RP7 Ecotoxicogenomics of Emerging Chemical Issues
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(COL-1117-829684) Metabolomics as a diagnostic tool for small fish toxicology research.

Collette, T¹, Ekman, D¹, Kenneke, J¹, Whitehead, T¹, Villeneuve, D², Kahl, M², Jensen, K², Ankley, G², ¹ U.S. EPA, ORD, NERL, ERD, Athens, GA, USA² U.S. EPA, ORD, NHEERL, MED, Duluth, MN, USA

ABSTRACT- Metabolomics involves the application of advanced analytical and statistical tools to profile changes in levels of endogenous metabolites in tissues and biofluids resulting from disease onset or stress. Nuclear Magnetic Resonance (NMR) spectroscopy-based metabolomics has proven useful in mammalian systems for distinguishing between sites and mechanisms of toxicity for tissue-specific toxins. Metabolomics has been characterized as the true measure of metabolic outcomes suggested by changes in gene and protein expression; as such, metabolomics provides a connection between these molecular endpoints and whole organism responses. Although used mostly in mammalian studies, metabolomics is now finding utility in a wide variety of other organisms including aquatic species. To better understand the mode-of-action of endocrine-disrupting chemicals (EDCs) within the hypothalamic-pituitary-gonadal (HPG) axis of small fish toxicology models (fathead minnow, zebrafish), we initiated metabolomic analyses with multiple tissues (brain, blood, liver, gonad) and urine. Initial metabolomic studies have focused on collection of baseline data for actively-spawning male and female fathead minnows. Subsequent work is focusing on animals exposed to potent estrogenic- or androgenic-receptor agonists, such as the steroids 17-ethinylestradiol (EE₂) and 17-trenbolone (trenbolone). We are developing hypotheses about which tissue- and biofluid-specific metabolite changes will be definitively related to exposure, based on the current understanding of modes-of-action for these chemicals. Results will allow testing of these hypotheses to refine understanding of activity, and will help ensure that molecular markers of EDC exposure - another outcome of this research - are meaningful. While certain metabolites are being specifically targeted in these studies, we will also discern changes in the complete metabolic profile using NMR spectroscopic data with statistical approaches that allow capturing subtle changes in less-abundant metabolites. These data will be integrated with genomic, proteomic, and whole organism data from untreated fish and those exposed to known EDCs.

Key words: metabolomics, EDCs, NMR spectroscopy, ecotoxicogenomics