Fig. 3. Ubx governs Dpp spread. (A,B) Wing (A) and haltere (B) imaginal discs of tub-Gal80^ts/ptc-Gal4; UAS-Dpp-GFP bx³/MKRS larvae, showing a more restricted spread of Dpp-GFP in the haltere disc. In tub-Gal80^ts/ptc-Gal4; UAS-Dpp-GFP bx³/TM2 haltere discs (C) the Dpp-GFP expression and spread in the A compartment are similar to those of the wing disc, but spread in the P compartment is much reduced compared with that of the wing disc. (D) A plot representing the average value of the intensity of the Dpp-GFP dots along the A/P axis in tub-Gal80^ts/ptc-Gal4; UAS-Dpp-GFP bx³/MKRS wing and haltere discs and in tub-Gal80^ts/ptc-Gal4; UAS-Dpp-GFP bx³/TM2 haltere discs. Note the reduction in extent and the abrupt fall of the Dpp-GFP signal when Ubx is present. Numbers in the x-axis indicate distance in microns from the A/P boundary (0 value). The anterior compartment is to the left. w, wing disc: h, haltere disc.