Aryl hydrocarbon receptor (AhR) inducers and estrogen receptor (ER) activities in surface sediments of Three Gorges Reservoir, China evaluated with in vitro cell bioassays

Abstract

Two types of biological tests were employed for monitoring the toxicological profile of sediment cores in the Three Gorges Reservoir (TGR), China. In the present study, sediments collected in June 2010 from TGR were analyzed for estrogen receptor (ER)-and aryl hydrocarbon receptor (AhR)-mediated activities. The estrogenic activity was assessed using a rapid yeast estrogen bioassay, based on the expression of a green fluorescent reporter protein. Weak anti-estrogenic activity was detected in sediments from an area close to the dam of the reservoir, and weak estrogenic activities ranging from 0.3 to 1 ng 17β-estradiol (E2) equivalents (EQ) g −1 dry weight sediment (dw) were detected in sediments from the Wanzhou to Guojiaba areas. In the upstream areas Wanzhou and Wushan, sediments demonstrated additive effects in coadministration of 1 nM E2 in the yeast test system, while sediments from the downstream Badong and Guojiaba areas showed estrogenic activities which seemed to be more than additive (synergistic activity). There was an increasing tendency in estrogenic activity from upstream of TGR to downstream, while this tendency terminated and converted into anti-estrogenic activity in the area close to the dam. The AhR activity was detected employing rat hepatoma cell line (H4IIE). EROD activities were found homogenously distributed in sediments in TGR ranging from 200 to 311 pg 2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD) EQ g −1 dw for total AhR agonists and from 45 to 76 pg TCDD EQ g −1 dw for more persistent AhR agonists. The known AhR agonists polycyclic aromatic hydrocarbon, polychlorinated biphenyl, and PCDD/F only explained up to 8 % of the more persistent AhR agonist activity in the samples, which suggests that unidentified AhR-active compounds represented a great proportion of the TCDD EQ in sediments from TGR. These findings of estrogenic potential and dioxin-like activity in TGR sediments provide possible weight-of-evidence of potential ecotoxicological causes for the declines in fish populations which have been observed during the past decades in TGR.

Water exposure assessment of aryl hydrocarbon receptor agonists in Three Gorges Reservoir, China using SPMD-based virtual organisms

“…However, TEQ calculated based on these three classes of chemicals often account for less than 20% of the TEQ bio (Kannan et al, 2008;Keiter et al, 2008;Nieuwoudt et al, 2009;Hong et al, 2012;Wang et al, 2014a), which suggests that unknown AhR agonists generally exist in sediments and soils. Similar phenomenon also occurred in other environmental matrix, for example, Muusse et al (2012) found PAH can only explain up to 9% of the AhR agonist activity in roadside snow samples in Norway.…”

“…Studies (Lu et al, 2010;Shi et al, 2011) demonstrated that local populations of the Yangtze fish might be exposed to endocrine-disrupting chemicals at concentrations sufficient to cause impairment of their reproductive physiology. Our recent study reported detectable level of AhR activity in the sediment of TGR which provided possible weight-of-evidence of potential ecotoxicological cause for the decline of fish populations in TGR (Wang et al, 2014a). However, little is known about the bioavailable AhR agonist pollution in the water of TGR and its long term risks to local biota.…”

Evaluation of Estrogenic Receptor (ER) and Aryl Hydrocarbon Receptor (AhR) Agonists in Three Gorges Reservoir, China Using SPMD-Based Virtual Organisms

“…Several studies [3] [4] demonstrate that local populations of Yangtze fish may be exposed to endocrinedisrupting chemicals (EDCs) at concentrations sufficient to cause impairment of their reproductive physiology. Our recent study also detected estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) activities in sediments from TGR [5]. However, limited information is available on ER and AhR activities in water of TGR.…”

“…The cell culture and EROD bioassay were performed according to the procedure described in our previous paper [5]. Briefly, cells were grown in Dulbecco's minimum essential medium supplemented with 10% fetal calf serum and incubated at 37˚C in a humidified 5% CO 2 incubator.…”

“…The bioassay was performed according to the procedure described in our previous paper [5]. Briefly, an agar plate containing the selective MM/L medium was inoculated with the yeast ERα cytosensor from a frozen −80˚C stock (20% glycerol v/v).…”