| Description |
A cell's morphology plays an important role in its function. Thus, the size, shape, and structure of cells can be strikingly different across biology. In order to create this variation, cells must divide and differentiate in specific and regulated ways. In this dissertation, I describe work using C. elegans sperm to understand the programs controlling development of specialized cells. During development, sperm undergo meiotic division and differentiation to become polarized, motile, and capable of fusing with oocytes. From studying these processes, I identified two genes that are important both for sperm development and in contexts beyond reproductive biology. The first chapters of this dissertation describe a new function for the conserved t-SNARE syntaxin 7 (syx-7) in cytokinesis, the process that separates cells from one another following nuclear division. Without syx-7, sperm complete most steps of division, but the final abscission fails. During cytokinesis in animal cells, an actin ring forms between newly partitioning cells. However, it is not currently understood how vesicle traffic is spatiotemporally coupled to actin during cytokinesis. As syx-7 sperm progress through division, actin becomes mislocalized, providing one of the first examples of a specific component of vesicle trafficking machinery with an impact on actin localization during cytokinesis. Additionally, a specialized lysosome-like organelle is disrupted in syx-7 sperm, raising interesting questions about the link between this family of organelles and cell division. If a functional contribution is established, this would represent a new role for lysosome-like organelles, which, when disrupted, cause several human disorders. The later chapters of this work focus on the final steps of sperm differentiation: cell polarization and acquisition of motility. Our lab identified a signaling pathway that induces sperm motility in response to an extracellular protease. Here, I describe discovery of snf-10, a Solute Carrier 6 (SLC6) family gene, which provides the first link connecting the protease signal to changes in sperm physiology, and ultimately motility. Positive regulation by a protease is a novel finding for a member of the SLC6 family, a group of genes that have numerous roles in human physiology, but have been studied in limited contexts. |
