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  • 1
    Electronic Resource
    Electronic Resource
    Assessing the impact of ozone on photosynthesis of European beech (Fergus sylvatica L.) in environmental chambers (1996)
    Springer
    Trees 10 (1996), S. 268-275 
    Details
    ISSN: 1432-2285
    Keywords: Beech ; Ozone ; Photosynthesis ; Closed chambers ; Critical Levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An exposure — response study with proportionalto-ambient ozone levels was conducted in closed chambers on 3-year-old European beech (Fagus sylvatica L.) of montane origin. The fumigation started in April 1990 and lasted for a single growing season. Climate data and ozone concentrations monitored at an experimental station of the Institute for Applied Plant Biology, Schönenbuch, Switzerland were simulated in the exposure chambers 12 days later (1*O3). To test exposure-response relations three additional treatments were applied, subambient (0.2*O3) and two proportionally increased ozone treatments (1.5*O3 and 2*O3). The photosynthetic behaviour of the trees in August revealed the light reactions to be less affected than parameters which are related to the dark reactions of photosynthesis. Assimilation (A350), apparent carboxylation efficiency (CE), and maximum photosynthetic capacity (A2500) were reduced with increasing ozone concentration. For the ozone response of CE and A2500 ‘Critical Levels’ were calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185679
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  • 2
    Electronic Resource
    Electronic Resource
    Assessing the impact of ozone on photosynthesis of European beech (Fagus sylvatica L .) in environmental chambers (1996)
    Springer
    Trees 10 (1996), S. 268-275 
    Details
    ISSN: 0931-1890
    Keywords: Key words Beech ; Ozone ; Photosynthesis ; Closed chambers ; Critical Levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  An exposure - response study with proportional-to-ambient ozone levels was conducted in closed chambers on 3-year-old European beech (Fagus sylvatica L.) of montane origin. The fumigation started in April 1990 and lasted for a single growing season. Climate data and ozone concentrations monitored at an experimental station of the Institute for Applied Plant Biology, Schönenbuch, Switzerland were simulated in the exposure chambers 12 days later (1*O3). To test exposure-response relations three additional treatments were applied, subambient (0.2*O3) and two proportionally increased ozone treatments (1.5*O3 and 2*O3). The photosynthetic behaviour of the trees in August revealed the light reactions to be less affected than parameters which are related to the dark reactions of photosynthesis. Assimilation (A350), apparent carboxylation efficiency (CE), and maximum photosynthetic capacity (A2500) were reduced with increasing ozone concentration. For the ozone response of CE and A2500′Critical Levels′ were calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185679
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The specific radioactivity of glycolic acid in relation to the specific activity of carbon dioxide evolved in light in photosynthesizing sunflower leaves (1978)
    Springer
    Planta 138 (1978), S. 257-261 
    Details
    ISSN: 1432-2048
    Keywords: Glycolic acid ; Helianthus ; Photosynthesis ; Photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Attached leaves of sunflower (Helianthus annuus L.) were exposed to 14CO2 during steady-state photosynthesis for 2 to 30 min in 345 μl/l CO2 and 21% O2 at 29° C and a light intensity of 1300 μE m-2s-1. Glycolic acid was extracted with water and diethyl ether, and was determined in the aqueous residue by high-pressure liquid column chromatography. The relative specific radioactivity of the glycolic acid synthesized during photosynthesis reached about 100% after 30 min of photosynthesis and was almost equal to that of the CO2 evolved during photorespiration, their ratio at all times being nearly one. These results provide strong in-vivo evidence that the glycolic acid is the substrate for CO2 evolved by sunflower leaves in light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386820
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  • 4
    Electronic Resource
    Electronic Resource
    Induction of intracellular carbonic anhydrases during the adaptation to low inorganic carbon concentrations in wild-type and ca-1 mutant cells of Chlamydomonas reinhardtii (1995)
    Springer
    Planta 196 (1995), S. 217-224 
    Details
    ISSN: 1432-2048
