Meeting Abstract

S3.1-2  Saturday, Jan. 4 08:30  Mechanisms of egg chamber elongation in Drosophila HORNE-BADOVINAC, Sally; The University of Chicago shorne@uchicago.edu

During development, discrete organs and entire body plans emerge from the coordinate actions of individual cells. These complex morphogenetic events require dynamic regulation of cell shape, polarity, and adhesion across cell populations. My lab seeks to understand how these diverse cellular behaviors are orchestrated to produce an organ’s functional shape. To this end, we are using the Drosophila egg chamber as a highly tractable system to investigate the cellular control of morphogenesis. Egg chambers are multicellular structures within fly ovaries that will each give rise to a single egg. They are composed of an inner germ cell cluster surrounded by an outer epithelial layer of follicle cells. The follicle cells secrete a basement membrane ECM that forms the egg chamber’s outer most layer. Though initially spherical, egg chambers lengthen as they develop. This morphogenesis depends on an unusual form of planar polarity, in which linear actin bundles at the basal follicle cell surfaces become aligned orthogonal to the elongation axis. Once oriented, the follicle cells undergo a directed migration along the inner basement membrane surface, a process that causes the entire egg chamber to rotate inside the stationary matrix. Importantly, the migrating follicle cells also secrete new basement proteins. Through a process that is still poorly understood, the combination of cell movement and matrix secretion creates fibril-like structures in the BM, perpendicular to the elongation axis. It has been proposed that this fibrillar matrix then constrains isometric egg chamber growth to promote axial elongation. In this talk, I will explore the relationship between follicle cell planar polarity, the fibrillar basement membrane and collective cell migration.