Figure 2.

UvrD is required for the recovery of replication following UV irradiation, but not for replication in the absence of damage. Cells grown in the presence of [¹⁴C]-thymine were pulse-labeled for 2 min with [³H]-thymidine at the times indicated following either UV irradiation with 27 J/m² (open symbols) or mock irradiation (closed symbols). Total DNA accumulation (¹⁴C incorporation, circles) and rate of synthesis (³H incorporation/ 2 min, squares) are plotted. Graphs represent the average of at least three independent experiments. Error bars represent the standard error of the mean. The level of [³H] and [¹⁴C] in preirradiated DNA ranged between 30,000–50,000 cpm and 3000–6000 cpm for all experiments.