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'Chlorophyll Fluorescence' in keywords Facet   Publication Year 1988  [X]
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1Author    Ulrich Schreiber, Christof Klughammer, Christian NeubauerRequires cookie*
 Title    Measuring P700 Absorbance Changes around 830 nm with a New Type of Pulse Modulation System  
 Abstract    A new measuring system for monitoring absorbance changes around 830 nm is described, which was developed by modification of a commercially available pulse modulation fluorometer. All modifications concern the emitter-detector unit of the fluorometer, such that only this unit needs to be exchanged when changing from fluorescence to absorbance measurements and vice versa. The new system is shown to be well-suited for measuring redox changes of P700, the reaction center of photosystem I, in intact leaves and isolated chloroplasts. The observed kinetic changes at 830 nm in response to single turnover or multiple turnover saturating flashes are practically identical to those previously measured around 700 nm. The signal/noise ratio is sufficiently high to give well-resolved kinetics without signal averaging. When P700 is oxidized by far-red back-ground light, valuable information on the state of the intersystem electron transport chain is given by the re-reduction kinetics induced by single or multiple turnover saturating flashes. Such meas-urements are facilitated by the use of poly-furcated fiberoptics. With intact leaves, almost identi-cal responses are found when measuring through the leaf (transmission mode) or from the leaf surface (remission mode). Modulated chlorophyll fluorescence can be measured in parallel; appli-cation of saturation pulses for fluorescence quenching analysis produces transient P700 oxidation without oversaturating the measuring system. The information on the P700 redox state comple-ments that obtained from fluorescence measurements, yielding a new practical tool in plant physiological research. 
  Reference    Z. Naturforsch. 43c, 686—698 (1988); received May 9 1988 
  Published    1988 
  Keywords    P700, Chlorophyll Fluorescence, Pulse Modulation, Photosynthesis 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0686.pdf 
 Identifier    ZNC-1988-43c-0686 
 Volume    43 
2Author    Wolfgang Schmidt, Ulrich Schreiber, Wolfgang UrbachRequires cookie*
 Abstract    The effects of short-time fumigation (0-60 min) of intact spinach leaves with S0 2 (2 ppm) on the photosynthetic apparatus were investigated. A rather high S0 2 concentration was applied to monitor immediate effects on the fluorescence behaviour with the influence of repair processes or secondary types of damage being minimized. Three different types of in vivo chlorophyll fluores-cence measurements were used: Rapid induction kinetics (Kautsky effect), slow induction kinetics with repetitive application of saturation pulses (saturation pulse method), and decay kinetics following a single turnover saturating flash. The slow induction kinetics with repetitive application of saturation pulses reacts in the most sensitive way indicating a primary damage at the level of the enzymatic reactions of the Calvin cycle. It is suggested that stromal acidification upon S0 2 uptake interferes with light activation of Calvin cycle enzymes. With longer fumigation times also damage at the level of photosystem II becomes apparent: A decrease in variable fluorescence yield reflects a lowering of photosystem II quantum yield, and the slowing down of fluorescence relaxation kinetics reveals an effect on the secondary electron transport from Q A to Q B . The detrimental effects of S0 2 depend to a great extent on the application of light during fumigation. Besides a light requirement for S0 2 uptake by stomata opening also the possibility of photoinhibitory damage is discussed. The susceptibility of leaves to photoinhibition may increase with a lowering of Calvin cycle activity by S0 2 . 
  Reference    Z. Naturforsch. 43c, 269—274 (1988); received December 7 1987 
  Published    1988 
  Keywords    Chlorophyll Fluorescence, S0 2, Spinach, Intact Leaves, Calvin Cycle 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0269.pdf 
 Identifier    ZNC-1988-43c-0269 
 Volume    43 
3Author    W. Bilger, U. Heber, U. SchreiberRequires cookie*
 Title    Kinetic Relationship between Energy-Dependent Fluorescence Quenching, Light Scattering, Chlorophyll Luminescence and Proton Pumping in Intact Leaves  
 Abstract    A measuring system was designed for simultaneous recording of modulated chlorophyll fluorescence and light scattering changes. The kinetic relationship was investigated between light-induced changes in non-photochemical fluorescence quenching, as determined by the saturation pulse method, and in light scattering, as measured via the apparent absorbance change at 543 nm. Very similar, but not identical kinetics were observed, reflecting a close non-linear relationship between these two indicators of thylakoid membrane energization. Fluorescence was found more sensitive at low levels of energization, while scattering continued indicating further increases in energization when quenching already was saturated. A general relationship between quenching and scattering is demonstrated which holds irrespective of whether energization is varied during induction or via changes in light intensity or C02 concentration. In the light-off responses, only part of fluorescence quenching was found to relax with the same kinetics as scattering. It is suggested that at high levels of energization slowly reversible membrane changes may be induced which have the potential of non-photochemical quenching at a low level of energization, and which are not accompanied by scattering changes. Neither quenching nor scattering changes displayed kinetics sufficiently fast to be taken as a direct expression of internal thylakoid acidifica-tion in intact leaves. This conclusion is drawn from comparative measurements of proton-uptake, as reflected by C02-solubilization upon light-induced stroma alkalization, and of chlorophyll luminescence. Both, the initial C02-gulp and the pH-dependent luminescence rise were found to clearly precede the development of energy-dependent quenching. 
  Reference    Z. Naturforsch. 43c, 877—887 (1988); received July 18 1988 
  Published    1988 
  Keywords    Chlorophyll Fluorescence, Light Scattering, Chlorophyll Luminescence, Thylakoid Membrane, Proton Pumping 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0877.pdf 
 Identifier    ZNC-1988-43c-0877 
 Volume    43