Two Pax genes, eye gone and eyeless, act cooperatively in promoting Drosophila eye development

We report the identification of a Drosophila Pax gene, eye gone ( eyg ), which is required for eye development. Loss-of-function eyg mutations cause reduction or absence of the eye. Similar to the Pax6 eyeless ( ey ) gene, ectopic expression of eyg induces extra eye formation, but at sites different from those induced by ey . Several lines of evidence suggest that eyg and ey act cooperatively: (1) eyg expression is not regulated by ey , nor does it regulate ey expression, (2) eyg -induced ectopic morphogenetic furrow formation does not require ey , nor does ey -induced ectopic eye production require eyg , (3) eyg and ey can partially substitute for the function of the other, and (4) coexpression of eyg and ey has a synergistic enhancement of ectopic eye formation. Our results also show that eyg has two major functions: to promote cell proliferation in the eye disc and to promote eye development through suppression of wg transcription.