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Do maternal progestogens impact the development of extra-embryonic membranes?​

Given the importance these membranes have to successful development, we are interested in understanding how their development might be regulated. Preliminary work suggests that membrane developement may be influenced by maternal progestogens, which are known to be abundant in eggs. Using we chickens as a model system, we are characterizing the response of extra-embryonic membranes to progestagen manipulations.

​​Do the metabolites of maternal testosterone impact developing embyros?​

In collaboration with Dr. Joe Casto and Dr. Rachel Bowden, we are investigating the effects steroid metabolites might have on developing embryos. We have previously demonstrated that maternal testosterone in metabolized to etiocholanolone in European starling (​Sturnus vulgaris) eggs. Etiocholanolone has also been shown to be present in red-eared slider turtle (Trachemys scripta) eggs. Current work is investigating whether etiocholanolone has any impacts on embryonic development.

Can embryos buffer themselves from maternal glucocorticoid exposure?​

Maternal stress effects occur when exposing mothers to adverse conditions has an impact on her offspring. Mechanistically, these effects are thought to arise when embryos are exposed to elevated levels of maternal glucocorticoids. We are examining how developing embryos regulate their exposure to maternal glucocorticoids in collaboration with Dr. Mark Haussmann (quail) and Drs. Alison Bell and Katie McGhee (stickleback). Results show that avian embryos, Japanese quail (Coturnix japonica), regulate exposure via steroid metabolism while fish embryos, threespined sticklebacks (Gasterosteus aculeatus), regulate exposure via active transport of glucocorticoids. Current work is investigating how embryonic regulation of exposure to maternal glucocorticoids impacts maternal stress effects.

Can endocrine disruptors alter embryonic exposure to maternal steroids?

Given that embryos appear to regulate their exposure to numerous maternal steroids, we are investigating the potental for endocrine disruptors to alter embryonic exposure to maternal steroids. An example of this comes from work with Dr. Bowden in the red-eared slider where Bisphenol-A (BPA) inhibits the metabolism of maternal estradiol and increases embryonic exposure to maternal estradiol. We are addressing this question by characterizing the impacts of endocrine disruptors on the metabolism of numerous maternal steroids in chicken eggs.

As projects proceed, this page will be updated. More information about my research can be found here: Google Scholar results for Ryan Paitz​

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