Fig. 2. tkv -independent Dpp signaling differences in the wing and haltere. (A) Wing and haltere discs in which tkv is uniformly expressed from the Actin 5C promoter (act>tkv). In the wing, the P-Mad gradient is compacted to a single stripe, similar to the pattern found in the wild-type haltere (Crickmore and Mann, 2006). (B) Intensity traces for P-Mad in the wing (blue) and haltere (red) shown in A. In the act>tkv wing, the P-Mad signal is symmetric along the AP axis relative to the AP organizer, which is approximated by peak P-Mad levels. In the act>tkv haltere, the P-Mad signal decays more gradually in the A compartment (blue arrow) than in the P compartment. The approximate position of the AP boundary is indicated by the arrow. (C,D) Enlargements of the wing and haltere discs shown in A. W, wing; H, haltere; A, anterior compartment; P, posterior compartment.