No abstract

The present study was planned aiming to investigate the effects of atrazine herbicide exposure on stress biomarkers acetylcholinesterase activity (AchE) and cortisol, oxidative stress responses and the histopathological changes in liver of female Clarias gariepinus and the ameliorative effect of vitamin E supplementation (240mg/kg diet) on the degree of atrazine sublethal toxicity (1.37mg/l) for 6 weeks. Chronic exposure to atrazine revealed a marked inhibition in the activity of AchE. But, significant increase of serum cortisol level was recorded. Moreover, atrazine exposure was associated with a marked induction of oxidative damage in liver tissue as evidenced by increased level of lipid peroxidation (LPO) and reduced glutathione (GSH) content. Atrazine exposure also led to a significant increase in the activities of catalase (CAT) and superoxide dismutase (SOD).Furthermore, histopathological examination of the liver of exposed fish showed dilatation and congestion of blood vessels, fatty degeneration, necrosis and pyknotic nuclei of hepatocytes. However, fish fed diet supplemented with vitamin E exhibited protective effect by minimizing the atrazine-induced toxicity, through measured values more or less similar to the control group fish.

iazinon is widely and effectively used in agriculture as well as in domestic and aquaculture aspects. As a result of its widespread application, its ecotoxicity study is needed to determine its effects on the aquatic organisms and its potential impact as an environmental contaminant. In this study, the half lethal concentration (LC 50) of diazinon for Clarias gariepinus was calculated. Diazinon toxicity was evaluated through acute and chronic exposures of fish to 1/2 and 1/10 the calculated LC 50 for 1w & 6 w respectively. Results showed that the LC 50 /96h was 5.98 ppm. The effects of both acute and chronic exposures revealed clinical abnormalities in the form of nervous and respiratory disorders manifested by erratic swimming and/or circling, rapid opercular movements and abnormal skin pigmentation that appeared in the form of skin fading. A significant increase in cortisol, glucose, AST & ALT activities, urea, uric acid, creatinine and serum Ca ++ levels were recorded. Furthermore, diazinon exposures were associated with an inhibition of cholinesterase activity, a decrease in total protein concentration in serum with a reduction in both albumin and globulin. This study declared that diazinon is an extremely toxic organophosphate pesticide for C. gariepinus, its improper application often results in contamination of the environment and consequently in deleterious health effects. So, strict precautions should be followed.

Limited efforts have been made to study the genotoxic effects of ammonia in cultured OOreochromi niloticus. Therefore, the present study was planned to assess the genotoxic effect of ammonia in cultured O. niloticus using random amplified polymorphic DNA (RAPD) assay. Fish was categorized into four groups. The 1st group exposed to 2.5 mg/L of total ammonia nitrogen (TAN) (0.16 NH 3 mg/L), the 2nd exposed to 5.0 mg/L of total ammonia nitrogen (TAN) (0.32 NH 3 mg/L) and the 3rd exposed to 10.0 mg/L of total ammonia nitrogen (TAN) (0.65 NH 3 mg/ L), in addition to control group for the treatment period of 6 days. The results revealed that some genes in O. niloticus are susceptible to DNA disturbances/mutation as a result of exposure to high concentration of ammonia in water, this clearly indicated using RAPD screening assay.

Fusarium genus includes a wide range of species, commonly found in plants, air, soil, marine water and freshwater (Michielse and Rep, 2009). Fusarium infections have been recorded in many aquatic animals such as sharks, dolphins, whales, shrimp, as well as ARTICLE INFO