Induction kinetics of heat emission before and after photoinhibition in cotyledons of Raphanus sativus

Buschmann, Claus

doi:10.1007/bf00032707

Cited by 42 publications

(16 citation statements)

References 29 publications

(35 reference statements)

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“…After 24 h of exposure, qP was decreased from 0.55 to 0.21 for E. gracilis, whereas this decrease was only from 0.74 to 0.61 for C. acidophila. When conversion of absorbed light energy into electron transport has deteriorated, it is known that the dissipation of energy will take place via thermal pathways [39]. This was indicative that nonphotochemical quenching of fluorescence qN, a parameter indicating thermal dissipation, was rapidly increased when E. gracilis was exposed to Al in comparison with C. acidophila (see Table 1).…”

Section: Resultsmentioning

confidence: 96%

Effect of aluminum on cellular division and photosynthetic electron transport in Euglena gracilis and Chlamydomonas acidophila

Perreault

Dewez

Fortin

et al. 2010

Enviro Toxic and Chemistry

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The present study investigated aluminum's effect on cellular division and the photosynthetic processes in Euglena gracilis and Chlamydomonas acidophila at pH 3.0, at which Al is present mostly as Al(3+), AlSO(4) (+), and Al(SO(4))(2) (-). These algal species were exposed to 100, 188, and 740 microM Al, and after 24 h cell-bound Al was significantly different from control only for the highest concentration tested. However, very different effects of Al on algal cellular division, biomass per cell, and photosynthetic activity were found. Aluminum stimulated cell division but decreased at some level biomass per cell in C. acidophila. Primary photochemistry of photosynthesis, as Photosystem II quantum yield, and energy dissipation via nonphotochemical activity were slightly affected. However, for E. gracilis, under the same conditions, Al did not show a stimulating effect on cellular division or photosynthetic activity. Primary photochemical activity was diminished, and energy dissipation via nonphotochemical pathways was strongly increased. Therefore, when Al is highly available in aquatic ecosystems, these effects may indicate very different response mechanisms that are dependent on algal species.

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Section: Resultsmentioning

confidence: 96%

Effect of aluminum on cellular division and photosynthetic electron transport in Euglena gracilis and Chlamydomonas acidophila

Perreault

Dewez

Fortin

et al. 2010

Enviro Toxic and Chemistry

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“…The rapid formation of QA under anaerobic conditions could eventually increase the resistance against photoinhibition as was suggested in Kirilovsky and Etienne (1990) if it led to a switching of the reaction center into a 'quenched center', with the ability to dissipate the lightenergy harmlessly as heat (see Cleland and Chritchley 1985, Buschmann 1987, Krause 1988). However, the data in Fig.…”

Section: Discussionmentioning

confidence: 96%

Characterization of the reversible state of photoinhibition occurring in vitro under anaerobic conditions

Sundby

Schiött²

1992

Photosynth Res

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Thylakoid membranes were subjected to photoinhibitory illumination. The use of oxygen-consuming enzymes to obtain strictly anaerobic conditions showed that while the absence of oxygen is a prerequisite for the formation of a reversibly photoinhibited state, the presence of oxygen is required for the recovery in the dark. The formation of the reversibly photoinhibited state did not protect the thylakoid membranes against irreversible damage. The effects of both bicarbonate and formate were found to be qualitatively different for photoinhibition under strictly anaerobic conditions compared to the effects observed under normal aerobic photoinhibition. It is suggested that there are two different mechanisms of photoinhibition, occurring to different extent under aerobic and anaerobic conditions, respectively, involving QA in both cases, but the QB-site in the former only.

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“…The photothermal signal contains direct information on the thermodynamic efficiency of photosynthesis (5,17). With some minor corrections, the measure of the thermal signal with and without saturating continuous light gives the thermodynamic efficiency, or quantum yield, of photosynthesis.…”

Section: Resultsmentioning

confidence: 99%

Determination of Oxygen Emission and Uptake in Leaves by Pulsed, Time Resolved Photoacoustics

Mauzerall¹

1990

Plant Physiol.

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Pulsed, time resolved photoacoustics has sufficient sensitivity to determine oxygen emission and uptake by single tumover flashes to leaves. The advantage over previous methodologies is that when combined with single turnover flashes the kinetics of the thermal and the gas signals can be resolved to 0.1 millisecond and separated. The S-state oscillations of oxygen formation are readily observed. The gas signal from common spongy leaves such as spinach (Spinacia sp.), Japanese andromeda (Pieris japonica), mock orange (Philadelphus coronarius) and viburnum (Viburnum tomentosum), after correction for instrumental rise time, show a lag of only 1 millisecond and a rise time of 5 milliseconds in the formation of oxygen. Thus a recent proposal that the formation of oxygen requires over 100 milliseconds cannot be true for choroplasts in vivo. The rapid emission is correlated with structure of the leaf. At low light flash energies a rapid gas uptake is observed. The uptake has slightly slower kinetics than oxygen evolution, and its magnitude increases with damage to the leaf. The pulse methodology shows that the uptake begins with the very first flash after dark adaption, and allows the detection of a positive signal (oxygen) on the third flash. These observations, the long wavelength of excitation (695 nanometers) and the magnitude of the signal support the contention that the gas uptake is oxygen reduction by electrons from photosystem 1. These results show that important physiological aspects of a leaf can be studied by pulsed, time resolved photoacoustics.The photoacoustic effect is caused by the thermal expansion of a fluid when the energy of absorbed photons is degraded to heat (17 ever, the inherent complexity of photosynthetic systems coupled with the limited data obtained in the usual photoacoustic methodology using modulated light has made progress slow. A complete analysis would require a dense set of both amplitude and phase measurements over a range of at least three orders of magnitude in frequency. Since the measurements are made one frequency at a time, it is not surprising that such data assets are rare (23). Further, the analysis of such a data set with multiple relaxation times having both positive and negative amplitudes is itself very difficult and may lead to ambiguous results. By contrast, the analysis of the photoacoustic response to a single short pulse of light is relatively straightforward. The signal to noise ratio is typically sufficient to obtain the complete kinetic trace of the signal in a single measurement over the accessible time range of 30 ,us to 100 ms. In addition to this enormous advantage of obtaining all of the accessible time data (i.e. reciprocal frequency) in one measurement, the use of classical single turnover flashes (so short the system can only turnover once [8]) provides the further advantage of identifying and distinguishing processes related to oxygen formation. The slower oxygen pressure signal is easily resolved from the faster photothermal signal because mol...

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Induction kinetics of heat emission before and after photoinhibition in cotyledons of Raphanus sativus

Cited by 42 publications

References 29 publications

Effect of aluminum on cellular division and photosynthetic electron transport in Euglena gracilis and Chlamydomonas acidophila

Effect of aluminum on cellular division and photosynthetic electron transport in Euglena gracilis and Chlamydomonas acidophila

Characterization of the reversible state of photoinhibition occurring in vitro under anaerobic conditions

Determination of Oxygen Emission and Uptake in Leaves by Pulsed, Time Resolved Photoacoustics

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