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First published online 16 August 2006
doi: 10.1242/dev.02524
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1 Department of Pathology, Department of Genetics and Development, College of
Physicians and Surgeons, Columbia University, 701 West 168th Street, Room
1120, New York, NY 10032, USA.
2 Center for Neurobiology and Behavior, Department of Genetics and Development,
College of Physicians and Surgeons, Columbia University, 701 West 168th
Street, Room 1120, New York, NY 10032, USA.
Author for correspondence (e-mail:
at41{at}columbia.edu)
Accepted 7 July 2006
The periphery of the fly eye contains a number of concentrically arranged cellular specializations that are induced by Wingless (Wg) signaling from the surrounding head capsule (HC). One of these is the pigment rim (PR), which is a thick layer of pigment cells that lies directly adjacent to the HC and completely circumscribes the rest of the retina. Many of the cells of the PR are derived from presumptive pigment cells that previously surrounded peripheral ommatidia that subsequently died. Here, we describe the Wgelicited expression of Snail family transcription factors in the eye periphery that directs the ommatidial death and subsequent PR formation. These transcription factors are expressed only in a subset of the ommatidial cells not including the photoreceptors. Yet, the photoreceptors die and, thus, a non-autonomous death signal is released from the Snail-family-expressing cells that direct the death of the photoreceptors. In addition, Wg also elicits a similar peripheral expression of Notum, an enzyme that limits the extent of Wg signaling. Furthermore, we describe a later requirement for Snail family proteins in the 2° and 3° pigment cells throughout the main body of the eye.
Key words: Wingless, Snail family transcription factors, Fly eye periphery
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