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'Mass Spectrometry' in keywords Facet   Publication Year 1995  [X]
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1Author    KlausP. Bader, Anja RöbenRequires cookie*
 Title    Mass Spectrometric Detection and Analysis of Nitrogen Fixation in Oscillatoria chalybea  
 Abstract    By means of mass spectroscopic m easurements in an artifical gas atmosphere containing the stable nitrogen isotope 15N2 we were able to demonstrate nitrogen fixation capacity in the filamentous cyanobacterium Oscillatoria chalybea. Our technique proved to be well-suited also for investigations on the light-induced nitrogen fixation in the purple bacteria Rhodobacter sphaeroides and Rhodobacter capsulatus. Oscillatoria chalybea grown without combined nitrogen showed a substantial 15N2-uptake which could clearly be correlated with nitrogen fixation. Nitrate grown cultures did not show this nitrogen uptake or only to a minimal extent. Addition of ammonium chloride resulted in a rapid deactivation of the nitro-genase system. Similar observations have been made with other so-called switch-off effectors like phenazine methosulfate. The structural integrity of the filaments appeared to be a pre­ requisite for nitrogen fixation also in this organism, as even mild mechanical homogenization strongly inhibited the N2-uptake signals. Illumination of the assays under conditions where the photooxidition of water is not operational (Bader, K. P. (1994), Biochim. Biophys. A cta 1188, 2 1 3 -2 1 9) did not affect the nitrogen fixation in Oscillatoria chalybea. Illumination of cultures with concom itant release of oxygen from the w ater splitting reaction resulted in strong inhibition of 15N2-uptake. 
  Reference    Z. Naturforsch. 50c, 199 (1995); received November 11 1994/January 30 1995 
  Published    1995 
  Keywords    Mass Spectrometry, Nitrogen Fixation, Photosynthesis, Cyanobacterium 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0199.pdf 
 Identifier    ZNC-1995-50c-0199 
 Volume    50 
2Author    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