The Development and Validation of a Quantitative ELISA forin vivoandin vitroSynthesized Vitellogenin from Mossambicus tilapia (Oreochromis mossambicus)

The implementation of a battery of in vivo and in vitro bioassays to assess river water for estrogenic endocrine disrupting chemicals

Previous research has shown that accurate evaluation of environmental water samples for estrogenic activity requires a panel of in vitro and in vivo bioassays, which are based on different molecular and cellular action mechanisms. In the current study, a test battery containing four assays was used to analyze water from the Eerste River, South Africa for estrogenicity. Three sites were used for analysis, namely Jonkershoek (control site situated in the mountains at the origin of the Eerste River), sewage effluent from Stellenbosch sewage treatment works and Spier site (sampling site on the Eerste River downstream from Stellenbosch). Estrogenicity was determined using an estrone enzyme linked immuno sorbent assay (ELISA), estrogen induced proliferation of human breast cancer adenocarcinoma cells (MCF-7) also known as the E-SCREEN, estrogen induced suppression of estrogen receptor alpha protein expression (ER-α) in MCF-7 cells (ERα assay) and by monitoring estrogen induced vitellogenin (VTG) synthesis in juvenile Oreochromis mossambicus (VTG assay). Low concentrations of estrone (ranging between 1.4 and 2.2 ng/l) near the detection limit of the assay were detected in samples collected from Jonkershoek. Water from this site shows no estrogenicity in the E-SCREEN, ERα assay or VTG synthesis bioassay. The estrone concentrations in the sewage effluent extracts, as well as Spier site extracts, ranged between 14.7 and 19.4 ng/l. The assays using ERα induction by the MCF-7 cell line, MCF-7 proliferation and in vivo VTG synthesis by juvenile tilapia showed that these samples are estrogenic. The results obtained for the assays in the battery are comparable.