Assessment of toxicity and clastogenicity of sterigmatocystin in Egyptian Nile tilapia

The increasing presence of genotoxic pollutants in the aquatic environment has led to the development of quick monitoring methods. Sterigmatocystin (Stg) is closely related to mycotoxins and has the carcinogenic potency in the experimental animal models. The exposure to genotoxic agents will give rise to alterations of DNA structure that can lead to abnormal changes of DNA fingerprints. Therefore, we have applied the random amplified polymorphism DNA (RAPD) method to evaluate the genotoxiceffects of Stg and to determine if the Egyptian montmorillonite (EM) has a protective effect against Stg. The experiment was conducted in vivo to evaluate the ability of EM at a level 0.5 mg/kg body weight(bw) to prevent the toxicity and genotoxicity induced by Stg in the Nile tilapia fish. Fishes were orally administrated with EM in corn oil with or without Stg (1.6 ìg/kg bw) twice a week for 4 weeks. Blood andtissue samples were collected at the end of the treatment. The results revealed that Stg had genotoxic and toxicopathological effects in Oreochromis niloticus fish. The genotoxic effects were indicated byappearance of some changes in polymorphism band patterns including lost of stable bands or occurrence of new bands. There also exists a distinct distance between the band patterns of exposed fish and protected or control fish samples. The effects on the tissues were manifested by different histopathological lesions in different organs including hyperplastic proliferation of branchial epithelium, necrobiotic changes in hepatic tissue and destruction of components of the spleen. These responses were virtually abolished or markedly decreased when fishes were exposed to EM combined with Stg. It could be conclude that addition of EM resulted in the inhibition of the toxicity andclastogenicity of St

Effect of water pollution on expression of immune response genes of Solea aegyptiaca in Lake Qarun

This research was aimed to study quality of water in Lake Qarun and effects of pollution on expression of immune genes in Egyptian sole (Solea aegyptiaca) fish. The study was carried out from August 2006to the end of April 2007. The water samples were collected from different locations of Lake Qarun at Al-Oberge within an area of 200 to 1500 meter from the shore. The samples were subjected to differentphysical and chemical analyses. The concentration of total dissolved solids (TDS) recorded an average value of 37.8 g/l while the chloride content was 14.3 g/l on average. The corresponding value of salinitywas 25.9 g/l. For the chemical oxygen demand and biochemical oxygen demand the results revealed that the average values were 98 ± 22 mg O2/l and 8.0 ± 2.1 mg O2/l for the chemical oxygen demand(COD) and biochemical oxygen demand (BOD), respectively. Analyses of nitrogen group indicated presence of low concentrations of all. For total pesticides which might be one of the most potential pollutants in the lake, the results showed an average value of 0.62 mg/l. Furthermore, the total viable bacterial count (TVBC) ranged from 103 colony forming unit (CFU) in the middle of the Lake to 107 (CFU)near the shore. Stressed total coliform group (STC), stressed faecal coliform group (SFC) and stressed faecal streptococci group (SFS) increased from the middle of the Lake to the shore. The differentialexpression of the immune genes, that is, GARP and SIMP genes, as a result of pollution influence was further confirmed by RT-PCR, with the up-regulation of these genes in the liver of the collected fish. Theapplication of the expression of the immune genes of fish might be time safe and cost effective in case there are different source of pollution