Date of Award
Summer 2020
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biological Sciences
First Advisor
Abbott, Allison L.
Second Advisor
Petrella, Lisa
Third Advisor
Yang, Pinfen
Abstract
While numerous individual miRNAs have been detected in the germline, the functions of most other specific miRNAs remain largely unknown. Functions of miRNAs have been difficult to determine as miRNAs often modestly repress target mRNAs and are suggested to sculpt or fine tune gene expression to allow for the robust expression of cell fates. Analysis of newly generated mir-44 family mutants has identified a group of miRNAs that modulate the pathway of germline sex determination in C. elegans. Mutants produce fewer sperm and display an earlier switch to producing oocytes. In the germline, cell fate decisions are made for germline sex determination during C. elegans hermaphrodite larval development when sperm are generated in a short window before the switch to oocyte production. To understand the genetic relationship between mir-44/45 and the genes that regulate the switch from producing sperm to oocytes, I examined several components of this pathway. The results suggest that mir-44/45 regulates proper fog-1 expression through fbf-1 and fem-3 to promote sperm specification. Our research indicates that the mir-44 family promotes sperm cell fate decision at the time of the developmental switch from spermatogenesis to oogenesis. In addition to the function of the mir-44 family in hermaphrodite sex determination, I have also identified a function of mir-44/45 in regulating the process of spermiogenesis and sperm transfer in males. Mutant male sperm frequently fail to activate and during mating mir-44/45 sperm often do not transfer following interaction with hermaphrodites. The combination of these results in males and hermaphrodites indicate that the mir-44 family of microRNAs functions to regulate multiple processes in C. elegans development and germline function.