Thesis (Ph.D.) - Cairo University - Faculty of African Postgraduate Studies - Department of Natural Resources

Bibliography: p. 123-98.

Acetamiprid (Aceta) is the most extensively used neonicotinoid which contaminate aquatic ecosystem from agricultural leaching. On juveniles of Oreochromis niloticus, the protective potential of ascorbic acid (Asc) against oxidative stress and genotoxicity induced by Aceta sub-lethal concentrations was investigated in this study. Fishes were divided into six groups and exposed to either; Asc (50 ppm), 10 ppm of Aceta, 20 ppm of Aceta, 10 ppm of Aceta and Asc (50 ppm), 20 ppm of Aceta and Asc (50 ppm). Unexposed animals were considered as control group. The experiment was conducted by the assessment of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities and their mRNA gene expression. DNA damage using comet assay in erythrocytes, hepatocytes and gill cells, in addition to mitotic index (MI), the existence of micronuclei (MN) and erythrocytic nuclear abnormalities (ENAs) were performed. The results showed that concentrations of Aceta (10 & 20 ppm) induced oxidative stress by decreasing the antioxidant enzyme activities and down-regulating gene expression of SOD, CAT and GPX compared to control group. However, LPO and NO levels were significantly elevated. Co-supplemented fish with Asc showed significant alleviations of oxidative status represented by substantial increases in the activities of SOD, CAT and GPX enzymes and diminished LPO and NO levels (P<0.05), along with a concomitant up-regulation of SOD and CAT gene expression (P < 0.05). There were genotoxic effects of Aceta exposure showed by the significant (P < 0.05) increase in DNA-damaged cells, MN, and ENA, meanwhile a decrease in MI. Supplementation with Asc reversed these effects in combined-exposure groups. Thus, results suggest that Aceta induced oxidative stress accompanied with genotoxicity. Further, Asc-combined exposure could be the effective treatment against Aceta-induced damage in O. niloticus.

أعدت هذه الدراسة لفحص القدرة الوقائية لحمض الأسكوربيك ضد الجهد التأكسدي والسمية الجينية المسببة بواسطة جرعات المبيد الحشري (إسيتامبريد على صغار أسماك البلطي النيلي.

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