid membrane and that the protein level does not significantly vary as a function of light irradiance or growth phase.
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    URL: http://dx.doi.org/10.1023/A:1006252013008
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    Effects of nitrogen supply on the acclimation of photosynthesis to elevated CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 389-400 
    Details
    ISSN: 1573-5079
    Keywords: elevated CO2 ; nitrogen supply ; photosynthesis ; acclimation ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A common observation in plants grown in elevated CO2 concentration is that the rate of photosynthesis is lower than expected from the dependence of photosynthesis upon CO2 concentration in single leaves of plants grown at present CO2 concentration. Furthermore, it has been suggested that this apparent down regulation of photosynthesis may be larger in leaves of plants at low nitrogen supply than at higher nitrogen supply. However, the available data are rather limited and contradictory. In this paper, particular attention is drawn to the way in which whole plant growth response to N supply constitutes a variable sink strength for carbohydrate usage and how this may affect photosynthesis. The need for further studies of the acclimation of photosynthesis at elevated CO2 in leaves of plants whose N supply has resulted in well-defined growth rate and sink activity is emphasised, and brief consideration is made of how this might be achieved.
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    URL: http://dx.doi.org/10.1007/BF00014593
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    The influence of ammonia on the growth and photosynthesis of Ruppia drepanensis Tineo from Doñana National Park (SW Spain) (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 219-231 
    Details
    ISSN: 1573-5117
    Keywords: Ruppia drepanensis ; ammonia toxicity ; temperature effects ; photosynthesis ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in Southern Spain were grown at 20 and 30 °C, at three different nitrogen levels. These levels were obtained by the addition of a slow release fertilizer (23% NH4NO3 by weight) to a sediment mixture of sand and clay (3:1). Several morphometric parameters were recorded during the first five weeks of the experiment, and photosynthesis and respiration were measured after 7 weeks of growth. Results showed a significant reduction of growth and development with increasing nitrogen and temperature levels. Dark respiration increased strongly at high nitrogen levels. At the same time, net photosynthesis at 250 and 500 µE m-2 s-1, Pm, Km and LCP were not affected by either factor. We attribute these phenomena to ammonia toxicity, since relatively high total ammonia (NH3 + NHf4 p+) levels were found in the interstitial water.
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    Environmental control of phytoplankton productivity in turbulent turbid systems (1994)
    Springer
    Hydrobiologia 289 (1994), S. 65-72 
    Details
    ISSN: 1573-5117
    Keywords: photosynthesis ; selective environments ; resuspension ; disturbance ; rivers ; shallow lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Factors affecting phytoplankton productivity are analysed in turbid systems, such as shallow lakes and rivers. When resuspension from the sediment or loading from the catchment significantly increases inorganic (non-algal) turbidity and hence light attenuation potentials for high production are not realised. Energy available for phytoplankton growth is strongly regulated by underwater light availability which depends on the critical mixing depth, fluctuating light intensities and algal circulation patterns. Higher production rates in shallow waters are often compensated by greater algal respiration due to higher water temperatures when compared to deeper lakes. Total daily integral production of turbulent, turbid environments can be predicted from a combination of easily measured variables such as maximum photosynthetic rates, algal biomass, surface irradiance and some measure of underwater light attenuation.
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    URL: http://dx.doi.org/10.1007/BF00007409
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    Forty years of microbial photosynthesis research: Where it came from and what it led to (1999)
    Springer
    Photosynthesis research 62 (1999), S. 1-29 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast ; chlorosome ; chromatophore ; granules ; inositol ; Neurospora ; path of carbon ; photosynthesis ; polythdroxyalkanoate (PHA) ; prokaryote cellular inclusions ; protozoan biochemistry ; ribulose 1 ; 5-bis-phosphate ; Tetrahymena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract What follows is a very personal account of my professional life and the early years that preceded it. I have described the social and economic conditions in America and how the nineteen twenties and thirties nurtured our scientific future. The description of the early part of post-World War II research covers my experience in the areas of nutritional biochemistry, biochemical genetics and proceeds to photosynthesis. The latter era lasted around 35 years. For me the most memorable research accomplishments in which I was a participant during this period was the first demonstration of the primary carboxylation enzyme in an in vitro system in algal and higher plants as well to show that it was structurally associated with the chloroplast.Our group while at Oak Ridge and the University of Massachusetts assembled data that described the complete macromolecular assembly of the photosynthetic apparatus of the unusual photosynthetic green bacterium Chloroflexus aurantiacus and created a model of that system which differed greatly from the chomatophore system for the purple bacteria. For the last decade, my scientific journey, with numerous new colleagues has turned to the exciting area of biomaterials.We characterized and modeled the completely new bacterial intracellular inclusions responsible for the synthesis and degredation of biosynthetic, biodegradable and biocompatible bacterial polyesters in the cytoplasm of Pseudomonads.
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    Minimal requirements for in vitro reconstitution of the structural subunit of light-harvesting complexes of photosynthetic bacteria (1999)
    Springer
    Photosynthesis research 62 (1999), S. 85-98 
    Details
    ISSN: 1573-5079
    Keywords: (bacterio)chlorophyll ; energy transfer ; light harvesting ; membrane proteins ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Unlike the α and β polypeptides of the core light-harvesting complex (LH1) of Rhodobacter (Rb.) sphaeroides, the α and β polypeptides of the peripheral light-harvesting complex (LH2) of this organism will not form a subunit complex by in vitro reconstitution with bacteriochlorophyll. Guided by prior experiments with the LH1 β polypeptides of Rb. sphaeroides and Rhodospirillum rubrum, which defined a set of interactions required to stabilize the subunit complex, a series of mutations to the Rb. sphaeroides LH2 β polypeptide was prepared and studied to determine the minimal changes necessary to enable it to form a subunit-type complex. Three mutants were prepared: Arg at position −10 was changed to Asn (numbering is from the conserved His residue which is known to be coordinated to bacteriochlorophyll); Arg at position −10 and Thr at position +7 were changed to Asn and Arg, respectively; and Arg at position −10 was changed to Trp and the C-terminus from +4 to +10 was replaced with the amino acids found at the corresponding positions in the LH1 β polypeptide of Rb. sphaeroides. Only this last multiple mutant polypeptide formed subunit-type complexes in vitro. Thus, the importance of the C-terminal region, which encompasses conserved residues at positions +4, +6 and +7, is confirmed. Two mutants of the LH1 β polypeptide of Rb. sphaeroides were also constructed to further evaluate the interactions stabilizing the subunit complex and those necessary for oligomerization of subunits to form LH1 complexes. In one of these mutants, Trp at position −10 was changed to Arg, as found in LH2 at this position, and in the other His at position −18 was changed to Val. The results from these mutants allow us to conclude that the residue at the −10 position is unimportant in subunit formation or oligomerization, while the strictly conserved His at −18 is not required for subunit formation but is very important in oligomerization of subunits to form LH1.
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    URL: http://dx.doi.org/10.1023/A:1006337827672
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    Effects of homobrassinolide application on plant metabolism and grain yield under irrigated and moisture-stress conditions of two wheat varieties (1994)
    Springer
    Plant growth regulation 14 (1994), S. 173-181 
    Details
    ISSN: 1573-5087
    Keywords: homobrassinolide ; irrigated ; membrane stability ; moisture-stress ; nitrate reductase activity ; photosynthesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Homobrassinolide (BR) was applied either as a seed treatment or foliar spray to two contrasting wheat varieties, viz. C306 (drought tolerant) and HD2329 (drought susceptible), to examine its effects on plant metabolism and grain yield under irrigated and moisture-stress/rainfed conditions. BR application resulted in increased relative water content, nitrate reductase activity, chlorophyll content and photosynthesis under both conditions. BR application also improved membrane stability (lower injury). These beneficial effects resulted in higher leaf area, biomass production, grain yield and yield related parameters in the treated plants. All the treatments were significantly better than the untreated control. Generally, 0.05 ppm either as a seed treatment or foliar spray was more effective than the 0.01 ppm treatment. The drought-tolerant genotype C306 showed more response to BR application under moisture-stress/rainfed condition than HD 2329. Increased water uptake, membrane stability and higher carbon dioxide and nitrogen assimilation rates under stress seemed to be related to homobrassinolide-induced drought tolerance.
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    URL: http://dx.doi.org/10.1007/BF00025220
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    Development and ecological importance of phytoplankton in a large lowland river (River Meuse, Belgium) (1994)
    Springer
    Hydrobiologia 289 (1994), S. 139-155 
    Details
    ISSN: 1573-5117
    Keywords: potamoplankton ; regulated river ; transport of carbon and nutrients ; photosynthesis ; respiration ; dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ecological importance of the River Meuse phytoplankton with regard to carbon and nutrient transport has been examined in two reaches of the Belgian course of the river. Field measurements of total particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate phosphorus (PP) show that the large autochtonous production of organic matter strongly affects the carbon and nutrient budget of the aquatic system. During the growing season, phytoplankton accounts for nearly 60% of the POC and dominates the PON. Calculations of the carbon and oxygen budget in the upper reach of the Belgian Meuse demonstrates that the ecosystem is autotrophic, i.e. that autochtonous FPOM (fine particulate organic matter) production is the major carbon input. This suggests that in large lowland rivers, primary production (P) may exceed community respiration (R), i.e. P:R〉1, whereas they are assumed to be heterotrophic (P:R〈1) in the River Continuum concept. The question of maintenance of phytoplankton in turbid mixed water columns is also addressed, and the case of the River Meuse is treated on the basis of studies of photosynthesis and respiration (ETS measurements). The results suggest that the potamoplankton may show some low-light acclimation, through an increase of chlorophyll a relative to biomass, when it comes to deep downstream reaches, and that algal respiration rate may be reduced. A simulation of the longitudinal development of the algal biomass shows the different phases of algal growth and decline along the river and brings support to the ‘importation hypothesis’ for explaining maintenance of potamoplankton in the downstream reaches.
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    A theoretical analysis and field evaluation of a light and temperature model of production by Ecklonia cava (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 361-373 
    Details
    ISSN: 1573-5117
    Keywords: production ; mathematical model ; Ecklonia cava ; light ; temperature ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dependence of photosynthesis on light and temperature is modelled through analysis of transition probabilities of photosystems. In the model, two transition probabilities are functions of light, and one transition probability is a function of temperature. The estimated light-saturated photosynthesis of Ecklonia cava blades at 20 °C was 0.037 mg C cm−2 h−1. The value of the activation energy, the standard enthalpy and the standard entropy were estimated to be 56.5 kJ mol−1, 204 kJ mol−1 and 678 J mol−1 K−1, respectively. A production model (an integral photosynthesis model) for an E. cava stand was developed using the photosynthesis model. Production calculated by the model agreed well with observed data during the growing period of an E. cava stand at a field observation site on the west side of Miura Peninsula, Japan. Results of the analysis of the effects of irradiance and temperature on the production of the E. cava community by the model are: 1. Production decreased with irradiance decrease. The estimated compensation irradiance was 26.5 μmol photons m−2 s−1 when the biomass was 3 kg wet mass m−2 (blade:stipe ratio = 2 kg m−2:1 kg m−2) and the temperature was 20 °C. 2. The optimum temperature decreased when irradiance decreased and when biomass increased. The highest estimated value for the optimum temperature was 24.0 °C. The estimated optimum temperature was 18.2 °C when the biomass was 12 kg wet mass m−2 and the photon irradiance was 200 μmol photons m−2 s−1. 3. The amount of biomass that resulted in the maximum production was influenced by irradiance and temperature. At 400 μmol photons m−2 s−1 and 20 °C, the estimated value of the biomass (blade:stipe = 2:1) giving the maximum pr oduction was about 5.3 kg wet mass m−2. However, at 100 μmol photons m−2 s−1 and 24 °C, the estimated value was about 3.0 kg wet mass m−2. The estimated values of the maximum production under the two conditions were 1.05 and 0.30 g C m−2 h−1, respectively.
