Assessment of pollution of river Ganges by tannery effluents using genotoxicity biomarkers in murrel fish, Channa punctatus (Bloch).

River pollution due to rapid industrialization and anthropogenic activities adversely affects the aquatic organisms, especially fish. Here, we assessed the genotoxicity, mutagenicity and bioaccumulative aspects of tannery effluents in freshwater murrel, Channa punctatus, an inhabitant of river Ganges. Test specimens were collected from three different polluted sites of the river within and nearby Kanpur area during different seasons and blood samples of these specimens were processed for comet assay and micronucleus test as genotoxicity biomarkers. A significantly (P < 0.05) higher micronuclei induction, nuclear abnormalities and % tail DNA was observed in the specimens collected from the polluted sites. Bioaccumulation studies in the muscle (1.202 µg/g) and gill tissues (< 0.300 µg/g) of the specimens revealed the concentration of chromium (core component of tanning industry) above the maximum permissible limits as prescribed by World Health Organization (WHO). The findings of the present analysis indicated contamination of river Ganges with tannery effluents which induce genotoxicity in fish with seasonal variation.

Assessment of genotoxic and mutagenic potential of hexavalent chromium in the freshwater fish Labeo rohita (Hamilton, 1822).

The present study was undertaken to investigate the genotoxicity and mutagenicity of sublethal concentrations of hexavalent chromium (potassium dichromate) in the Indian major carp, Labeo rohita. The 96 h LC50 value of potassium dichromate estimated was 118 mg L(-1) by probit analysis using SPSS (version 16.0) software. Based on 96 h LC50 value, three sublethal test concentrations of potassium dichromate (29.5, 59.0 and 88.5 mg L(-)(1)) were selected and specimens were exposed in vivo to these test concentrations for 96 h. The mutagenic and genotoxic effects of potassium dichromate were evaluated in gill and blood cells using micronucleus (MN) test and comet assay. In general, significant (p < 0.05) effects due to the concentrations and the exposure durations were observed in exposed specimens. The MN induction was highest at 96 h at all the test concentrations in the peripheral blood. A similar trend was observed for the DNA damage, measured in terms of percentage of tail DNA, in erythrocyte and gill cells. The study indicated hazardous effect of the hexavalent chromium to fish and other aquatic organisms and indirectly to human beings.

Molecular characterization of major and minor rDNA repeats and genetic variability assessment in different species of mahseer found in North India.

Relationship among the mahseer species (Family: Cyprinidae) has long been debated in fish systematics. Present study concentrates on the nature of the phylogenetic relationship among the five mahseer species using the sequence of major ribosomal DNA (45S rDNA). We have covered rDNA sequence of approximately 5.2 kb per individual, 26.0 kb per species and 130.0 kb as a whole. We also characterized the 45S and 5S rDNA regions with respect to their nucleotide composition. For phylogenetic analyses, nucleotide sequences were divided into four datasets. First and second datasets contained 18S rDNA and ITS1 sequence, whereas third and fourth datasets consisted of ITS2 and complete 18S-ITS1-5.8S-ITS2-28S, respectively. The NJ tree was constructed for all the datasets. The mahseer species under study formed a monophyletic group well separated from the outgroup species. Similarly, the individuals of Neolissochilus hexagonolepis form monophyletic group with Tor species, indicating Neolissochilus as a sister genus of Tor. The findings from the present study provide greater insights into taxonomic status of mahseer, and set the stage for future investigations dealing with phylo-geography, taxonomy, conservation and co-evolution within this interesting and important group of fish.

Mutagenic and genotoxic assessment of atrazine-based herbicide to freshwater fish Channa punctatus (Bloch) using micronucleus test and single cell gel electrophoresis.

The mutagenic and genotoxic effect of 'Rasayanzine', an atrazine herbicide, was carried out in fish Channa punctatus using micronucleus and single cell gel electrophoresis (SCGE) assays. Three sub-lethal concentrations of the test material viz., SL-I (1/5th LC(50)=∼8.48 mgL(-1)), SL-II (1/8th LC(50)=∼5.30 mgL(-1)) and SL-III (1/10th LC(50)=∼4.24 mgL(-1)) were calculated using LC(50) value and the fish specimens were exposed to these concentrations. Erythrocyte and gill cells were sampled on day 0, 1, 3, 5, 7, 14, 21, 28 and 35 of exposure for assessment of micronuclei induction in blood erythrocytes and DNA damage using SCGE assay in both blood erythrocytes and gill cells. Significant effects (p<0.01) for both concentration and time of exposure were observed in treated fish. Micronuclei induction in erythrocytes was highest (8.4 mgL(-1)) on day 7 of exposure. The highest level of DNA damage in the SCGE was observed in both tissues on day 5 at all concentrations followed by gradual non-linear decline. This study further confirmed that the micronucleus and SCGE assays are useful in determining potential genotoxicity of water pollutants and might be appropriate as part of monitoring program.