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1Author    GeorgH. Schmid, Pierre ThibaultRequires cookie*
 Title    Characterization of a Light-Induced Oxygen-Uptake in Tobacco Protoplasts  
 Abstract    Protoplasts prepared from the wild type tobacco N. tabacum var. John W illiam 's Broadleaf ex­ hibit photosynthetic oxygen-evolution if the suspension medium is supplemented with bicarbonate. In the absence of bicarbonate no steady state oxygen-evolution is observed with such prepara­ tions. Instead, an appreciable uptake which is mainly insensitive to D C M U and which persists over hours, and therefore is no mduction phenomenon, is seen. Protoplasts of the tobacco aurea mutant Su/su, which is a plant with an exceptionally high photorespiration, show an oxygen con­ 
  Reference    Z. Naturforsch. 34c, 570—575 (1979); received April 2 1979 
  Published    1979 
  Keywords    Protoplasts, Oxygen-Uptake, Photorespiration, Action Spectrum 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0570.pdf 
 Identifier    ZNC-1979-34c-0570 
 Volume    34 
2Author    GeorgH. Schmid, KlausP. Bader, Richard Gerster, Christian Triantaphylides, Marcel AndréRequires cookie*
 Title    Dependence of Photorespiration and Photosynthetic Unit Sizes on Two Interdependent Nuclear Gene Factors in Tobacco  
 Abstract    A new set of tobacco mutants was obtained by selfing a single variegated plant which emerged in a seed lot of Nicotiana tabacum var. Consolation. The seeds obtained from this mutant give rise to four phenotypes: variegated, yellow, yellow-green, and green seedlings. The green, yellow-green and yellow characters are due to two interdependent nuclear gene factors. The yellow-green phenotype is the homozygous (aabb) true breeding condition, whereas the green and the yellow phenotype are heterozygous (AaBb) with respect to both nuclear factors, the difference in the yellow and green phenotype being the addition of a labile gene factor pair, Cc, in the yellow condition. If photorespiration is measured as the Warburg effect or as 180 2-consumption by mass spectrometry it appears that the heterozygous green phenotype is the defective condition with high photorespiration. The three phenotypes differ with respect to chlorophyll content and photosynthetic unit sizes, the photosynthetic unit size in the yellow phenotype being approxi­ mately 1/10 of that of the green type. The gene expression for photorespiration (measured as 180 2-uptake for example) in the heterozygous green type is suppressed by the addition of the labile gene factor pair Cc in heterozygous condition which leads to the yellow phenotype. In the yellow and green phenotype the photosynthetic unit size is different but not the ratio of photosys­ tem I/photosystem II activity. Moreover, from the present studies it appears that the Warburg effect i. e. an increase of photo­ synthetic rate upon anoxia, can only partly be due to an inhibition of ribulose 1,5-biphosphate oxygenase or glycolate oxidase. 
  Reference    Z. Naturforsch. 36c, 662—671 (1981); received March 23 1981 
  Published    1981 
  Keywords    Photorespiration, Mass Spectrometry, Photosynthetic Units, Tobacco Mutants 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0662.pdf 
 Identifier    ZNC-1981-36c-0662 
 Volume    36 
3Author    Remigius Manderscheid, Aloysius WildRequires cookie*
 Title    Characterization of Glutamine Synthetase of Roots, Etiolated Cotyledons and Green Leaves from Sinapis alba (L.)  
