43rd ANNUAL DROSOPHILA RESEARCH CONFERENCE PROGRAM AND ABSTRACT VOLUME |
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9W The Drosophila visual system is derived from the eye field, an unpaired anlage located in the dorsomedial head of the early embryo. During later stages this anlage splits into a left and right visual primordium, each of which migrates laterally and differentiates into optic lobe, larval eye, and adult eye primordium. Previous results had uncovered the role of Dpp and Hh signaling in visual system development. Dpp, expressed in a dorso-ventral gradient, turns on regulatory genes that are required for eye/optic lobe fate, including sine oculis (so) and eyes absent (eya). The gene zerknuellt (zen), expressed in response to peak levels of Dpp in the dorsal midline, secondarily represses so and eya in the dorso-medial domain, which accounts for the split of the eye field. Hh triggers the expression of determinants for larval eye (atonal) and adult eye (eyeless). We here describe the role of EGFR in embryonic visual system development and discuss its interaction with Dpp. At an early stage, EGFR is required for the viability of the visual primordium. This role is evidenced best by expressing a dominant negative (dn) form of EGFR under the control of So-Gal4, a driver line we designed for expression of genes specifically in the eye field. So-Gal4 driven dnEGFR causes the complete absence of optic lobe and larval eye. At a later stage of embryogenesis, EGFR promotes inductive signaling among precursors of the larval eye and modulates morphogenesis in the optic lobe and larval eye. Loss of EGFR results in the failure of optic lobe cells to invaginate and to separate from the larval eye. We provide evidence that part of this latter effect of EGFR is due to its control of E-cadherin mediated cell adhesion. Wolbachia |