FIG. 2.

ICRF-193 treatment does not induce DNA damage detectable by PFGE. Late S/G2-phase synchronized V79B and XR-V15B cells were incubated in the presence of increasing concentrations of ICRF-193 for 4 h. For bleomycin treatment, G₀/G₁ synchronized cells were released into medium supplied with 10% FCS and different drug concentrations for 16 h. Cells were included in 1% low-melting-point agarose at a final density of 6 × 10⁶/ml. DNA from approximately 200,000 lysed cells was migrated by PFGE as described in Materials and Methods. At the end of migration, the DNA was transferred onto a nylon membrane and hybridized with a ³²P-labeled probe of V79B genomic DNA. Note that intact chromosomal DNA remained in the wells, while fragmented DNA migrated into the gel. Representative autoradiographs of four experiments are shown. Higher exposures of these membranes did not reveal increased DNA damage in the presence of ICRF-193 compared to controls.