In-Vivo Evaluation of Hexavalent Chromium Induced DNA Damage by Alkaline Comet Assay and Oxidative Stress in Catla catla

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 LC₅₀). 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.