American Journal of Environmental Science 9 (6): 470-482, 2013 ISSN: 1553-345X ©2013 Science Publication doi:10.3844/ajessp.2013.470.482 Published Online 9 (6) 2013 (http://www.thescipub.com/ajes.toc) Corresponding Author: Kantha Deivi Arunachalam, Center for Environmental Nuclear Research, Directorate of Research, SRM University, Chennai, Tamil Nadu, 603203, India Tel: 044-27417144; Fax: 044-27417146 470 Science Publications AJES In-Vivo Evaluation of Hexavalent Chromium Induced DNA Damage by Alkaline Comet Assay and Oxidative Stress in Catla catla Kantha Deivi Arunachalam, Sathesh Kumar Annamalai and Jaya Krishna Kuruva Center for Environmental Nuclear Research, Directorate of Research, SRM University, Chennai, Tamil Nadu, 603203, India Received 2013-10-25; Revised 2014-01-14; Accepted 2014-01-15 ABSTRACT In the present study, the acute toxicity of Chromium in fingerlings of Catla catla, an Indian major carp, was evaluated with renewal bioassay method. In vivo studies were designed to assess the extent of Micronucleus Assay, Comet Assay under the exposure of common heavy-metal compounds, namely, Chromium Nitrate, using Catla catla (2n = 20), as a test model. The laboratory acclimatized fishes were divided into four groups. Group I served as positive control and the other three as exposed groups for three different time durations of 7, 14 and 21 days and were subjected to uninterrupted sub lethal concentrations (50% of 96 h LC 50 ). The experiments were planned in such a way that fish from all the groups were sacrificed on the same day. The frequencies of micronuclei and bi-nuclei were evaluated comparatively in peripheral erythrocytes. As a result, it was observed that, the fishes and different tissues showed differential sensitivity to the heavy-metal treatment. A significant increase in the frequencies of micronucleated and binucleated cells and percentage increase in DNA tail (p<0.001) through Alkaline Comet Assay were observed after 21 days of exposure to chromium. Our results also showed decrease in enzyme Superoxide Dismutase (SOD) activity and increase in catalase enzyme due to increasing chromium concentration. The bio-concentration factor profiles of Chromium in Catla catla during sub lethal toxicity study was also calculated. Keywords: Chromium, Micronucleus, Catla catla, Cytotoxicity, Comet Assay 1. INTRODUCTION Aquatic ecosystem is the final sink for many chemicals used in industry and agriculture and has become a global problem (Adeogun and Chukwuka, 2012). When contaminants are released into the Aquatic Ecosystem, they finally get accumulated in the major aquatic organisms, almost invariably (Lavanya et al., 2011). Among all the contaminants, chromium is the one which are directly or indirectly released into aquatic ecosystem (Gheju, 2011). The influx of this global environmental toxicant into aquatic ecosystems from naturally occurring and anthropogenic sources is a serious problem throughout the world (Kumar et al., 2009). Chromium is a common contaminant in surface water and groundwater because it is used widely in electroplating and other industries and occurs naturally at high concentrations in ultramafic rocks. Under oxidizing conditions, Cr is highly soluble and mobile as the Cr (VI) anions chromate (CrO 4 2− ) and bichromate (HCrO 4− ) (Ellis et al., 2002). The health effects and toxicity or carcinogenicity of chromium are mainly related to the oxidation state of the metal at exposure. Trivalent (Cr[III]) and Hexavalent (Cr[VI]) compounds are thought to be the most biologically significant, (Jomova and Valko, 2011). Hexavalent chromium is widely used in many industrial processes such as electroplating, wood preservation. The remediation of chromium contaminated sites poses several unique challenges. Ranipet regions of Tamil Nadu, a Province in India, have Leather Tanneries