CHARACTERIZING THE ROLES OF SEC24CD IN OOCYTE DETERMINATION AND POLARITY IN DROSOPHILA MELANOGASTER

Abstract

The establishment of anterior-posterior polarity in early oogenesis is essential for the process of oocyte fate determination and is sustained by intracellular trafficking and contact with neighboring nurse cells. Yet, the processes of oocyte fate specification and maintenance in Drosophila melanogaster are currently not well understood. The JV91 mutant line was isolated in an ethyl methanesulfonate (EMS) screen and shown to exhibit a missing oocyte and ring canal clustering phenotype. It was later found to be an allele of Sec24CD, which encodes for a protein involved in COPII-mediated vesicle transport. Using Drosophila oogenesis as a model system, we investigate the role of Sec24CD in oogenesis and the mechanisms underlying oocyte polarity. In this study, we present the spatial and temporal localization of Sec24CD in germline cells, showing that Sec24CD accumulates at the posterior pole of the oocyte in early and mid-stage egg chambers. Furthermore, we discovered that Sec24CD co-localizes with the oocyte-specific factors Orb and Bic-D at the posterior of the oocyte. In analyzing microtubule-disrupted egg chambers, we found that the polarized localization of Sec24CD in the oocyte is lost along with Bic-D, providing strong evidence that Sec24CD localization is microtubule-dependent. Although further work is necessary to fully elucidate the role of Sec24CD in these processes, these findings provide considerable insight into the mechanism of oocyte determination in Drosophila, highlighting new roles for the COPII complex in this process.