�ber den Einflu� der Vorbelichtung auf die anschlie�ende Phosphorylierung im Dunkeln bei einzelligen Gr�nalgen (Ankistrodesmus braunii)
✍ Scribed by Kanai, Ryuzi ;Simonis, Wilhelm
- Publisher
- Springer-Verlag
- Year
- 1968
- Weight
- 717 KB
- Volume
- 63
- Category
- Article
- ISSN
- 0003-9276
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✦ Synopsis
Influence o/PreiUumination on Subsequent Phosphorylation in the Darkness
o/ Unicellular Green Algae (Ankistrodesmus braun[i) Summary. Preilluminated unicellular green algae (AnIcistrodesmus brauniiJ were treated in the subsequent darkness with 32P04. The post-illumination dark incorporation was considerably increased compared with the control in continuous dark. The labeling of the separated phosphate-fractions was similar to that of continuous light. The light-induced dark incorporation depended from the light intensity as well as from the time of preillumination. A preillumination of 7 rain was required for a maximal enhancement of this preillumination effect. On the other hand the effect diminished in darkness with a half life of approximately 4 rain. Finally the enhancement was found to be greater in the absence of CO 2 than in the presence of CO 2.
The experiments demonstrate the light-induced formation of a state in the algae, which permits the enhancement of ~2P-incorporation into several phosphatefractions for a limited time during subsequent darkness.
It is discussed, that this may be performed through the formation of a lightreduced substance "R" maintaining for a limited time a cyclic electron transport in darkness, coupled with phosphorylation. On the other hand it seems possible, that preillumination induces a high energy intermediate "XE"--this could also be a pool of protons--formed in the course of energy-transfer from electron transport to ATP-formation. But we must consider also the possibility that light accellerates the ATP-Pi exchange on chloroplast-membranes for a time after preillumination. Zusammen/assung. Wird einzelligen Algen (Ankistrodesmus braunli) nach Vorbelichtung in anschliel]ender Dunkelheit a~P-markiertes Phosphat geboten, so tritt gegenfiber Dauerdunkel eine erhehliche FSrderung der a2P-Einlagerung auL Die nach Vorbelichtung bestimmte Markierung der aufgetrennten Phosphatfraktionen ~hnelt sehr derjenigen im Dauerlicht. Die erhShte ])unkelphosphorylierung nach Vorbelichtung h~ngt yon der C02-Konzentration, yon der Lichtintensit~it und der Zeit der Vorbelichtung ab. Unter den vorliegenden Bedingungen waren 7 rain Vorbelichtung zur maximalen FSrderung nStig. Die ttalbwertzeit des Abklingens betrug etwa 4 min. * Stipendiat der Nishina-Ged~chtnis-Stiftung (Japan) ffir 1963.