FIG. 2.
UVC-induced DNA damage inhibits replicon initiation. NHF1 cells were uniformly labeled as described above and sham treated or irradiated with 1 J/m2 UVC. Following treatment, cells were incubated in reserved medium for either 30 (A), 60 (B), or 90 (C) min prior to a 15-min pulse with [3H]thymidine. Velocity sedimentation analysis of nascent DNA was done as described in the legend to Fig. 1C. Open circles represent profiles from sham-treated cells, while closed circles represent those from UVC-irradiated cultures. Arrows point to the position in which the nascent DNA distribution from irradiated cells diverges noticeably from that observed with sham-treated cells.