Fig. 7. The dpp pathway and Ubx regulate haltere size. (A) Thorax of a Drosophila wild-type adult, showing the different size of the wing (W) and the haltere (H). (B) A Ubx mutant clone in the haltere disc of a third instar larva showing that the size of the clone (absence of GFP expression, in green) and that of the twin spot (more stained due to the two doses of the Ubi-GFP construct) are similar. (C) Wild-type (left) and dpp-Gal4/UAS-dpp (right) haltere discs showing the bigger pouch of the latter. (D-F) The P compartments of en-Gal4 UAS-GFP/UAS-dally (E) and en-Gal4 UAS-GFP/UAS-mtv (F) haltere discs are enlarged with respect to en-Gal4 UAS-GFP controls (D). The three compartments are marked with GFP and delimited by arrows. (G-I) In dpp^d12/dpp^d5 adults the size of the distal part of the haltere (the capitellum, c) is reduced (H) compared with the wild type (G), and in dpp^d12/dpp^d5; TM2/+ flies (I) this reduction is alleviated. (J-L) Wings of wild-type (J), dpp-Gal4/UAS-Ubx (K) and dpp-gal4/UAS-tkv (L) adults, showing the reduction in size of the latter two. (M) Haltere of a Ubx^6.28/+ adult, showing a slightly bigger haltere than in wild-type flies (G) due to the haploinsufficient phenotype of the Ubx locus. (N) In Df tkv/+; Ubx^6.28/+ siblings the size of the haltere is increased. (O-R) In pbx/Ubx^6.28 (O) and ptc-Gal4/+; bx³/Ubx^6.28 (Q) haltere discs there is an increase in the size of the P and A compartments, respectively (delimited by arrows). These increments are reduced if tkv is expressed in the posterior (en-gal4/+; pbx/UAS-tkv Ubx^6.28 larvae; P) or anterior (ptc-Gal4/+; bx³/UAS-tkv Ubx^6.28 larvae; R) compartments. The P compartment is marked by anti-En antibody (in red in O), by GFP (in green in P), and by anti-Ubx (in red in Q and R). A summary of the results is shown in U. (S) A ptc-Gal4/+; Df109 UAS-dsRNA>Ubx/tub-Gal80^ts fly, showing a patch of haltere tissue (delimited by the discontinuous line in S') bigger than the anterior compartment of a wild-type haltere. Detail of the boxed region is shown in S'; w, wing territory; P, posterior compartment. (T) A capitellum of a ptc-Gal4/UAS-flp; FRT Ubx^6.28/FRT GFP adult with Ubx mutant clones (cells transformed into wing, w) showing more haltere tissue (h) than in the wild type (compare with G). (U) Histograms showing the P/A (left) or A/P (right) ratios of different genotypes. P/A ratios: wild type (wt), 0.34 (n=16), pbx/Ubx^6.28, 1 (n=14), en-gal4/+; pbx/UAS-tkv Ubx^6.28, 0.63 (n=11), en-Gal4/UAS-mtv, 0.53 (n=8), and en-gal4/UAS-dally, 0. 41 (n=13). A/P ratios: wt, 2.9 (n=16), ptc-Gal4/+; bx³/Ubx^6.28, 4.6 (n=14) and ptc-Gal4/+; bx³/UAS-tkv Ubx^6.28, 3,9 (n=12).