Ectopic eye development in Drosophila induced by directed dachshund expression.

The dachshund gene encodes a nuclear protein that is required for normal eye development in Drosophila. In the absence of dachshund function, flies develop with severely reduced or no eyes. We show that targeted expression of dachshund is sufficient to direct ectopic retinal development in a variety of tissues, including the adult head, thorax and legs. This result is similar to that observed with the highly conserved Drosophila gene eyeless, which can induce ectopic eye formation on all major appendages. Here, we show that dachshund and eyeless induce the expression of each other and that dachshund is required for ectopic retinal development driven by eyeless misexpression. These results suggest that the control of eye development requires the complex interaction of multiple genes, even at the very highest regulatory levels.