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'Chlorophyll Fluorescence' in keywords Facet   Publication Year 1984  [X]
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1984[X]
1Author    D. Anny, J. Blubaugh, G. OvindjeeRequires cookie*
 Title    Comparison of Bicarbonate Effects on the Variable Chlorophyll a Fluorescence of C 0 2-Depleted and Non-C02-Depleted Thylakoids in the Presence of Diuron  
 Abstract    Evidence is presented from chlorophyll a fluorescence transient data for two sites o f bicar­ bonate (H C O j*) action in photosystem II. Both the absence o f H C O j (H C O j-depleted thyla­ koids) and a high concentration o f H C O j (60 m M H C O j added to non-depleted thylakoids) accelerate the variable chlorophyll a fluorescence rise in the presence o f 10 |i m diuron (D C M U). In non-HCOj-depleted thylakoids the effect is independent o f the order in which H C O j and DCM U are added, whereas in H CO J-depleted thylakoids, the effect is seen only when H C O j is added before DCM U. We propose that the effect seen in H C O j-depleted thylakoids is indirectly due to the binding o f H C O j functionally near the site o f D C M U binding, which is also where H CO j exerts its major effect on electron transport between the primary quinone QA and the plasto-quinone pool. We suggest that the smaller effect seen in non-HCOj-depleted thylakoids is due to the binding of HCOj at a second, lower affinity site. Binding at this site appears to require light, in con­ trast to the higher affinity site, which is inhibited by light. Bathocuproine, an inhibitor o f the H20 -to-silicomolybdate partial reaction, is synergistic with H C O j in its effect on the variable chlorophyll a fluorescence o f non-H C O j-depleted thylakoids, and may bind heterotropically with H CO j. Thus, this second site o f H C O j binding appears to be functionally near the batho­ cuproine binding site. 
  Reference    Z. Naturforsch. 39c, 378 (1984); received N ovem ber 14 1983 
  Published    1984 
  Keywords    Bicarbonate Effect, Chlorophyll Fluorescence, Photosystem II, Diuron, Bathocuproine 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0378.pdf 
 Identifier    ZNC-1984-39c-0378 
 Volume    39 
2Author    J.M D Ucruet, P. G. Aillard, J. V. IenotRequires cookie*
 Title    Use of Chlorophyll Fluorescence Induction Kinetics to Study Translocation and Detoxication of DCMU-Type Herbicides in Plant Leaves  
 Abstract    Transient levels o f the fluorescence induction rise were used to quantify partial photosynthesis inhibition by DC M U -type herbicides in w hole leaves. Assays in different crop or weed species showed a good accuracy in measurements (generally, variation was lower than 5%). This technique was applied to the problem o f varietal selectivity o f wheat towards chlortoluron. 
  Reference    Z. Naturforsch. 39c, 354 (1984); received N ovem ber 15 1983 
  Published    1984 
  Keywords    Chlorophyll Fluorescence, Photosystem II, H erbicides Translocation, D etoxication 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0354.pdf 
 Identifier    ZNC-1984-39c-0354 
 Volume    39 
3Author    Z. NaturforschRequires cookie*
 Title    Redox-State Dependent Changes of Inhibitor-Binding to the Photosystem II Acceptor Complex  
 Abstract    Binding o f radioactively labelled D C M U , ioxynil and terbutryn to spinach chloroplasts is determined following preillum ination by single-turnover, saturating light flashes. W ith all o f the three herbicides binary oscillations o f binding are observed. D ark-adapted sam ples, or those pre­ illuminated by an even number o f flashes, bind more inhibitor than sam ples preillum inated by an odd number o f flashes. Binding oscillations depend on inhibitor incubation tim e and on the seasonal adaptation o f the plants. The binding kinetics follow ing a single flash display three phases, the last two o f which can be correlated with reoxidation kinetics o f the secondary p h oto­ system II acceptor Qb, as determined by fluorescence measurem ents. Analysis o f the binding at DCM U concentrations up to 10"7 M free D C M U yields identical binding constants for dark-and flash preilluminated samples, but much less binding sites follow ing one flash. It is concluded that up to 10~7 M free DCM U, centers with bound Q b do not contribute significantly to total binding. Displacement o f Q b from the binding site is half-saturated at about 10-6 M D C M U , as m onitored via fluorescence induction. The data are considered strong support for the Velthuys 'inhibitor-Q i competition model'. 
  Reference    Z. Naturforsch. 39c, 397 (1984); received D ecem ber 1 1983 
  Published    1984 
  Keywords    Inhibitor Binding, Photosystem II, Binary O scillation, Chlorophyll Fluorescence 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0397.pdf 
 Identifier    ZNC-1984-39c-0397 
 Volume    39 
4Author    Salil Bose, R. M. Annar, M. Annan, C. J. ArntzenRequires cookie*
 Title    Increased Synthesis of Photosystem II in Triticum vulgare when Grown in the Presence of BAS 13-338  
 Abstract    Addition o f BAS 13-338 (4-chloro-5-dim ethylam ino-2-phenyl-3(2H)-pyridazinone) to a sus­ pension o f chloroplast thylakoids caused an increase in the / level o f chlorophyll fluorescence induction without affecting the F0 level and with a slight decrease in the Fmax level in a manner similar to the addition o f D C M U to a thylakoid suspension. A ddition o f BAS 13-338 also inhibited the rate o f Hill reaction H20 -» dichlorophenol indophenol with 50% inhibition occurring at about 10 hm BAS 13-338. The inhibition was not reversed by diphenyl carbazide used as an artificial electron donor to photosystem II. These results suggest that the site o f in h ib i­ tion by BAS 13-338 is between Q (next to the primary electron acceptor) and plastoquinone. When the plants were grown in the presence o f sublethal dose o f BAS 13-338, the follow ing changes were noted in the thylakoids o f the treated plants as com pared to the thylakoids isolated from the control plants: The F0 and the norm alized variable fluorescence (4F/F0) levels increased, chlorophyll a/b ratio decreased, chlorophyll/P 700 ratio increased. Furthermore, the rate o f photosystem II electron transport both under saturated intensity and the lim iting intensity of illumination increased, and the ratio o f plastoquinone to Q decreased. These observations have been interpreted as due to an increase in the ratio o f photosystem II to photosystem I in plants grown in the presence o f BAS 13-338. 
  Reference    Z. Naturforsch. 39c, 510 (1984); received D ecem ber 1 1983 
  Published    1984 
  Keywords    Photosynthesis, Electron Transport, Chlorophyll Fluorescence, Photosystem II, BAS 13-338 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0510.pdf 
 Identifier    ZNC-1984-39c-0510 
 Volume    39