PM16 Molecular Indicators for Ecological Exposure
Exhibit Hall
8:00 AM - Monday
(PM268) Aromatase (CYP19) expression in fathead minnows (Pimephales promelas) exposed to perfluorooctane sulfonate (PFOS) and the aromatase inhibitor fadrozole.
Knoebl, I.1, Villeneuve, D.2, Kahl, M.2, Jensen, K.2, Kuehl, D.2, Ankley, G.2, 1 U.S. Environmental Protection Agency/ORD/NERL/EERD, Cincinnati, OH, USA2 U.S. Environmental Protection Agency/MED, Duluth, MN, USA
ABSTRACT- Perfluorooctane sulfonate (PFOS) is a fluorinated organic contaminant that is globally distributed in both humans and wildlife. PFOS belongs to a family of perfluorinated sulfonates that are highly persistent in the environment and have been commercially produced for over 40 years. These compounds are used in paint, polishes, food packaging, fire-fighting foams and fabric treatment. Although PFOS has been measured in a variety of wildlife, information as to its toxic mode of action (MOA) is scarce. PFOS may be an inhibitor of CYP19 aromatase, the P450 enzyme that converts testosterone to estradiol in vertebrates. To evaluate this possible MOA of PFOS in fish, we have developed a quantitative real-time PCR (TaqMan) assay to measure induction or inhibition of the aromatase gene in the brains and ovaries of fathead minnows in response to exposure to test chemicals. An aromatase cDNA sequence was isolated and cloned from the brains of fathead minnows and was used to construct a standard curve and to design sequence-specific primers and a probe. The assay was optimized and used to quantitate CYP19 gene expression in fish exposed to PFOS and to a known aromatase inhibitor, the pharmaceutical fadrozole. Fish were exposed to fadrozole (50, 17.7, 5.55, 1.85 
g/L) for 7 days, and to PFOS (.03, 0.3, 0.1, 1.0 mg/L) for 21 days. We present data comparing aromatase gene expression in brains and ovaries of the exposed fish, and make comparisons to aromatase enzyme activity in those tissues. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
Key words: aromatase, perfluorooctane sulfonate (PFOS), quantitative real-time PCR (TaqMan), fathead minnow