Figure 2.

Starch phosphorylation in light and darkness in Chlamydomonas. Algal cells equivalent to 7.2 μg of Chl were agitated in light (white symbols) or darkness (black symbols) for the times indicated, and the amount of ³²P incorporation into starch was determined. The radioactivity in control samples in which the cells were lysed prior to addition of the label was subtracted (<40 cpm). Values are means of duplicate samples. A, Continuous labeling. B, Transient labeling (pulse and chase). Following incubation for 1 h with 40 μm ³²P (6 μCi), unlabeled phosphate was added to give a final concentration of 20 mm (chase). The radioactivity incorporated into starch during 1 h in darkness was set to 100%.