Validation and application of a yeast bioassay for screening androgenic activity in calf urine and feed

In vitro bioassays for the study of endocrine-disrupting food additives and contaminants

“…There is therefore a requirement for development of a sample-preparation method that can extract, concentrate and clean up samples of interest. Common methods for sample preparation include organic-solvent extraction, centrifugation and solid-phase extraction or their variations [15,33,55,60,68,69]. The sample extracts must be prepared in solution for application to the in vitro bioassay.…”

“…However, yeast assays do have several other advantages for consideration, as they can be run relatively cheaply, are easy to handle, present a lack of endogenous receptors and do not require the preparation of steroid-free media. Probably the biggest advantage attributed to yeast cells is that they are extremely robust and can survive extracts from dirty sample matrices (e.g., urine and feed) [33]. A yeast-androgen RGA was recently compared with liquidchromatography tandem mass spectrometry (LC-MS 2 ) detection of anabolic steroids in food supplements [60].…”

“…The chemical-activated luciferase gene expression (CALUX) bioassay was the first bioassay to be validated for food applications, the determination of dioxins and PCBs in bovine milk [15]. The new RIKILT yeast androgen bioassay (RAA) [18] is the first bioassay that has been fully validated according to the international criteria put forward in EC Decision 2002/657 [33]. Although a complete overview of assay validation and/or approval for food testing is outside the scope of this review, the interested reader can find up-todate information about assay-validation status in the Environmental Protection Agency (EPA) Endocrine Disruptor Screening Program (EDSP) [34].…”

A yeast estrogen screen without extraction provides fast, reliable measures of estrogenic activity

“…Dhooge et al [17] and Bovee et al [16] conclude that yeastbased assays are at least as good as mammalian cell-based bioassays for screening estrogen agonists. Dhooge et al [17] and Bovee and Pikkemaat [15] further conclude that, under proper experimental conditions, the yeast assay is a sensitive and specific tool that yields reproducible results across laboratories.…”

“…Numerous studies have compared yeast methods for measuring estrogenic activity with other methods. Although there are limitations to the results from yeast methods [12,14], many studies conclude that yeast methods are equal to others for rapid, reliable, and reproducible quantification of estrogenic activity [15][16][17][18][19].…”