GENOTOXIC EFFECTS OF METHYLMERCURY ON THE FISH <i>Colossoma macropomum</i> (CHARACIFORMES: CHARACIDAE) AS EVALUATED USING THE COMET ASSAY

Abstract

Comet assay has been used increasingly to evaluate genotoxicity of many metals and their organic compounds in aquatic ecosystems. The use of endemic aquatic organisms as biological sentinels has proved to be useful to environmental monitoring. In this study, the genetic damages caused by methylmercury (MeHg) in the widely distributed Amazonian fish, Colossoma macropomum (commonly called tambaqui), was assessed using the comet assay. Specimens of C. macropomum were acclimatized in aquariums to laboratory conditions and then exposed to 2mg.L-1 MeHg by hydric way. Peripheral blood samples were obtained from specimens and subjected to the comet assay. Exposure to MeHg significantly increased the frequency of tailed nucleoids in the erythrocytes of fishes exposed (p<0.0005), indicating DNA damage. The results obtained show that the neotropical fish C. macropomum is not only important as eatable species, but also an adequate model for biological studies that evaluate genotoxic effects of mercury in aquatic environments.