A-YESHT for the detection of estrogenic effects

The biological test system A-YESHT (Arxula-Yeast Estrogen Screen for High Throughput-applications) is based on the use of estrogen sensitive yeast, Arxula adeninivorans. The test was developed for parallel screening of large sample sizes, utilizing ready-to-use 384-well test plates and an optimized fluorescence reporter based on dsRED. The test can therefore be used in combination with automated liquid handling systems.

A-YESHT contains the growth medium and yeast mixed and lyophilized in every well. Only 40 µl of sample has to be added to each well. After 18 to 22 hours of incubation, the fluorescence (excitation 535 nm, emission 595 nm) can be measured directly. On request we offer individual configuration of the 384-well test plates for analyzing special test controls e. g. blanks (wells without yeast).

A-YESHT can be used for:

  • Determination of potential estrogenic effects of drug candidates

  • Qualitative analysis of ultrapure-, drinking- and mineral water

  • Qualitative analysis of ground-, well- and surface water with low matrix effects

The test is not suitable for samples with high matrix load e. g. wastewater samples.

Response (Relative Fluorescence Units, RFU) of various estrogens and estrogen active substances analyzed using A-YESHT.

Duration of  assayca. 26 h
Number of Samples (EEQ)max. 40
Validationinterlaboratory trial
Calibration range*0 – 80
Limit of Detection*1.8

* ng/L  17β-Estradiol (E2)

The A-YESHT test is based on a genetically modified strain of the A. adeninivorans yeast which has been modified to bind with the human estrogen receptor, hERα. Binding of androgenic substances to the receptor subsequently activates production of a secretory reporter enzyme. The amount of enzyme activity correlates to the total concentration of estrogenic substances in the sample. With the addition of the chromogenic substrate p-nitrophenyl phosphate, enzyme activity can be measured photometrically. 17 β-estradiol (E2) is used as a reference standard for calibration and quantification.

TEFp = translation-elongation factor promotor / hERα = human estrogen receptor alpha gene / GAAp = glucoamylase promotor / phyK = phytase reporter gene.

The detection is carried out photometrically after enzymatic reaction with a chromogenic substrate (p-nitrophenylphosphate).

The color-change reaction is catalyzed by the enzyme phytase:

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