Anurag Dabas

Genotoxicity and antioxidant enzyme activity induced by hexavalent chromium in Cyprinus carpio after in vivo exposure.

Abstract Fish, being an important native of the aquatic ecosystem, are exposed to multipollution states and are therefore considered as model organisms for ecotoxicological studies of aquatic pollutants, including metal toxicity. We investigated oxidative stress (OS) in liver, kidney and gill tissues through antioxidant enzyme activities and genotoxicity induced in whole blood and gill tissues through comet assay and micronucleus (MN) test in Cyprinus carpio after 96-hour in vivo static exposure to potassium dichromate at three sublethal (SL) test concentrations, including SL-I [93.95 mg/L, i.e. one quarter of half-maximal lethal concentration (LC50)], SL-II (187.9 mg/L, i.e. one half of LC50), and SL-III (281.85 mg/L, i.e. three quarters of LC50), along with a control. The 96-hour LC50 value for potassium dichromate was estimated to be 375.8 mg/L in a static system in the test species. Tissues samples were collected at 24, 48, 72 and 96 hours postexposure. Results indicated that the exposed fish experienced OS as characterized by significant (p < 0.05) variation in antioxidant enzyme activities, as compared to the control. Activities of superoxide dismutase and glutathione peroxidase increased, whereas activity of catalase decreased with the progression of the experiment. The mean percent DNA damage in comet tail and MN induction in gills and whole blood showed a concentration-dependent increase up to 96-hour exposure. The findings of this study would be helpful in organ-specific risk assessment of Cr(VI)-induced OS and genotoxicity in fishes.

Genotoxic and Mutagenic Assessment of Hexavalent Chromium in Fish Following In Vivo Chronic Exposure

ABSTRACT Chromium is a well-documented carcinogen. To evaluate the genotoxic potential of hexavalent chromium on an aquatic bio-system, freshwater murrel fish (Channa punctatus) were exposed to potassium dichromate. The 96-h LC50 for potassium dichromate was 61.80 mg/L for the test fish in a static system. On the basis of the 96-h LC50, fish were exposed to sublethal concentrations of the test chemical. Fish exposed to the test chemical were sampled on days 1, 7, 14, 21, and 28 post-exposure and blood and gill cells were collected. Significantly (p < .05) higher DNA damage in both lymphocyte and gillcells and micronuclei formation in whole blood was observed at different test concentrations and sampling times of the test chemical as compared to control fish. The mean% tail DNA in the comet tail assay showed a concentration-dependent increase and the maximum% tail DNA was observed on day 7 of exposure in both cells. A similar trend was also observed in micronuclei induction in blood with maximum induction on day 21. Hexavalent chromium showed genotoxic potential in chronic exposure of C. punctatus, and the micronucleus test and the comet assay are the methods for sensitive and rapid detection of the genetic effects.

In situ assessment of genotoxic and mutagenic potential of polluted river water in Channa punctatus and Mystus vittatus

River Gomti, a tributary of river Ganga in northern India, is being polluted due to indiscriminate disposal of domestic sewage and industrial wastes that contain genotoxic chemicals. The study was conducted to evaluate the genotoxic potential of polluted water of river Gomti in two fish species, namely Channa punctatus and Mystus vittatus. The fishes were exposed in situ in nylon cages to the polluted water of river Gomti fixed near a distillery outlet located in Lucknow. The induction of DNA damage and micronuclei were determined in blood erythrocytes using comet assay and micronucleus test, respectively. The induction in micronuclei frequencies and DNA damage were found to be significantly elevated (p < 0.01) in exposed specimens after 3 days post-exposure as compared to the control, i.e. from laboratory-acclimatized fish specimens. The comparison of DNA damage between the two species indicated that C. punctatus is more sensitive to aquatic pollutants. Thus, this fish could be used as a bio-indicator of genotoxicity for bio-monitoring of water bodies. The results further revealed that the river Gomti is being contaminated with potential genotoxic and mutagenic chemicals produced from industrial and domestic activities; therefore, immediate measures are needed to reduce the inflow of pollutants in the river.

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

Abstract 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.

Investigation of Cadmium-Induced Genotoxicity and Oxidative Stress Response in Indian Major Carp, Labeo rohita

ABSTRACT We investigated genotoxicity and oxidative stress in the gills of Labeo rohita exposed to 33.6, 67.1, and 100.6 mg L–1of cadmium chloride at 96 h. Genotoxicity was assessed using single cell gel electrophoresis whereas oxidative stress was monitored through lipid peroxidation induction and antioxidant response parameters, namely reduced glutathione (GSH), glutathione peroxidase, glutathione-S-transferase, superoxide dismutase, and catalase (CAT) activities. Significant (p < .05) effect of both concentration and time of exposure was observed on the extent of DNA damage in treated fish. Similarly, malondialdehyde content, level of GSH, and activities of antioxidant enzymes were significantly elevated in treated groups, except CAT. The increased DNA damage and lipid peroxidation (LPO) content along with fluctuation in antioxidant defense system in fish indicated the interaction of cadmium (Cd) with DNA repair processes and production of reactive oxygen species. Thus, Cd is liable for induction of LPO, alteration of antioxidant defenses, and DNA damage in gills of L. rohita.

Mutagenic, genotoxic and bioaccumulative potentials of tannery effluents in freshwater fishes of River Ganga

ABSTRACT The tannery industries are the reason of major environmental concerns as they release toxic heavy metals, like chromium, in rivers posing risks of genotoxicity and mutagenicity in aquatic organism and indirectly in humans through food chain. In the present analysis, the freshwater inhabitant fishes of River Ganges, viz., Labeo calbasu, Puntius sophore, and Mystus vittatus, were examined for assessing the genotoxic, mutagenic, and bioaccumulative potentials of tannery effluents. For genotoxicity assessment, the blood and gill samples of fishes prevailed from polluted sites of River Ganges adjoining Kanpur city were utilized for comet assay and micronucleus test. The present investigation revealed the presence of significantly (p < 0.05) higher micronuclei induction and % tail DNA in erythrocytes and gill cells of the fishes collected from the polluted sites. The bioaccumulation studies revealed chromium concentration in muscle (0.89 µg/g) and gill tissues (0.24 µg/g) of L. calbasu; muscle (0.44 µg/g) and gills (1.23 µg/g) of P. sophore; and muscle (0.9617 µg/g) and gills (0.3628 µg/g) of M. vittatus, quite higher than the permissible limits of the World Health Organization. Consequently, the present study indicates strongly that River Ganges is contaminated with harmful tannery pollutants causing genotoxicity and mutagenicity in freshwater fishes.