Fig. 7. Recruitment of presumptive notal cells to the wing fate by ectopic Wg- and Vg-expressing cells. (A-B') Wild-type Drosophila discs containing Tub1>Gal4/UAS-vg UAS-wg clones located within the presumptive notum, probed for Vg (A, red), 5XQE-DsRed (B, red) and rn-lacZ (B', blue) expression and marked by Vg overexpression (A, bright red) or loss of GFP (B). Arrows indicate clones that have induced `ectopic' wing pouches; note that rn-lacZ expression (B') extends beyond that of 5XQE-DsRed (B), as in the normal pouch. (C-F) Discs that express UAS-vg in A compartment border cells under dpp-Gal4 control [red by ectopic 1XQE-lacZ (D) and Vg (E,F) expression] and contain P compartment clones of Tub1>Nrt-wg cells (indicated by the arrow in C; black by the absence of CD2, green. The arrowed clone in F is shown at higher magnification in E,E'. Cells within the clones that are located within 10-20 cell diameters of the A-P boundary ectopically express normal peak levels of 1XQE-lacZ (D) and endogenous Vg (E') and induce immediately adjacent cells across the clone border to do the same (appear yellow in overlap with CD2). (G-H') UAS>Nrt-wg (G,G') or UAS>arm^* (H,H') clones (marked green by Flu epitope staining of Nrt-Wg and Arm^*) located within the presumptive notum ectopically express normal peak levels of endogenous Vg (dull red) when they abut UAS>vg clones (bright red by Vg overexpression) and are located within 10-20 cell diameters of the A-P boundary. The UAS>Nrt-wg clones, but not the UAS>arm^* clones, also induce their immediate neighbors to do the same.