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(027) Transcriptional markers of oxidative stress in rainbow trout.
Marwood, Christopher*,1, Oris, James1, 1 Miami University, Oxford, Ohio, U.S.A.
ABSTRACT- Transcriptional modulation of antioxidant enzyme activity in aquatic organisms may be a sensitive marker of exposure to environmental stress and certain contaminants that exert toxicity via reactive oxygen species. These ubiquitous enzymes are regulated by intracellular levels of oxygen radicals and oxidation products produced by exposure to, or metabolism of various contaminants. Polycyclic aromatic hydrocarbons (PAH) are one such group of chemicals to which aquatic organisms are commonly exposed, through contaminated sediments and exhaust from watercraft. To assess the ability of transcriptional antioxidant markers to detect cellular stress in field exposures, enzyme induction was quantified in rainbow trout caged in sub-alpine Sierra Nevada lakes with varying levels of human impact. Lakes were classified according to several criteria, including boat traffic, land use, and water quality. Twenty-five juvenile hatchery fish were caged at 5 locations within each lake for 48 hours. Hepatic levels of mRNA corresponding to glutathione S-transferase (GST), glutathione peroxidase (GPx), and superoxide dismutase (SOD) were amplified by reverse-transcription polymerase chain reaction using primers specific for each enzyme in rainbow trout and quantified on agarose gels by densitometry. Transcript levels of GST, GPx and SOD differed significantly among lakes: GST and GPx transcription differed by more than 2- and 6-fold, respectively, between fish caged in the lake of highest impact versus those in a pristine lake. However, transcript levels were not always correlated with the level of human development or boat motor use during the exposure. Other factors, such as water temperature and time of year may have contributed to differences in expression of these markers.
Key words: antioxidant, biomarker, rainbow trout, PAH
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