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    URL: http://dx.doi.org/10.1023/A:1017086012839
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    An active Mehler-peroxidase reaction sequence can prevent cyclic PS I electron transport in the presence of dioxygen in intact spinach chloroplasts (1994)
    Springer
    Photosynthesis research 41 (1994), S. 429-437 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; ascorbate peroxidase ; Mehler reaction ; cyclic PS I ; chlorophyll fluorescence ; 9-aminoacridine fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of 9-aminoacridine (9-AA) fluorescence quenching, O2-uptake and chlorophyll fluorescence of intact spinach chloroplasts were carried out to assess the relationship between the transthylakoidal ΔpH and linear electron flux passing through Photosystem II. Three different types of O2-dependent electron flow were investigated: (1) Catalysed by methyl viologen; (2) in the absence of a catalyst and presence of an active ascorbate peroxidase (Mehler-peroxidase reaction); (3) in the absence of a catalyst and with the ascorbate peroxidase being inhibited by KCN (Mehler reaction). The aim of this study was to assess the relative contribution of ΔpH-formation which is not associated with electron flow through Photosystem II and, which should reflect Photosystem I cyclic flow under the different conditions. The relationship between the extent of 9-AA fluorescence quenching and O2-uptake rate was found to be almost linear when methyl viologen was present. In the absence of methyl viologen (Mehler reaction) an increase of 9-AA fluorescence quenching to a value of 20% at low light intensities was associated with considerably less O2-uptake than in the presence of methyl viologen, indicating the involvement of cyclic flow. These findings are in agreement with a preceding study of Kobayashi and Heber (1994). However, when no KCN was added, such that the complete Mehler-peroxidase reaction sequence was operative, the relationship between 9-AA fluorescence quenching and the flux through PS II, as measured via the chlorophyll fluorescence parameter ΔF/Fm′ × PAR, was identical to that observed in the presence of methyl viologen. Under the assumption that methyl viologen prevents cyclic flow, it is concluded that there is no significant contribution of cyclic electron flow to ΔpH-generation in intact spinach chloroplasts.
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    Heat sensitivity of chloroplasts and leaves: Leakage of protons from thylakoids and reversible activation of cyclic electron transport (1999)
    Springer
    Photosynthesis research 59 (1999), S. 81-93 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; cyclic electron flow ; high temperature ; light scattering ; photosynthesis ; Photosystems II and I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In illuminated intact spinach chloroplasts, warming to and beyond 40 °C increased the proton permeability of thylakoids before linear electron transport through Photosystem II was inhibited. Simultaneously, antimycin A-sensitive cyclic electron transport around Photosystem II was activated with oxygen or CO2, but not with nitrite as electron acceptors. Between 40 to 42 °C, activation of cyclic electron transport balanced the loss of protons so that a sizeable transthylakoid proton gradient was maintained. When the temperature of darkened spinach leaves was slowly increased to 40°C, reduction of the quinone acceptor of Photosystem II, QA, increased particularly when respiratory CO2 production and autoxidation of plastoquinones was inhibited by decreasing the oxygen content of the atmosphere from 21 to 1%. Simultaneously, Photosystem II activity was partially lost. The enhanced dark QA reduction disappeared after the leaf temperature was decreased to 20 °C. No membrane energization was detected by light-scattering measurements during heating the leaf in the dark. In illuminated spinach leaves, light scattering and nonphotochemical quenching of chlorophyll fluorescence increased during warming to about 40 °C while Photosystem II activity was lost, suggesting extra energization of thylakoid membranes that is unrelated to Photosystem II functioning. After P700 was oxidized by far-red light, its reduction in the dark was biphasic. It was accelerated by factors of up to 10 (fast component) or even 25 (slow component) after short heat exposure of the leaves. Similar acceleration was observed at 20 °C when anaerobiosis or KCN were used to inhibit respiratory oxidation of reductants. Methyl viologen, which accepts electrons from reducing side of Photosystem II, completely abolished heat-induced acceleration of P700+ reduction after far-red light. The data show that increasing the temperature of isolated chloroplasts or intact spinach leaves to about 40 °C not only inhibits linear electron flow through Photosystem II but also activates Photosystem I-driven cyclic electron transport pathways capable of contributing to the transthylakoid proton gradient. Heterogeneity of the kinetics of P700+ reduction after far-red oxidation is discussed in terms of Photosystem I-dependent cyclic electron transport in stroma lamellae and grana margins.
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    URL: http://dx.doi.org/10.1023/A:1006149317411
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    Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers (1999)
    Springer
    Photosynthesis research 59 (1999), S. 95-104 
    Details
    ISSN: 1573-5079
    Keywords: bacteriochlorophyll a ; electron transfer ; light harvesting ; photosynthesis ; Rhodobacter sphaeroides ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for the primary electron transfer reaction through an effect on the reduction potential of the primary donor. A lowering of the redox potential of the primary donor due to the presence of the core antenna is consistently observed in a series of reaction center mutants in which the reduction potential of the primary donor was varied over a 130 mV range. Estimates of the magnitude of the change in driving force for charge separation from time-resolved delayed fluorescence measurements in the mutant reaction centers suggest that the mutations exert their effect on the driving force largely through an influence on the redox properties of the primary donor. The results demonstrate that the energetics of light-driven electron transfer in reaction centers are sensitive to the environment of the complex, and provide indirect evidence that the kinetics of electron transfer are modulated by the presence of the LH1 antenna complexes that surround the reaction center in the natural membrane.
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    Feedback inhibition of photosynthesis in rice measured by O2 dependent transients (1999)
    Springer
    Photosynthesis research 59 (1999), S. 187-200 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; CO2 ; oxygen ; photosynthesis ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kinetic properties of photosynthesis (both transient and steady-state) were monitored using three non-invasive techniques to evaluate limitations on triose-phosphate (triose-P) conversion to carbohydrate in rice. These included analyzing the O2 sensitivity of CO2 fixation and the assimilatory charge (AC) using gas exchange (estimate of the ribulose 1,5- bisphosphate pool) and measuring Photosystem II activity by chlorophyll fluorescence analysis under varying light, temperature and CO2 partial pressures. Photosynthesis was inhibited transiently upon switching from 20 to 2 kPa O2 (reversed O2 sensitivity), the degree of which was correlated with a terminal, steady-state suppression of low O2 enhancement of photosynthesis. Under current ambient levels of CO2 and moderate to high light, the transient pattern was more obvious at 18 °C than at 26 °C while at 34 °C no tra nsient response was observed. The transient inhibition at 18 °C ranged from 15% to 31% depending on the pre-measurement temperature. This pattern, symptomatic of feedback, was observed with increasing light and CO2 partial pressures with the degree of feedback decreasing from moderate (18 °C) up to high temperature (34 °C). Under feedback conditions, the rate of assimilation is shifted from being photorespiration limited to being triose-P utilization limited. Transitory changes in CO2 assimilation rates (A) under low O2 indicative of feedback coincided with a transitory drop in assimilatory charge (AC) and inhibition of electron transport. In contrast to previous studies with many C3 species, our studies indicate that rice shows susceptibility to feedback inhibition under moderate temperatures and current atmospheric levels of CO2.
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    Diurnal changes in leaf gas exchange and chlorophyll fluorescence in tropical tree species with contrasting light requirements (1999)
    Springer
    Ecological research 14 (1999), S. 77-88 
    Details
    ISSN: 1440-1703
    Keywords: chlorophyll fluorescence ; Macaranga gigantea ; Neobalanocarpus heimii ; photosynthesis ; Shorea leprosula ; tropical rainforest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Interspecific ecophysiological differences in response to different light environments are important to consider in regeneration behavior and forest dynamics. The diurnal changes in leaf gas exchange and chlorophyll fluorescence of two dipterocarps, Shorea leprosula (a high light-requiring) and Neobalanocarpus heimii (a low light-requiring), and a pioneer tree species (Macaranga gigantea) growing in open and gap sites were examined. In the open site, the maximum net photosynthetic rate (Pn), photosystem II (PSII) quantum yield (δ; F/Fm′), and relative electron transport rate (r-ETR) through PSII at a given photosynthetic photon flux density (PPFD) was higher in S. leprosula and M. gigantea than in N. heimii, while non-photochemical quenching (NPQ) at a given PPFD was higher in N. heimii. The maximum values of net photosynthetic rate (Pn) in M. gigantea and S. leprosula was higher in the open site (8–11 μmol m−2 s−1) than in the gap site (5 μmol m−2 s−1), whereas that in N. heimii was lower in the open site (2 μmol m−2 s−1) than in the gap site (4 μmol m−2 s−1), indicating that N. heimii was less favorable to the open site. These data provide evidence to support the hypothesis that ecophysiological characteristics link with plant’s regeneration behavior and successional status. Although Pn and stomatal conductance decreased at midday in M. gigantea and S. leprosula in the open site, both r-ETR and leaf temperature remained unchanged. This indicates that stomatal closure rather than reduced photochemical capacity limited Pn in the daytime. Conversely, there was reduced r-ETR under high PPFD conditions in N. heimii in the open site, indicating reduced photochemical capacity. In the gap site, Pn increased in all leaves in the morning before exposure to direct sunlight, suggesting a relatively high use of diffuse light in the morning.
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    Effects of two sesquiterpene lactones isolated fromArtemisia annua on physiology ofLemna minor (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 969-978 
    Details
    ISSN: 1573-1561
    Keywords: Artemisinin ; arteannuic acid ; photosynthesis ; respiration ; chlorophyll ; Lemna minor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of artemisinin and arteannuic acid extracted fromArtemisia annua on the physiology ofLemna minor were evaluated. Changes in frond production, growth, dry weight, and chlorophyll content ofL. minor were determined. Photosynthesis and respiration were evaluated with a differential respirometer. Artemisinin (5 µM) inhibitedL. minor frond production and dry weight 82 and 83%, relative to methanol controls. Chlorophyll content was reduced 44% by artemisinin (2.5 µM). Arteannuic acid (10 µM) was less active, inhibiting frond production 61% and reducing chlorophyll content 66% at 5 µM. Artemisinin (1 µM) reducedL. minor photosynthesis 30% and 2.5 µM reduced respiration 39%. Arteannuic acid had no significant effect on photosynthesis or respiration at the levels tested.
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    URL: http://dx.doi.org/10.1007/BF02059591
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    Photosynthetic electron transport and anaerobic metabolism in purple non-sulfur phototrophic bacteria (1994)
    Springer
    Antonie van Leeuwenhoek 66 (1994), S. 151-164 
    Details
    ISSN: 1572-9699
    Keywords: purple non-sulfur bacteria ; Rhodobacter ; photosynthesis ; CO2 fixation ; anaerobic respiration ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Purple non-sulfur phototrophic bacteria, exemplifed byRhodobacter capsulatus andRhodobacter sphaeroides, exhibit a remarkable versatility in their anaerobic metabolism. In these bacteria the photosynthetic apparatus, enzymes involved in CO2 fixation and pathways of anaerobic respiration are all induced upon a reduction in oxygen tension. Recently, there have been significant advances in the understanding of molecular properties of the photosynthetic apparatus and the control of the expression of genes involved in photosynthesis and CO2 fixation. In addition, anaerobic respiratory pathways have been characterised and their interaction with photosynthetic electron transport has been described. This review will survey these advances and will discuss the ways in which photosynthetic electron transport and oxidation-reduction processes are integrated during photoautotrophic and photoheterotrophic growth.
