title: The in ovo conversion of oestrone to oestrone sulfate is rapid and subject to inhibition by Bisphenol A.
abstract: Vertebrate embryos develop in the presence of maternally derived steroids. While these steroids can influence development, embryonic enzymes are thought to buffer some steroid sensitive processes, such as gonadal differentiation, from the effects of maternal steroids. Many of these same enzymes may also buffer the embryo from chemicals present in the environment, but this may alter their capacity to metabolize maternal steroids. Here, we characterized the ability of red-eared slider (Trachemys scripta) embryos to metabolize oestrone immediately following oviposition and tested whether a prevalent environmental chemical, Bisphenol A (BPA), would affect the in ovo conversion of oestrone to oestrone sulfate. We found that tritiated oestrone applied at the time of oviposition is mostly converted to oestrone sulfate within 6 h. However, when BPA is present, that conversion is inhibited, resulting in elevated oestrone levels. Our finding of rapid in ovo metabolism of steroids suggests that maternally derived enzymes are present in the egg and can alter embryonic exposure to exogenous chemicals. The disruption of this metabolism by BPA demonstrates how environmental chemicals might change embryonic exposure to endogenous substances within the egg. Taken together, these findings highlight the dynamic nature of the early endocrine environment in developing vertebrates.
authors.affiliation: School of Biological Sciences, Illinois State University, Campus Box 4120, Normal, IL 61790-4120, USA rpaitz@ilstu.edu.
authors.forename: Ryan T
authors.identifier: http://orcid.org/0000-0003-4609-4359
authors.initials: RT
authors.lastname: Paitz
authors.affiliation: School of Biological Sciences, Illinois State University, Campus Box 4120, Normal, IL 61790-4120, USA.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Bowden
mesh_terms: D000818:Animals; D001559:Benzhydryl Compounds / Q000633:toxicity*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D052244:Endocrine Disruptors / Q000633:toxicity*; D004785:Environmental Pollutants / Q000633:toxicity*; D004970:Estrone / Q000031:analogs & derivatives* / Q000378:metabolism; D010063:Ovum / Q000187:drug effects / Q000378:metabolism; D010636:Phenols / Q000633:toxicity*; D014426:Turtles / Q000196:embryology / Q000378:metabolism*; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D004970:Estrone; D010636:Phenols; C006780:bisphenol A; D000098826:Bisphenol A Compounds; C017296:estrone sulfate
keywords: endocrine disruption; maternal effect; oestrone; sulfonation