DISSERTATION RESEARCH: Endocrine Mechanisms and Evolution of the Placenta

在从产卵到生育的进化过程中，必须发生一些生理和生理变化来支持胚胎的发育。胎盘提供了母亲和胎儿之间的接口，允许维持生命的氧气、营养物质和废物的运输。由于胎盘的结构也允许类固醇激素的交换，相对新近进化的胎盘物种可能面临调节母体和胎儿激素水平的额外挑战。类固醇激素影响妊娠维持和胎儿发育，因此胎盘对这些过程的影响可能具有关键的后果。哺乳动物胎盘生理学的进化研究一直是有限的，因为真兽哺乳动物的胎盘只有一个进化起源。然而，在爬行动物中，胎盘最近独立进化了多达100次，使其成为比较进化研究的理想群体。本研究旨在明确伴随胎盘进化的激素机制及其对胎儿和母体激素水平的影响。PIs最近的工作表明，通过降低某些激素的水平，山刺蜥蜴的胎盘可能有助于隔离母体和胎儿的激素环境。一系列的三个额外的研究将确定胎盘类固醇产品，检查胎盘和胎儿腺体之间的相互作用，并确定胎盘在母体对胎儿激素水平影响的中介中的作用。这种比较机制的方法有望为胎盘激素功能的进化提供新的视角。

During the evolutionary transition from egg-laying to live-bearing, several physical and physiological changes must occur to support the developing embryo. The placenta provides an interface between the mother and fetus, allowing life-sustaining transport of oxygen, nutrients, and wastes. Because the structure of the placenta also permits exchange of steroid hormones, species with relatively recently evolved placentation may face the additional challenge of regulating maternal and fetal hormone levels. Steroid hormones influence pregnancy maintenance and fetal development, so placental effects on these processes could have critical consequences. Study of the evolution of placental physiology in mammals has been limited, because the placenta of eutherian mammals has only one evolutionary origin. However, in reptiles, the placenta has evolved recently and independently as many as 100 times, making this an ideal group for comparative evolutionary study. This proposal aims to define hormonal mechanisms that accompany the evolution of the placenta, and their effects on fetal and maternal hormone levels. The PIs recent work demonstrated that, by reducing the levels of some hormones, the placenta of the mountain spiny lizard may contribute to the isolation of the maternal and fetal hormonal environments. A series of three additional studies will identify placental steroid products, examine interactions between the placenta and fetal glands, and determine the placenta's role in mediation of maternal effects on fetal hormone levels. This comparative mechanistic approach promises to provide novel perspectives on the evolution of placental hormone function.