SGER: Plasma and Yolk Hormones in a Viviparous TSD Lizard

鳄鱼、大多数海龟和一些蜥蜴物种的性别决定受卵孵化温度的调节，这种现象被称为温度依赖性性别决定（TSD）。TSD发生在一些胎生石龙子物种中的发现可能是近年来TSD领域最令人惊讶和最有趣的发展，值得在Nature上发表一篇文章（Robert和Thompson，2001）。虽然TSD的潜在机制仍然难以捉摸，并且负责将环境温度线索转化为分子信号的过程尚不清楚，但雌二醇（E2）与性别决定过程有关。本研究将探讨胎生TSD石龙子，Eulamprys tympanum的激素特性。 在这项研究中，五种类固醇激素的激素水平将在暴露于不同环境温度的雄性成年人、雌性成年人和发育中的胚胎的血清或蛋黄样本中进行测量。 因为E.鼓膜胚胎在子宫内发育，它们暴露于它们各自的卵黄激素，加上母体循环的激素，这项研究也将记录妊娠雌性的血浆激素水平。 由于石龙子是迄今为止已知的唯一胎生TSD物种，因此该项目将为温度依赖性性别决定及其机制的进化提供有价值的见解。 明尼苏达大学克鲁克斯顿校区的本科生将参与这项工作，接受激素分离和表征方面的培训，并与该项目的国际合作者进行互动。

Sex determination in crocodilians, most turtles and some lizard species is regulated by egg incubation temperature, a phenomenon termed temperature-dependent sex determination (TSD).The discovery that TSD occurs in some species of viviparous skinks was perhaps the most surprising and intriguing development in the field of TSD in recent years and merited an article in Nature (Robert and Thompson, 2001). Though the underlying mechanisms of TSD remain elusive and the process responsible for converting an environmental temperature cue to a molecular signal is unknown, estradiol (E2) has been implicated in the sex determination process. This research will examine the hormone characteristics of the viviparous TSD skink, Eulamprys tympanum. In this study, hormone levels for five steroid hormones will be measured in serum or yolk samples from male adults, female adults and developing embryos that have been exposed to different environmental temperatures. Because E. tympanum embryos develop in utero, they are exposed to both their individual yolk hormones, plus those of maternal circulation, this study will document plasma hormone levels in gravid females as well. Because skinks are the only viviparous TSD species known to date, this project will provide valuable insights into the evolution of temperature-dependent sex determination and its mechanisms. Undergraduate students at the University of Minnesota Crookston campus will be involved in this work receiving training in hormone isolation and characterization and also interacting with an international collaborator on the project.