Uranium (U-238)-induced ROS and cell cycle perturbations, antioxidant responses and erythrocyte nuclear abnormalities in the freshwater iridescent shark fish Pangasius sutchi

摘要

The strategic plan of this study is to analyze any possible radiological impact on aquatic organisms from forthcoming uranium mining facilities around the Nagarjuna Sagar Dam in the future. The predominantly consumed and dominant fish species Pangasius sutchi, which is available year-round at Nagarjuna Sagar Dam, was selected for the study. To comprehend the outcome and to understand the mode of action of U-238, the fish species Pangasius sutchi was exposed to 1/4 and 1/2 of the LC50 doses of waterborne U-238 in a static system in duplicate for 21 days. Blood and organs, including the gills, liver, brain and muscles, were collected at different time periods-0 h, 24 h, 48 h, 72 h, 96 h, 7, days 14 days and 21 days using ICP-MS to determine the toxic effects of uranium and the accumulation of 238U concentrations. The bioaccumulation of U-238 in P. sutchi tissues was dependent on exposure time and concentration. The accumulation of uranium was, in order of magnitude, measured as gills > liver > brain > tissue, with the highest accumulation in the gills. It was observed that exposure to 238U significantly reduced antioxidant enzymes such as superoxide dismutase, catalase, and lipid peroxidase. The analysis of DNA fragmentation by comet assay and cell viability by flow cytometry was performed at different time intervals. DNA histograms by flow cytometry analysis revealed an increase in the G2/M phase and the S phase. The long-term 238U exposure studies in fish showed increasing micronucleus frequencies in erythrocytes with greater exposure time. The higher the concentration of 238U is, the greater is the effect observed, suggesting a close relationship between accumulation and toxicity. A possible ROS-mediated U-238 toxicity mechanism and antioxidant responses have been proposed. (C) 2017 Elsevier B.V. All rights reserved.