Browsing by Subject "Ovulation."
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Item Identification of germline and somatic cell specific genes essential for ovulation in Caenorhabditis elegans.(2011-05-12T15:49:31Z) Rongali, Sharath C.; Lee, Myeongwoo.; Biology.; Baylor University. Dept. of Biology.The process of ovulation is an integral part of sexual reproduction in Caenorhabditis elegans. Various genes and signaling pathways are responsible for the successful process of ovulation to occur. Identification of these key mechanisms will help us gain knowledge into the mechanisms underlying the process of ovulation. C. elegans, a free living soil nematode, was used to identify and study the genes that are essential for ovulation. To facilitate this study we have used RNA interference (RNAi), a reverse genetics process, to restrict the function of the genes. RNAi causes degradation of the target gene by introduction of a double stranded RNA which has sequence specificity to the gene of interest. I have analyzed data pertaining to sterile (Ste) phenotype from the previous genome-wide RNAi screens. This search yielded 259 genes which caused Ste phenotype in the wild type background. In this screen, we analyzed 259 genes by RNAi in the wild type and various RNAi resistant mutant backgrounds. A detailed study of the gonad morphology was done to analyze the effect of the depletion of each gene on ovulation. Based on the ability of the mutants to suppress sterility, the genes were categorized as germline or somatic cell specific. In order to study the morphological changes related to gonad arm, we have conducted nomarski microscopy and nuclear staining techniques. Based on our study, 20 genes were categorized as germline specific for ovulation and 9 genes somatic cell specific. Genes that have been identified as germline specific belong to functional classes which code for protein synthesis, gene expression regulation, protein transport and modification, protein degradation, ATP synthesis and RNA specific functional classes. The somatic cell specific genes mainly constitute cell architecture, signaling and other functional groups.Item Roles of focal adhesion, phosphoinositide lipids and cytoskeleton in Caenorhabditis elegans ovulation.(2007-02-19T16:52:33Z) Xu, Xiaojian.; Lee, Myeongwoo.; Biology.; Baylor University. Dept. of Biology.Ovulation provides us with a robust in vivo model to study how the gonad contracts and releases eggs. By dissecting different molecules and signaling pathways in the process of gonad contraction, I have gained insights on how focal adhesion, phosphoinositide lipids, and cytoskeleton coordinate ovulation, a rhythmic behavior of C. elegans. Integrin plays an essential role in ovulation via the phosphoinositide signaling pathway. My studies have determined that ovulation defects caused by RNAi of pat-3/ [beta] integrin or ECM molecules is suppressed by increased IP3 signaling, demonstrating that cell-ECM interaction is essential for ovulation, which is mediated via IP3 signaling. Additional studies have demonstrated that loss of other focal adhesion molecules, pat-4/ILK and unc-112/Mig-2 causes defects in gonad sheath contraction and spermatheca dilation and disrupts gonad cytoskeleton. I have also identified one more IP3 signaling gene involved in C. elegans ovulation, which is phosphatidylinositol-4-phosphate 5' kinase (ppk-1/PIP5K). ppk-1 is mainly expressed in the somatic gonad. Depletion of PPK-1 results in sterility and impairs gonad sheath contractility. Further analysis reveals that ppk-1 RNAi induced sterility can be suppressed by increased IP3 signaling and that ppk-1 is also linked to unc-54/myosin B, demonstrating that ppk-1 plays an important role in IP3 signaling and organizes cytoskeleton in somatic gonad. Taken together, these studies enable me to conclude that ovulation is a rhythmic cellular behavior that requires coordination of signaling paths: focal adhesion, phosphoinositide lipids and cytoskeleton proteins to induce timely release of a matured egg from the ovary to the spermatheca for fertilization.