Figure 1.

Loss of DER signaling generates cell fate transformations in the wing disk. (A) DNRaf (UAS-DNRaf^3.1 expressed ectopically under the control of en-Gal4 throughout the posterior wing compartment (raised at 25°C). (Inset) The posterior to anterior transformation of the wing margin. Similar results were obtained after ectopic expression of UAS-DNRas (a dominant-negative form of Ras1). (B), DER^tsla/DER^co flies raised at 17°C, transferred to 25°C for 24 h at second instar larval stages, and then returned to 17°C (see Materials and Methods). Wing mirror-image duplication. (C and D) Overexpression of DNRaf^3.1 in clones generated by the flip-out technique and induced at 36 ± 12 h after egg laying (see Materials and Methods). (C) Wing mirror-image duplication. (D) Notum to wing transformation. (E) En (UAS-En) expressed ectopically under the control of en-Gal4 throughout the posterior wing compartment interferes with en autoregulation (17). Posterior to anterior transformations of distal (wing) and proximal (notum) structures (arrowheads). Also see ref. 8. (F) Early induced clones of Wg overexpression (36 ± 12 h after egg laying). Notum to wing transformation (arrowhead). No posterior to anterior cell fate changes are induced. Also see ref. 3. (G) cnk mutant showing a wing-mirror-image duplication (arrowheads). (H) Distribution of Wg expression and MAPK activity in early third instar wing discs. MAPK activity, detected with an anti-dpERK antibody (green), is excluded from the wing pouch (arrowhead) and complementary to Wg expression (red).