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    Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 311-329 
    Details
    ISSN: 1572-9699
    Keywords: photosynthesis ; chlorophyll ; bacteriochlorophyll ; reaction center ; electron transfer ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.
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    URL: http://dx.doi.org/10.1007/BF00872216
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    Improvement of acclimatization of micropropagated grapevine: Photosynthetic competence and carbon allocation (1999)
    Springer
    Plant cell, tissue and organ culture 58 (1999), S. 31-37 
    Details
    ISSN: 1573-5044
    Keywords: carbohydrates ; chlorophylls ; photosynthesis ; tissue culture ; Vitis vinifera L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grapevine plantlets multiplied in vitro were acclimatized at 40 or 90 μmol m−2 s−1 photon flux density for 12 or 16 h per day, respectively. In the high-light regime a decrease in total chlorophyll and an increase in chlorophyll a/chlorophyll b ratio occurred. However, at high-light intensity lower photosynthetic capacities and higher apparent photosynthesis were measured than at the low-light regime. In leaves expanded during acclimatization, the light compensation point was higher in plantlets under high-light while quantum yield was higher in low-light conditions. High-light also gave rise to an increase in carbohydrate concentration. As a whole, the results suggest that high-light increases carbon assimilation and growth although with a low investment in the photosynthetic apparatus.
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    Genetic variation for resistance to low-temperature photoinhibition of photosynthesis in maize (Zea mays L.) (1994)
    Springer
    Euphytica 80 (1994), S. 85-93 
    Details
    ISSN: 1573-5060
    Keywords: maize ; Zea mays ; photoinhibition ; photosynthesis ; low-temperature adaptation ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixty-seven inbred lines of maize were evaluated for resistance to low-temperature photoinhibition of photosynthesis, using a pulse-modulated chlorophyll fluorescence technique. The evaluation procedure was based on leaf discs, which were exposed to a high irradiance (1000 µmol/m2/s) at 7°C. The efficiency of open PSII reaction centres as a reflection of overall photosynthesis was measured before and after a photoinhibition-inducing treatment. Exposure of leaf discs to photoinhibitory condition for 2, 4, and 8 hours resulted in an efficiency reduction of 30, 53 and 83%, respectively. Testing of inbred lines showed large differences for photoinhibition susceptibility. The difference in photosynthetic efficiency between the most extreme lines after a treatment of eight hours was 39%. Resistance to photoinhibition was shown to be relevant under cool field conditions. It proved to be a trait strongly amenable to selection.
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    Optimal acclimation of the C3 photosynthetic system under enhanced CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 401-412 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; elevated CO2 ; source-sink interactions ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A range of studies of C3 plants have shown that there is a change in both the carbon flux and the pattern of nitrogen allocation when plants are grown under enhanced CO2. This paper examines evidence that allocation of nitrogen both to and within the photosynthetic system is optimised with respect to the carbon flux. A model is developed which predicts the optimal relative allocation of nitrogen to key enzymes of the photosynthetic system as a function of CO2 concentration. It is shown that evidence from flux control analysis is broadly consistent with this model, although at high nitrogen and under certain conditions at low nitrogen experimental data are not consistent with the model. Acclimation to enhanced CO2 is also assessed in terms of resource allocation between photosynthate sources and sinks. A means of assessing the optimisation of this source-sink allocation is proposed, and several studies are examined within this framework. It is concluded that C3 plants probably possess the genetic feedback mechanisms required to efficiently ‘smooth out” any imbalance within the photosynthetic system caused by a rise in atmospheric CO2.
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    URL: http://dx.doi.org/10.1007/BF00014594
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    Biochemical and molecular basis for impairment of photosynthetic potential (1994)
    Springer
    Photosynthesis research 39 (1994), S. 453-462 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Rubisco ; ozone ; oxidative stress ; rbcS mRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ozone induces reductions in net photosynthesis in a large number of plant species. A primary mechanism by which photosynthesis is reduced is through impact on carbon dioxide fixation. Ozone induces loss in Rubisco activity associated with loss in concentration of the protein. Evidence is presented that ozone may induce oxidative modification of Rubisco leading to subsequent proteolysis. In addition, plants exposed to ozone sustain reduction in rbcS, the mRNA for the small subunit of Rubisco. This loss in rbcS mRNA may lead to a reduced potential for synthesis of the protein. The regulation of O3-induced loss of Rubisco, and implications of the decline in this protein in relation to accelerated senescence are discussed.
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    URL: http://dx.doi.org/10.1007/BF00014598
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    Reminiscence about‘Chloropseudomonas ethylicum’ and the FMO-protein (1994)
    Springer
    Photosynthesis research 41 (1994), S. 3-5 
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    ISSN: 1573-5079
    Keywords: bacteriochlorophylla-protein ; green sulfur bacteria ; Prosthecochloris aestuarii ; Chlorobium limicola ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 1961 the green sulfur bacterium-containing mixed culture known as‘Chloropseudomonas ethylicum’ was brought to Brookhaven National Laboratory (USA) from Moscow State University (USSR). The water-soluble bacteriochlorophylla-protein (FMO-protein) was extracted, purified and characterized by absorption and circular dichroism spectroscopy, by X-ray crystallography and by primary structure determination.
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    URL: http://dx.doi.org/10.1007/BF02184138
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    Rates of vectorial proton transport supported by cyclic electron flow during oxygen reduction by illuminated intact chloroplasts (1994)
    Springer
    Photosynthesis research 41 (1994), S. 419-428 
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    ISSN: 1573-5079
    Keywords: 9-aminoacridine fluorescence ; cyclic electron transport ; Mehler reaction ; photosynthesis ; photosystems ; transthylakoid proton gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The light-dependent quenching of 9-aminoacridine fluorescence was used to monitor the state of the transthylakoid proton gradient in illuminated intact chloroplasts in the presence or absence of external electron acceptors. The absence of appreciable light-dependent fluorescence quenching under anaerobic conditions indicated inhibition of coupled electron transport in the absence of external electron acceptors. Oxygen relieved this inhibition. However, when DCMU inhibited excessive reduction of the plastoquinone pool in the absence of oxygen, coupled cyclic electron transport supported the formation of a transthylakoid proton gradient even under anaerobiosis. This proton gradient collapsed in the presence of oxygen. Under aerobic conditions, and when KCN inhibited ribulose bisphosphate carboxylase and ascorbate peroxidase, fluorescence quenching indicated the formation of a transthylakoid proton gradient which was larger with oxygen in the Mehler reaction as electron acceptor than with methylviologen at similar rates of linear electron transport. Apparently, cyclic electron transport occured simultaneously with linear electron transport, when oxygen was available as electron acceptor, but not when methylviologen accepted electrons from Photosystem I. The ratio of cyclic to linear electron transport could be increased by low concentrations of DCMU. This shows that even under aerobic conditions cyclic electron transport is limited in isolated intact chloroplasts by excessive reduction of electron carriers. In fact, P700 in the reaction center of Photosystem I remained reduced in illuminated isolated chloroplasts under conditions which resulted in extensive oxidation of P700 in leaves. This shows that regulation of Photosystem II activity is less effective in isolated chloroplasts than in leaves. Assuming that a Q-cycle supports a H+/e ratio of 3 during slow linear electron transport, vectorial proton transport coupled to Photosystem I-dependent cyclic electron flow could be calculated. The highest calculated rate of Photosystem I-dependent proton transport, which was not yet light-saturated, was 330 μmol protons (mg chlorophyll h)−1 in intact chloroplasts. If H+/e is not three but two proton transfer is not 330 but 220 μmol (mg Chl H)−1. Differences in the regulation of cyclic electron transport in isolated chloroplasts and in leaves are discussed.
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    URL: http://dx.doi.org/10.1007/BF02183044
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    Pigment orientation changes accompanying the light state transition in Synechococcus sp. PCC 6301 (1994)
    Springer
    Photosynthesis research 40 (1994), S. 35-44 
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    ISSN: 1573-5079
    Keywords: allophycocyanin ; chlorophyll a ; linear dichroism ; phycobilisome ; photosynthesis ; state transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Low temperature (77 K) linear dichroism spectroscopy was used to characterize pigment orientation changes accompanying the light state transition in the cyanobacterium, Synechococcus sp. PCC 6301 and those accompanying chromatic acclimation in Porphyridium cruentum in samples stabilized by glutaraldehyde fixation. In light state 2 compared to light state 1 intact cells of Synechococcus showed an increased alignment of allophycocyanin parallel to the cells' long axis whereas the phycobilisomethylakoid membrane fragments exhibited an increased allophycocyanin alignment parallel to the membrane plane. The phycobilisome-thylakoid membrane fragments showed less alignment of a short wave-length chlorophyll a (Chl a) Qy transition dipole parallel to the membrane plane in state 2 relative to state 1. To aid identification of the observed Chl a orientation changes in Synechococcus, linear dichroism spectra were obtained from phycobilisome-thylakoid membrane fragments isolated from red light-grown (increased number of PS II centres) and green light-grown (increased number of PS I centres) cells of the red alga Porphyridium cruentum. An increased contribution of short wavelength Chl a Qy transition dipoles parallel to the long axis of the membrane plane was directly correlated with increased levels of PS II centres in red light-grown P. cruentum. Our results indicate that the transition to state 2 in cyanobacteria is accompanied by an increase in the orientation of allophycocyanin and a decrease in the orientation of Chl a associated with PS II with respect to the thylakoid membrane plane.
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    Photoinhibition of photosynthesis in chilled potato leaves is not correlated with a loss of Photosystem-II activity (1994)
    Springer
    Photosynthesis research 40 (1994), S. 75-92 
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    ISSN: 1573-5079
    Keywords: chilling temperature ; oxygen toxicity ; photoinhibition ; photosynthesis ; photosystems ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When 23 °C-grown potato leaves (Solanum tuberosum L.) were irradiated at 23 °C with a strong white light, photosynthetic electron transport and Photosystem-II (PS II) activity were inhibited in parallel. When the light treatment was given at a low temperature of 3 °C, the photoinhibition of photosynthesis was considerably enhanced, as expected. Surprisingly, no such stimulation of photoinhibition was observed with respect to the PS II function. A detailed functional analysis of the photosynthetic apparatus, using in-vivo fluorescence, absorbance, oxygen and photoacoustic measurements, and artificial electron donors/acceptors, showed a pronounced alteration of PS I activity during light stress at low temperature. More precisely, it was observed that both the pool of photooxidizeable reaction center pigment (P700) of PS I and the efficiency of PS I to oxidize P700 were dramatically reduced. Loss of P700 activity was shown to be essentially dependent on atmospheric O2 and to require a continued flow of electrons from PS II, suggesting the involvement of the superoxide anion radical which is produced by the interaction of O2 and the photosynthetic electron-transfer chain through the Mehler reaction. Mass spectrometric measurements of O2 exchange by potato leaves under strong illumination did not reveal, however, any stimulation of the Mehler reaction at low temperature, thus leading to the conclusion that O2 toxicity mainly resulted from a chilling-induced inhibition of the scavenging system for O2-radicals. Support for this interpretation was provided by the light response of potato leaves infiltrated with an inhibitor (diethyldithiocarbamate) of the chloroplastic Cu-Zn superoxide dismutase. It was indeed possible to simulate the differential inhibition of the PS II photochemical activity and the linear electron transport observed during light stress at low temperature by illuminating at 23 °C diethyldithiocarbamate-poisoned leaves. The experimental data presented here suggests that (i) the previously reported resistance of PS I to photoinhibition damage in-vivo is not an intrinsic property of PS I but results from efficient protective systems against O2 toxicity, (ii) PS I is photoinhibited in chilled potato leaf due to the inactivation of this PS I defence system and (iii) PS I is more sensitive to superoxide anion radicals than PS II.