    Keywords: Carbonic anhydrase ; Chlamydomonas ; Carbon dioxide concentrating mechanism ; Photosynthesis ; Pyrenoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mass-spectrometric measurements of 18O exchange from 13C18O2 were used to follow changes in the intracellular carbonic anhydrase (CA) activity of cells of Chlamydomonas reinhardtii Dang, wild type and the ca-1 mutant during adaptation to air. With intact cells as well as with crude homogenates total intracellular CA activity in wild-type cells increased six to tenfold within 4 h after transferring cells from 5% CO2 (high inorganic carbon, Ci) to ambient air (air adapted). After that time the activity slowly declined to a level similar to that observed with cells which had been continuously grown in air (low-Ci grown). In the ca-1 mutant, total CA was induced to a similar extent during 4 h of adaptation; however, absolute activities were two to three times lower in ca-1 than in the wild type regardless of the CO2 supply. When crude extracts from wild-type cells were separated into soluble and insoluble fractions, each fraction contained about half of the internal CA activity. Within 4 h of adaptation, both forms of CA activity were simultaneously enhanced by nine to tenfold, reaching levels similar to those found in low-Cigrown cells. In contrast, in the ca-1 mutant the soluble CA activity was only enhanced by about eightfold while the level of insoluble CA was very low even in low-Ci cells. After isolation of intact chloroplasts from wild-type cells and further subfractionation, around 70–80% of total chloroplastic CA activity was found to be in the insoluble fraction while 17–20% remained in the soluble fraction. Both chloroplastic CA activities were inducible within the first 4 h of adaptation to air, with each of them being eight to ten times higher than in high-Ci algae. After that time their activities were similar to the corresponding CA values in low-Ci-grown cells. In contrast, plastids from high-Ci cells of the ca-1 mutant showed 40% less insoluble-CA activity compared to the wild type and this insoluble-CA activity was not increased at all by transferring algae to air. In addition, no soluble-CA activity was detected in chloroplasts from high-Ci and air-adapted ca-1 cells. These results indicate the presence of three intracellular CA activities in high-Ci air-adapted and low-Ci cells of the wild type and that two of them are associated with the chloroplasts. All three activities are completely induced within the first 4 h of adaptation to air in wild-type cells. In contrast, it was not possible to induce any of the chloroplastic CA activities in the ca-1 mutant. The possibility that the soluble chloroplastic CA represents a pyrenoid-located CA is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201377
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  • 5
    Electronic Resource
    Electronic Resource
    Reversible photoinhibition of unhardened and cold-acclimated spinach leaves at chilling temperatures (1990)
    Springer
    Planta 180 (1990), S. 181-187 
    Details
    ISSN: 1432-2048
    Keywords: Cold acclimation ; Electron transport ; Fluorescence of chlorophyll ; Photoinhibition ; Photosynthesis ; Spinacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photoinhibition of photosynthesis at chilling temperatures was investigated in cold-acclimated and unhardened (acclimated to +18° C) spinach (Spinacia oleracea L.) leaves. In unhardened leaves, reversible photoinhibition caused by exposure to moderate light at +4° C was based on reduced activity of photosystem (PS) II. This is shown by determination of quantum yield and capacity of electron transport in thylakoids isolated subsequent to photoinhibition and recovery treatments. The activity of PSII declined to approximately the same extent as the quantum yield of photosynthesis of photoinhibited leaves whereas PSI activity was only marginally affected. Leaves from plants acclimated to cold either in the field or in a growth chamber (+1° C), were considerably less susceptible to the light treatment. Only relatively high light levels led to photoinhibition, characterized by quenching of variable chlorophyll a fluorescence (FV) and slight inhibition of PSII-driven electron transport. Fluorescence data obtained at 77 K indicated that the photoinhibition of cold-acclimated leaves (like that of the unhardened ones) was related to increased thermal energy dissipation. But in contrast to the unhardened leaves, 77 K fluorescence of cold-acclimated leaves did not reveal a relative increase of PSI excitation. High-light-treated, cold-acclimated leaves showed increased rates of dark respiration and a higher light compensation point. The photoinhibitory fluorescence quenching was fully reversible in low light levels both at +18° C and +4° C; the recovery was much faster than in unhardened leaves. Reversible photoinhibition is discussed as a protective mechanism against excess light based on transformation of PSII reaction centers to fluorescence quenchers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193993
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  • 6
    Electronic Resource
    Electronic Resource
    Xanthophyll cycle and energy-dependent fluorescence quenching in leaves from pea plants grown under intermittent light (1994)
    Springer
