Fluorescence and Photosynthetic Activity of Chloroplasts in Acid and Alkaline Zones of Chara corallina

Bulychev, A.A.; Cherkashin, A.A.; Vredenberg, W.J.; Rubin, A.B.; Zykov, V.S.; Müller, S.C.

Авторы: Bulychev A.A., Cherkashin A.A., Vredenberg W.J., Rubin A.B., Zykov V.S., Müller S.C.
Журнал: Russian Journal of Plant Physiology
Том: 48
Номер: 3
Год издания: 2001
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 326
Последняя страница: 332
DOI: 10.1023/A:1016610315798
Аннотация: Continuous profiles of local pH near the cell surface of Chara corallina were recorded during uniform longitudinal movement of an internodal cell relative to a stationary pH microelectrode. Under illumination, the pH profile consisted of alternating acid and alkaline bands with a pH difference of up to 3 pH units. After darkening, the bands disappeared and pH became uniformly distributed along the cell length. Chlorophyll fluorescence of chloroplasts was measured by microfluorometry at different locations within one cell, and significant differences were observed in close relation to light-dependent pH banding. The chlorophyll fluorescence yield was lower in zones of low external pH than in alkaline zones both under actinic and saturating light. The fluorescence parameters F and F " m and the quantum yield of photosystem II (PSII) displayed variations along the cell length in accordance with pH changes in unstirred layers of the medium. The results show that PSII photochemical efficiency and the rate of noncyclic electron transport are higher in the chloroplasts of acid zones (zones of H + extrusion from the cell) than in alkaline zones. The dependence of photosynthetic electron transport on local pH near the cell surface may result from different contents of CO 2 in acid and alkaline regions. The acid zones are enriched with CO 2 that readily permeates through the membrane providing the substrate for the Calvin cycle. Conversely, a poorly permeating form, HCO – 3 is predominant in alkaline zones, which may restrict the dark reactions and photosynthetic electron flow.
Добавил в систему: Булычев Александр Александрович

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Fluorescence and Photosynthetic Activity of Chloroplasts in Acid and Alkaline Zones of Chara corallinaстатья

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