The ratio of deoxyadenosine to deoxyguanosine adducts formed by (+)-(7R, 8S, 9S, 10R)-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene in purified calf thymus DNA and DNA in V-79 cells is independent of dose

The hypothesis that the decrease in the proportion of mutations at AT base pairs in Chinese hamster V-79 cells treated with increasing doses of (+)-(R ,S,S,R)-benzo[a]pyrene diol epoxide ((+)-BPDE) is due to saturation of A 'h ot spots' for adduct formation was investigated by comparing the ratio of d A to dG adducts formed at high (0.48 mu M) and low (0.04 mu M) doses of [H- 3]-labeled (+)-BPDE. The dA to dG adduct ratio was similar in both calf thy mus DNA and the genomic DNA in V-79 cells, and did not change with dose. Fo r the V-79 cells, this ratio was also unaffected by a 24-h post treatment r epair incubation.