Fig. 6. Ubx repression of dally restricts the extent of Dpp activity in the haltere disc. (A) dally (dally-lacZ) expression in the wing disc, showing stronger signal in the dorsal-ventral and A/P boundaries (arrow) and in the lateral regions. (B) In the haltere disc, dally is not transcribed in AB cells and the signal in the dorsal-ventral boundary is restricted to the anterior compartment. There is also lower signal throughout the pouch. (C) An omb-gal4; Df109 UAS-dsRNA>Ubx/+ haltere disc, showing a dally pattern similar to that of the wing disc. The arrow marks the A/P stripe. (D,D') Ubx-expressing clones in the wing disc, marked by the GFP expression (D, in green), eliminate dally signal (D,D', in red; arrows). (E) The expression of dally under the control of the ap-Gal4 line extends the P-Mad signal in the dorsal domain (d, arrows), where the line drives expression; v, ventral region. (F) The ectopic expression of activated Tkv in the dorsal (d) domain of the wing pouch (MS1096-Gal4 driver) downregulates mtv transcription; v, ventral region. (G,H) In the dorsal haltere pouch of MS1096; UAS-tkv^DN/+ larvae, the expression of a dominant-negative form of Tkv does not activate mtv (G) or dally (H) expression at the A/P boundary.