Genes required for the oocyte-to-embryo transition in C. elegans

The reproduction of a genetically distinct organism is a delicate process, and requires, in most organisms, the faithful reproduction of a male and female gamete, which must then find one another and fuse, and then undergo the transition to developing embryo. This thesis is an examination of the molecules required for fertilization in C. elegans, emphasizing the molecules involved in the oocyte-to-embryo transition. The first chapter provides an introduction to the importance of fertility research, the general processes of fertilization with an emphasis on mammalian reproduction, the utility of C. elegans as a model organism for studying fertilization, and the basics of reproduction in C. elegans. The second chapter discusses the general processes of the oocyte-to-embryo transition in C. elegans, then outlines a module of molecules, which are known to act during this process. Particular focus is given to the elucidation of the egg-4/5 genes, which are required for coupling the oocyte-to-embryo transition to the advancement of the cell cycle. The EGG-4/5 proteins represent a new class of molecules identified as protein-tyrosine phosphatase-like, and participate in a novel method of kinase regulation. The third chapter introduces the importance of the cortical granule exocytosis during the oocyte-to-embryo transition, and later to embryogenesis. A potential new member of the cortical granules is described, egg-6, a C. elegans gene which had been identified in previous works as being necessary to osmotic integrity. Early molecular work may link the egg-6 gene to the establishment of polarity in the embryo. The fourth chapter outlines the phenotypic and partial molecular characterization of a gene required for spermiogenesis, spe-43. The process of spermiogenesis in C. elegans is not only critical to fertility, but represents a model both for differentiation without de novo protein synthesis, and for the evolutionary development of an androdioecious species from a gonochoristic one. The fifth chapter provides summary discussion the molecules discussed, and their roles in reproduction, with a particular focus on the oocyte-to-embryo transition.Ph.D.Includes bibliographical referencesIncludes vitaby Jean Michele Parr