 Abstract    Glutamine synthetase of roots, etiolated cotyledons and green leaves from mustard plants cannot all clearly be separated by DEAE-Sephacel chromatography. However, the enzyme of the roots, etiolated cotyledons and green leaves, respectively, differed in the kinetic properties deter­ mined in the crude extract. The root enzyme showed a pH-optimum of about 6.9, a K m value of 3 m M for glutamate and a temperature optimum at 48 °C. Glutamine synthetase of etiolated cotyledons possessed a Km for glutamate of 6 or 12 m M , depending on the dithioerythritol con­ centration in the homogenisation buffer and a temperature optimum at 46 °C. The enzyme of green leaves was characterized by a temperature optimum at 40 °C, a pH-optimum at about 7.4 and a low glutamate affinity with positive cooperative substrate binding. Based on isolation of chloroplasts and identification of glutamine synthetase the enzyme of green leaves seems to be the chloroplastic form. This enzyme was purified by DEAE-Sephacel, hydroxylapatite and Sephacryl S-300 chromatography. Affinity for glutamate and M g S04 of the purified enzyme differed from that found in the crude extract. The function of the different isoenzymes is discussed. Intro du ction 
  Reference    Z. Naturforsch. 41c, 712 (1986); received March 17 1986 
  Published    1986 
  Keywords    Enzyme Purification, Glutamine Synthetase, Isoenzymes, Photorespiration, Sinapis alba 
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 TEI-XML for    default:Reihe_C/41/ZNC-1986-41c-0712.pdf 
 Identifier    ZNC-1986-41c-0712 
 Volume    41 
4Author    Christine Ziegler, Aloysius WildRequires cookie*
 Title    The Effect of Bialaphos on Ammonium-Assimilation and Photosynthesis II. Effect on Photosynthesis and Photorespiration  
 Abstract    The application of bialaphos (phosphinothricyl-alanyl-alanine) effects a quick photosynthesis inhibition under atmospheric conditions (400 ppm C 0 2, 21% 0 2). However, under conditions (1000 ppm C 0 2, 2% 0 2) under which photorespiration cannot occur there is no photosynthesis inhibition. In the previous investigation it could be shown that bialaphos splits in plants into phosphinothricin and alanine. The inhibition of glutamine synthetase through freed phosphino­ thricin results in an NH4+-accumulation and a decrease in glutamine. With the addition of glutamine, photosynthesis inhibition by bialaphos can be reduced. An NH4+-accumulation takes place under atmospheric conditions as well as under non-photorespiratory conditions; though in the latter case, in less amounts. After adding glutamine and other amino acids the NH4+-accumu-lation increases especially. This indicates that NH4+-accumulation cannot be the primary cause for photosynthesis inhibition by bialaphos. The investigations indicate that for the effectiveness of either bialaphos or phosphinothricin, a process in connexion with photorespiration plays a consid­ erable role. The glyoxylate transamination in photorespiration could be inhibited, which results probably on a glyoxylate accumulation. Corresponding investigations showed inhibition of photo­ synthesis as well as a direct inhibition of RubP-carboxylase with glyoxylate. 
  Reference    Z. Naturforsch. 44c, 103 (1989); received September 23 1988 
  Published    1989 
  Keywords    Ammonium-Accumulation Bialaphos, Phosphinothricin, Photorespiration, Photosynthesis 
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 TEI-XML for    default:Reihe_C/44/ZNC-1989-44c-0103.pdf 
 Identifier    ZNC-1989-44c-0103 
 Volume    44 
5Author    Yoshihiro Shiraiwa, GeorgH. SchmidRequires cookie*
 Title    Effect of pH on Glycolate and Ammonia Excretion in L-MSO Treated Chlorella Cells  
 Abstract    The effect of pH changes on the excretion of ammonia and glycolate from algal cells into the medium was investigated in L-MSO (final concentration, 0.5 mM) -treated High-and Low C 02-cells of Chlorella vulgaris 211-11 h. The excretion was analyzed in the condition in which the cells were continuously gassed with air at 25 °C. At the values tested, generally more ammonia was excreted in L-MSO-treated Low C 02-cells than in L-MSO treated High CÖ2-cells. In both kinds of algal cells more ammonia was excreted at low pH-values and absolutely no ammonia was excreted at pH 8. In the dark, no or only slight ammonia excretion was observed in both L-MSO-treated High and Low C 02-cells. Under all these conditions no or only very low glycolate excretion was observed in both L-MSO treated High and Low C 02-cells. In High C 02-cells rates of photosynthesis were high at pH 6 and lower at higher pH values. On the other hand Low C 02-cells showed practically little dependence of photosynthetic rates on the pH. This result might indicate that the major part of the ammonia excretion observed, was not due to the inhibition of photosynthesis at acid pH values. It is known that ammonia excretion in L-MSO treated algal cells is due to the inhibition of the refixation of ammonia which originates from the glycine-serine aminotransferase reaction in the glycolate pathway. Our results demonstrate that glycolate production and glycolate metabolism are more intense at low pH values when compared to high pH values. This is valid for both High and Low C 0 2-cells. Low C 02-cells in Chlorella vulgaris 211-11 h exhibit a more active glycolate metabolism than High C 02-cells. 
