Figure 1. Screen for tissue competency to support eye development.

(A) Schematic depiction of a GAL4 screen wherein 219-GAL4 driver lines were crossed to 8 single and 15 double responder lines for a total of 5037 genetic combinations. (B) A schematic representation of the retinal determination network containing only members that were expressed individually or in combination in this screen. Not show are the eyegone and twin of eyegone genes, which were also used in this study and that function to promote proliferation in the retina. (C) Example of an adult fly exhibiting ectopic eyes on the wings and halteres. (D) Visualization of GFP in the pGawB71B expression domain within the wing, which serves as an example of a broad expression pattern yielding an ectopic in a subset of cells. (E) Ectopic eye formation is observed by expression of ELAV, a pan-neuronal marker; note that region occupied by photoreceptors is less than that occupied by GFP.