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

Abstract

The genotoxic activity of cadmium chloride (CC) has been evaluated in the somatic mutation and recombination test (SMART) in Drosophila melanogaster. In addition, its possible modulating effect on the genotoxicity of two known mutagenic agents, potassium dichromate (PDC) and ethyl methanesulfonate (EMS), was investigated. Three different types of combined treatments of CC with the two genotoxins were performed: pretreatment, cotreatment, and posttreatment. The SMART assay is based on the principle that loss of heterozygosity for the recessive markers, multiple wing hairs (mwh) and flare-3 (flr(3)), leads to the formation of mutant clones in the imaginal disks of larvae, which are expressed as mutant spots on the wings of adult flies. Thus, after adult emergence, the wings of the adult flies were scored for the presence of single and/or twin spots. Our results show that CC alone was not effective in increasing the frequency of any of the three categories of spots (small, large, and twin). In the cotreatment experiments, CC increased the genotoxicity of PDC but it decreased the genotoxicity of EMS. No effects of CC were observed in the pretreatment or posttreatment experiments; however, only low concentrations of CC, PDC, and EMS were tested in the pretreatment assays due to the high toxicity of the treatment. Although our results with PDC are consistent with the hypothesis that cadmium can interfere with repair mechanisms, the EMS data suggest that other modulating mechanisms are also involved in the genotoxicity of this metal.

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

“…The average spontaneous frequency of total spots (0.40) was consistent with the historical water control frequency observed in our laboratory, and was in good agreement with the normal range of background frequencies previously reported by different authors [Frei and Würgler, 1995;Torres et al, 1998;Rizki et al, 2004]. EMS (1 mM), the positive control, significantly increased the frequency of all categories of spots.…”

“…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].…”

Modulatory effects of the antioxidant ascorbic acid on the direct genotoxicity of doxorubicin in somatic cells of Drosophila melanogaster

“…The fruit fly Drosophila melanogaster with its well development array of genotoxicity test systems has been used in a number of studies on the modulatory effects of various compounds, along with somatic mutation and recombination tests (SMART) have been employed (Graf et al, 1998;Kaya et al, 2002;Rizki et al, 2004;Sinigaglia et al, 2004;Romero-Jiménez et al, 2005;Costa and Nepomuceno, 2006). …”

Assessing potential harmful effects of CdSe quantum dots by using Drosophila melanogaster as in vivo model

“…This would confirm that the comet assay is more sensitive than the wing-spot assay (Alaraby et al, 2014). In fact, non-genotoxic effects of CdCl 2 in Drosophila using the wing-spot test were observed early by our group (Rizki et al, 2004). Indirect genotoxicity of QDs in Drosophila has already been determined by means of the tunnel assay (Galeone et al, 2012) and positive effects of CdCl 2 have been reported in midgut cells (Shukla et al, 2011) and in hemocytes of spiders fed with Drosophila treated with CdCl 2 (Stalmach et al, 2014).…”