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是由卵孵化温度控制的，这种现象被称为温度相关性别决定(TSD)。在某些种类的胎生石龙子中发现TSD可能是近年来TSD领域最令人惊讶和有趣的发展，值得在《自然》杂志上发表一篇文章(Robert和Thompson，2001)。尽管TSD的潜在机制仍不清楚，负责将环境温度线索转换为分子信号的过程也尚不清楚，但雌二醇(E2)已与性别决定过程有关。这项研究将检测胎生的TSD石龙鱼的激素特性。在这项研究中，将测量血清或卵黄样本中五种类固醇激素的水平，这些样本来自成年男性、成年女性和处于不同环境温度下的发育中的胚胎。由于鼓室棘球绦虫胚胎在子宫内发育，它们同时暴露在各自的卵黄激素以及母体血液循环中，这项研究也将记录怀孕女性的血浆激素水平。由于石龙子是迄今为止已知的唯一胎生的TSD物种，该项目将为温度相关性别决定的进化及其机制提供有价值的见解。明尼苏达大学克鲁克斯顿分校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.