Rotation of photoreceptor clusters in the developing drosophila eye requires the nemo gene
The Drosophila eye consists of a reiterative hexagonal array of photoreceptor cell clusters, the ommatidia. During normal morphogenesis, the clusters in the dorsal or ventral halves of the disc rotate 90° in opposite directions, forming mirror images across a dorsoventral equator. In the mutant nemo (nmo), there is an initial turning of approximately 45°, but further rotation is blocked. Genetic mosaic analysis indicates that the nmo gene acts upon each cluster as a whole; normal nmo function in one or more photoreceptor cells appears to be sufficient to induce full rotation. The nmo gene sequence encodes a serine/threonine protein kinase homolog, suggesting that the kinase is required to initiate the second step of rotation. In another mutant, roulette, excessive rotation through varying angles occurs in many ommatidia. This defect is suppressed by nmo, indicating that nmo acts upstream in a rotation-regulating pathway.
© 1994 Cell Press. Received 20 October 1993, Revised 26 May 1994. Address correspondence lo S. B. We thank Rosalind Young and Lynette Dowling for expert technical assistance, and our colleagues for suggestions on the manuscript. We thank William Leiserson for the r/t mutant, Gary Hime and Robert Saint for pbl deficiency stocks, John Tamkun for the cosmid library, and Kalpana White for anti-elav antibody. We are indebted to an anonymous reviewer for the suggestion to use the P[w^+]33 strain for mosaic analysis and to Todd Laverty of Gerald Rubin's laboratory for furnishing the strain. This research was supported by a postdoctoral fellowship (to K.-W. C.) from the Drown Foundation and grants (to S. B.) from the National Science Foundation (BCS-8908154), the National Eye Institute of the National Institutes of Health (EY09278), and the James G. Boswell Foundation.