The anti-estrogenic activity of sediments from agriculturally intense watersheds: Assessment using in vivo and in vitro assays

Abstract

The goal of the current study was to determine whether sediments from agriculturally-intense watersheds can act as a potential source of anti-estrogenic endocrine-disrupting compounds. The specific objectives of the current study were to determine 1) whether female fathead minnows (Pimephales promelas) experience alterations in endocrine function when exposed to sediments collected from agriculturally-intense watersheds and 2) if these sediments display anti-estrogenic activity in an in vitro assay. In addition, sediment samples were analyzed for the presence of steroid hormones and pesticides associated with local agricultural practices. To accomplish this, sediments and water were collected from three sites within two agriculturally-intense Nebraska watersheds (Bow Creek and the Elkhorn River). In 2009, minnows were exposed to sediment and/or water collected from the two Bow Creek sites (East Bow Creek and the Confluence) in the laboratory, while in 2010, minnows were exposed to sediment and/or water from East Bow Creek, the Confluence and the Elkhorn River. Following the 7-d exposure period, the hepatic mRNA expression of two-estrogen responsive genes, estrogen receptor α (ERα) and vitellogenin (Vtg) was determined. In 2009, females exposed to Confluence sediments, in the presence of laboratory water or Confluence water, experienced significant reductions in ERα expression relative to unexposed and Confluence water-exposed females. The defeminization of these females suggests the presence of a biologically-available anti-estrogenic compound in sediments collected from this site. In 2010, sediments were assessed for anti-estrogenic activity on days 0 and 7 of the exposure period using a four-hour yeast estrogen screen. Lipophilic extracts (LEs) of day 0 sediments collected from the Confluence and the Elkhorn River induced significant reductions in the estrogenic reporter activity of treated yeast cultures suggesting the presence of a lipophilic anti-estrogenic compound in these extracts. Chemical analysis revealed the presence of a variety of steroid hormones, including those associated with the production of beef cattle (ie: β-trenbolone, α-zearalanol and α-zearalenol), in sediments indicating that compounds utilized by local beef cattle operations are capable of entering nearby watersheds. Overall, the results of this study indicate that an environmentally-relevant anti-estrogenic compound is present in sediments from agriculturally-intense watersheds and that this compound is bioavailable to fish. Furthermore, the presence of steroid hormones in sediments from these watersheds provides evidence indicating that steroids are capable of sorbing to sediments. Clearly, sediments are capable of acting as a source of endocrine-disrupting compounds in the aquatic environment.

The Hourglass: A Conceptual Framework for the Transport of Biologically Active Compounds from Agricultural Landscapes

“…For example, Sellin Jeffries et al . () collected sediment from a site in the Bow Creek (Nebraska) watershed but did not find detectable concentrations of testosterone or progesterone immediately following collection. However, when these sediments were immersed in surface water collected from the same field site, the sediments accumulated detectable concentrations of these steroid hormones after seven days, suggesting that steroids present in the overlying water had sorbed to sediments during the course of the seven‐day period.…”

“…Caged fish studies conducted in the Elkhorn River and Bow Creek watersheds have shown that female fish deployed in these watersheds experienced alterations in endocrine function, as indicated by reductions in the mRNA expression of estrogen‐responsive genes (Sellin et al ., ; Sellin Jeffries et al ., ) (Figure ). When females were exposed to sediments from these watersheds under laboratory conditions, they experienced reductions in mRNA expression similar to those observed among females deployed in the field; however, this effect was not observed when females were exposed to overlying surface waters (Sellin et al ., ; Sellin Jeffries et al ., ). This finding indicates that sediments from these two agriculturally intense watersheds are a source of biologically available BACs.…”

“…Steroid hormones have also been detected in sediments collected from watersheds impacted by agricultural runoff. Specifically, sediments from two Nebraska watersheds characterized by beef cattle feeding operations and row crop production — the Elkhorn River and Bow Creek watersheds — contained both estrogenic ( α ‐estradiol, α ‐zeralenol, and estrone) and androgenic ( β ‐trenbolone and testosterone) steroid hormones (Sellin Jeffries et al ., ). Furthermore, Kolpin et al .…”

From ‘Omics to Otoliths: Responses of an Estuarine Fish to Endocrine Disrupting Compounds across Biological Scales

“…EDCs originate from a variety of sources, such as treated wastewater effluent and agricultural, ranch, or urban run-off [2], [3], and are widespread in the aquatic environment [1], [4]. Examples of hormonal disruptions in fishes produced by EDCs include altered secondary sexual characteristics, males producing egg proteins (vitellogenin, choriogenin), and reduced sperm quality [5], [6], [7].…”

“…Recent studies have utilized the results from single-EDC laboratory exposures to produce predictive population models [10], [11], to assess multiple genomic and organismal level endpoints in response to known environmental mixtures [12], and to link EDC-perturbations in gonad or gene expression changes in fish with reduced reproductive performance or varying degrees of urbanization or agricultural activity [2], [13], [14]. However, to date no single study has attempted to link exposure to different environmental EDC mixtures, such as urban and ranch run-off, with responses at multiple tiers of the biological hierarchy, including population-level effects, within one study system.…”