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    Sixty years in algal physiology and photosynthesis (1994)
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    Photosynthesis research 40 (1994), S. 207-221 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; unicellular algae ; ion effects ; manganese ; blue light ; synchronized growth ; algal mass cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This personal perspective records research experiences in chemistry and biology at four German universities, two before and two after World War II. The research themes came from cytophysiology of green unicellular algae, in particular their photosynthesis. The function of inorganic ions in photosynthesis and dark respiration was investigated at different degrees of specific mineral stress (deficiencies), and the kinetics of recovery followed after the addition of the missing element. Two types of recovery of photosynthesis were observed: indirect restitution via growth processes and immediate normalisation. From the latter case (K+, phosphate, Mn++) the effect of manganese was emphasized as its role in photosynthetic O2 evolution became established during our research. Other themes of our group, with some bearing on photosynthesis were: synchronization of cell growth by light-dark change and effects of blue (vs. red) light on the composition of green cells. Some experiences in connection with algal mass cultures are included. Discussion of several editorial projects shows how photosynthesis, as an orginally separated field of plant biochemistry and biophysics, became included into general cell physiology and even ecophysiology of green plants. The paper contains an appreciation of the authors' main mentor Kurt Noack (1888–1963) and of Ernst Georg Pringsheim (1881–1970), founder of experimental phycology.
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    URL: http://dx.doi.org/10.1007/BF00034771
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    Gene nomenclature recommendations for green photosynthetic bacteria and heliobacteria (1994)
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    Photosynthesis research 41 (1994), S. 27-28 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; reaction center ; green bacteria ; heliobacteria ; gene ; chlorosome ; cytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recommendations are given for naming of genes coding for reaction center, antenna and electron transport proteins in green photosynthetic bacteria and heliobacteria
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    URL: http://dx.doi.org/10.1007/BF02184142
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    Redox effects on the bacteriochlorophyll α-containing Fenna-Matthews-Olson protein fromChlorobium tepidum (1994)
    Springer
    Photosynthesis research 41 (1994), S. 89-96 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Chlorobium tepidum ; antenna ; bacteriochlorophylla protein ; energy transfer ; chlorosome ; green bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The BChla-containing Fenna-Matthews-Olson (FMO) protein from the green sulfur bacteriumChlorobium tepidum was purified and characterized. Fluorescence spectra indicate that efficient excited state quenching occurs at neutral or oxidizing redox potentials. The major fluorescence lifetime at room temperature is approximately 60 ps in samples that are in neutral or oxidizing conditions, and approximately 2 ns in samples where the strong reductant sodium dithionite has been added. A similar change is observed in pump-probe picosecond absorbance difference experiments, where the long life time component increases after dithionite addition. A 16 Gauss wide EPR signal with g factor =2.005 is observed in samples without dithionite. This signal largely disappears upon addition of dithionite. Dithionite induces large reversibile changes in the 77 K absorbance spectra of the purified FMO protein and in whole cells. These results indicate that the FMO protein contains redox active groups, which may be involved in the regulation of energy transfer. Room temperature circular dichroism and low temperature absorption spectra show that dithionite also induces conformational or structural changes of the FMO protein complex.
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    URL: http://dx.doi.org/10.1007/BF02184148
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    Responses to drought and flooding in tropical forage grasses (1994)
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    Plant and soil 164 (1994), S. 97-105 
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    ISSN: 1573-5036
    Keywords: alcohol dehydrogenase ; drought ; flooding ; photosynthesis ; tropical grasses ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long dry seasons or permanent flooding, typical of tropical savannas, severely limit the growth of pasture plants. This study compares the responses of water relations, carbon assimilation and alcohol dehydrogenase (ADH) activity to drought and flooding in four perennial C4 grasses: the tufted or caespitose Hyparrhenia rufa and Andropogon gayanus (CIAT 621) and the stoloniferous Brachiaria mutica and Echinochloa polystachya. Plants of the four species were subjected to medium term flooding (20–25 days) and moderate drought in a greenhouse. Leaf water potential (Ψ), stomatal conductance (Gs) and photosynthesis rate (Pn) were measured throughout the experiment and ADH activity was measured in flooded and control plants. Moderate drought produced similar effects in all grasses reducing Gs which caused reduced Pn. Net photosynthesis compensation point was reached at the lowest Ψ in A. gayanus which was considered as the most drought tolerant. The responses to flooding varied across species. Andropogon gayanus and H. rufa showed early stomatal closure without concurrent decrease in Ψ and leaf turgor. This low Gs was responsible of reduced Pn and growth rate. There was a slight increase of Gs in the middle of the flooding period and both grasses recovered pre-stress Gs and Pn after drainage. ADH activity increased markedly only in A. gayanus under flooding suggesting that this grass was the most flood-sensitive. Stomatal aperture, Pn and ADH activity in B. mutica and E. polystachya were not affected by flooding. The higher flood-tolerance in these grasses might be attributed to enhanced oxygen diffusion to the roots through the hollow stolons, development of advantitious rootlets and large aerenchyma in the roots which compensate for the reduction of soil oxygen and permit the maintenance of root activity.
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    Gene action and heritability for photosynthetic activity in two wheat crosses (1994)
    Springer
    Euphytica 76 (1994), S. 235-238 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; photosynthesis ; gene action ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5 th leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC1 and BC2). Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5 th leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity.
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    URL: http://dx.doi.org/10.1007/BF00022168
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    Singlet oxygen production in thylakoid membranes during photoinhibition as detected by EPR spectroscopy (1994)
    Springer
    Photosynthesis research 39 (1994), S. 191-199 
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    ISSN: 1573-5079
    Keywords: photoinhibition ; photosynthesis ; protein degradation ; singlet oxygen ; TEMP (2,2,6,6-tetramethylpiperidine) ; thylakoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of isolated spinach thylakoids to high intensity illumination (photoinhibition) results in the well-characterized impairment of Photosystem II electron transport, followed by degradation of the D1 reaction centre protein. In the present study we demonstrate that this process is accompanied by singlet oxygen production. Singlet oxygen was detected by EPR spectroscopy, following the formation of stable nitroxide radicals from the trapping of singlet oxygen with a sterically hindered amine TEMP (2,2,6,6-tetramethylpiperidine). There was no detectable singlet oxygen production during anaerob photoinhibition or in the presence of sodium-azide. Comparing the kinetics of the loss of PS II function and D1 protein with that of singlet oxygen trapping suggests that singlet oxygen itself or its radical product initiates the degradation of D1.
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    Changes in the antenna size of Photosystem I and Photosystem II in Synechococcus sp. strain PCC 7942 grown in the presence of SANDOZ 9785 — a Photosystem II inhibitor (1994)
    Springer
    Photosynthesis research 41 (1994), S. 303-313 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; excitation energy ; herbicide ; photochemical apparatus ; photosynthesis ; pyridazinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract SANDOZ 9785, also known as BASF 13.338, is a pyridazinone derivative that inhibits Photosystem II (PS II) activity leading to an imbalance in the rate of electron transport through the photosystems. Synechococcus sp. strain PCC 7942 cells grown in the presence of sublethal concentration of SANDOZ 9785 (SAN 9785) for 48 hours exhibited a 20% decrease in Chl a per cell. However, no changes were observed in the content of phycocyanin per cell, the size of the phycobilisomes or in the PS II:PS I ratio. From an estimate of PS II electron transport rate under varying light intensities and spectral qualities and analysis of room temperature Chl a fluorescence induction, it was deduced that growth of Synechococcus PCC 7942 in the presence of SAN 9785 leads to a redistribution of excitation energy in favour of PS II. Though the redistribution appears to be primarily caused by changes affecting the Chl a antenna of PS II, the extent of energetic coupling between phycobilisomes and PS II is also enhanced in SAN 9785 grown Synechococcus PCC 7942 cells. There was a reduction in the effective size of PS I antenna based on measurement of P700 photooxidation kinetics. These results indicate that when PS II is partially inhibited, the structure of photosynthetic apparatus alters to redistribute the excitation energy in favour of PS II so that the efficiency of utilization of light energy by the two photosystems is optimized. Our results suggest that under the conditions used, drastic structural changes are not essential for redistribution of excitation energy between the photosystems.
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    Acclimation of photosynthesis to increasing atmospheric CO2: The gas exchange perspective (1994)
    Springer
    Photosynthesis research 39 (1994), S. 351-368 
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    ISSN: 1573-5079
    Keywords: CO2 enrichment ; gas exchange ; greenhouse effect ; photosynthesis ; responses to CO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of photosynthetic acclimation to elevated CO2 is evaluated from the results of over 40 studies focusing on the effect of long-term CO2 enrichment on the short-term response of photosynthesis to intercellular CO2 (the A/Ci response). The effect of CO2 enrichment on the A/Ci response was dependent on growth conditions, with plants grown in small pots (〈 5 L) or low nutrients usually exhibiting a reduction of A at a given Ci, while plants grown without nutrient deficiency in large pots or in the field tended to exhibit either little reduction or an enhancement of A at a given Ci following a doubling or tripling of atmospheric CO2 during growth. Using theoretical interpretations of A/Ci curves to assess acclimation, it was found that when pot size or nutrient deficiency was not a factor, changes in the shape of A/Ci curves which are indicative of a reallocation of resources within the photosynthetic apparatus typically were not observed. Long-term CO2 enrichment usually had little effect or increased the value of A at all Ci. However, a minority of species grown at elevated CO2 exhibited gas exchange responses indicative of a reduced amount of Rubisco and an enhanced capacity to metabolize photosynthetic products. This type of response was considered beneficial because it enhanced both photosynthetic capacity at high CO2 and reduced resource investment in excessive Rubisco capacity. The ratio of intercellular to ambient CO2 (the Ci/Ca ratio) was used to evaluate stomatal acclimation. Except under water and humidity stress, Ci/Ca exhibited no consistent change in a variety of C3 species, indicating no stomatal acclimation. Under drought or humidity stress, Ci/Ca declined in high-CO2 grown plants, indicating stomata will become more conservative during stress episodes in future high CO2 environments.
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    Effects of UV-B radiation on photosynthesis and growth of terrestrial plants (1994)
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    Photosynthesis research 39 (1994), S. 463-473 
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    ISSN: 1573-5079
    Keywords: global climate change ; ozone depletion ; photosynthesis ; Photosystem II ; productivity ; UV-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic apparatus of some plant species appears to be well-protected from direct damage from UV-B radiation. Leaf optical properties of these species apparently minimizes exposure of sensitive targets to UV-B radiation. However, damage by UV-B radiation to Photosystem II and Rubisco has also been reported. Secondary effects of this damage may include reductions in photosynthetic capacity, RuBP regeneration and quantum yield. Furthermore, UV-B radiation may decrease the penetration of PAR, reduce photosynthetic and accessory pigments, impair stomatal function and alter canopy morphology, and thus indirectly retard photosynthetic carbon assimilation. Subsequently, UV-B radiation may limit productivity in many plant species. In addition to variability in sensitivity to UV-B radiation, the effects of UV-B radiation are further confounded by other environmental factors such as CO2, temperature, light and water or nutrient availability. Therefore, we need a better understanding of the mechanisms of tolerance to UV-B radiation and of the interaction between UV-B and other environmental factors in order to adequately assess the probable consequences of a change in solar radiation.
