Effects of eutrophication on vitellogenin gene expression in male fathead minnows (Pimephales promelas) exposed to 17a-ethynylestradiol in field mesocosms Denise A. Gordon a , Gregory P. Toth a , David W. Graham b, ** , James M. Lazorchak a , Tirumuru V. Reddy a , Charles W. Knapp b , Frank deNoyelles Jr. c , Scott Campbell c , David L. Lattier a, * a Molecular Indicators Research Branch, Ecological Exposure Research Division, National Exposure Research Laboratory, Office of Research and Development, United States Environmental Protection Agency, 26 West Martin L. King Dr., m/s 642, Cincinnati, OH 45268, USA b Department of Civil, Environmental and Architectural Engineering, University of Kansas, 4112 Learned Hall, Lawrence, KS 60045, USA c Kansas Biological Survey, University of Kansas, Foley Hall, 2021 Constant Avenue, Lawrence, KS 66047, USA Received 3 June 2005; received in revised form 30 September 2005; accepted 13 October 2005 Nutrient condition in surface waters strongly influences vitellogenin gene expression in male fathead minnows. Abstract This study evaluated the effect of aquatic secondary nutrient supply levels (nitrogen and phosphorus) on the subcellular response of adult male fathead minnows (Pimephales promelas) exposed to a single nominal concentration of 17a-ethynylestradiol (EE2), a potent synthetic estrogen, under quasi-natural field conditions. Outdoor mesocosms were maintained under low, medium, and high nutrient supply conditions as categorized by total phosphorus (TP) level (nominal 0.012, 0.025, and 0.045 mg TP/L, respectively), and treated with EE2 with and without a carrier solvent. Using reverse transcription-polymerase chain reaction methods, vitellogenin gene (Vg) expression was determined in the fish collected at 0 h, 8 h, 24 h, 4 d, 7 d, and 14 d post-exposure. Induction of Vg was detected as early as 8 h post-exposure, with and without the carrier solvent, and persisted through Day 14. Results showed Vg to be significantly greater at low nutrient levels ( p < 0.05), suggesting that EE2 bioavailability to the fish was likely greater under less-turbid water conditions. Published by Elsevier Ltd. Keywords: Nutrient enrichment; 17a-Ethynylestradiol; Fathead minnow; Vitellogenin; Mesocosms 1. Introduction The effects of a variety of endocrine disrupting compounds (EDCs), ranging from metals to organochlorine pesticides to synthetic estrogenic pharmaceuticals, in both laboratory and field studies, continue to be widely reported (e.g., Ahmed, 2000; Guillette and Gunderson, 2001; Kavlock et al., 1996; McMaster, 2001; Oberdo ¨rster and Oliver Cheek, 2001; Tyler et al., 1998). The relevance of such studies to human health and ecological risk assessment has been strengthened by re- ports which revealed the presence of multiple EDCs in surface waters across the United States at concentrations known to cause adverse effects (Ankley et al., 1998; Campbell and Hutchinson, 1998; Foster, 2001; Hutchinson, 2002; Kolpin et al., 2002; Tyler et al., 1998). Most recently, the Canadian * Corresponding author. Tel.: þ1 513 569 7976; fax: þ1 513 569 7609. ** Technical issues related to mesocosm/nutrient systems can be directed to: David W. Graham. Tel.: þ1 785 864 2945; fax: þ1 785 864 5631. E-mail addresses: dwgraham@ku.edu (D.W. Graham), lattier.david@ epa.gov (D.L. Lattier). 0269-7491/$ - see front matter Published by Elsevier Ltd. doi:10.1016/j.envpol.2005.10.041 Environmental Pollution 142 (2006) 559e566 www.elsevier.com/locate/envpol