PhD Transfer Exam – Morley Willoughby (Bruce lab)

PhD Transfer Exam

Wednesday May 24^th, 10:10 am – Ramsay Wright Building, Rm. 432

Morley Willoughby (Bruce lab)

“Investigating the Role of the Small GTPase Rab25 during Zebrafish Epiboly”

Abstract

The adult body plan of an organism is established during a process called gastrulation. Despite the diversity of organisms across the animal kingdom, gastrulation occurs through a limited number of dynamic, large scale cellular movements. Epiboly is a conserved morphogenetic movement that is defined as the thinning and expansion of a cellular sheet. Understanding the molecular mechanisms that control this process is critical to our understanding of developmental biology. The small GTPase Rab25 becomes upregulated at the onset of zebrafish epiboly.  Rab25 is a member of the Rab11 subfamily of GTPases, and is known to direct apical vesicle trafficking and transcytosis in polarized epithelial cells. Rab25 morpholino knockdown or knockout using CRISPR/Cas9 gene editing technology results in an epiboly delay during zebrafish morphogenesis. Remarkably, while rab25 expression becomes restricted to the enveloping epithelial layer (EVL), a single cell thick epithelium during epiboly, the underlying loosely packed deep cells exhibit a larger epiboly delay. I hypothesize that the small GTPase Rab25 functions in the EVL during zebrafish epiboly. I propose to use the CRISPR/Cas9 Gene Editing technology to create an endogenous Rab25 fusion protein in the zebrafish genome to examine the intracellular localization of Rab25 in live embryos. I will then characterize defects within the EVL of Rab25 mutant embryos to understand how aberrant vesicle trafficking is leading to the observed epiboly delay. It is anticipated that my project will help uncover the relatively unknown molecular mechanisms controlling epiboly.

Ramsay Wright is a wheelchair accessible building.