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    State adaptations in the cyanobacterium Synechcoccus 6301 (PCC): Dependence on light intensity or spectral composition? (1994)
    Springer
    Photosynthesis research 40 (1994), S. 107-117 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; state adaptations ; shade adaptation ; cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A profile of high light to intense self-shading conditions was constructed using a white light source and cultures of the cyanobacterium Synechococcus 6301; this profile approximates to a natural self-shading gradient of decreasing light intensity and PS II/PS I excitation ratio. Samples of S.6301 were placed along this profile and allowed to state adapt. To separate the effects of light intensity and wavelength on state adaptation, samples were also placed in a shade profile produced by a white light source and neutral density filters. After adaptation, samples were fixed in their resulting state by the addition of glutaraldehyde, and fluorescence measurements were made at 35° C or –160 °C. It is concluded: 1. Under conditions of deep shade (〈5 μmol m−2s−1 PAR) and weak shade (〉200 μmol m−2s−1 PAR), cells adapt to a low PS II fluorescence state (state 2); in moderate shade (20–60 μmol m−2s−1PAR) cells adapt to a high PS II fluorescence state (state 1). We suggest these findings provide evidence for the operation of different factors on the control of state adaptations in cyanobacteria; one set operates at low light and another at high light intensities. 2. Under conditions of self-shading, there is little evidence to support the contention that state adaptations in cyanobacteria are produced by wavelength-dependent changes in the PS II/PS I excitation ratio, instead, it appaers they are produced by changes in the intensity of incident irradiation. 3. The observed fluorescence changes do not appear to involve major changes in the phycobilisome sensitisation of PS II and PS I. Instead, it appears that these changes are effected by alterations in ΦF of PS II (i.e. changes in PS II excitation density caused by alterations in the rate constants controlling spillover to PS I, photochemistry, fluorescence emission or thermal deactivation.
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    An enzyme and13C-NMR study of carbon metabolism in heliobacteria (1994)
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    Photosynthesis research 41 (1994), S. 75-88 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; carbon assimilation ; photosynthetic bacteria ; citric-acid cycle ; pyruvate synthase ; fermentation ; heliobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heliobacteria are a group of anoxygenic phototrophs that can grow photoheterotrophically in defined minimal media on only a limited range of organic substrates as carbon sources. In this study the mechanisms which operate to assimilate carbon and the routes employed for the biosynthesis of cellular intermediates were investigated in a newHeliobacterium strain, HY-3. This was achieved using two approaches (1) by measuring the activities of key enzymes in cell-free extracts and (2) by the use of13C nuclear magnetic resonance (NMR) spectroscopy to analyze in detail the labelling pattern of amino-acids of cells grown on [13C] pyruvate and [13C] acetate.Heliobacterium strain HY-3 was unable to grow autotrophically on CO2/H2 and neither (ATP)-citrate lyase nor ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBPcase) were detectable in cell-free extracts. The enzyme profile of pyruvate grown cells indicated the presence of a pyruvate:acceptor oxidoreductase at high specific activity which could convert pyruvate to acetyl-Coenzyme A. No pyridine nucleotide dependent pyruvate dehydrogenase complex activity was detected. Of the citric-acid cycle enzymes, malate dehydrogenase, fumarase, fumarate reductase and an NADP-specific isocitrate dehydrogenase were readily detectable but no aconitase or citrate synthase activity was found. However, the labelling pattern of glutamate in long-term 2-[13C] acetate incorporation experiments indicated that a mechanism exists for the conversion of carbon from acetyl-CoA into 2-oxoglutarate. A 2-oxoglutarate:acceptor oxidoreductase activity was present which was also assayable by isotope exchange, but no 2-oxoglutarate dehydrogenase complex activity could be detected. Heliobacteria appear to use a type of incomplete reductive carboxylic acid pathway for the conversion of pyruvate to 2-oxoglutarate but are unable to grow autotrophically using this metabolic route due to the absence of ATP-citrate lyase.
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    Spectroscopic evidence for the presence of an iron-sulfur center similar to Fx of Photosystem I inHeliobacillus mobilis (1994)
    Springer
    Photosynthesis research 41 (1994), S. 115-123 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; bacteriochlorophyll ; electron acceptor ; iron-sulfur center ; Photosystem I ; heliobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Treatment of membranes ofHeliobacillus mobilis with high concentrations of the chaotropic agent urea resulted in the removal of the iron-sulfur centers FA and FB from the reaction center, as indicated by EPR spectra under strongly reducing conditions. In urea-treated membranes, transient absorption measurements upon a laser flash indicated a recombination between the photo-oxidized primary donor P798+ and a reduced acceptor with a time constant of 20 ms at room temperature. Benzylviologen, vitamin K-3 and methylene blue were found to accept electrons from the reduced acceptor efficiently. A differential extinction coefficient of 225–240 mM−1 cm−1 at 798 nm was determined from experiments in the presence of methylene blue. Transient absorption difference spectra between 400 and 500 nm in the presence and absence of artificial acceptors indicated that the electron acceptor involved in the 20 ms recombination has an absorption spectrum similar to that of an iron-sulfur center. This iron-sulfur center was assigned to be analogous to FX of Photosystem I. Our results provide evidence in support of the presence of FX in heliobacteria, which was proposed on the basis of the reaction center polypeptide sequence (Liebl et al. (1993) Proc. Natl. Acad. Sci. USA 90: 7124–7128). Implications for the electron transfer pathway in the reaction center of heliobacteria are discussed.
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    URL: http://dx.doi.org/10.1007/BF02184151
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    Molecular organization of bacteriochlorophyll in chlorosomes of the green photosynthetic bacteriumChloroflexus aurantiacus: Studies of fluorescence depolarization accompanied by energy transfer processes (1994)
    Springer
    Photosynthesis research 41 (1994), S. 181-191 
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    ISSN: 1573-5079
    Keywords: energy transfer ; green bacteria ; photosynthesis ; picosecond spectroscopy ; pigment system ; (Chloroflexus aurantiacus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Examination was made of changes in fluorescence polarization plane by energy transfer in the chlorosomes of the green photosynthetic bacterium,Chloroflexus aurantiacus. Fluorescence anisotropy in the picosecond (ps) time region was analyzed using chlorosomes suspended in solution as well as those oriented in a polyacrylamide gel. When the main component of BChlc was preferentially excited, the decay of fluorescence anisotropy was found to depend on wavelength. In the chlorosome suspension, the anisotropy ratio of BChlc changed from 0.31 to 0.24 within 100 ps following excitation. In the baseplate BChla region, this ratio decreased to a negative value (−0.09) from the initial 0.14. In oriented samples, the degree of polarization remained at 0.68 for BChlc, and changed from 0.25 to −0.40 for the baseplate BChla by excitation light whose electric vector was parallel to the longest axis of chlorosomes. In the latter case, there was a shift from 0.30 to −0.55 by excitation perpendicular to the longest axis. Time-resolved fluorescence polarization spectra clearly indicated extensive changes in polarization plane accompanied by energy transfer. The directions of polarization plane of emission from oriented samples were mostly dependent on chlorosome orientation in the gel but not on that of the polarization plane of excitation light. Orientations of the dipole moment of fluorescence components was consistent with that of absorption components as determined by the linear dichroism (Matsuura et al. (1993) Photochem. Photobiol. 57: 92–97). A model for molecular organization of BChlc anda in chlorosomes is proposed based on anisotropic optical properties.
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    URL: http://dx.doi.org/10.1007/BF02184159
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    Evolution of heliobacteria: Implications for photosynthetic reaction center complexes (1994)
    Springer
    Photosynthesis research 41 (1994), S. 285-294 
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    ISSN: 1573-5079
    Keywords: heliobacteria ; reaction center ; photosynthesis ; 16S rRNA sequence ; cyanobacteria ; Gram-positive bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolutionary position of the heliobacteria, a group of green photosynthetic bacteria with a photosynthetic apparatus functionally resembling Photosystem I of plants and cyanobacteria, has been investigated with respect to the evolutionary relationship to Gram-positive bacteria and cyanobacteria. On the basis of 16S rRNA sequence analysis, the heliobacteria appear to be most closely related to Gram-positive bacteria, but also an evolutionary link to cyanobacteria is evident. Interestingly, a 46-residue domain including the putative sixth membrane-spanning region of the heliobacterial reaction center protein shows rather strong similarity (33% identity and 72% similarity) to a region including the sixth membrane-spanning region of the CP47 protein, a chlorophyll-binding core antenna polypeptide of Photosystem II. The N-terminal half of the heliobacterial reaction center polypeptide shows a moderate sequence similarity (22% identity over 232 residues) with the CP47 protein, which is significantly more than the similarity with the Photosystem I core polypeptides in this region. An evolutionary model for photosynthetic reaction center complexes is discussed, in which an ancestral homodimeric reaction center protein (possibly resembling the heliobacterial reaction center protein) with 11 membrane-spanning regions per polypeptide has diverged to give rise to core of Photosystem I, Photosystem II, and of the photosynthetic apparatus in green, purple, and heliobacteria.
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    URL: http://dx.doi.org/10.1007/BF02184169
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    The photoproduction of superoxide radicals and the superoxide dismutase activity of Photosystem II. The possible involvement of cytochrome b559 (1994)
    Springer
    Photosynthesis research 41 (1994), S. 327-338 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Photosystem II ; superoxide radical ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the present study the light induced formation of superoxide and intrinsic superoxide dismutase (SOD) activity in PS II membrane fragments and D1/D2/Cytb559-complexes from spinach have been analyzed by the use of ferricytochrome c (cyt c(III)) reduction and xanthine/xanthine oxidase as assay systems. The following results were obtained: 1.) Photoreduction of Cyt c (III) by PS II membrane fragments is induced by addition of sodium azide, tetracyane ethylene (TCNE) or carbonylcyanide-p-trifluoromethoxy-phenylhydrazone (FCCP) and after removal of the extrinsic polypeptides by a 1M CaCl2-treatment. This activity which is absent in control samples becomes completely inhibited by the addition of exogenous SOD. 2.) The TCNE induced cyt c(III) photoreduction by PS II membrane fragments was found to be characterized by a half maximal concentration of c1/2=10 μM TCNE. Simultaneously, TCNE inhibits the oxygen evolution rate of PS II membrane fragments with c1/2≈ 3 μM. 3.) The photoproduction of O2 − is coupled with H+-uptake. This effect is diminished by the addition of the O2 −-trap cyt c(III). 4.) D1/D2/Cytb559-complexes and PS II membrane fragments deprived of the extrinsic proteins and manganese exhibit no SOD-activity but are capable of producing O2 − in the light if a PS II electron donor is added. Based on these results the site(s) of light induced superoxide formation in PS II is (are) inferred to be located at the acceptor side. A part of the PS II donor side and Cyt b559 in its HP-form are proposed to provide an intrinsic superoxide dismutase (SOD) activity.
