Induction of Vitellogenin and Histological Effects in Wild Fathead Minnows from a Lake Experimentally Treated with the Synthetic Estrogen, Ethynylestradiol

Abstract

Potential effects of exposure to contaminants with estrogenic activity are currently being examined in fish from a lake experimentally treated with the synthetic estrogen, ethynylestradiol (EE2). EE2 was added to Lake 260, a small Precambrian shield lake in the Experimental Lakes Area (ELA) of northwestern Ontario, from late May to October 2001. Concentrations of EE2 in epilimnetic waters ranged between 4.0 and 8.1 ng/L, with a mean (±SD) of 6.0 ± 2.8 ng/L. Male fathead minnows (Pimephales promelas) captured from Lake 260 after EE2 additions began contained 9000-fold higher concentrations of the egg yolk precursor vitellogenin (VTG), than were detected in fish captured from the same lake prior to the EE2 additions, or when compared to fatheads from reference lakes during the same sample period. VTG in females was induced 8- to 80-fold and was sustained beyond the normal window of vitellogenesis in Lake 260. Histological examination of tissues from EE2-exposed male fatheads in Lake 260 showed widespread fibrosis and inhibition of testicular development. Enlargement of liver cells, edema in the interstitium between kidney tubules, and eosinophilic deposits in the kidney tubule lumen were also evident in male fatheads from Lake 260. Further studies will examine the relationships between biochemical and histological alterations and population level effects.

Collapse of a fish population after exposure to a synthetic estrogen

“…The loss of smaller size classes of fathead minnow was not observed in reference Lake 442 (Fig. 3A), a system with similar species composition, water volume, and trophic status (24,28). In addition, the mean Ϯ SE size of adult fish from Lake 260 increased from 50 Ϯ 0.28 mm (n ϭ 300) in 2001, just after the first EE2 additions, to 62 Ϯ 0.18 mm (n ϭ 263) in the fall of 2003, because of a shift in the age structure of the remaining population.…”

“…In this study, testicular tissues of all of the male fathead minnow collected during the first spring after EE2 additions displayed delayed spermatogenesis, widespread fibrosis, and malformations of the tubules (see ref. 24). Testicular germinal tissue from all EE2-exposed males consisted primarily of spermatogonia instead of the spermatocytes that were normally observed at this time of year in the reference lakes and in Lake 260 before EE2 additions.…”

“…For VTG analyses, whole fish were placed in sterile plastic bags, immediately frozen on dry ice, and kept at Ϫ90°C until analyzed. Whole-body homogenates were used to quantify the VTG by using the indirect competitive ELISA methods detailed previously (24). Reagent VTG from fathead minnow was obtained from the Core Biomarker Facility (University of Florida, Gainesville, FL).…”

THE OPTIMAL IMPLEMENTATION OF THETROJAN Y CHROMOSOMEERADICATION STRATEGY OF AN INVASIVE SPECIES

“…However, these efforts usually involve massive scale poisoning of the aquatic species and can have highly variable results. 9 In 2009, a local eradication of invasive Asian carp was carried out, resulting in the poisoning of tens of thousands of fish but only collecting one invasive Asian carp.…”

Detailed Review Paper on Fish Screening Assays for the Detection of Endocrine Active Substances

“…The effects of endocrine disruptive agents on the tissues and cells of fish can be observed in several organs including the liver, pituitary, kidneys, circulatory system, and the gonads (Wester et al 2003, Palace et al 2002. However, for the purposes of screening chemicals for disruption of reproductive function in fish, gonadal histopathology appears to be diagnostic.…”