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1998 (1)
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1Author    Jürgen Beck, Gerhart DrewsRequires cookie*
 Title    Tetrapyrrol Derivatives Shown by Fluorescence Emission and Excitation Spectroscopy in Cells of Rhodopseudomonas capsulata Adapting to Phototrophic Conditions  
 Abstract    Aerobically in the dark grown cells were incubated semiaerobically (30 min) and afterwards 180 min anaerobically in the light During phototrophic induction the bacteriochlorophyll concentra­ tion increased from 0.26 to 2 . 1 0 nmol/mg cell protein. In samples taken at different times after lowering o f oxygen partial pressure the following tetrapyrrol derivatives were identified by fluorescence emission and excitation spectroscopy at 1.7 K: Mg-protoporphyrin EX-monomethylester, Mg-2,4-divinylphaeoporphyrin a5-monomethylester, 2-de-vinyl-2 -hydroxyethyl-chlorophyllide, 2 -devinyl-2 -hydroxyethyl-pheophorbide, chlorophyllide a, pheophorbide, bacteriopheophorbide, bacteriopheophytin, bacteriochlorophyllide and bacte­ riochlorophyll a in different pigment complexes. The highest relative concentrations o f bacte­ riochlorophyll precursors normalized to the total amount o f bacteriochlorophyll a were found in cells during the first hour o f adaptation at 0.5 ^g Bchl/mg cell protein or less. 
  Reference    Z. Naturforsch. 37c, 199 (1982); received December 29 1981 
  Published    1982 
  Keywords    Bacteriochlorophyll Complexes, Precursors, Tetrapyrrols, Rhodopseudomonas capsulata, Photosynthetic Apparatus 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0199.pdf 
 Identifier    ZNC-1982-37c-0199 
 Volume    37 
2Author    Kiriakos Kotzabasis3, D. Ieter, D. Örnem AnnbRequires cookie*
 Title    Differential Changes in the Photosynthetic Pigments and Polyamine Content during Photoadaptation and Photoinhibition in the Unicellular Green Alga Scenedesmus obliquus  
 Abstract    In the unicellular green alga Scenedesmus obliquus the level o f photoinhibition and the recovery of the cells after reversal to the initial light conditions in relation to the pre-photo-adaptation of the culture to low, medium and high light intensity was determined. The changes in the photosynthetic pigment content and in the intracellular polyam ine concentra­ tion allowed to distinguish between photoadaptation and photoinhibition. In particular, the level of chlorophylls, xanthophylls and carotenoids decreased inversely proportional to the light intensity applied during photoadaptation, whereas their concentrations remained con­ stant during photoinhibition. The violaxanthin/zeaxanthin and the loroxanthin/lutein cycle work only under photoinhibitory conditions, but not under photoadaptive premises. Changes in the level of these carotenoids in relation to the changes in the photosynthetic apparatus during photoadaptation are discussed. In addition, it was found that the intracellular polya­ mine level increased only under stress conditions, i. e. during photoinhibition, and decreased during recovery of the cells after reversal to the initial light conditions. The increase of the putrescine level during photoinhibition is inversely proportional to the light intensity used for pre-adaptation. This rise of the polyamine level in the cells photoadapted to high light conditions is an additional indication for the finding that photoadaptation and photoinhibi­ tion are different phenomena which are clearly distinguishable from each other. Finally, the changes of the chlorophyll, violaxanthin, zeaxanthin, loroxanthin, lutein and polyamine levels under photoadaptation in high light intensity (50 W m '2) in relation to the range of photo­ adaptation in Scenedesmus obliquus are discussed. 
  Reference    Z. Naturforsch. 53c, 833—8 (1998); received May 8/June 15 1998 
  Published    1998 
  Keywords    Polyamines, Photosynthetic Apparatus, Photoinhibition, Photoadaptation, Scenedesmus obliquus 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-0833.pdf 
 Identifier    ZNC-1998-53c-0833 
 Volume    53 
3Author    StefanD. Renkard3, JürgenM. Aguhnb, D. Ietm Ar Knoppik3Requires cookie*
 Title    Simultaneous Gas-Exchange and Fluorescence Measurements with Ozone-Fumigated Spruce  
 Abstract    A method was developed for carrying out gas-exchange and chlorophyll-fluorescence measurements simultaneously during fumigation of spruce twigs with peroxidic photooxi­ dants. It is thus now possible to investigate how a pollutant affects distinct sectors of the photosynthetic apparatus of the plant: whereas fluorescence reveals any changes in the pri­ mary light reaction, C 0 2 gas-exchange measurements supply information about the bio­ chemical reactions of the Calvin cycle. Results of short-time fumigation with 750 ppb ozone are presented here. Gas-exchange and fluorescence data are affected strongly in early sum­ mer, but not in autumn. The assimilation rate decreases significantly: primarily as a result of Rubisco activity and possibly because of direct inhibition of the electron-transport chain as well. Closure of the stomata leads to further reduction in the assimilation rate. Though no damage becomes visible on the needles, the perturbance of the photosynthetic apparatus caused by ozone fumigation is not reversible within 24 h. 
  Reference    Z. Naturforsch. 49c, 819—833 (1994); received June 21 1994 
  Published    1994 
  Keywords    Spruce, Photosynthetic Apparatus, Gas Exchange, Chlorophyll Fluorescence, Ozone Fumigation 
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 TEI-XML for    default:Reihe_C/49/ZNC-1994-49c-0819.pdf 
 Identifier    ZNC-1994-49c-0819 
 Volume    49 
4Author    AugustoF. Garcia, G.Erhart DrewsRequires cookie*
 Title    Properties of Membrane Fractions Prepared by Chromatophore-Liposome Fusion  
 Abstract    Intracytoplasmic membrane vesicles (chromatophores) isolated from Rhodopseudomonas capsulata cells were fused with liposom es by a pH transition procedure. Vesicles o f lower density and higher lipid contents and larger diam eter than chrom atophores were obtained. Similar results were observed by Ca2+ induced fusion and by the freeze-thawing method. Respiratory and light-induced electron transport were m easured in chrom atophores and fused vesicles. Light-induced reaction center bleaching was observed in all types o f vesicles, whereas repiratory electron transport was substantially dim inished by lipid incorporation. U biquinone 10 restored to some extent respiratory electron transport and oxidative phosphorylation and it m odified the photophosphorylation kinetics under continuous light. Electrochrom ic carotenoid band-shift and the 9-aminoacridine fluorescence quenching indicate that the capacity o f the fused vesicles to maintain an electrochemical proton gradient has not been substantially dim inished. From the kinetics o f 9-aminoacridine quenching an increased K+-perm eability seem s to be apparent. 
  Reference    Z. Naturforsch. 39c, 1112—1119 (1984); received July 23 1984 
  Published    1984 
  Keywords    Photosynthetic Apparatus, Respiratory Chain, Rhodopseudom onas capsulata, M embrane Fusion, Liposomes, Photophosphorylation 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-1112.pdf 
 Identifier    ZNC-1984-39c-1112 
 Volume    39