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REPRODUCTION AND AROMATASE ACTIVITY IN THE MARINE FISH CUNNER (TAUTOGOLABROUS ADSPERSUS) EXPOSED TO ATRAZINE AND OCTYLPHENOL IN THE LABORATORY
Citation:
Mills, L J., R E. GutjahrGobell, D B. Horowitz, S C. Laws, AND G Zaroogian. REPRODUCTION AND AROMATASE ACTIVITY IN THE MARINE FISH CUNNER (TAUTOGOLABROUS ADSPERSUS) EXPOSED TO ATRAZINE AND OCTYLPHENOL IN THE LABORATORY. Presented at The Society of Toxicology Annual Meeting, New Orleans, LA, March 3-6, 2005.
Description:
This study was conducted to test the hypothesis that reproduction in fish is altered by exposure to endocrine-disrupting chemicals (EDCs) that modify aromatase activity. Aromatase, a product of the CYP19 gene, is the enzyme that catalyzes the conversion of the androgens androstenedione and testosterone to the estrogens estrone and estradiol. Atrazine and octylphenol are EDCs common in aquatic environments, and both have been reported to alter serum estrogens in fish or rats. During our laboratory experiments, cunner in spawning condition were monitored daily to determine egg production, egg fertility, and egg viability both before and after exposure to atrazine (nominal concentrations 0.1-5 ppm) or octylphenol (nominal concentrations 1-100 ppm). After one week of monitoring pre-exposure reproduction, treatments were delivered by subcutaneous implantation of test chemical or solvent (controls) in a slow-release matrix of Ethocel? and coconut oil just below the dorsal fin of each fish. Reproduction was monitored for two more weeks, and then fish were euthanized and dissected. Brain, gonad and liver samples were flash-frozen and archived for later analysis. Results of these experiments indicate that atrazine and octylphenol had very little effect on daily egg production, number of fertile eggs, number of viable eggs, or ability of eggs to hatch. Only fish implanted with the highest concentration of atrazine (5 ppm) showed a significant reduction in egg production compared to controls. All males, regardless of treatment, produced milt and had motile sperm. Preliminary analysis of brains from fish exposed to atrazine show a significant elevation of aromatase activity in male cunner, and a complete analysis of tissues is now underway. Our results to date suggest short-term exposure to an EDC that modifies aromatase activity does not necessarily translate into an impact on the reproductive success of exposed fish once spawning has begun.