  Reference    Z. Naturforsch. 42c, 525 (1987); received December 5 1986 
  Published    1987 
  Keywords    Ammonia Excretion, Glycolate Excretion, Chlorella vulgaris, Photorespiration, pH-Effect 
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 TEI-XML for    default:Reihe_C/42/ZNC-1987-42c-0525.pdf 
 Identifier    ZNC-1987-42c-0525 
 Volume    42 
6Author    U. H. Eber, J. Viil, S. Neimanis, T. Mimura, K.-J DietzRequires cookie*
 Title    Photoinhibitory Damage to Chloroplasts under Phosphate Deficiency and Alleviation of Deficiency and Damage by Photorespiratory Reactions  
 Abstract    D edicated to P rofessor A chim Trebst on the occasion o f his 60th birthday Effects of Pi deficiency on photosynthesis ot isolated spinach chloroplasts were examined. The following observations were made: (1) Chloroplasts isolated in Pi-free media evolved oxygen in the light in the absence of added Pi until acid-extractable P, in the chloroplasts had decreased to 1 to 2.5 m M . This Pj was unavailable for photophosphorylation as shown by the inability of the chloroplasts to respond by oxygen evolution to the addition of PGA. In the state of Prdeficiency, stromal ATP to A DP ratios were in the light close to or below ratios observed in the dark. In the presence of 2 mM PGA, addition of 20 (j.m Pi was insufficient to increase ATP to ADP ratios, but sufficient for appreciable oxygen evolution. (2) More Pi was available for oxygen evolution of phosphate-deficient chloroplasts at low levels of C 0 2 than at high levels. This was due mainly to the suppression of oxygenation of RuBP by high C 0 2 levels which prevented formation of phosphoglycolate and the subsequent release of Pi into the chloroplast stroma. (3) More oxygen was produced by phosphate-deficient chloroplasts at a low light intensity than at a high light intensity. This was due to increased availability of endogenous Pi under low light and to photoinhibition of the chloroplasts by high light. The main product of photosynthesis of phosphate-deficient chloroplasts in the presence of a high bicarbonate concentration was starch, and the main soluble product was PGA. (4) After phosphate-deficient chloroplasts had ceased to evolve oxygen in the light, they be­ came photosensitive. Part of the loss of the capacity for oxygen evolution is attributed to leakage of PGA, but the main reason for loss of function is photoinactivation of electron transport. Both photosystems of the electron transport chain were damaged by light. (5) Protection against photoinactivation was provided by coupled electron transport. Photo­ inactivation of phosphate-deficient chloroplasts was less extensive in the presence of low C 0 2 concentrations which permitted oxygenation of RuBP than at high CO: concentrations. Electron transport to C 0 2 and other physiological electron acceptors and to the herbicide methylviologen was also protective. However, electron transport to oxygen in the Mehler reaction failed to provide appreciable protection against high light intensities, because oxygen reduction is slow and reactive oxygen species produced in the light contribute to photoinactivation. 
  Reference    Z. Naturforsch. 44c, 524 (1989); received February 3 1989 
  Published    1989 
  Keywords    Photosynthesis, Photoinhibition, Photorespiration, Electron Transport, Phosphate Deficiency, Phosphate Homeostasis 
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 TEI-XML for    default:Reihe_C/44/ZNC-1989-44c-0524.pdf 
 Identifier    ZNC-1989-44c-0524 
 Volume    44 
7Author    P. He, K. P. Bader, A. Radunz, G. H. SchmidRequires cookie*
 Title    Consequences of High C 0 2-Concentrations in Air on Growth and Gas-Exchange Rates in Tobacco Mutants  
 Abstract    Wild type tobacco N. tabacum var. John William's Broadleaf and the tobacco aurea mutant Su/su were permanently grown under 700 ppm C 0 2 in air. In comparison to plants grown under 350 ppm C 0 2 in air but under otherwise identical conditions growth was substantially enhanced. Gas exchange measurem ents carried out by mass spectrometry show that the rate of photosynthesis in the wild type and in the mutant is increased by more than 100%. The photorespiratory rate in the wild type measured as 180 2-uptake in the light in the "700 ppm C 0 2-plants" is not reduced to the extent expected or deduced from experiments in which the 350 ppm system responds under in vitro conditions to 700 ppm C 0 2. An analysis of the induction kinetics of room tem perature fluorescence kinetics of the adapted (700 ppm C 0 2) system and the control system (350 ppm C 0 2) under various C 0 2-partial pressures shows that perm anent growth under the elevated C 0 2-partial pressure leads to a structural modifi­ cation of the photosynthetic apparatus. 
  Reference    Z. Naturforsch. 50c, 781—788 (1995); received July 3/July 30 1995 
  Published    1995 
  Keywords    High C 0 2-Pressure, Mass Spectrometry, Tobacco, Photosynthesis, Photorespiration 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0781.pdf 
 Identifier    ZNC-1995-50c-0781 
 Volume    50