Figure 5. Photosynthesis activation following anoxic incubation in a double mutant deficient for both state transition and hydrogenase activity.

A. Chla fluorescence (black) and O₂ evolution (red) traces upon illumination (250 µmol.m⁻².s⁻¹) of a double mutant stt7-9/hydEF, a hydrogenase deficient mutant locked in state 1, following a 10 min (upper graph) or 40 min (lower graph) anoxic incubation in the dark . Saturating light flashes (1 s flashes of 3000 µmol.m⁻².s⁻¹ every 50 s) were applied during the induction process in order to saturate transiently all PSII reaction centers and determine the maximal fluorescence yield Fm′ in the light. B. Evolution of the fraction of closed PSII centers (1-qp), in wild-type and in hydEF, stt7-9 and stt7-9hydEF mutant suspensions of algae during illumination (250 µmol.m⁻².s⁻¹) following a 40 min anoxic incubation in the dark. Error bars indicate standard error of the mean of three independent experiments.