Figure 5.
POLD3 but not Polζ is required to maintain replication fork progression on UV damaged DNA. (A) Intact postreplicative gap filling in pold3 cells. Indicated cells without UV (upper panel) or with UV (5 J/m2) (lower panel) were pulse-labeled with [methyl-14C] thymidine, then incubated a further in fresh medium containing 10 μM unlabeled thymidine for the indicated time. Samples were separated on 5–20% alkaline sucrose gradient sedimentation. (B) Representative image showing stained DNA fibres. DT40 cells were labelled sequentially with IdU and CldU with or without UV treatment after IdU labeling. (C) The data for cells carrying the indicated genotypes was plotted as a cumulative percentage (y-axis) of forks at each ratio (x-axis). The P-values of the Kolmogorov–Smirnov test for ratio distribution of each mutant for UV compared to wild-type are indicated. n.s.: not significant.