Fig. 3. Overexpression of pygo blocks several Wg readouts. (A-I) Confocal images of third instar wing imaginal discs containing random clones of cells overexpressing pygo. The clones were marked with GFP (A,D,G) and immunostained with antibodies against Wg (B), Sens (E) or Dll (H). Merged images are shown (C,F,I). Derepression of Wg (B,C) and lack of Sens (E,F; n=9) and Dll (H,I) expression were observed, consistent with a block in Wg signaling. The arrows in I indicate boundary regions that are clearly GFP positive (and thus expressing pygo) where Dll expression is not reduced. (J,K) Third instar mesothoracic legs of from P[Ptc-Gal4]/+ (J) and P[Ptc-Gal4]/P[UAS- pygo] (K) larva. dpp expression is monitored using P[dpp-lacZ]. (J) Wild-type pattern, with lacZ repressed on the ventral side of the disc (arrow). When pygo is overexpressed in this domain, 37% of the legs exhibit complete derepression of lacZ on the ventral side (arrow in K indicates a representative of this group); 41% show moderate derepression and 22% show slight or no depression (data not shown; n=27).