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(07-05) Effects of Salinity on the Bioactivation of Xenobiotics in Fish. Schlenk, Daniel*,1, 1 University of California, Riverside, Riverside, CA ABSTRACT- In arid regions of the world used for agriculture, waterways are continuously impacted by many environmental and anthropogenic factors. Examples include, but are not limited to, hypersalinity, pesticide runoff and irrigation-derived organometalloids (i.e. organoselenides). During the past decade we have shown that hypersaline water increases the toxicity of several compounds to susceptible fish species. For example, the carbamate insecticide aldicarb is significantly more toxic to rainbow trout and Japanese medaka when exposure occurs in brackish water. However, recent studies in tilapia and striped bass have shown that salinity does not affect aldicarb toxicity. These results appear to be consistent with the enhanced expression of bioactivating enzymes of aldicarb known as flavin-containing monooxygenases which are induced by hypersaline conditions in slow osmoconforming species. In contrast, rapid osmoconformers appear to be resistant to the enhanced toxicity in saltwater. Further studies with organoselenides and hypersalinity have indicated a similar response with enhanced activation to glutathione oxidant intermediates in these species; however, without subsequent mortality. Risk assessment paradigms derived from these mechanistic studies to predict species susceptibility and resistance to these compounds will be discussed. Key words: Salinity, Aldicarb, Biotransformation, Selenium |
