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  • Articles  (13)
  • photosynthesis
  • Springer  (13)
  • American Meteorological Society
  • 1995-1999  (2)
  • 1990-1994  (11)
  • 1965-1969
  • 1955-1959
  • Chemistry and Pharmacology  (13)
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  • Articles  (13)
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  • 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
    Assessment of Hg2+ toxicity to a N2-fixing cyanobacterium in long- and short-term experiments (1992)
    Springer
    BioMetals 5 (1992), S. 149-156 
    Details
    ISSN: 1572-8773
    Keywords: Hg2+ toxicity ; cyanobacterium ; Nostoc calcicola ; growth ; photopigments ; nucleic acids ; photosynthesis ; membrane integrity ; nutrient uptake ; enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Toxicological responses of the filamentous N2-fixing cyanobacteriumNostoc calcicola Bréb. towards Hg2+ were studied to enumerate the decisive lethal events. In low-dose, long-term experiments (0.05–0.25 μm Hg2+, 10 days), photoautotrophic growth was severely inhibited with concurrent loss of photosynthetic pigments (phycocyanin〉chlorophyll α〉carotenoids) and nucleic acids. The termination of growth after a day 4 exposure to 0.25 μm Hg2+ has been attributed to the complete inhibition ofin vivo photosynthetic activity in the cyanobacterium (O2 evolution〉14CO2 incorporation). The elevated Hg2+ concentrations irreversibly damaged the cell membrance as observed under light microscopy, and as indicated by the leakage of intracellular electrolytes and phycocyanin. In high-dose, short-term experiments (0.5–20.0 μm Hg2+, up to 6 h), thein vivo activities of selected enzymes (glutamine synthetase 〉 nitrate reductase 〉 nitrogenase) were less inhibited by Hg2+ than the uptake of nutrient ions (NH 4 + 〉NO 3 − 〉PO 4 3− ).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01061321
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of juglone on growth, photosynthesis, and respiration (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 559-568 
    Details
    ISSN: 1573-1561
    Keywords: Juglone ; allelopathy ; allelochemical ; photosynthesis ; chioroplast ; mitochondria ; Lemna minor ; Glycine max
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The impacts of juglone on plant growth and several other physiological functions were evaluated in this study. Juglone inhibitedLemna minor growth, chlorophyll content, and net photosynthesis at treatments between 10 and 40μM. Soybean leaf disks vacuum infiltrated with as little as 10μM juglone had reduced photosynthesis. Oxygen evolution by chloroplasts isolated fromPisum sativum was inhibited by juglone with an I50 of 2μM. Micromolar treatments of juglone stimulated oxygen uptake in mitochondria isolated fromGlycine max. These data suggest perturbations of chloroplast and mitochondrial functions may contribute to plant growth reductions observed in juglone-mediated allelopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00994325
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  • 4
    Electronic Resource
    Electronic Resource
    The osmochemistry of electron-transfer complexes (1991)
    Springer
    Bioscience reports 11 (1991), S. 539-571 
    Details
    ISSN: 1573-4935
    Keywords: proton translocation ; respiration ; photosynthesis ; quinones ; bc complexes ; cytochrome oxidase ; NADH-quinone oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Detailed molecular mechanisms of electron transfer-driven translocation of ions and of the generation of electric fields across biological membranes are beginning to emerge. The ideas inherent in the early formulations of the chemiosmotic hypothesis have provided the framework for this understanding and have also been seminal in promoting many of the experimental approaches which have been successfully used. This article is an attempt to review present understanding of the structures and mechanisms of several osmoenzymes of central importance and to identify and define the underlying features which might be of general relevance to the study of chemiosmotic devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01130217
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  • 5
    Electronic Resource
    Electronic Resource
    Dimerization constant and single-channel conductance of Gramicidin in thylakoid membranes (1992)
    Springer
    The journal of membrane biology 126 (1992), S. 265-275 
    Details
    ISSN: 1432-1424
