الفهرس 
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Abstract
The contamination of aquatic environment by toxicants has become one of the most important problems in the world. Nanotechnology has noticeably developed with diverse applications in every science specially by using nanomaterial. The development of nanotechnology also has a negative impact on the environment as many nanoparticles are discharged into the aquatic environment and cause a serious effect on living organisms. Aquatic animals particularly fish could serve as biological indicators for ecosystem health. Tilapia species are extremely recommended as one of successful culturing fishes as they tolerate wide ranges of environmental conditions.
The present study carried out on the Nile tilapia, O.niloticus to study the effect of sublethal concentrations of zinc oxide bulk particles (ZnOBPs) compared to zinc oxide nanoparticles (ZnONPs) on biochemical paramaters by monitoring the change in the activities of glucose, liver function (ALT and AST), kidney function (Creatinine ,Urea and Uric acid), Albumin , Cholesterol and antioxidant enzymes (SOD, CAT and GST) after 7,14,21 and 28 days of exposure duration. In addition, the study tended to indicate the effect of vitamin (E + C) on biochemical parameters and oxidative Stress in O. niloticus exposed to sublethal concentrations of ZnOBPs and ZnONPs. Also, determination the accumulation potency of zinc in different tissues (muscle and gill) and evaluation of the proximate chemical composition in muscle tissue of O. niloticus exposed to sublethal concentration of zinc ZnOBPs or ZnONPs alone and then with vitamin (E + C) for different experimental periods.
The results could be summarized as follow:
5. Toxicity tests were carried out on O. niloticus showed that 96 hr LC50 values of ZnOBPs and ZnONPs were 84 mg/l and 5.6 mg/l respectively. Concentration less than 96hr LC50 were considered sublethal concentrations. Three tested concentrations (sublethal concentrations) equivalent to (1/8, 1/4 and1/2 LC50) of ZnOBPs and ZnONPs were selected, which found to be (10.5, 21 and 42 mg/L) and (0.7, 1.4 and 2.8 mg/L) respectively.
6. O.niloticus fish exposed to sublethel concentrations of ZnOBPs or ZnONPs showed a significant increase (p<0.05) in serum glucose AST, ALT creatinine, urea, uric acid, and cholesterol concentrations compared to control value after 7, 14, 21 and 28 day. The values increase with increasing concentration of ZnOBPs or ZnONPs and with increasing exposure time and dose.
7. The exposure of O.niloticus fish groups to ZnOBPs or ZnONPs plus dietary supplementation with vitamin E and C have reduced serum glucose, AST, ALT creatinine, urea, uric acid, and cholesterol concentrations compared to the groups without supplementation after 7, 14, 21 and 28 day. The values returned to similar levels established in the controls at low concentrations particularly after 7 day but still higher than control at higher concentrations.
8. Serum albumin levels were decreased significantly (p<0.05) compared to control at the exposure period of the experiment in all treated groups with ZnOBPs or ZnONPs. Then increased in groups supplemented by vitamin (E and C) compared to groups without supplementation.
9. Antioxidant defense enzymes (SOD, CAT and GST) activity in O.niloticus fish were increased significantly (p<0.05) when exposed to different concentration of ZnOBPs or ZnONPs compared to the control value. Then supplementation with vitamin (E and C) decreased SOD, CAT and GST enzymes activity in these groups to become less than those recorded in groups treated with ZnOBPs or ZnONPs without supplemetation.
10. The exposure of O. niloticus fish to different concentrations of ZnONPs or ZnOBPs resulted in more Zn concentrations in muscle and gill tissue of this fish compared to control group.
11. Tissues showed different capacities for accumulating Zn metal, Zn was accumulated in gill tissue higher than muscle tissue.
12. Results showed greater bioaccumulation potency of ZnONPs compared to ZnOBPs in muscle and gill tissues.
13. The moisture content of O. niloticus muscle increased in fish exposed to sublethal concentrations of ZnOBPs or ZnONPs compared to control. Also, dry ash content is found to increase with increased ZnOBPs or ZnONPs concentrations.
14. Protein and fat content decreased in ZnOBPs or ZnONPs exposed fish compared to control. Then increased in groups supplemented by vitamin (E and C) compared to groups without supplementation.