Micronuclei, nuclear lesions and interphase silver-stained nucleolar organizer regions (AgNORs) as cyto-genotoxicity indicators in Oreochromis niloticus exposed to textile mill effluent

Abstract

In this study, cyto-genotoxic effects of a textile mill effluent on fish Oreochromis niloticus were investigated using the micronucleus (MN) test and methods to analyze interphase silver-stained nucleolar organizer regions (AgNORs). Fishes were exposed to three different concentrations of textile mill effluent (5, 10 and 20% (v/v)) for 3, 6 and 9 days. Cyclophosphamide (2 mg/l) was used as a positive control. Micronucleus frequencies were examined in peripheral blood erythrocytes and gill cells. Nuclear abnormalities (NA) other than micronuclei such as binuclei, lobed nuclei, blebbed nuclei and notched nuclei were also evaluated in peripheral erythrocytes. Interphase AgNOR parameters were examined in epithelial cells obtained from the edge of caudal fins after 90 and 180 min of exposure. As a result, dose-dependent increases in the frequencies of micronuclei and other NA in erythrocytes were observed. MN frequencies in gill cells also significantly increased, while the interphase AgNOR parameters in fin cells decreased, as a result of textile effluent and cylophosphamide treatments.