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    URL: http://dx.doi.org/10.1007/BF00019410
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    Thermoluminescence as a probe of Photosystem II in intact leaves: Non-photochemical fluorescence quenching in peas grown in an intermittent light regime (1994)
    Springer
    Photosynthesis research 41 (1994), S. 371-379 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; chlorophyll fluorescence ; high energy-state quenching ; calcium release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have measured thermoluminescence (TL) and chlorophyll fluorescence from leaves of peas grown under an intermittent light regime (IML) and followed changes in those leaves during greening. IML peas show low variable fluorescence and a certain capacity for reversible non-photochemical quenching. It has been suggested that reversible quenching may be caused by pH-dependent release of Ca2+ from Photosystem II (PS II) (Krieger and Weis (1992) Photosynthetica 27: 89–98). Under conditions in which reversible non-photochemical quenching occurs, a TL band at around 50 °C is observed, in the presence of DCMU, in IML leaves. A band in this temperature range has previously been observed in PS II depleted of Ca2+ (Ono and Inoue (1989) Biochimica et Biophysica Acta 973: 443–449). The 50 °C band disappears upon dark adaptation. In mature leaves, no significant band is seen at 50 °C. It is concluded that, in IML leaves, reversible quenching may be related to the release of Ca2+ from Photosystem II. However, it seems that in the mature system, under most conditions, such release does not contribute significantly to quenching
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    URL: http://dx.doi.org/10.1007/BF02183039
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    Measurements of mesophyll conductance, photosynthetic electron transport and alternative electron sinks of field grown wheat leaves (1994)
    Springer
    Photosynthesis research 41 (1994), S. 397-403 
    Details
    ISSN: 1573-5079
    Keywords: electron transport rate ; mesophyll conductance to CO2 diffusion ; photosynthesis ; photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic electron transport drives the carbon reduction cycle, the carbon oxidation cycle, and any alternative electron sinks such as nitrogen reduction. A chlorophyll fluorescence— based method allows estimation of the total electron transport rate while a gas-exchange-based method can provide estimates of the electron transport needed for the carbon reduction cycle and, if the CO2 partial pressure inside the chloroplast is accurately known, for the carbon oxidation cycle. The gas-exchange method cannot provide estimates of alternative electron sinks. Photosynthetic electron transport in flag leaves of wheat was estimated by the fluorescence method and gasexchange method to determine the possible magnitude of alternative electron sinks. Under non-photorespiratory conditions the two measures of electron transport were the same, ruling out substantial alternative electron sinks. Under photorespiratory conditions the fluorescence-based electron transport rate could be accounted for by the carbon reduction and carbon oxidation cycle only if we assumed the CO2 partial pressure inside the chloroplasts to be lower than that in the intercellular spaces of the leaves. To further test for the presence of alternative electron sinks, carbon metabolism was inhibited by feeding glyceraldehyde. As carbon metabolism was inhibited, the electron transport was inhibited to the same degree. A small residual rate of electron transport was measured when carbon metabolism was completely inhibited which we take to be the maximum capacity of alternative electron sinks. Since the alternative sinks were small enough to ignore, the comparison of fluorescence and gas-exchange based methods for measuring the rate of electron transport could be used to estimate the mesophyll conductance to CO2 diffusion. The mesophyll conductance estimated this way fell as wheat flag leaves senesced. The age-related decline in photosynthesis may be attributed in part to the reduction of mesophyll conductance to CO2 diffusion and in part to the estimated decline of ribulose 1,5-bisphosphate carboxylase amount.
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    URL: http://dx.doi.org/10.1007/BF02183042
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    Changes in the photosynthetic light response curve during leaf development of field grown maize with implications for modelling canopy photosynthesis (1994)
    Springer
    Photosynthesis research 42 (1994), S. 217-225 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; leaf age ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the photosynthetic light-response curve during leaf development were determined for the fourth leaf of maize crops sown on 23 April and 10 June. Temperatures were unusually mild during late spring/early summer and neither crop experienced chilling damage. The concept of thermal time was used to take into account the effects of different temperature regimes on developmental stage, thereby enabling photosynthetic light-response data to be combined for both crops to describe the general response. Large variations in the upper asymptote (Asat) and convexity (Θ) of the light-response curve occurred during leaf development, but the maximum quantum yield of CO2 assimilation remained relatively constant throughout. Dark respiration rates showed a small but significant decrease with leaf age and generally ranged between 5 and 10% of Asat. A simple mathematical model was developed to assess the sensitivity of daily leaf photosynthesis (AL) to reductions in the Asat, Θ and the initial slope (Φ) of the light-response curve at different stages of leaf development. On bright sunny days, and at all developmental stages, AL was ca. twice as sensitive to reductions in Asat than to reductions in Φ and Θ. In overcast conditions, however, all three parameters contributed significantly to reductions in leaf photosynthesis, although the contribution of Φ was greatest during early leaf growth, while older leaves were most sensitive to depressions in Asat. The implications of these results for modelling the sensitivity of canopy photosynthesis to chill-induced photoinhibition of the light-response curve are discussed.
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    URL: http://dx.doi.org/10.1007/BF00018264
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    Questions about the complexity of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase (1999)
    Springer
    Photosynthesis research 60 (1999), S. 29-42 
    Details
    ISSN: 1573-5079
    Keywords: enzyme catalysis ; evolution ; genetic engineering ; photosynthesis ; protein assembly ; protein degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) has played a central role in our understanding of chloroplast biogenesis and photosynthesis. In particular, its catalysis of the rate-limiting step of CO2 fixation, and the mutual competition of CO2 and O2 at the active site, makes Rubisco a prime focus for genetically engineering an increase in photosynthetic productivity. Although it remains difficult to manipulate the chloroplast-encoded large subunit and nuclear-encoded small subunit of crop plants, much has been learned about the structure/function relationships of Rubisco by expressing prokaryotic genes in Escherichia coli or by exploiting classical genetics and chloroplast transformation of the green alga Chlamydomonas reinhardtii. However, the complexity of chloroplast Rubisco in land plants cannot be completely addressed with the existing model organisms. Two subunits encoded in different genetic compartments have coevolved in the formation of the Rubisco holoenzyme, but the function of the small subunit remains largely unknown. The subunits are posttranslationally modified, assembled via a complex process, and degraded in regulated ways. There is also a second chloroplast protein, Rubisco activase, that is responsible for removing inhibitory molecules from the large-subunit active site. Many of these complex interactions and processes display species specificity. This means that attempts to engineer or discover a better Rubisco may be futile if one cannot transfer the better enzyme to a compatible host. We must frame the questions that address this problem of chloroplast-Rubisco complexity. We must work harder to find the answers.
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    URL: http://dx.doi.org/10.1023/A:1006240202051
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    Part of the fluorescence of chlorophyll a may originate in excited triplet states (1999)
    Springer
    Photosynthesis research 60 (1999), S. 165-177 
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    ISSN: 1573-5079
    Keywords: absorption ; Kennard–Stepanov theory ; photosynthesis ; spectral equilibration ; thermal equilibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Absorption and fluorescence spectra of chlorophyll a have been analyzed on the basis of an extended version of Kennard–Stepanov (KS) theory. It is proposed that at least one new electronic state lies just below the normal S1 − S0 transition (Qy), borrowing approximately 2–4% of its strength and contributing to the fluorescence in the tail. The KS anomalies leading to this hypothesis occur in a wide variety of cases, including chlorophyll a in solution and protein-bound chlorophyll a, suggesting that the phenomenon is an intrinsic property of the molecule. Natural candidates for the new state(s) are the second and third triplet states. The relationship of the fluorescence excitation spectrum to KS theory is investigated and applied to explain a red drop in yield.
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    URL: http://dx.doi.org/10.1023/A:1006284510090
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    Molecular rearrangements of thylakoids after heavy metal poisoning, as seen by Fourier transform infrared (FTIR) and electron spin resonance (ESR) spectroscopy (1999)
    Springer
    Photosynthesis research 61 (1999), S. 241-252 
    Details
    ISSN: 1573-5079
    Keywords: ESR ; electron transport ; FTIR ; lipid ; membrane structure ; protein ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The specific effects exerted by different heavy metals on both the function and the structure of the photosynthetic apparatus were addressed. The functional analysis performed via the fluorescence induction kinetics revealed that the applied toxic heavy metals can be classified into two groups: Cd and Ni had no significant effect on the photosynthetic electron transport, while Cu, Pb and Zn strongly inhibited the Photosystem II (PS II) activity, as evidenced by the dramatic decreases in both the variable (Fv) and the maximal (Fm) fluorescence. The structural effects of the heavy metal ions on the thylakoid membranes were considered in three relations: (1) lipids, (2) proteins — studied by Fourier transform infrared (FTIR) spectroscopy, and (3) lipid—protein interactions — investigated by electron spin resonance (ESR) spectroscopy using spin-labeled probe molecules. The studied heavy metal ions had only a non-specific rigidifying effect on the thylakoid lipids. As regards proteins, Cd and Ni had no effect on the course of their heat denaturation. The heat denaturation of the proteins was accompanied by a decrease in the α-helix content (1656 cm-1), a parallel increase in the disordered segments (1651 cm-1), a decrease in the intramolecular β-sheet (1636 cm-1) content and the concomitant appearance of an intermolecular β-structure (1621 cm-1). In contrast with Cd and Ni, Cu and Zn blocked the appearance of the intermolecular β-structure. Pb represented an intermediate case. It seems that these heavy metals alter the native membrane structure in such a way that heat-induced aggregation becomes more limited. The ESR data revealed that certain heavy metals also affect the lipid—protein interactions. While Cd and Ni had hardly any effect on the solvation fraction of thylakoid lipids, Cu, Pb and Zn increased the fraction of lipids solvating the proteins. On the basis of the FTIR and ESR data, it seems that Cu, Pb, and Zn increase the surfaces available for lipid—protein interactions by dissociating membrane protein complexes, and that these ‘lipidated’ proteins have a smaller chance to aggregate upon heat denaturation. The data presented here indicate that the damaging effects of poisonous heavy metals are element-specific, Cu, Pb and Zn interact directly with the thylakoid membranes of the photosynthetic apparatus, while Cd and Ni interfere rather with other metabolic processes of plants.
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    Homeostatic regulation upon changes of enzyme activities in the Calvin cycle as an example for general mechanisms of flux control. What can we expect from transgenic plants? (1999)
    Springer
    Photosynthesis research 61 (1999), S. 227-239 
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    ISSN: 1573-5079
    Keywords: CO2 assimilation ; metabolic control analysis ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to explain the mechanisms of Calvin-cycle regulation, the general properties of metabolic systems under homeostatic flux control are analyzed. It is shown that the main characteristic point for an enzyme in such a system can be the value of a sharp transition from some constant homeostatic flux to a limitation by this enzyme. A special method for the quantitative treatment of the experimental dependence of a metabolic flux such as photosynthesis on enzyme content is developed. It is pointed out that reactions close to a thermodynamic equilibrium under normal conditions can considerably limit the homeostatic fluxes with a decrease of the enzyme content. Calvin-cycle enzymes are classified as non-limiting, near-limiting and limiting. The deduced rules for the regulation of a homeostatic metabolic pathway are used to explain the data obtained for transgenic plants with reduced activities of Calvin-cycle enzymes. The role of compensating mechanisms that maintain the photosynthesis rate constant upon the changes of enzyme contents is analyzed for the Calvin cycle. The developed analysis explains the sharp transitions between limiting and non-limiting conditions that can be seen in transgenic plants with reduced content of some Calvin-cycle enzymes, and the limiting role of such reversible enzymes as aldolase, transketolase and others. The attempt is made to predict the properties of plants with increased enzyme contents in the Calvin cycle.
