Antioxidant Responses and Nuclear Deformations in Freshwater Fish, Oreochromis niloticus, Facing Degraded Environmental Conditions.

Two sites of collection along river Nile, nearby metal-related factories (site2) and 7 km downstream (site3) were compared to unpolluted reference fish farm (site1). Metals concentration (Cu, Zn, Pb, Fe, Mn and Cd) in water and sediment samples showed highly significant (p < 0.01) differences among sites. According to contamination factor and pollution load index values, overall pollution was ordered as site2 > site3 > site1. Compared with Oreochromis niloticus of site1, activities of superoxide dismutase, catalase and glutathione-S-transferase as well as malondialdehyde formation were significantly (p < 0.01) increased in both liver and gills of fish collected from metal contaminated sites. This increment showed a tissue-specific pattern with higher rate of increment in liver than in gills. While reduced glutathione level was sharply decreased in site2 and site3. Micronucleus test was assessed as an environmental genotoxic endpoint in erythrocytes. Assessment of eight nuclear deformations showed gradient frequencies related to the distance from the industrial discharges.