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Titolo:
STIMULATION OF PHOTOCURRENT IN CHLOROPLASTS RELATED TO LIGHT-INDUCED SWELLING OF THYLAKOID SYSTEM
Autore:
BULYCHEV AA; DASSEN JHA; VREDENBERG WJ; OPANASENKO VK; SEMENOVA GA;
Indirizzi:
WAGENINGEN UNIV AGR,DEPT PLANT PHYSIOL WAGENINGEN NETHERLANDS WAGENINGEN UNIV AGR,DEPT PLANT PHYSIOL WAGENINGEN NETHERLANDS MOSCOW MV LOMONOSOV STATE UNIV,FAC BIOL,DEPT BIOPHYS MOSCOW RUSSIA RUSSIAN ACAD SCI,INST SOIL SCI & PHOTOSYNTH PUSHCHINO 142292 RUSSIA RUSSIAN ACAD SCI,INST THEORET & EXPT BIOPHYS PUSHCHINO 142292 RUSSIA
Titolo Testata:
Bioelectrochemistry and bioenergetics
fascicolo: 1, volume: 46, anno: 1998,
pagine: 71 - 78
SICI:
0302-4598(1998)46:1<71:SOPICR>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
PATCH-CLAMP; CHLOROPHYLL FLUORESCENCE; INTACT CHLOROPLASTS; ELECTRON-TRANSPORT; MEMBRANE; PHOTOSYNTHESIS; CURRENTS; LEAVES;
Keywords:
PEPEROMIA METALLICA; CHLOROPLAST; THYLAKOID MEMBRANES; ELECTRICAL POTENTIAL; PHOTOCURRENT; AMMONIUM; ELECTRON TRANSPORT; BIOENERGETICS; ELECTRON MICROSCOPY; ULTRASTRUCTURAL CHANGES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
A.A. Bulychev et al., "STIMULATION OF PHOTOCURRENT IN CHLOROPLASTS RELATED TO LIGHT-INDUCED SWELLING OF THYLAKOID SYSTEM", Bioelectrochemistry and bioenergetics, 46(1), 1998, pp. 71-78

Abstract

The photocurrent in patch-clamped chloroplasts of Peperomia metallicawas strongly modified by full or partial replacement of 50 mM KCI with NH4Cl in the external medium. Two effects of ammonium were observed at zero holding potential: (1) the sustained current in prolonged light pulses was substantially increased and (2) the peak current induced by a single-turnover flash (8 mu s) was amplified, with a concomitant shortening of its relaxation time. Under control conditions, in the presence of KCl, the photocurrent rose to an initial peak and declined in continuous light, whereas in the presence of NH4Cl, an initial rise of inward current was followed by a further rise (within 0.5-1 s) to ahigh steady level. This effect of ammonium is partially explained by the absence of pH gradient which makes electron turnovers more frequent. However, the current induced by an 8-mu s flash in the presence of NH4+ was also stimulated (by 50-150%) after 1-s preillumination of dark-adapted plastids. Hence, the apparent photoactivation of electrogenic activity was not only due to acceleration of electron turnovers. Either (i) latent reaction centers turn active during preillumination or (ii) the patch pipette becomes a more effective sink for current, owing to NH4+-dependent swelling of lumen and the resulting reduction in the longitudinal lumenal resistance. In support of the latter view, theflash-induced response in NH4+-treated plastids had a shorter relaxation time in preilluminated than in dark-adapted plastids. Thus, the light-induced structural changes of the thylakoid system, confirmed by electron microscopy, strongly affect the photocurrents probed by the patch-clamp technique. (C) 1998 Elsevier Science S.A. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 14:18:02