Title of project

Characterization of microRNA regulation of ovulation in C. elegans

Faculty Advisor

Allison Abbott (Marquette University) Lynne Gildensoph (St. Catherine University)



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Characterization of microRNA regulation of ovulation in C. elegans

microRNAs are essential regulators of animal development and physiology. They are small, non coding ~22 nucleotide RNAs that function post-transcriptionally to regulate gene expression. Mutations in the microRNA biogenesis pathway result in lethality in worms, flies, fish and mice. One process in worms that requires microRNAs is the process of ovulation. Although microRNAs are required for ovulation, the steps that require microRNAs remain unexplored. Using a conditional allele of the gene, pash-1, which is required for microRNA biogenesis, we are able to study the effects of reduced microRNA activity on the process of ovulation. Worms with the mj100 temperature sensitive pash-1allele are unable to ovulate at the restrictive temperature of 25°C at which few, if any, mature microRNAs are generated. In this study, I examined ovulation in worms grown at the permissive temperature of 15°C and an intermediate temperatures of 17.5°C. pash-1 (ts) mutants have a reduced number of progeny as well as a reduced oocyte maturation rate. Using video microscopy, we find spermatheca entry defects in which part of the proximal oocyte gets pinched off as it enters the spermatheca. These data indicate that the process of ovulation is sensitive to reduced microRNAs. Specifically, spermatheca valve dilation and gonadal sheath contractions require microRNA activity. Future work will include performing calcium imaging to determine if pash-1(ts) worms have defects in calcium signaling during ovulation.