T2 PM 'Omic' Technologies: Current and Future Applications to Environmental Toxicology (Part 2)
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in Ballroom 2

(HOF-1117-746304) Gene Expression Profiling using Affymetrix GeneChips in Zebrafish Exposed to 17–Ethinylestradiol.

Hoffmann, J¹, Torontali, S¹, Lee, D¹, Brill, J¹, Price, B¹, Carr, G¹, Versteeg, D¹, ¹ The Procter and Gamble Company

ABSTRACT- Genomic, proteomic, and metabonomic technologies continue to receive increasing interest from environmental toxicologists. This interest is due to the great potential to identify detailed modes of action and to provide assistance in the evaluation of a contaminant's risk to aquatic organisms. Using the Affymetrix GeneChip arrays, our experimental model is the zebrafish (Danio rerio) exposed to reference endocrine disrupting compounds in order to investigate compound-induced changes in gene transcript profiles. Adult, female zebrafish were exposed to 0, 15, 40, and 100 ng/L of 17–Ethinylestradiol (EE2) and dose and time-dependent changes in hepatic gene expression were examined. At 1, 2, and 7 days, fish were sacrificed and liver mRNA extracted for gene expression analysis (1 and 7 day only). In an effort to link gene expression changes to effects on higher levels of biological organization, body and ovary weight were measured and blood was collected for measurement of plasma steroid hormones (17-estradiol (E2), testosterone (T)) and vitellogenin using ELISA. We observed that 1575 genes were significantly affected (up- or down-regulated by at least 1.5-fold (p≤0.001) in a dose-dependent manner by EE2 exposure. EE2 exposure altered transcription for genes involved in insulin metabolism, retinoic acid metabolism, cell cycle, and steroid hormone/action were altered by EE2 exposure. Plasma vitellogenin was significantly increased at 1, 2, and 7 days (p<0.05) at 40 and 100 ng/L and at 15 ng/L at 7 days. 17–-estradiol and testosterone were significantly reduced following EE2 exposure at 48 hours and 7 days. GSI was decreased in a dose-dependent manner at 168 hours. In this study, we identified genes involved in a variety of biological functions that have the potential to be used as markers of exposure to estrogenic substances. Future work will evaluate the use of these genes in an in vitro screening assay with zebrafish hepatocytes.

Key words: Zebrafish, 17-Ethinylestradiol, Genechip, Liver