Estrogenicity yeast-based assays

Traceability and Interlaboratory Studies on Yeast-based Assays for the Determination of Estrogenicity... 

Relative Estrogenic Potency Determined by Yeast-based Assays... 

Reporter gene assays that measure ER binding-dependant transcriptional and translational activity. The yeast-based assays fall within this group. The vast majority of yeast-based assays are based on S. cerevisiae containing a stably transfected human estrogen, receptor (hER), although there are several variations in strain and detection method (NICEATM, 2002)... 

Another much used yeast-based assay is the yEGFP assay (first described by Bovee et al., 2004). In this assay recombinant yeast cells are constructed that express the human estrogen reporter a (ER a) and yeast enhanced green fluorescence protein), the estrogenic potential is then measured by a Fluorometer. 

RELATIVE ESTROGENIC POTENCY DETERMINED BY YEAST-BASED ASSAYS... 

Figure 5.3.1 Relative estrogenic potential determined by yeast-based assays (diamonds) and...

Acceptable variation coefficients are determined by the application of the assay, for prescreening purposes with a sufficiently low limit of detection, it is acceptable to have high variation coefficients. But when trying to establish a correlation between chemical data and results from yeast-based assays a variation coefficient on the relative estrogenic potential of more than 100% is quite problematic. 

Ramamoorthy K, Wang F, Chen I-C, et al. 1997. Estrogenic activity of a dieldrin/toxaphene mixture in the mouse uterus, MCF-7 human breast cancer cells, and yeast-based estrogen receptor assays No apparent synergism. Endocrinology 138(4) 1520-1527. 

YES Yeast-based recombinant estrogen receptor-reporter assay... 

An example of a TIE approach is that described by Desbrow et al. [7]. In this work, the endocrine disrupting activity detected in effluents of seven UK WWTPs by means of a yeast-based screening assay [52] was mainly attributed to the presence of estradiol, estrone, and ethynylestradiol. However, to assess the estrogenic activity different bioassays may be used, e.g., the yeast-based recombinant estrogen receptor-reporter assay (YES), the MCF-7 cell proliferation (E-screen), and the estrogen receptor-mediated chemically activated... 

Fig. 8.3 Yeast-based screen for agonists or antagonists of the human estrogen receptor. The hormone estrogen (estradiol) binds to the estrogen receptor which is expressed from a gene driven by the PGK promoter. The hormone-receptor complex binds to an estrogen-responsive element (ERE) that controls the expression of the p-galactosidase reporter gene. The assay measures the activity of the enzyme using a substrate that forms a colored product on conversion.

An extract of Chinese rhubarb induced estrogenic activity at a concentration of 0.1 mg/ml in a yeast-based estrogen receptor activity assay (Kang et al. 2006). 

Yeast reporter gene assays and MCF-7 cell-based proliferation assays (E-screen) are particularly popular. The E-screen, in which proliferation of human breast cancer cells (MCF-7) is measured as a response to estrogen, has also been used to determine the estrogenicity of sewage effluent and surface water (Kdrner et al., 2001). 

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