Effects of eutrophication on vitellogenin gene expression in male fathead minnows ( Pimephales promelas) exposed to 17α-ethynylestradiol in field mesocosms

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 17α-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. Nutrient condition in surface waters strongly influences vitellogenin gene expression in male fathead minnows.