    Planta 192 (1994), S. 176-182 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll a/b-binding protein ; Energy-dependent fluorescence quenching ; Intermittent light ; Photosynthesis ; Pisum ; Xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possible role of zeaxanthin formation and antenna proteins in energy-dependent chlorophyll fluorescence quenching (qE) has been investigated. Intermittent-light-grown pea (Pisum sativum L.) plants that lack most of the chlorophyll a/b antenna proteins exhibited a significantly reduced qE upon illumination with respect to control plants. On the other hand, the violaxanthin content related to the number of reaction centers and to xanthophyll cycle activity, i.e. the conversion of violaxanthin into zeaxanthin, was found to be increased in the antenna-protein-depleted plants. Western blot analyses indicated that, with the exception of CP 26, the content of all chlorophyll a/b-binding proteins in these plants is reduced to less than 10% of control values. The results indicate that chlorophyll a/b-binding antenna proteins are involved in the energy-dependent fluorescence quenching but that only a part of qE can be attributed to quenching by chlorophyll a/b-binding proteins. It seems very unlikely that xanthophylls are exclusively responsible for the qE mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194450
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  • 7
    Electronic Resource
    Electronic Resource
    Xanthophyll cycle and energy-dependent fluorescence quenching in leaves from pea plants grown under intermittent light (1994)
    Springer
    Planta 192 (1994), S. 176-182 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll a/b-binding protein ; Energy-dependent fluorescence quenching ; Intermittent light ; Photosynthesis ; Pisum ; Xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possible role of zeaxanthin formation and antenna proteins in energy-dependent chlorophyll fluorescence quenching (qE) has been investigated. Intermittent-light-grown pea (Pisum sativum L.) plants that lack most of the chlorophyll a/b antenna proteins exhibited a significantly reduced qE upon illumination with respect to control plants. On the other hand, the violaxanthin content related to the number of reaction centers and to xanthophyll cycle activity, i.e. the conversion of violaxanthin into zeaxanthin, was found to be increased in the antenna-protein-depleted plants. Western blot analyses indicated that, with the exception of CP 26, the content of all chlorophyll a/b-binding proteins in these plants is reduced to less than 10% of control values. The results indicate that chlorophyll a/b-binding antenna proteins are involved in the energy-dependent fluorescence quenching but that only a part of qE can be attributed to quenching by chlorophyll a/b-binding proteins. It seems very unlikely that xanthophylls are exclusively responsible for the qE mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01089032
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Intracellular carbonic anhydrase activities in Dunaliella tertiolecta (Butcher) and Chlamydomonas reinhardtii (Dangeard) in relation to inorganic carbon concentration during growth: further evidence for the existence of two distinct carbonic anhydrases associated with the chloroplasts (1996)
    Springer
    Planta 199 (1996), S. 177-184 
    Details
    ISSN: 1432-2048
    Keywords: Carbonic anhydrase ; Chlamydomonas ; CO2 concentrating mechanism ; Dunaliella ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using mass-spectrometric measurements of 18O exchange from 13C18O2 intracellular carbonic anhydrase (CA) activity was investigated in the unicellular green algae Dunaliella tertiolecta and Chlamydomonas reinhardtii which were either grown on air enriched with 5% CO2 (high-Ci cells) or on air (low-Ci cells). In D. tertiolecta high- and low-Ci cells had detectable levels of internal CA activity when measured under in-vivo conditions and this activity could be split up into three distinct forms. One CA was not associated with the chloroplasts, while two isozymes were found to be located within the plastids. The activities of all intracellular CAs were always about twofold higher in low than in high-Ci cells of D. tertiolecta and the chloroplastic enzymes were completely induced within 4 h of adaptation to air. One of the chloroplastic CAs was found to be soluble the other was insoluble. In addition to the physical differences, MgSO4 in vitro caused a more than twofold stimulation of the soluble activity while the insoluble form of CA remained rather unaffected. In C. reinhardtii, MgSO4 increased the soluble CA activity by 346% and the concentration of MgSO4 required for half-maximum stimulation was between 10 and 15 mM. Again, the insoluble CA activity was not affected by MgSO4. Furthermore, the soluble isoenzyme was considerably more sensitive to ethoxyzolamide, a potent inhibitor of CA, than the insoluble enzyme. The concentration of inhibitor causing 50% inhibition of soluble CA activity was 110 and 85 μM ethoxyzolamide for D. tertiolecta and C. reinhardtii, respectively. From these data we conclude that the two chloroplast-associated CAs are distinct enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196557
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