Volume changes of isolated spinach chloroplasts on illumination in the presence of phenazine methosulfate

概要

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Chloroplasts suspended in phosphate buffer with PMS swelled rapidly on illumination, their volumes reaching a maximum level within 5 min. Subsequently they shrank noticeably. Both swelling and subsequent shrinkage were reversible; in the former, chloroplasts swelled on illumination and shrank on turning off the light. In the latter, volume change occurred in the opposite direction. Light-induced swelling in the presence of PMS disappeared on alternating light and dark several times. Thereafter, only shrinkage was observed. Only shrinkage took place on illumination when PMS was added to Tris-washed, or heated chloroplasts, or when chloroplasts were suspended in phosphate buffer with other electron transport cofactors such as FMN and vitamin K_3 or in acetate buffer instead of phosphate in the presence of PMS. PMA and CCCP (low concentration) inhibited swelling with PMS. Quinacrine had no effect on volume changes with PMS, while antimycin A and CCCP (high concentration) completely prevented both swelling and shrinkage. These suggest that volume changes are a result of competition between swelling and shrinking activities which depend on utilization of high energy intermediates formed by PMS-induced photochemical reactions.
日本植物生理学会の論文