Mutations at six additional loci of Drosophila melanogaster cause alkylation hypermutability

8 mutagen-sensitive strains of Drosophila melanogaster were examined for their effects on alkylation-induced mutagenesis. Using methylnitrosourea as the DNA-damaging agent and the sex-linked recessive lethal test as the monitor of genetic endpoint, 6 of these strains were shown to be hypermutable following exposure to this alkylating agent. Previous studies of 6 other genes have demonstrated that strains exhibiting alkylation hypermutability are completely defective in repair replication following alkylation-induced DNA damage. The present observations suggest that at least 12 loci may be required for excision repair of alkylation DNA damage in this species.