الفهرس 
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Abstract
This study was conducted on Oreochromis niloticus, during autumn 2015, from Lake Burullus. The study aimed to assess different types of pollutants (heavy metals and pesticides) in water and fish from the Lake and assessment of genotoxicity of these pollutants by evaluation of altered gene expression of) TNFα ، IL-1β، IL-8، IgM، Vtg،GST، CAS، MT( and assessment of DNA fragmentation in fish by using comet assay and micronucleus assay. To achieve these objectives we collected water and fish samples from three sections of Lake Burullus and a control group from National Institute of Oceanography and Fisheries (NIOF), physico-chemical parameters of water samples were assessed, pesticide residue status of ten organochlorines, one organophosphorus and six pyrethroid was determined in fish and water samples using GC-analysis, Heavy metals levels of (Fe, Mn, Cu, Zn, Ni, Pb) were assessed in water and fish samples, quantitative real time PCR was performed to evaluate gene expression of GST, CAS, Vtg , MT , IgM, TNFα , IL-1β , IL-8 and β-actin, micronucleus (MN) assay and comet assay were used to evaluate DNA damage. We can summarize the obtained results as following: for the physico-chemical parameters of water samples pH was slightly alkaline at the eastern section while the middle one contains the least level of dissolved oxygen. The assessment of pesticide residue status revealed that the highest concentrations recorded in the middle section of the lake. Heavy metals assessment demonstrated that their concentrations in the Lake took the following sequence Fe > Mn > Ni >Cu > Zn > Pb.
Gene expression analysis revealed that mRNA transcript level of hepatic antioxidant genes GST and Vtg was down regulated in all the three sections of the lake, however the expression of CAS gene with slight down regulation in the middle and western section. MT is downregulated in the three sections. IgM and TNF were significantly downregulated at eastern and western section of the lake; meanwhile the expression of IL8 is down regulated at the three sections. IL1 was significantly upregulated at eastern and middle sections. The micronucleus assay revealed that Western section fish showed the highest number of micronucleated cells. Comet assay demonstrated that the most sever DNA damage was in middle and western section fishes.