Nuclear anomalies and blood protein variations in fish of the Hooghly-Matlah River system, India, as an indicator of genotoxicity in water

Fish can be useful models for analyzing the genotoxic potential of the aquatic environment as they are constantly in direct contact with water. Attempts have been made since the 1980s to assess genotoxic activity by examining the incidence of micronuclei (MN) in peripheral blood cells of fish (Hooftman and de Raat 1982; Manna et al. 1985). Subsequently this rapid-screening method became useful to test genotoxicity in various fishes as an indicator of possible pollution (Hose et al. 1987; Metcalfe 1988; Carassco et al. 1990; de Flora et al. 1993; Al-Sabti 1994; Al-Sabti and Metcalfe, 1995; Minissi et al. 1996; Poongothai et al. 1996). The other protocols commonly used to assess genotoxicity in mammalian studies, such as chromosome aberrations and sister-chromatid exchanges (SCE), are not suitable for use in fish species due to their large number of small chromosomes and low mitotic index, particularly in brackish water fish (Khuda-Bukhsh and Chakrabarti 1999; Chakrabarti and Khuda-Bukhsh 2000). Therefore, in order to strengthen the basis for ascertaining genotoxic stress to which the fish may be exposed in their natural habitat, due to various pollutants/toxicants, it was felt necessary to assess if some other parameters of study like nuclear shape anomaly, nucleo-cytoplasmic ratio, and gel electrophoretic profiles of blood plasma and hemoglobin could be of any additional help. Thus, in the present study, apart from recording incidence of micronucleated erythrocytes and erythrocytes with abnormal nucleus in natural populations of seven brackish water species of fishes collected from mainly three strategic localities, gel electrophoretic profiles of two blood proteins, namely, plasma protein and hemoglobin (Hb) have also been critically analyzed for their possible correlation with the degree of aquatic pollution, if any.