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    URL: http://dx.doi.org/10.1023/A:1006342812049
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    Microbial ribulose 1,5-bisphosphate carboxylase/oxygenase: A different perspective (1999)
    Springer
    Photosynthesis research 60 (1999), S. 1-28 
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    ISSN: 1573-5079
    Keywords: biodiversity ; carboxylase ; genetic selection ; photosynthesis ; regulation ; specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Marine and terrestrial photosynthetic and chemoautotrophic microorganisms assimilate considerable amounts of carbon dioxide. Like green plastids, the predominant means by which this process occurs is via the Calvin-Benson-Bassham reductive pentose phosphate pathway, where ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) plays a paramount role. Recent findings indicate that this enzyme is subject to diverse means of control, including specific and elaborate means to guarantee its high rate and extent of synthesis. In addition, powerful and specific means to regulate Rubisco activity is a characteristic feature of many microbial systems. In many respects, the diverse properties of microbial Rubisco enzymes suggest interesting strategies to elucidate the molecular basis of CO2/O2 specificity, the ‘holy grail’ of Rubisco biochemistry. These systems thus provide, as the title suggests, ‘different perspectives’ to this fundamental problem. These include vast possibilities for imaginative biological selection using metabolically versatile organisms with well-defined genetic transfer capabilities to solve important issues of Rubisco specificity and molecular control. This review considers the major issues of Rubisco biochemistry and regulation in photosynthetic microoganisms including proteobacteria, cyanobacteria, marine nongreen algae, as well as other interesting prokaryotic and eukaryotic microbial systems recently shown to possess this enzyme.
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    URL: http://dx.doi.org/10.1023/A:1006211417981
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    Estimation of rate constants of the partial reactions of carboxylation of ribulose-1,5-bisphosphate in vivo (1999)
    Springer
    Photosynthesis research 60 (1999), S. 247-256 
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    ISSN: 1573-5079
    Keywords: irradiance ; kinetics ; method ; photosynthesis ; regulation ; rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An in vivo method for the estimation of kinetic parameters of partial reactions of carboxylation of ribulose 1,5-bisphosphate (RuBP) catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is described. Rubisco in barley, wheat and bean is different in the ability of its active centers to bind RuBP. The rate constant of the formation of the Rubisco-RuBP complex in these plants at 25 °C is 0.414, 0.245 and 0.660 mM-1 s-1, respectively. The rate constant of the reaction of the Rubisco-bound enediol with CO2 does not differ significantly in barley and wheat, and averages 66 mM-1 s-1. Decreased irradiance inhibits Rubisco in two ways: by reducing the concentration of operating catalytic sites and by decreasing the rate constant of binding of RuBP to Rubisco. High concentrations of CO2 inhibit Rubisco by decreasing the concentration of competent carboxylation centers, without any s ignificant influence upon the rate constants of partial reactions.
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    Modification of electron transfer from the quinone electron carrier, A1, of Photosystem 1 in a site directed mutant D576→L within the Fe-Sx binding site of PsaA and in second site suppressors of the mutation in Chlamydomonas reinhardtii (1999)
    Springer
    Photosynthesis research 61 (1999), S. 33-42 
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    ISSN: 1573-5079
    Keywords: EPR ; iron-sulphur ; photosynthesis ; P700 ; reaction center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A site directed mutant of the Photosystem I reaction center of Chlamydomonas reinhardtii has been described previously. [Hallahan et al. (1995) Photosynth Res 46: 257–264]. The mutation, PsaA: D576L, changes the conserved aspartate residue adjacent to one of the cysteine ligands binding the Fe-SX center to PsaA. The mutation, which prevents photosynthetic growth, was observed to change the EPR spectrum of the Fe-SA/B centers bound to the PsaC subunit. We suggested that changes in binding of PsaC to the PsaA/PsaB reaction center prevented efficient electron transfer. Second site suppressors of the mutation have now been isolated which have recovered the ability to grow photosynthetically. DNA analysis of four suppressor strains showed the original D576L mutation is intact, and that no mutations are present elsewhere within the Fe-SX binding region of either PsaA or PsaB, nor within PsaC or PsaJ. Subsequent genetic analysis has indicated that the suppressor mutation(s) is nuclear encoded. The suppressors retain the altered binding of PsaC, indicating that this change is not the cause of failure to grow photosynthetically. Further analysis showed that the rate of electron transfer from the quinone electron carrier A1 to Fe-SX is slowed in the mutant (by a factor of approximately two) and restored to wild type rates in the suppressors. ENDOR spectra of A1 ·– in wild-type and mutant preparations are identical, indicating that the electronic structure of the phyllosemiquinone is not changed. The results suggest that the quinone to Fe-SX center electron transfer is sensitive to the structure of the iron-sulfur center, and may be a critical step in the energy conversion process. They also indicate that the structure of the reaction center may be modified as a result of changes in proteins outside the core of the reaction center.
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    URL: http://dx.doi.org/10.1023/A:1006205811407
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    Effects of growth-light quantity, growth-light quality and CO2 concentration on Rubisco deactivation during low PFD or darkness (1999)
    Springer
    Photosynthesis research 61 (1999), S. 65-75 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; photosynthetic induction ; sunflecks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of CO2 concentration and the effects of growth-light conditions on Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) deactivation were examined for Spinacea oleracea (spinach). Rubisco deactivation kinetics and the degree that Rubisco activation limited the rise in photosynthesis following an increase in photon flux density (PFD) were determined from gas-exchange time courses. There were no significant differences in the apparent relaxation time for Rubisco deactivation among leaves exposed to high or low CO2 (50 or 1000 μmol mol-1) and low PFD (170 μmol m-2 s-1) or darkness. However, when PFD was increased to 1700 μmol m-2 s-1 following a period of low PFD or darkness, leaves exposed to low CO2 × low PFD showed a lower contribution to the photosynthetic induction process by the activation of Rubisco than leaves exposed to the other treatments. For the growth-light experiments, spinach was grown under high PFD × high red:far-red ratio (R:FR), low PFD × high R:FR, or low PFD × low R:FR light environments. Leaves that matured under the low PFD × low R:FR treatment showed a lower percent change in photosynthesis due to Rubisco activation than leaves exposed to the other growth-light treatments. However, there were no significant differences among the growth-light treatments in the maximum contribution of Rubisco activation to the induction response or in the apparent relaxation time for Rubisco deactivation during shade events.
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    Relationship of CO2 concentrations to photosynthesis of intertidal macroalgae during emersion (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 355-359 
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    ISSN: 1573-5117
    Keywords: CO2 ; emersion ; macroalgae ; photosynthesis ; seaweeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to assess the ecological impacts of the atmospheric CO2 increase on the intertidal macroalgae during emersion, the photosynthesis of Enteromorpha linza (a green alga), Ishige okamurae (a brown alga) and Gloiopeltis furcata (a red alga) was investigated in air as a function of CO2 concentrations and water loss. Their photosynthesis was not saturated at the present atmospheric CO2 level (350 μl l −1 or 15.6 μM), the CO2 compensation point and $$K_{[{\text{mCO}}_{\text{2}} ]} $$ increased with increasing desiccation, showing that desiccation lowers the CO2 affinity of the intertidal macroalgae. It was concluded that E. linza, I. okamurae and G. furcata, while exposed to air, can benefit from atmospheric CO2 rise, especially when the algae have lost some water.
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    URL: http://dx.doi.org/10.1023/A:1017072303189
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    Photosynthetic and respiratory responses of the agarophyte Gelidiella acerosa collected from tidepool, intertidal and subtidal habitats (1999)
    Springer
    Hydrobiologia 398-399 (1999), S. 321-328 
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    ISSN: 1573-5117
    Keywords: photosynthesis ; respiration ; Gelidiella acerosa ; culture ; tidal habitat ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several samples of the red seaweed, Gelidiella acerosa (Forssk.) Feldmann & Hamel occurring in tidepools, high intertidal rocks, and shallow subtidal areas on a reef flat in Ilocos Norte, northern Philippines were studied in terms of their photosynthetic and respiratory responses (μl O2 gDW−1 h−1) to four salinity (22, 28, 34, 40‰) and three temperature (22, 28, 34 °C) combinations. The upper intertidal plants tolerated low salinities (22–28‰) better than high salinities (34–40‰), while tidepool and subtidal plants were not affected. Temperatures of 22 through 34 °C resulted in a one-fold increase in their photosynthetic rates and insignificant differences in their respiratory rates while tidepool and subtidal plants almost doubled their photosynthetic rates and their respiration rates increased by about 5–50 times. There were no interaction effects. Therefore, intertidal plants appe ared to be more tolerant to wide temperature fluctuations and low salinity levels; while tidepool and subtidal plants were least affected by salinity variations but were quite sensitive to temperature fluctuations. Vegetative and tetrasporic plants had similar photosynthetic and respiratory responses to salinity and temperature variations, although vegetative plants had significantly higher net photosynthesis under the minimum and maximum temperatures tested (22 and 34 °C). Reproductive G. acerosa showed greater tolerance to temperature fluctuations. These responses indicated that physiological changes may have occurred when the species became reproductive. Tolerance of G. acerosa to low salinities suggests that lowering the salinities in culture tanks could be used to eradicate contaminants, i.e., dinoflagellates and filamentous green algae. Temperature of 28 °C appeared to be optimum for all plant types as reflected by their high photosynthetic and low respiratory rates .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017024421845
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  • 86
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    Cd/Fe Interaction in Higher Plants - Its Consequences for the Photosynthetic Apparatus (1999)
    Springer
    Photosynthetica 36 (1999), S. 321-331 
    Details
    ISSN: 1573-9058
    Keywords: Calvin cycle enzymes ; chlorophyll ; chloroplast structure ; heavy metals ; photosynthesis ; photosystems ; plant growth ; uptake of mineral elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cadmium is one of the most dangerous environmental pollutants, affecting, among other things, plant mineral composition. It easily interacts with iron, one of the most important elements for plant growth and metabolism. This interaction, including modifying effects of lowered or excessive Fe supply on Cd-exposed plants and its consequences for the photosynthetic apparatus is reviewed. The influence of modified Fe and Cd supply on the uptake of both metals, their distribution, plant growth, and photosynthesis is also explained. Moderate Fe excess has a beneficial influence on Cd-treated plants, resulting in more intensive growth, photosynthetic pigments accumulation, and more efficient light phase of photosynthesis. Nutrient-medium Fe deficiency increases plant susceptibility to Cd. The main open questions of Cd/Fe interaction are: (1) the strong Fe-dependency of Cd mobility within the plant, and (2) photosynthetic dark phase adaptation to Cd stress.
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    URL: http://dx.doi.org/10.1023/A:1007097518297
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  • 87
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    The Development of Chloroplast Ultrastructure and Hill Reaction Activity During Leaf Ontogeny in Different Maize (Zea Mays L.) Genotypes (1999)
    Springer
    Photosynthetica 36 (1999), S. 497-507 
    Details
    ISSN: 1573-9058
    Keywords: chloroplast dimensions ; electron microscopy ; peripheral reticulum ; photosynthesis ; plastoglobuli ; starch ; stereology ; stroma ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in Hill reaction activity (HRA) and ultrastructure of mesophyll cell (MC) chloroplasts were studied during the ontogeny of third leaf of maize plants using polarographic oxygen evolution measurement, transmission electron microscopy, and stereology. The chloroplast ultrastructure was compared in young (actively growing), mature, and senescing leaves of two different inbreds and their reciprocal F1 hybrids. Statistically significant differences in both HRA and MC chloroplast ultrastructure were observed between different stages of leaf ontogeny. Growth of plastoglobuli was the most striking characteristic of chloroplast maturation and senescence. The chloroplasts in mature and senescing leaves had a more developed system of thylakoids compared to the young leaves. Higher HRA was usually connected with higher thylakoid volume density of MC chloroplasts.
