Cellular Determinants of Granulosa Cell Differentiation in Avian Ovarian Follicles

在每个排卵周期排卵数量有限的雌性脊椎动物(如哺乳动物、鸟类、一些爬行动物)中，卵巢卵泡的选择过程代表着通往繁殖力的限速步骤。卵泡选择是指在排卵前选择性地招募一个(或多个)未分化卵泡(S)进入成熟的最后阶段，但目前在脊椎动物中这一过程的潜在机制尚不清楚。最终，选择机制决定了在任何给定的生殖周期内可以产生的后代的最大数量。目前的研究将检验这一假设，即未分化的卵泡不能自发地进行卵泡选择通常是由于卵泡颗粒细胞层分化所需的一个或多个基因(如卵泡刺激素受体；FSHR)的主动抑制所致。重要的是，颗粒细胞层在整个卵泡发育过程中滋养着卵母细胞。需要检验的第二个假设是，在卵泡选择时，FSHR基因表达的负调控转换为表达上调。这一事件被广泛认为是卵泡成熟到排卵前阶段的先决条件。实验设计结合了细胞和分子技术，旨在识别基因组机制，通过这些机制，对鸡的选择过程至关重要的基因的表达被抑制或增强。这些研究的结果预计将影响我们在濒危物种和家养食用动物中提高女性生育力的能力，并更好地了解女性不孕的选定原因。更广泛地说，拟议的研究将有助于为其职业目标包括教学和/或研究的本科生和研究生(包括那些来自代表性不足人群的学生)提供相关和前沿的培训。

In female vertebrate animals that ovulate a limited number of oocytes (eggs) per ovulation cycle (e.g., mammals, birds, some reptiles), it is the process of ovarian follicle selection that represents the rate-limiting step to fecundity. Follicle selection entails the selective recruitment of one (or more) undifferentiated follicle(s) into the final stages of maturation prior to ovulation, yet the underlying mechanisms of this process are currently undefined in any vertebrate species. Ultimately, the selection mechanism determines the maximum number of offspring that can be produced within any given reproductive cycle. The present studies will test the hypothesis that the inability of undifferentiated follicles to spontaneously undergo follicle selection is normally due to the active suppression of one or more genes (e.g., the Follicle Stimulating Hormone receptor; FSHR) that are required for the differentiation of the follicle's granulosa cell layer. Importantly, it is the granulosa cell layer that nurtures the oocyte throughout follicle development. A second hypothesis to be tested is that at the time of follicle selection there is a switch from a negative regulation of FSHR gene expression to an upregulation of expression. This event is widely assumed to be prerequisite for the maturation of ovarian follicles to the preovulatory stage. The experimental design incorporates cellular and molecular techniques directed at identifying genomic mechanisms by which the expression of genes critical to this selection process in chickens is repressed or enhanced. Results from these studies are predicted to impact our ability to enhance female fertility in endangered species and domesticated food animals, and to better understand select causes of infertility in women. More broadly, the proposed research will serve to provide relevant and cutting-edge training to undergraduate and graduate students (including those from underrepresented populations) whose career goals include teaching and/or research.