Figure 5.

Formation and removal of CPDs in the DHFR gene in AA8 and UV61 transfectant cell lines. Genomic DNA (10 μg) was isolated from either unirradiated (−UV) or UV irradiated (20 J/m²) cells at 0, 8, and 24 h after exposure as described in MATERIALS AND METHODS. The DNA was subsequently digested with KpnI and either treated with T4 endonuclease V (+) or untreated (−). DNA was electrophoresed through an alkaline agarose gel (0.5%) and quantitatively transferred to a nylon membrane. The membrane was hybridized to ³²P-labeled denatured double-stranded DNA probe for the DHFR gene. Hybridization of gene-specific ³²P-labeled DHFR probes to membranes was detected by PhosphorImager analysis.