CAA: Temperature Dependent Sex Determination in Reptiles: Differential Gene Expression

小行星9509017 发育中胚胎的性别是由胚胎发生过程中特定时间特定基因序列的表达决定的。 在哺乳动物、鸟类和一些爬行动物中，导致雄性或雌性的基因表达的起始信号是Y染色体（哺乳动物）或W染色体（鸟类，一些爬行动物）的存在。 然而，在其他爬行动物物种中，发育中的胚胎的性别是由妊娠关键时期的孵化温度决定的。 该提案将使用普通滑龟（Trachemys scripta），一种不濒危的物种，容易获得，并且是许多海龟物种的代表，因为较高的孵化温度（约32 ℃）导致雌性孵化，较低的孵化温度（约26 ℃）导致雄性孵化，以研究分子水平上的温度依赖性性别决定现象。 具体地说，卵将在实验室中在26 ℃或32 ℃下孵育，胚胎将在妊娠约2-3周时处死，这是性腺组织形成的关键时期。 将从性腺组织中分离RNA，并通过称为差异显示聚合酶链反应的技术分析在两种温度下表达的序列差异。 在26 ℃下表达而在32 ℃下不表达的RNA种类可能参与雄性发育途径。 相反，在32 ℃，但不是在26 ℃发现的RNA种类可能参与女性特定的发育过程。 这个为期一年的项目的目标是编制一个基因序列的“目录”，这些基因序列是进一步分析温度依赖性性别决定的关键因素的候选者。 了解这种生态现象不仅对濒危爬行动物物种的保护很重要，而且对了解性别决定机制一般如何发挥作用也很重要。 ***

9509017 Spotila The sex of a developing embryo is determined by the expression of specific gene sequences at defined times during embryogenesis. In mammals, birds and some reptiles the initiating signal for the expression of genes that lead to maleness or femaleness is the presence of the Y chromosome (mammals) or the W chromosome (birds, some reptiles). In other reptilian species, however, the sex of the developing embryo is determined by the incubation temperature during a critical time of gestation. This proposal will use the common slider turtle (Trachemys scripta) a species that is not endangered, is readily obtainable, and is representative of many turtle species in that a higher incubation temperature (about 32 C) results in female hatchlings and a lower incubation temperature (about 26 C) results in male hatchlings, to investigate the phenomenon of temperature-dependent sex determination at the molecular level. Specifically, eggs will be incubated in the laboratory at 26 C or 32 C and embryos will be sacrificed at about 2-3 weeks of gestation, the time period that is critical for formation of gonadal tissue. RNA will be isolated from gonadal tissue and analyzed for differences in the sequences expressed at the two temperatures by a technique called Differential Display Polymerase Chain Reaction. RNA species that are expressed at 26 C, but not at 32 C may be involved in the male developmental pathway. Conversely, RNA species found at 32 C, but not at 26 C may be involved in female-specific developmental processes. It is the goal of this one-year project to compile a "catalogue" of gene sequences that are candidates for further analysis as critical factors in temperature-dependent sex determination. Understanding of this ecological phenomenon is important not only for the conservation of endangered reptile species, but also for the insight that might be gained as to how sex-determining mechanisms function in general. ***