Date Available


Year of Publication


Document Type



Arts and Sciences



First Advisor

Douglas Harrison

Second Advisor

John Rawls


The Janus kinase (JAK) pathway is an integral part of signaling through a variety of ligands and receptors in mammals. The extensive reutilization and pleiotropy of this pathway in vertebrate development is conserved in other animals as well. In Drosophila melanogaster, JAK signaling is involved in embryonic pattern formation, sex determination, larval blood cell development, wing venation, planar polarity in the eye, and formation of other adult structures. Here we describe several roles for JAK signaling in Drosophila oogenesis. The gene for a JAK pathway ligand, unpaired, is expressed specifically in the polar follicle cells, two pairs of somatic cells at the anterior and posterior poles of the developing egg chamber. A primary defect of chambers with reduced JAK activity is fusion of successive chambers. These chambers exhibit an expansion of the polar cell population and concomitant loss of interfollicular stalk cells. Mosaic analysis of both JAK pathway transducers, hopscotch and stat92E, reveals that JAK signaling is specifically required in the somatic follicle cells. Another role of JAK signaling is in oocyte localization. In chambers mosaic for loss of hop activity, oocyte mislocalization results. Proper localization occurs only when the posterior follicle cells are wild type for hop.