Influence of sodium arsenite on the genotoxicity of potassium dichromate and ethyl methanesulfonate: studies with the wing spot test in Drosophila

The wing spot test in Drosophila melanogaster was used to investigate the genotoxicity of arsenic and its effects on the action of two clearly genotoxic agents: potassium dichromate (PDC) and ethyl methanesulfonate (EMS). This assay is based on the principle that the loss of heterozygosity of the suitable recessive markers multiple wing hairs (mwh) and flare-3 (flr(3)) can lead to the formation of mutant clones of larval cells, which are then expressed as spots on the wings of adult flies. These spots can be attributed to different genotoxic events: either mitotic recombination or mutation (deletion, point mutation, and specific types of translocation). Pretreatments and chronic cotreatments were comparatively used for combined treatments. From the results obtained it is evident that sodium arsenite (SA) does not increase the frequency of any of the three categories of spots recorded (small, large, and twin spots) at the concentrations tested. The effects of SA in combination with PDC, in both cotreatments and pretreatments, indicate that SA almost suppressed the clones induced by PDC. Nevertheless, no effects of arsenic were observed with respect to the pre- and cotreatments with EMS. Thus, SA does not modify the frequencies of mutant clones induced by EMS.