Fig. 6. Effect of the Abd-A and Abd-B proteins on Ubx permanent repression in the haltere disc. (A) Haltere disc of a MS372-Gal4/UAS-abd-A larva. Ubx is repressed in a large area of the disc. (B) Ubx-Gal4^SS.2/UAS-abd-A adults, showing a strong transformation of the haltere into wing. (C) In UAS-Abd-B/+; MS372-Gal4/+ flies, there is barely an increase in haltere size and only the occasional appearance of some bristles or a small amount of wing tissue. (D-G) An ap-Gal4 UAS-GFP/UAS-Abd-B; tub-Gal80^ts/+ haltere disc, grown for 3 days at 29°C. GFP (green, D) and Abd-B (red, E) are expressed in the dorsal compartment, whereas Ubx (greyscale, F) is repressed. Merged image in G. (H) In ap-Gal4 UAS-GFP/UAS-Abd-B; tub-Gal80^ts/+ haltere discs from larvae that were grown at 17°C after 3 days at 29°C, the repression of Ubx is only occasionally maintained. (I) In most UAS-Ubx^HX/+; UbxGal4^SS.2/+ adults, there are transformations of haltere into wing (arrowhead). (K) By contrast, in UbxGal4^SS.2/UAS-Ubx^UbdA flies, the halteres are abnormal but they are not transformed into wings. These transformations correlate with Ubx expression in discs that went through the standard treatment. (J,L) In ap-Gal4 UAS-GFP/+; tub-Gal80^ts/UAS-Ubx^HX haltere discs (J), there is repression of Ubx in the dorsal compartment but such repression is never observed in ap-Gal4 UAS-GFP/+; tub-Gal80^ts/UAS-Ubx^UbdA haltere discs (L) under the same experimental conditions. (M) In ap-Gal4 UAS-GFP/UAS-Ubx^UbdA; Ubx^lac1/+ haltere discs, grown at 29°C for 5 days, there is strong repression of the lacZ gene in most dorsal cells. d, dorsal compartment. Magnification in I and K is the same, but different from that in B and C. Discs are oriented with the anterior compartment towards the left and the ventral compartment upwards.