Preferential formation of deletions following in vivo exposure of postmeiotic Drosophila germ cells to the DNA etheno‐adduct‐forming carcinogen vinyl carbamate

DNA sequence changes induced in the vermilion gene of Drosophila following in vivo treatment of postmeiotic male germ cells with vinyl carbamate (VCA), an etheno-adduct-forming carcinogen, are primarily deletions. With VCA, 65% (13/20) of the vermilion mutants isolated from crosses of NER' (nucleotide excision repair) males with NER + females and 40% (6/15) obtained from matings with NER females were intra- or multi-locus deletions. Due to the insufficiently low mutagenic activity in NER * genotypes of vinyl bromide (VB), another e-adduct-forming carcinogen, vermilion mutants could only be isolated from crosses of VB-treated males with NER - females. Of 14 vermilion mutants induced by VB, three carried large deletions. Twenty-two of 23 base substitutions derived from either VCA or VB experiments fell into one of the four categories expected from e-adducts: three vermilion mutants had GC - AT transitions, five had AT - GC transitions, 7 carried GC - TA transversions, and 7 were AT -TA transversions. In view of the similarities in the response of mouse and Drosophila germ lines to several classes of alkylating agents, a high incidence of deletions is predicted to occur as well in postmeiotic germ cells of mice exposed to these types of agents.