THE INDUCTION OF SEX-LINKED RECESSIVE LETHALS BY FORMALDEHYDE IN 2 STRAINS OF DROSOPHILA-MELANOGASTER

Two strains of Drosophila melanogaster have been previously characteri zed as resistant (CO3) and sensitive (RCI) to the mutagenic action of chemical and physical agents (Andrade and Marques, Brazil. J. Genet. 3 : 251-264, 1980). To evaluate the role played by excision repair in th e differential sensitivity of these two strains, we compared their res ponse to the induction of sex-linked recessive lethals (SLRL) by forma ldehyde, a mutagen which induces DNA lesions mainly processed by excis ion repair. There was a significant increase in the frequency of SLRL in both strains. However, the resistant strain had a lower mutation fr equency. We conclude that the RCI strain is defective in the excision- resynthesis repair mechanism.