Evolution of Abalone Egg Coat Proteins

描述(申请人提供)：这项建议旨在加深我们对精子和卵子蛋白之间的相互作用，以及推动生殖蛋白进化的进化力量的理解。这项工作采用了鲍鱼系统，该系统提供了研究最广泛的精子-卵子相互作用系统之一，并且适合于在其他分类群中难以进行的生化和实验研究。提出了两个特定的目标：(1)鉴定和鉴定鲍鱼精子蛋白SP18的卵细胞质膜结合受体；(2)鉴定已鉴定的候选SP18受体(ZPD)在鲍鱼物种内和物种之间的多态和差异，并测试与SP18的共同进化。特异性目标1利用生物化学方法(免疫沉淀和亲和层析柱)和质谱仪从与SP18高度特异性结合的鸡蛋分离成分中鉴定蛋白质。这项工作将测试SP18和鸡蛋分子之间直接功能相互作用的证据。特殊目的2检查在卵壳蛋白基因组筛查中确定的候选SP18受体基因座(ZPD)的多态性，以及该基因座在加州鲍鱼物种之间的差异。ZPD的多态模式和序列差异将被测试，以寻找正选择以及与SP18共同进化的证据。因为这些信号是为SP18受体预测的，所以它们提供了一种独立和平行的方法来区分候选鸡蛋受体(包括ZPD和任何其他可能在特定目标1下识别的受体)。总而言之，这些研究目标代表着我们在理解精子和卵子之间的分子相互作用方面取得的重大进展，并有助于更广泛地理解包括人类生殖在内的生殖生物学。 在人类生殖研究中，精子和卵子分子在受精过程中的相互作用已被证明是难以捉摸的。这项研究中使用的模式生物(鲍鱼，一种海洋腹足动物)与脊椎动物(包括人类和其他哺乳动物)有着共同的分子基础，表现出精子和卵子蛋白快速分化的共同模式，并允许采用其他动物不可能的实验方法。因此，拟议的工作涉及生殖生物学的一般主题，并可能阐明与人类生殖相关的精子和卵子相互作用的分子基础。

DESCRIPTION (provided by applicant): This proposal is aimed at furthering our understanding of the interactions between sperm and egg proteins, and the evolutionary forces driving reproductive protein evolution. The work employs the abalone system, which provides one of the most extensively studied sperm-egg interaction systems and which is amenable to biochemical and experimental studies difficult in other taxa. Two specific aims are proposed: (1) identify and characterize the egg plasma-membrane bound receptor of the abalone sperm protein sp18; and (2) characterize polymorphism and divergence of a candidate sp18 receptor already identified (ZPD) within and among abalone species, and test for co-evolution with sp18. Specific Aim 1 utilizes biochemical approaches (immunoprecipitation and affinity columns) and mass spectrometry to identify proteins from fractionated egg components which bind with high specificity to sp18. This work will test for evidence of direct functional interactions between sp18 and egg molecules. Specific Aim 2 examines polymorphism at a candidate sp18 receptor locus (ZPD) identified in genomic screens for egg coat proteins, as well as divergence at this locus among California abalone species. Patterns of polymorphism and sequence divergence for ZPD will be tested for evidence of positive selection as well as coevolution with sp18. Because these signatures are predicted for the sp18 receptor, they provide an independent and parallel means of distinguishing among candidate egg receptors (including ZPD and any others which may be identified under Specific Aim 1). Together these research aims represent a significant advancement in our understanding of the molecular interactions between sperm and egg, and contribute to a broader understanding of reproductive biology including human reproduction. The interactions between sperm and egg molecules during fertilization have proven elusive in studies of human reproduction. The model organism used in this study (abalone, a marine gastropod) shares a common molecular basis with vertebrates (including humans and other mammals), exhibits a common pattern of rapid divergence of sperm and egg proteins, and allows for experimental approaches not possible in other animals. Thus the proposed work addresses general themes in reproductive biology, and may shed light on the molecular basis of sperm and egg interactions of relevance to human reproduction.