Evidence for a linear variation of the miss and single hit S-state probabilities with the flash number, measured by oxygen evolution in Dunaliella tertiolecta

Meunier, Pascal; Popovic, Radovan

doi:10.1007/bf00035443

Cited by 7 publications

(16 citation statements)

References 25 publications

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“…We have recently shown that the miss probability becomes lower with the flash number in a sequence of O2 evolution in Dunaliella tertiolecta (Meunier and Popovic 1989). Figure flashes are fired at a frequency of l0 Hz.…”

Section: Resultsmentioning

confidence: 99%

“…This permitted benzoquinone to diffuse into the gel, to keep the sample at a constant concentration of benzoquinone during dark adaptation. All other experimental conditions were the same as previously described (Meunier and popovic 1989). The oxygen evolution data was fitted by eq.…”

Section: Methodsmentioning

confidence: 99%

“…The determination of the sigma coefficients, of the average miss and double-hit probabilities ("sigma analysis") and of their standard deviations was performed as previously described (Meunier and Popovic 1989). The apparent misses determined by this method (or any method known to date) cannot differentiate between "true" misses and misses caused by deactivations (cf.…”

Section: Methodsmentioning

confidence: 99%

“…We recently observed, using a high-accuracy apparatus (Meunier and Popovic 1988b), that misses become lower with the flash number in a sequence of 02 evolution in the algae Dunaliella tertiolecta (Meunier and Popovic 1989). This variation cannot be predicted from one of the models above, in which the properties of OECs are assumed to be constant.…”

Section: Introductionmentioning

confidence: 92%

“…We recently observed a linear lowering of the miss probability with the flash number (Meunier and Popovic 1989). Therefore, we investigated in Dunaliella tertiolecta the link between the average miss probability and the redox state of plastoquinone after n flashes.…”

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confidence: 99%

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Control of misses in oxygen evolution by the oxido-reduction state of plastoquinone in Dunaliella tertiolecta

Meunier

Popovic

1990

Photosynth Res

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The way misses happen in oxygen evolution is subject to debate (Govindjee et al. 1985). We recently observed a linear lowering of the miss probability with the flash number (Meunier and Popovic 1989). Therefore, we investigated in Dunaliella tertiolecta the link between the average miss probability and the redox state of plastoquinone after n flashes. The effect of flashes was to oxidize the plastoquinone pool; we found that the oxidation of plastoquinone highly correlated (linear regression: R (2)=0.996) with the lowering of the miss probability. The flash frequency was found to affect both the miss probability and the redox state of plastoquinone. When pre-flashes were given using a high flash frequency (10 Hz), the plastoquinone pool was oxidized and misses were low; however, if long dark intervals between flashes were used, the oxidizing effect of flashes was lost and the misses were high. We could not explain our results by assuming equal misses over all S-states; but unequal misses, caused by deactivations, were coherent with our results. We deduced that chlororespiration was responsible for the reduction of plastoquinone in the dark interval between flashes. We compared oxygen evolution with and without benzoquinone, using a low flash frequency (0.5 Hz) for maximum misses. Benzoquinone lowered the misses from 34% to 3%, and raised the amplitude of oxygen evolution by more than a factor of two (2). From this we deduced that the charge carrier "C" postulated to explain misses (Lavorel and Maison-Peteri 1983) did not account for more than 3% of miss probability in Dunaliella tertiolecta. These results indicate that the misses in oxygen evolution are controlled by the redox state of plastoquinone, through deactivations.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

mentioning

confidence: 99%

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Control of misses in oxygen evolution by the oxido-reduction state of plastoquinone in Dunaliella tertiolecta

Meunier

Popovic

1990

Photosynth Res

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Oxygen evolution by Photosystem II: The contribution of backward transitions to the anomalous behaviour of double-hits revealed by a new analysis method

Meunier

1993

Photosynth Res

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Backward transitions in the analysis of oxygen production under flashing light were introduced by Packham et al., 1988, Photosynth. Res. 15: 221-232. In order to take backward transitions into account, a new method of analysis is presented: the 'eigenvalue method'. This method is based on the recurrence relation of oxygen production with four coefficients (also known as the four 'sigma' coefficients). It shows less susceptibility to round-off errors than other methods and permits the computation of double-hits directly from the coefficients, which was not possible before. With it we discovered that the inconsistent behaviour of double-hits observed previously under low flash intensities or low flash frequencies was mainly due to the inclusion of the backward transitions into the double-hit probability. In these conditions backward transitions seemed to be due either to the combination of an S-state deactivation and a miss, or to two S-state deactivations and a single-hit.In the presence of 3-(3, 4-Dichlorophenyl)-1, 1-dimethylurea (DCMU), the previous methods of 'sigma' analysis failed. In contrast, the new method resolved all four S-state probabilities; thus it has the further advantage of being more 'robust' (robustness being defined as the ability to yield a meaningful answer under difficult conditions).

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Improved 5-step modeling of the Photosystem II S-state mechanism in cyanobacteria

1996

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We present a model of the S-state mechanism, as well as an improved eigenvalue analysis, that integrate into a coherent ensemble several features found since the S-state model was initially developed. These features include the presence of S-1, deactivations in the dark interval between flashes, and the change in the number of active PS II centers by photoinhibition or photoactivation. A new feature is the capacity to predict the steady-state distribution of S-states under conditions of steady photoinhibition or photoactivation. The improved eigenvalue analysis allowed the calculation of the initial S-state distribution. In addition, the model resolved 'true' photochemical misses from apparent misses due to deactivations in the dark interval between flashes. The model suggested that most of the misses that are commonly reported are due to deactivations, and not to an intrinsic inefficiency of the photochemical mechanism of PS II. Because models that allow double-hits encompassing the S2 to S3 transition often predict negative initial quantities of S2 in cyanobacteria, our proposed model specifically prohibited them. The model accounts for inhomogeneous misses and a steady-state distribution of the type (S2)≈(S1)>(S3)≈(S0). This 5-step model uses only 4 probabilities, and is therefore easy to handle. The use of this model is critical for the analysis of several cyanobacterial strains, as well as for any species that show non-negligible deactivations in the dark interval between flashes.

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Evidence for a linear variation of the miss and single hit S-state probabilities with the flash number, measured by oxygen evolution in Dunaliella tertiolecta

Cited by 7 publications

References 25 publications

Control of misses in oxygen evolution by the oxido-reduction state of plastoquinone in Dunaliella tertiolecta

Control of misses in oxygen evolution by the oxido-reduction state of plastoquinone in Dunaliella tertiolecta

Oxygen evolution by Photosystem II: The contribution of backward transitions to the anomalous behaviour of double-hits revealed by a new analysis method

Improved 5-step modeling of the Photosystem II S-state mechanism in cyanobacteria

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