Non chloroplastic pyridine nucleotides concentrations in acetabularia as related with the developmental program: Circadian modulation of the concentrations

Abstract The concentrations of non chloroplastic NAD+, NADP+, NADH and NADPH were followed during the development of the unicellular green alga Acetabularia. When Acetabularia enters the rapid growth phase, a slight increase in NAD+ level is observed, and a slight decrease in both NADH and NADPH levels. In contrast, a huge decrease in both NAD+ and NADP+ concentrations take place at the time caps are initiated and develop, together with a slight increase in both reduced pyridine nucleotides concentrations. This increase has been confirmed and extended from the primordium stage to the cysts bearing caps: NADH and NADPH steadily increase in concentration. The circadian rhythms of the four pyridine nucleotide concentrations have also been studied in the non chloroplastic fraction of Acetabularia. Both NAD+ and NADP+ concentrations oscillate in phase according to a biphasic mode. The first peak occurs at 3 h (CT) and the second one at 15h, whereas the troughs are at 6 and 22 h. The rhythms are maintained in c...