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

Abstract

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.

Genotoxicity modulation by cadmium treatment: Studies in the Drosophila wing spot test

“…The average control frequency of mutant spots (0.26) was consistent with the normal background range reported by different authors [Frei and Würgler, 1995;Torres et al, 1998;Rizki et al, 2002]. Thus, in the wing spot test, CC does not appear to be genotoxic, which agrees with the only results previously reported in somatic cells of Drosophila using the zeste test [Rasmuson, 1985].…”

Metabolism of arsenic in Drosophila melanogaster and the genotoxicity of dimethylarsinic acid in the Drosophila wing spot test

“…3b and 3c), which increases the background level of arsenic in the larvae (0.07 ng As/larva) 47-fold. This retention of high levels of inorganic arsenic was not accompanied by genotoxicity, as we demonstrated in a previous study [Rizki et al, 2002]. The lack of biomethylation does not mean that Drosophila are totally devoid of detoxication mechanisms for inorganic arsenic.…”

“…Arsenite also induces chromosome aberrations, endoreduplication, aneuploidy, and micronucleus formation [Gurr et al, 1993;Huang et al, 1995;Kochhar et al, 1996]. A recent study indicated that arsenite was not genotoxic in the somatic cells of D. melanogaster (wing spot test) [Rizki et al, 2002], confirming the results of Ramos-Morales and Rodriguez-Arnaiz [1995] in the same test system.…”

“…The SMART is a powerful system for detecting mutation and recombination in somatic cells, as well as for discovering possible interactions between chemicals [e.g., Rizki et al, 2001Rizki et al, , 2002Rizki et al, , 2004. Previous studies indicate that inorganic sodium arsenite is inactive in the Drosophila SMART assay [Ramos-Morales and Rodriguez-Arnaiz, 1995;Rizki et al, 2002]. To determine whether these negative findings are related to the metabolism of arsenic, we fed inorganic arsenic to Drosophila larvae and adults, and analyzed them for the presence of methylated arsenic.…”

“…This organism is widely used in genotoxicity studies and, in particular, for the somatic mutation and recombination test (SMART; also known as the Drosophila wing spot test) [Graf et al, 1984]. The SMART is a powerful system for detecting mutation and recombination in somatic cells, as well as for discovering possible interactions between chemicals [e.g., Rizki et al, 2001Rizki et al, , 2002Rizki et al, , 2004. Previous studies indicate that inorganic sodium arsenite is inactive in the Drosophila SMART assay [Ramos-Morales and Rodriguez-Arnaiz, 1995;Rizki et al, 2002].…”