Figure 2.

Recovery of PSII and PSI in intact cells after removal of sorbitol. After cells had been incubated for 2 h with 1.0 m sorbitol, they were washed twice with fresh BG-11 medium and incubated in the presence of either lincomycin or p-chloromercuriphenyl-sulfonic acid and in the absence of these chemicals. At designated times, a portion of each cell suspension was withdrawn and the activities of PSII and PSI were determined. A, The oxygen-evolving activity of PSII was examined after the addition of 1.0 mm BQ to the suspension. The activity that corresponded to 100% was 544 ± 38 μmol O₂ mg⁻¹ Chl h⁻¹. B, The activity of PSI was determined by monitoring the uptake of oxygen after the addition of 15 μm DCMU, 0.1 mm DCIP, 5 mm ascorbate, and 0.1 mm MV to the suspension. The rate of oxygen uptake that corresponded to 100% was 364 ± 52 μmol O₂ mg⁻¹ Chl h⁻¹ in the absence of both chemicals (○); in the presence of 100 μm p-chloromercuriphenyl-sulfonic acid (▵); in the presence of 100 μg lincomycin mL⁻¹ (□). Each point represents the average with se of results from four independent experiments.