Screening of Potentially Hormonally Active Chemicals Using Bioluminescent Yeast Bioreporters

Abstract

Saccharomyces cerevisiae bioluminescent bioreporter assays were developed previously to assess a chemical's estrogenic or androgenic disrupting potential. S. cerevisiae BLYES, S. cerevisiae BLYAS, S. cerevisiae BLYR, were used to assess their reproducibility and utility in screening 68, 69, and 71 chemicals for estrogenic, androgenic, and toxic effects, respectively. EC(50) values were 6.3 +/- 2.4 x 10(-10)M (n = 18) and 1.1 +/- 0.5 x 10(-8)M (n = 13) for BLYES and BLYAS, using 17beta-estradiol and 5alpha-dihydrotestosterone over concentration ranges of 2.5 x 10(-12) through 1.0 x 10(-6)M, respectively. Based on analysis of replicate standard curves and comparison to background controls, a set of quantitative rules have been formulated to interpret data and determine if a chemical is potentially hormonally active, toxic, both, or neither. The results demonstrated that these assays are applicable for Tier I chemical screening in Environmental Protection Agency's Endocrine Disruptor Screening and Testing Program as well as for monitoring endocrine-disrupting activity of unknown chemicals in water.

Analysis of Environmental Samples with Yeast-Based Bioluminescent Bioreporters

“…The BLYES and BLYAS assays are consistent with previously published yeast-based reporter assays (Sanseverino et al, 2009). The 40 -50% variability of the EC 50 values shown in Figure 3 reaffirms the suggestion that no single assay should be used to determine an absolute EC 50 value but rather as a first step in estimating the hormonal activity of a chemical (Beresford et al, 2000).…”

“…reproducibility and utility in screening 69, 68, and 71 chemicals for estrogenic, androgenic, and toxic effects, respectively (Sanseverino et al, 2009). This screening was part of an assessment of the United States Environmental Protection Agency's Tiered screening of chemicals for endocrine-disrupting ability.…”

“…In this study, EC 50 values were 6.3 ± 2.4 x 10 -10 M (n = 18) and 1.1 ± 0.5 x 10 -8 M (n = 13) for BLYES and BLYAS, using 17 -estradiol and 5 -dihydrotestosterone A B C 9 (DHT) over concentration ranges of 2.5 x 10 -12 thru 1.0 x 10 -6 M, respectively. Based on analysis of replicate standard curves, comparison to background controls, and screening a variety of chemicals, a set of quantitative rules was formulated to interpret data and determine if a chemical is potentially hormonally active, toxic, both, or neither (Sanseverino et al, 2009). The results demonstrated that these assays were applicable for Tier I chemical screening in EPA's Endocrine Disruptor Screening and Testing Program as well as for monitoring endocrine disrupting activity of unknown chemicals in water.…”

Dose-dependent acceleration in the delayed effects of neonatal oral exposure to low-dose 17α-ethynylestradiol on reproductive functions in female Sprague-Dawley rats

“…The treatment increased the circulating EE levels 6 hr after the final dosing at that of estradiol-17β on the day of proestrus (Smith et al, 1975;Asai et al, 2002;Nozawa et al, 2014;Usuda et al, 2014) even at 2 μg/kg/day of EE. Because the relative in vitro estrogenic activity of EE was found to be 90-250% of estradiol-17β (Soto et al, 1995;Coldham et al, 1997;Fang et al, 2000;Nishihara et al, 2000;Sanseverino et al, 2009), estrogenic activity of the circulating EE after the administration of 0.4 μg/kg/day seemed to be equivalent to or lower than basal estradiol-17β levels in the cyclic rats. Thus, very slight estrogenic stimulus during the neonatal period exerts irreversible effects on the animals.…”

“…The relative in vitro estrogenic activity of EE to estradiol-17β is varied among studies. While the reported lowest value was 50% (Nakamuro et al, 2002), most of in vitro studies estimated the value ranged 90-250% (Soto et al, 1995;Coldham et al, 1997;Fang et al, 2000;Nishihara et al, 2000;Sanseverino et al, 2009).…”