UNRAVELING THE MECHANISMS INVOLVED IN THE DROSOPHILA MELANOGASTER BAM HYPOMORPH FERTILITY RESCUE BY WOLBACHIA PIPIENTIS Catherine Herminia Kagemann, Ph.DCornell University 2023 Bag of marbles (Bam) is a protein known to play a role in germline stem cell (GSC) daughter cell differentiation and self-renewal in female Drosophila melanogaster. Bam interacts with a maternally inherited endosymbiont, Wolbachia pipientis. W. pipientis are known to infect ~40-75% of insects and manipulate the reproduction of their hosts. W. pipientis infection of female bam hypomorphs rescues the mutant fertility phenotype when otherwise the flies would be partially to completely sterile. We aimed to investigate the mechanisms through which W. pipientis rescues the fertility phenotype associated with the bam hypomorph. We determined that W. pipientis in the ovaries and outside of the ovaries correlates with increases in bam hypomorph fertility. Our RNA-seq analysis of the bam hypomorph showed that W. pipientis does not influence bam transcription but influences transcription of bam’s genetic and physical interactors. We functionally confirmed the involvement of candidate genes in the bam hypomorph fertility rescue by W. pipientis using genes identified from our RNA-seq analysis and literature. We identified that ubiquitin-associated genes, Ubi-p63E, CycA, otu, and the testis specific transcript, phf7 have novel interactions with W. pipientis and the knockdown of these genes in the bam hypomorph rescued the mutant fertility phenotype. Together, we find that W. pipientis likely modulates the D. melanogaster hosts ubiquitin processes and restores sexual identity to the female germline to rescue bam hypomorph fertility.