Figure 4.

Rapid exchange between D1:1 and D1:2 with increasing levels of supplemented UV-B irradiation and subsequent recovery. Synechococcus sp. PCC 7942 wild-type cells grown at 37°C with white light at 50 μmol of photons per m² per s and bubbled with 5% CO₂ were supplemented with UV-B at 0.2, 0.4, or 0.8 W/m² for 2 h and then allowed to recover for 1 h without UV-B. Protein extracts were taken at the indicated times, and the composition of D1 protein was determined by immunoblotting with polyclonal antibodies specific for either D1:1 or D1:2. The figure shows results representative of three replicates.