Genotoxicity evaluation of tilapia (Oreochromis niloticus) exposed to waters from two sites of Itajaí-Açu River (SC, Brazil)

Abstract

The relationship between the genes and the effects attributed to them has been object of many studies, especially those seeking to establish the response of genes to environmental prod. The aim of this work was to establish a standard system to monitor effluents by using juvenile Nile tilapia ( Oreochromis niloticus ) as a bioindicator of genotoxicity, utilizing micronuclei test and comet assay. For this, the fish were exposed during 24, 48, 72 and 240 hours (10 days), to water samples collected at two sites of the Itajai-Acu River: Ilhota and Blumenau, in the Santa Catarina State, Brazil. For positive control the herbicide 2,4-D (75 ppm) was utilized, and the negative control of each fish were the values obtained before the exposure to the river water, termed time zero (T 0 ). Water samples from both sites of the Itajai-Acu River showed significant genotoxic effects in erythrocytes of the exposed fishes. The comet assay was a more sensitive test to detect genotoxic damage in shorter exposure times (24 and 48 hours) than the micronuclei test. Key words : genotoxicity, comet assay, micronuclei test, Oreochromis niloticus , bioindicator