Fig. 4. Misexpression of omb or brk preferentially eliminates or displaces the L2 and L5 veins. (A) A wing from an MS1096-GAL4; UAS-omb fly is severely reduced in size and lacks posterior veins. (B) A wing from a C765-GAL4; UAS-brk fly displays a central shift of the L2 and L5 veins resulting in L2 approaching or fusing with L3 (i.e. 0-4 cells apart compared with 10-12 cells apart in wild type), and L5 approaching or fusing with L4 (i.e. 0-9 cells apart compared with 18-20 cells apart in wild type). By contrast, the space between the central L3 and L4 veins remained relatively unaltered (14-16 cells apart compared with 16-17 cells in wild type). All distance measurements between veins were made in the central region of the wing. (C) A third instar larval wing imaginal disc (anterior at the top) from a brk-lacZ; Vg^B-GAL4; UAS-GFP individual, grown at 22°C, stained for ß-Gal expression (red) and examined for GFP fluorescence (green). Note the posterior domain in which green Vg^B>GFP expression abuts the posterior edge of the brk expression domain (arrow), and note that expression of GFP continues along the margin. Stronger and wider GFP expression was observed in discs of the same genotype raised at 25°C (data not shown). (D) A wing from a Vg^B-GAL4; UAS-brk fly grown at 25°C displays a central shift of the L2 and L5 veins resulting in fusion of L2 with L3, and of L4 with L5. (E) A wing from a Vg^B-GAL4; UAS-omb fly grown at 22°C, which has a notched margin, truncated L5 vein (arrow) and a long ectopic vein posterior to L5 (arrowhead). Scale bars: 0.5 mm.