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    URL: http://dx.doi.org/10.1023/A:1007031818695
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  • 88
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    Carbon Balance of a Winter Wheat-Root Microbiota System Under Elevated CO2 (1999)
    Springer
    Photosynthetica 36 (1999), S. 341-354 
    Details
    ISSN: 1573-9058
    Keywords: carbon partitioning ; photosynthesis ; plant growth ; microbial biomass ; respiration rate ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the carbon budget of young winter wheat plants and their associated microorganisms as affected by a doubling of the atmospheric CO2 concentration (700 µmol mol-1). Plants were grown hydroponically in pre-sterilised sand at a controlled irradiance and temperature regime. Net photosynthesis (PN) and respiration (RD) rates of roots and shoots were measured continuously, plant growth and carbon distribution in the plant-root medium-associated microorganism system were determined destructively in interval-based analyses. PN in elevated CO2 grown plants (EC) was 123% of that in the control (AC) plants when averaged over the whole life span (39-d-old plants, 34 d in EC), but the percentage varied with the developmental stage being 115, 88, and 167% in the pretillering, tillering, and posttillering phase, respectively. There was a transient depression of PN, higher amplitude of day/night fluctuations of the chloroplast starch content, and depression of carbon content in rhizosphere of EC plants during the period of tillering. After 34 d in EC, carbon content in shoots, roots, and in rhizodepositions was enhanced by the factors 1.05, 1.28, and 1.96, respectively. Carbon partitioning between above and belowground biomass was not affected by EC, however, proportionally more C in the belowground partitioning was allocated into the root biomass. Carbon flow from roots to rhizodepositions and rhizosphere microflora was proportional to PN; its fraction in daily assimilated carbon decreased from young (17%) to order (3-4%) plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007081419206
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  • 89
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    Perpetual Adaptation in a Perpetually Changing Environment as a Survival Strategy of Plants: A Case Study in Foraminifers Concerning Coral Reef Bleaching (1999)
    Springer
    Photosynthetica 37 (1999), S. 71-85 
    Details
    ISSN: 1573-9058
    Keywords: Amphisorus ; Amphistegina ; chlorophyll fluorescence kinetics ; electron transport ; irradiance ; photosynthesis ; photosystem 2 ; quantum yield ; Sorites ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coral reef bleaching is a global phenomenon poorly understood today. We investigated during 7 d the photosynthetic behaviour of symbionts of coral reef and temperate foraminifers in hospite, by means of the JIP-test. By this screening test the fast fluorescence rise O-J-I-P, measured by a Plant Efficiency Analyser (PEA) with 10 µs time resolution and 12 bit signal resolution, was analysed. It informs about the structure and function of photosystem 2 being at different physiological states established by adaptation to different irradiance and temperature. The test needs a measuring time in vivo of only 1 to 5 s, and thus many samples can be analysed. The measurements can be done continuously even on a single cell in a test tube or on the reef. The reef foraminifers tested here were Amphistegina and Amphisorus, freshly collected in Mauritius. As a temperate foraminifer, Sorites from the Mediterranean Sea was tested. The cells are very sensitive to slight temperature changes (25 to 32 °C). The comparison showed that the more the foraminifers live in an environment with constant temperature the less they are able to respond to temperature changes and, thus, the less they can adapt. Rising the temperature increases in general the sensitivity to different stress factors, such as high irradiance, pH, CO2, etc. After the test series, the cells recovered fully and were kept in an aquarium for long time observation.
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    URL: http://dx.doi.org/10.1023/A:1007070913866
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  • 90
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    Effects of Inorganic Nitrogen Availability on the Sporophytes of Acrostichum Aureum L. (1999)
    Springer
    Photosynthetica 36 (1999), S. 259-266 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll fluorescence ; fern ; fertilization ; growth ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants grown at low irradiance were fertilized with 0, 60, and 600 g m-3 NH4NO3 once every fortnight. Plants treated with high N concentrations showed an increased growth, producing longer and broader fronds with larger areas, and were darker green in colour. Nitrogen also increased the content of chlorophyll (Chl) and carotenoids per leaf area unit. Different N treatments did not affect the photosynthetic efficiency of photosystem 2, as reflected by the high values of Chl fluorescence kinetics Fv/Fm, ranging between 0.81 to 0.84, and Fv/F0 of 4.30 to 5.10. An increase in photochemical quenching (qP), accompanied by a decrease in non-photochemical quenching (qN), was observed in sporophytes fertilized with increased concentrations of NH4NO3. Nitrogen availability allowed sporophytes of Acrostichum aureum to become more established under natural condi tions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007055812264
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  • 91
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    Ecophysiological Responses to Neighbor Removal in an Old-Field and a Prairie in Northeastern Kansas, USA (1999)
    Springer
    Photosynthetica 36 (1999), S. 471-476 
    Details
    ISSN: 1573-9058
    Keywords: Ambrosia trifida ; Apocynum cannabinum ; Aster pilosus ; competition ; Eryngium yuccifolium ; Lespedeza capitata ; photosynthesis ; Solidago canadensis ; stomatal conductance ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ecophysiological approach was used to determine if competition can be detected among plants in a recently abandoned old-field and in a native tallgrass prairie in northeastern Kansas. In situ photosynthetic parameters and water potentials (Ψ) of target plants were measured 1-2 d after neighbor (intra- and interspecific) removal as well as 1-4 weeks later, and compared with values for plants with neighbors. Only two of the six study species (four old-field and two prairie species) responded to removal of neighboring plants, and only after several weeks had elapsed. Net photosynthetic rates (PN) and stomatal conductances (gs) of Ambrosia trifida in an old-field increased after removal of both intra- and interspecific neighbors. For Apocynum cannabinum, another old-field species, PN of target plants without neighbors was significantly higher than that of target plants with neighbors. For both these species, values of Ψ were not different between target plants with and without neighbors, suggesting that increased availability of nutrients may have been responsible for the observed ecophysiological responses. Though numerous past studies indicate that competition is a major factor influencing plants in old-field and in prairie communities, the experimental approach used in this study revealed that neighbor removal had only limited effects on ecophysiology of the target plants in either community.
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    URL: http://dx.doi.org/10.1023/A:1007040506838
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  • 92
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    Gas Exchange and Chlorophyll Fluorescence in Symbiotic and Non-Symbiotic Ryegrass Under Water Stress (1999)
    Springer
    Photosynthetica 37 (1999), S. 107-112 
    Details
    ISSN: 1573-9058
    Keywords: endophyte ; Lolium perenne ; Neotyphodium lolii ; photosynthesis ; stomatal conductance ; transpiration rate ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The symbiotic association of endophyte fungus, Neotyphodium lolii, and ryegrass improves the ryegrass resistance to drought. This is shown by a 30 % increase in the number of suckers in infected plants (E+), compared to plants lacking endophyte (E−), and by a higher water potential in the E+ than E− plants. The E+ plants have higher stomatal conductance (g s), transpiration rate, net photosynthetic rate (P N), and photorespiratory electron transport rate than the E− plants. The maximal photochemical efficiency (Fv/Fm) and the actual photochemical efficiency (ΦPS2) are not affected by the endophyte fungus. The increase in P N of the E+ plants subjected to water stress was independent from internal CO2 concentration. An increased P N was observed in E+ plants also in optimal water supply. Hence the drought resistance of E+ plants results in increased g s, P N, and photorespiratory electron transport rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007027131613
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  • 93
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    Differences in Field Gas Exchange and Water Relations Between a C3 Dicot (Plantago Asiatica) and a C4 Monocot (Eleusine Indica) (1999)
    Springer
    Photosynthetica 37 (1999), S. 123-130 
    Details
    ISSN: 1573-9058
    Keywords: diurnal pattern ; intercellular CO2 concentration ; leaf conductance ; leaf water potential ; micro-habitat ; photosynthesis ; seasonal dominance ; soil-to-leaf hydraulic conductance ; trampling tolerance ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field gas exchange and water potential in the leaves of a C3 dicot, Plantago asiatica L., and a C4 monocot, Eleusine indica Gaertn., which dominate in trampled vegetation in eastern Japan were surveyed during the growing periods for two consecutive years. Net photosynthetic rate (P N) of E. indica increased with photosynthetic photon flux density (PPFD) and leaf temperature (TL). P N was not saturated at PPFDs above 1500 µmol m−2 s−1 and at TL above 30 °C. On a sunny day in mid summer, maximum P N was two times higher in E. indica than in P. asiatica [42 vs. 20 µmol(CO2) m−2 s−1], but their transpiration rate (E) and the leaf water potential (ΨL) were similar. Soil-to-leaf hydraulic conductance, which probably plays a role in water absorption from the trampled compact soil, was higher in E. indica than in P. asiatica. The differences in photosynthetic traits between E. indica explain why E. indica communities more commonly develop at heavily trampled sites in summer than the P. asiatica communities.
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    URL: http://dx.doi.org/10.1023/A:1007031332521
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  • 94
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    Among-Provenance Variability of Gas Exchange and Growth in Response to Long-Term Elevated CO2 Exposure (1999)
    Springer
    Water, air & soil pollution 116 (1999), S. 403-412 
    Details
    ISSN: 1573-2932
    Keywords: Genetic variability ; elevated CO2 ; climate change ; pine ; conifer ; photosynthesis ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Genetic variability can have profound effects on the interpretation of results from elevated CO2 studies, and future forest management decisions. Information on which varieties are best suited to future atmospheric conditions is needed to develop future forest management practices. A large-scale screening study of the effects of elevated CO2 on 15 half-sibling sources of genetically superior ponderosa pine (Pinus ponderosa Dougl ex P. Laws.) is presented. These sources represent multiple elevations and latitudes throughout California. Among-provenance variability in the effects of elevated CO2 on gas exchange and growth, and their correlation with geographic origin were investigated in ponderosa pine seedlings subjected to ambient or elevated CO2 concentrations (525 μmol mol-1 CO2, and 700 μmol mol-1 CO2) for more than two years in open-top chambers. Substantial among-provenance variability in growth response to elevated CO2 was evident, with 8 sources demonstrating no significant growth response to elevated CO2 while 7 sources responded positively. For all sources, elevated CO2 increased photosynthesis (ranging from 19% increase at 525 μmol mol-1 CO2 to 49% increase at 700 μmol mol-1 CO2). A modest correlation existed between geographic origin and above ground growth response to elevated CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005203024884
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    Mechanisms of Hydroquinone-Induced Growth Reduction in Leafy Spurge (1999)
    Springer
    Journal of chemical ecology 25 (1999), S. 1611-1621 
    Details
    ISSN: 1573-1561
    Keywords: Hydroquinone ; allelopathy ; plant water balance ; photosynthesis ; chlorophyll fluorescence ; 13C isotopes ; leafy spurge ; Euphorbia esula ; small everlasting ; Antennaria microphylla Rydb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Field observations indicate leafy spurge (Euphorbia esula) is inhibited by the presence of Antennaria microphylla. Hydroquinone (HQ), one of several compounds isolated from A. microphylla has been shown to inhibit leafy spurge seed germination, root elongation, and callus culture growth. The present study was designed to analyze the effects of HQ on water relations and photosynthesis of leafy spurge. Plants grown in 0.25 mM HQ had consistently higher leaf diffusive resistance and lower transpiration rates than control plants (P 〈 0.05). Chlorophyll fluorescence was significantly lower than controls (P 〈 0.05) towards the end of the treatment period. At the end of the treatment, tissue from 0.25 mM HQ plants had higher levels of 13C, indicating there had been a sustained interference with stomatal function. These data suggest that a disruption of the plant water balance is one mechanism of leafy spurge inhibition by A. microphylla.
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    URL: http://dx.doi.org/10.1023/A:1020892917434
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