EAPSI: Investigating the effect of environmental contaminants on female reproductive systems in American alligators, an indicator species

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There is increasing evidence that exposure to environmental contaminants during embryonic development can lead to impaired adult reproductive function. A well-known example is how exposure to the pesticide DDT severely impacted the reproductive success of many wild birds via eggshell thinning. Studies have shown that exposure to DDT prenatally alters the development of the female reproductive tract (FRT) of birds, causing structural changes that alter adult reproductive function. This study will focus on the development of the FRT in an important sentinel species, the American alligator, which holds a unique evolutionary position with a reproductive tract that bears similarities to other reptiles as well as to birds. This study will investigate whether pathways related to estrogen changes play a role in the development of alligator FRT. This research will be conducted at the National Institute for Basic Biology in Okazaki, Japan, in collaboration with Dr. Taisen Iguchi, a renowned expert on the role of estrogens in female reproductive system development and endocrine disruption. In mammals, regional development of the female reproductive tract is influenced by spatiotemporal expression of Hoxa 5' genes. Regional expression of these genes in the developing mammalian FRT is regulated by estrogens. Due to the highly conserved nature of Hox genes in body plan specification across vertebrate taxa, this study hypothesizes that Hox genes are also involved in regional differentiation of the developing alligator FRT, and, further, that these genes are regulated by endogenous estrogens. Hoxa 5' expression in the embryonic alligator FRT will be localized via in situ hybridization, and the role of estrogens in regulating these genes will be characterized by comparing expression patterns in tissues exposed to exogenous estrogen and estrogen receptor isoform-specific agonists. This study will provide insight into the factors critical for healthy reproductive system formation in this sentinel species, and the potential disruptive impact of exposure to estrogenic environmental contaminants. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.