Figure 2. Quantification of CPD formation and removal in telomeres from UVC exposed BJ-hTERT.

(a) Cells were untreated or exposed to 10 J m⁻² UVC followed by harvesting at various repair times (0–48 h). Telomeres were isolated from purified genomic DNA (100 μg each time point) and loaded on blots (7 ng, lane 2) with equal amounts of genomic DNA (7 ng, loaded in duplicate lanes 1 and 3). The blot was sequentially probed with a CPD antibody, a radiolabelled telomere probe, and a radiolabelled Alu repeat probe. The telomere probes remained bound (hashed box) since membranes could not be stripped without losing DNA. (b) Purified genomic DNA (100 μg) was exposed to 100 J m⁻² UVC in vitro. Telomeres were isolated and blotted (3 ng) with equal amounts of genomic DNA, and probed with a CPD antibody and radiolabelled telomere probe. The CPD signal intensity was quantitated and normalized to genomic DNA for comparison; from three independent experiments. (c) The CPD signal intensity was quantitated for experiments in a, normalized to 0 h, and plotted against recovery time. Values and error bars are the mean and s.e.m. from three independent experiments. The difference between the curves is statistically significant (P=0.0034) by two-way ANOVA.