MP7 Toxicogenomics in Environmental Studies
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(STA-1117-848996) Microarray Analysis of Liver from Rainbow Trout (Oncorhynchus mykiss) Fed Polycyclic Aromatic Hydrocarbons.

Stanley, K¹, Bravo, C¹, Curtis, L¹, Bayne, C², Gerwick, L², Lambertini, E³, Loge, F³, Hahn, M⁴, Williams, D¹, ¹ Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon, USA² Department of Zoology, Oregon State University, Corvallis, Oregon, USA³ Department of Civil and Environmental Engineering, University of California Davis, Davis, California, USA⁴ Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA

ABSTRACT- Polycyclic aromatic hydrocarbons (PAHs) are present in aquatic ecosystems where they commonly exist as complex mixtures. Exposure to individual PAHs is known to cause cancer and immunotoxicity in aquatic organisms. Laboratory experiments using environmentally relevant concentrations of PAHs are necessary to gain insight into mechanisms of toxicity in fish in the field. Aryl hydrocarbon receptor activation is one possible mechanism of PAH toxicity in fish. Rainbow trout were fed 160ppm of benzo[a]pyrene, 160ppm benzo[e]pyrene, or a 400ppm mixture of ten high molecular weight PAHs for 50 days. A vehicle control group was also included. Blood, liver and kidney were collected from fish in all treatment groups after 3, 7, 14, 28, and 50 days of feeding. DNA damage, cytochrome P450 activity and lipid peroxidation were measured using the comet assay, EROD, and isoprostanes, respectively. Percent DNA damage increased after 14 days and then decreased from this maximum after 28 or 50 days in all treatments. The same results were obtained for the cytochrome P450 measurements. Lipid peroxidation was significantly higher in the 400ppm treatment on day 50 compared to the control. The aryl hydrocarbon binding assay was conducted by incubating rainbow trout AhR2a with a 2nm solution of [3H]TCDD and 1, 10, or 100nm solutions of DMSO, benzo[a]pyrene or benzo[e]pyrene. As expected, benzo[a]pyrene competed with TCDD for binding to the receptor. Benzo[e]pyrene did not compete for binding, proposing an oxidative stress mechanism independent of AhR. Microarrays selective for rainbow trout genes involved in immune, toxicological, endocrine, and stress responses were hybridized with hepatic total RNA. Relationships between phenotypic features and PAH-dependent changes in gene expression are of special interest.

Key words: pahs, microarray