Regeneration of photosystem II and phycobilin pigments in photoorganotrophically grown Anabaena variabilis

Regeneration of photosynthetic activity and phycobilin pigmentswas studied with cells of Anabaena variabilis lacking photosystemII activity and phycobilin pigments. Regeneration was achievedonly when the cells were incubated in the presence of nitrateor nitrite. The addition of ammonium salts or urea was far lesseffective. Nitrate-directed regeneration was independent oflight and inhibited by chlorate. Dark-regenerated cells, however,differed from light-regenerated ones in that the former wereincapable of excitation transfer from phycocyanin to pigmentsystemII chlorophyll a, although they emitted fluorescence of pigmentsystem II chlorophyll a origin, if illuminated by the lightabsorbed by chlorophyll. The regeneration process inAnabaenacells is assumed to consist of two steps: 1] light-independent,nitratesupported synthesis of phycobilin pigments and photosystemII integrity, followed by 2] light-directed formation of excitationtransfer from phycocyanin to pigment system II chlorophyll a.An antibiotic study revealed that the former is associated withprotein synthesis, while the latter isnot. ¹ Present address: Ocean Research Institute, University of Tokyo,Nakano, Tokyo 164, Japan. (Received November 19, 1975; )