SOMATIC REVERSION OF SOME COPIA-LIKE INDUCED MUTATIONS, AT THE WHITE LOCUS OF DROSOPHILA-MELANOGASTER, AFTER TREATMENT WITH ALKYLATING-AGENTS

It has been suggested that transposable elements can be associated wit h different types of genotoxic effects. For this reason it seems appro priate to outline suitable systems to detect changes in the phenotypic expression of the loci containing transposable elements, as well as t hose agents that induce such changes. The sex-linked white locus offer s a suitable experimental system for studying such events because most of the spontaneous mutations at the white locus are the result of ins ertions of repeated mobile sequences, and it is easy to follow mutatio nal changes of the locus due to the possibility of detecting even slig ht changes in eye color. Here we report the results obtained in differ ent strains of Drosophila melanogaster with copia-like induced mutatio ns at the white locus, after treatment with three alkylating agents: e thyl methanesulfonate (EMS), methyl methanesulfonate (MMS), and N-nitr oso-N-ethylurea (ENU). The three insertional white mutants used in thi s work were w(a4), w(bf), and w(sp55), With the w(a2) mutation used as control because its mutant phenotype is the result of a point mutatio n instead of the insertion of a DNA fragment. Our data constitute evid ence that EMS, MMS, and ENU induce a clear increase in the frequencies of somatic-revertant sectors in the three strains carrying a white al lele with an inserted copia-like element. For the w(a2) strain, whose mutant phenotype is the result of a point mutation, only ENU at the hi ghest concentration tested is able to induce a significant increase in the somatic reversion frequency. In addition, our results indicate th at the use of D. melanogaster strains with transposable elements in th e white locus is suitable for detecting genotoxic damage induced by ch emicals. (C) 1995 Wiley-Liss, Inc.