Figure 4.

Ectopic induction of Distal-less in eyeless² mutant eye-antennal discs by the activation of Notch signaling driven by ey-GAL4. (a) Bright-field micrograph of an eye-antennal disc of UAS-N^act ey-GAL4 ey²larva. Note the hyperplasia of the eye disc. (b) Immunostaining of same disc as in a with antibody against DLL. Ectopic DLL expression is induced in the eye disc (arrowhead). Arrow indicates original DLL expression in the antennal disc. (c) Bright-field micrograph of an eye-antennal disc of a ey² larva. The eye disc is reduced. (d) Immunostaining of the same disc as in c with antibody against DLL. DLL expression is confined to the antennal disc. (e) Bright-field micrograph of an eye-antennal disc of a UAS-N^act ey-GAL4 larva. (f) Immunostaining of the same disc as in e with antibody against DLL. Ectopic DLL expression is induced in a few cells of the antennal disc (arrowhead). Arrow indicates original DLL expression in the antennal disc. (g) Wild-type expression of DLL in eye-antennal disc. (h) Wild-type expression of EY in eye-antennal disc. (i) Immunostaining of same disc as in k with an antibody against DLL. Arrowhead indicates the repression of DLL in the region of ectopic EY expression. (k) Immunostaining of an eye-antennal disc of UAS-ey dpp-GAL4 larva with antibody against EY. Arrowhead indicates the ectopic expression of EY in the antennal disc. Posterior is to the left and dorsal is up. (Bars = 50 μm.)