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'Electron Transport' in keywords Facet   Publication Year 1990  [X]
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1Author    G. Á Bor Horváth, M. Agdolna, D. Roppa, Ágnes PuskáRequires cookie*
 Title    Fluorescence Induction Characteristics of Wild-Type and Herbicide-Resistant Strain of the Photosynthetic Bacterium Rhodobacter capsulatus  
 Abstract    Fluorescence induction characteristics have been studied in wild-type and atrazine-resistant mutant o f Rhodobacter capsulatus. Fluorescence induction was found to be a useful technique to monitor the altered electron transfer in the atrazine-resistant mutants as well as in the differ­ ent membrane fractions o f wild-type R. capsulatus. In both cases, the proportion o f the fast rise o f variable fluorescence was increased indicating the enhancement o f QA. In the mutant strain, the / 50 value o f triazine herbicide terbutryn was increased by 1 0 0 -fold whereas the natu­ ral resistance o f R . capsulatus against diuron was abolished by the mutation. 
  Reference    Z. Naturforsch. 45c, 452 (1990); received N ovem ber 9 1989 
  Published    1990 
  Keywords    Fluorescence Induction, Electron Transport, Herbicide, Purple Bacteria, Photosynthesis 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0452.pdf 
 Identifier    ZNC-1990-45c-0452 
 Volume    45 
2Author    JeffA. Nemson, Anastasios MelisRequires cookie*
 Title    Light-Induced Oxidation-Reduction Reactions of Photosystem II in Dichlorophenyl-dimethyl Urea (DCM U) Inhibited Thylakoids  
 Abstract    Illumination o f thylakoid membranes in the presence o f 3-(3',4'-dichlorophenyl)-1,1-di-methyl urea (D C M U) causes the reduction o f the primary quinone acceptor QA o f photosys­ tem II (PS II) and the storage o f a positive charge on the donor side o f the photochem ical reac­ tion center. These oxidation-reduction reactions are accompanied by characteristic changes o f absorbance in the ultra-violet region o f the spectrum. The PS II-related absorbance difference spectra (2 5 0 -3 5 0 nm) were compared in control and hydroxylamine-treated thylakoid mem­ branes, and in thylakoids suspended in the presence o f carbonyl cyanide-/7-(trifluoromethoxy)-phenylhydrazone (FCCP). The light minus dark difference spectra were dominated by the QA minus QA difference spectrum. Qualitatively, the three spectra were identical in the 3 0 0 -3 5 0 nm region, however, they showed distinct differences in the 2 5 0 -3 0 0 nm region. The latter arose because o f different contributions from the donor side o f PS II in the thylakoid membrane o f the three samples. The result suggested that FCCP acts as the ultimate electron donor in D C M U -poisoned chloroplasts. Therefore, the absorbance difference spectrum in the presence o f FCCP reflected a contribution from the QA minus QA com ponent only. D econvolu­ tion o f the absorbance difference spectra o f control and hydroxylamine-treated thylakoids yielded difference spectra attributed to the oxidation o f a com ponent on the donor side o f PS II. This com ponent did not conform with the known M n(III) — ■ > M n(IV) transition. R ath­ er, it indicated the oxidation o f a modified form o f Mn in the presence o f D C M U , probably a Mn(II) —> M n(III) transition. The results are discussed in terms o f the use o f D C M U -poisoned thylakoid membranes in the quantitation o f the primary quinone acceptor Q A by spectro-photom etric approaches. 
  Reference    Z. Naturforsch. 45c, 258 (1990); received July 25/August 21. 1989 
  Published    1990 
  Keywords    Absorbance Difference Spectra, Photosystem II, Electron Transport, Primary Quinone Acceptor, Electron D onor Tyrosine 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0258.pdf 
 Identifier    ZNC-1990-45c-0258 
 Volume    45 
3Author    Jack Dekker, RonaldG. BurmesterRequires cookie*
 Title    Differential Pleiotropy in a psbA Gene Mutant of Brassica napus Implies Altered Temporal Photosynthesis and Thermal Tolerance  
 Abstract    Studies were conducted to test the hypothesis that the mutation to the psbA. plastid gene that confers s-triazine resistance (R) also results in an altered diurnal pattern o f photosynthetic car­ bon reduction (CER) relative to that o f the susceptible (S) wild-type. In all experiments CER approximated the increasing and decreasing light levels during the diurnal. S C ER exceeded that o f R during the midday period, but R CER was greater early and late in the diurnal at 25 °C. R CER exceeded that o f S for most o f the diurnal at 35 °C and in older, crowded, nitrogen-starved plants. These studies support the stated hypothesis and indicate a more complex model o f photosynthetic productivity than previously observed. An assessment o f the photosynthetic competence o f either biotype may be a function o f the time o f day or the environmental condi­ tions the plants are exposed to, especially temperature. 
  Reference    Z. Naturforsch. 45c, 474 (1990); received October 18 1989 
  Published    1990 
  Keywords    Photosystem II, D -l Protein, Electron Transport, C hronobiology, Diurnal Rhythms 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0474.pdf 
 Identifier    ZNC-1990-45c-0474 
 Volume    45