Understanding the role of a sperm-oocyte protein complex (SPE-11-OOPS-1) in C. elegans egg activation
Date
2025
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
The cornerstone of sexual reproduction is fertilization, in which a sperm and an oocyte fuse to form a zygote. Although both the sperm and oocyte are products of meiosis and contain a haploid genome, they are highly differentiated and specialized to fulfill their unique roles. Comparing the two gametes, the oocyte is much larger and contains most of the stockpiled materials required for the early embryonic development of the zygote. Conversely, the male gamete is streamlined for the singular purpose of locating and fertilizing the oocyte therefore it is consequently small and compact. The traditional view of the sperm’s contribution towards embryogenesis is limited to the haploid genome and a pair of centrioles. However, work in several model organisms has shown that the sperm also contributes other factors that are required for proper embryogenesis. Mutants lacking these factors are known as paternal-effect embryonic lethal (PEL). In C. elegans, the only known strictly PEL gene is spe-11. Oocytes fertilized by sperm lacking SPE-11 show severe defects during the early stages of embryogenesis resulting in embryonic lethality, whereas spe-11 mutant oocytes fertilized by wild-type sperm are completely viable. Recently, we identified OOPS-1, an oocyte partner of SPE-11. OOPS-1 is a protein expressed throughout the maternal germ line, and it is a maternal-effect embryonic lethal gene. ☐ In this dissertation, I explore the connection between SPE-11 and OOPS-1. I found that they are essential proteins, as mutants of both spe-11 and oops-1 produce non-viable progeny that fail at an early stage of development. Mutants of spe-11 and oops-1 display identical defects across a number of egg activation phenotypes, including eggshell formation and meiotic arrest. From this, I explore the function of the SPE-11 and OOPS-1 complex, and their role in C. elegans egg activation, eggshell formation and the oocyte-to-embryo transition. Alongside this, I also briefly explored another SPE-11 associated protein, SPSP-1 and investigated the role of EGG-1 and EGG-2, a pair of oocyte plasma membrane proteins in which their function remains unclear due to prior technical limitations. Apart from the main focus of my graduate research with the SPE-11-OOPS-1 complex, I will also be presenting my work on understanding the role of TDPT-1, a C. elegans homolog of human tyrosyl DNA phosphodiesterase 2, and its role in suppressing the topoisomerase II mutant-mediated segregation defects.
Description
Keywords
Plasma membrane, Embryonic lethality, Lethal gene, Oocytes, Sperm