    Keywords: photosynthesis ; thylakoids ; electrochromism ; gramicidin ; conductance ; dimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effect of the pore-forming antibiotic gramicidin on pure lipid membranes is well characterized. We studied its action in protein-rich thylakoid membranes that contain less than 25% (wt/wt) acyl lipids. A transmembrane voltage was induced by flashing light, and its decay was measured and interpreted to yield the distribution of gramicidin over thylakoids, its dimerization constant and its single-channel conductance in this membrane. The distribution of gramicidin over the ensemble of thylakoids was immediately homogeneous when the antibiotic was added under stirring, while it became homogeneous only after 20 min in a stirred suspension that was initially heterogeneous. The dimerization constant, 5×1014 cm2/mol, was about 10 times larger than in pure lipid membranes. This was attributed to the upconcentration of gramicidin in the small fractional area of protein free lipid bilayer and further by a preference of gramicidin for stacked portions of the membrane. The latter bears important consequences with regard to bioenergetic studies with this ionophore. As gramicidin was largely dimerized from a concentration of 1 nm (in the suspension) on, the membrane's conductance then increased linearly as a function of added gramicidin. When the negative surface potential at the thylakoid membrane was screened, the conductance of a single gramicidin dimer agreed well with figures reported for bilayers from neutral lipid (about 0.5 pS at 10 mm NaCl). The modulation of the conductance by the surface potential in spinach versus pea thylakoids and between different preparations is discussed in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232323
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  • 6
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020280710067
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  • 7
    Electronic Resource
    Electronic Resource
    The role of plasma membrane redox activity in light effects in plants (1991)
    Springer
    Journal of bioenergetics and biomembranes 23 (1991), S. 393-408 
    Details
    ISSN: 1573-6881
    Keywords: Signal transduction ; photosynthesis ; blue light ; plasma membrane redox ; light-induced absorbance change ; flavin ; cytochromeb ; sphingoid bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Stimulations by light of electron transport at the plasma membrane make it possible that redox activity is involved in light-induced signal transduction chains. This is especially true in cases where component(s) of the chain are also located at the plasma membrane. Photosynthetic reactions stimulate transplasma membrane redox activity of mesophyll cells. Activity is measured as a reduction of the nonpermeating redox probe, ferricyanide. The stimulation is due to production of a cytosolic electron donor from a substance(s) transported from the chloroplast. It is unknown whether the stimulation of redox activity is a requirement for other photosynthetically stimulated processes at the plasma membrane, but a reduced intermediate may regulate proton excretion by guard cells. Blue light induces an absorbance change (LIAC) at the plasma membrane whose difference spectrum resembles certainb-type cytochromes. This transport of electrons may be due to absorption of light by a flavoprotein. The LIAC has been implicated as an early step in certain blue light-mediated morphogenic events. Unrelated to photosynthesis, blue light also stimulates electron transport at the plasma membrane to ferricyanide. The relationship between LIAC and transmembrane electron flow has not yet been determined, but blue light-regulated proton excretion and/or growth may depend on this electron flow. No conclusions can be drawn regarding any role for phytochrome because of a paucity of information concerning the effects of red light on redox activity at the plasma membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00771011
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  • 8
    Electronic Resource
    Electronic Resource
    Thebc 1 complexes ofRhodobacter sphaeroides andRhodobacter capsulatus (1993)
    Springer
    Journal of bioenergetics and biomembranes 25 (1993), S. 195-209 
    Details
    ISSN: 1573-6881
    Keywords: Cytochrome ; bc 1 ; complex III ; Q-cycle ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Photosynthetic bacteria offer excellent experimental opportunities to explore both the structure and function of the ubiquinol-cytochromec oxidoreductase (bc 1 complex). In bothRhodobacter sphaeroides andRhodobacter capsulatus, thebc 1 complex functions in both the aerobic respiratory chain and as an essential component of the photosynthetic electron transport chain. Because thebc 1 complex in these organisms can be functionally coupled to the photosynthetic reaction center, flash photolysis can be used to study electron flow through the enzyme and to examine the effects of various amino acid substitutions. During the past several years, numerous mutations have been generated in the cytochromeb subunit, in the Rieske iron-sulfur subunit, and in the cytochromec 1 subunit. Both site-directed and random mutagenesis procedures have been utilized. Studies of these mutations have identified amino acid residues that are metal ligands, as well as those residues that are at or near either the quinol oxidase (Qo) site or the quinol reductase (Qi) site. The postulate that these two Q-sites are located on opposite sides of the membrane is supported by these studies. Current research is directed at exploring the details of the catalytic mechanism, the nature of the subunit interactions, and the assembly of this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762582
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  • 9
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059591
