Photosynthetic Efficiency During the Cell Cycle of the Green Alga Desmodesmus armatus Reaches Maxima in G1 Phases and Minima in G1/S Transients

Abstract

Chlorococcal green algae divide by multiple fissions. Cell division in such algae can be readily synchronized by alternating light:dark cycle. At the applied conditions, in synchronized cultures of Desmodesmus, each cell divides into eight autospores. This means that each cell must reach three commitment points (G1/S) to initiate three successive cell divisions, preceded by the appropriate growth phase (G1). The analysis of chlorophyll fluorescence transients (O-J-I-P) performed during the cell cycle (CC) of Desmodesmus revealed the characteristic course of primary photochemistry of active reaction centre of PS II (φE0). The maxima φE0 occurred in successive G1 phases of the cell cycle whereas the minima occurred when the cells passed through the commitment points of G1 phases.