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  • 10
    Electronic Resource
    Electronic Resource
    Exchange of carbonyl sulfide (COS) between agricultural plants and the atmosphere: Studies on the deposition of COS to peas, corn and rapeseed (1993)
    Springer
    Biogeochemistry 23 (1993), S. 47-59 
    Details
    ISSN: 1573-515X
    Keywords: atmosphere ; biosphere ; carbonyl sulfide ; CO2 assimilation ; COS compensation point ; COS deposition ; emission ; photosynthesis ; reduced sulfur compounds ; trace gas exchange ; vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Young corn, pea and rapeseed plants were exposed to compressed synthetic air containing varying COS concentrations. The results suggest that COS exchange depends highly on the ambient COS mixing ratios. Ambient COS mixing ratios larger than 150 pptv resulted in a deposition of COS to all plant species studied. Significant (confidence level 95%) COS emission was only detected from rapeseed leaves at COS mixing ratios lower than 90 pptv. We computed COS compensation points around 90 (57–135) pptv and 144 (0–328) pptv COS for rapeseed and corn. For both plant species we found a close correlation between the photosynthetic CO2 assimilation and the COS uptake. In contrast to the gas exchange studies with corn and rapeseed, experiments with pea plants revealed neither a change in response to increased COS concentrations of between 350 and 900 pptv COS nor any correlation with photosynthesis. However, for all three plants studied we found indications that COS is taken up preferentially over CO2 under normal ambient conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002922
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  • 11
    Electronic Resource
    Electronic Resource
    Reduced sulfur compound exchange between the atmosphere and tropical tree species in southern Cameroon (1993)
    Springer
    Biogeochemistry 23 (1993), S. 23-45 
    Details
    ISSN: 1573-515X
    Keywords: atmosphere ; canopy top ; carbonyl sulfide (COS) ; dimethyl sulfide (DMS) ; photosynthesis ; reduced sulfur compounds ; trace gas exchange ; tropical rainforest ; vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We measured the concentrations of reduced sulfur compounds in the atmospheric boundary layer over an equatorial African rain forest. Results obtained from a dirigible hot air balloon and a tethered balloon system in the early morning hours reflect a multilayered structure of the atmospheric boundary layer with gradients of COS and CS2 indicating an uptake/production of these trace gases by the soil/vegetation system. In addition, we studied emission and deposition fluxes of volatile reduced sulfur compounds from tropical tree species using cuvettes to directly measure the exchange behavior of tree twigs. These cuvettes were operated at young trees in a forest clearing near ground level as well as at a mature tree species on top of the forest canopy, employing a specially designed tree top jungle raft (‘Treetop Raft III, Dirigible version’) placed on the canopy crown. The results show qualitative and quantitative disparities between different tree species as well as between individuals of the same species near ground level (young) and at the top of the canopy (mature). We found some correlations between photosynthetic CO2 assimilation and emission of sulfur compounds. Comparison between measurements at the ground and at the canopy top show that the studied tree species adapts its photosynthetic CO2 assimilation in response to the climatic conditions at the canopy top. This is accompanied by a quantitative change in trace gas emission. Lower CO2 fixation rates are accompanied by an increase in the emission of reduced sulfur compounds. We propose the increase of DMS emission at the canopy top to be explained by a potential demand of nitrogen in the foliage resulting in an accumulation of sulfur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002921
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  • 12
    Electronic Resource
    Electronic Resource
    Effects of root exudate sorgoleone on photosynthesis (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 369-375 
    Details
    ISSN: 1573-1561
    Keywords: Sorgoleone ; allelochemical ; allelopathy ; photosynthesis ; chloroplast ; root exudate ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The aim of this investigation was to determine if sorgoleone (SGL), ap-benzoquinone inSorghum bicolor root exudate, is a photosynthesis inhibitor. Assays usingGlycine max leaf disks showed concentrations as low as 10μM SGL inhibited oxygen evolution more than 50%. Tests conducted on chloroplasts isolated fromPisum sativum showed that SGL is a powerful inhibitor of CO2-dependent oxygen evolution. Using a chloroplast suspension equivalent to 80–100μg chlorophyll, the I50 was approximately 0.2μM SGL. These data indicate inhibition of photosynthesis is part of the explanation for growth reduction caused by this allelochemical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993702
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  • 13
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020892917434
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