Wing vein expansion induced by overexpression of Pri/Tal peptides. (A-H) Adult wings. (A) Wild-type wing. The AP boundary is indicated by the dotted line, and the dpp-Gal4 expression region is marked by the bracket. (B-H) Strong L3 vein expansion and formation of a large number of ES organs on the L3 vein are observed in flies co-expressing phyl and pri/tal (F), or in flies co-expressing phyl and pep1 (H). Expression of pep1 also induces mild vein expansion at the tip of L3 vein (D). (I-L) X-gal staining of the wing discs dissected from E(spl)mβ-lacZ pupae at 20-24 hr APF. The black arrows indicate the L3 vein boundaries expressing normal levels of E(spl)mβ-lacZ. White arrow in (K) points to the reduced E(spl)mβ-lacZ expression at the posterior boundary of the L3 vein. (M) Wild-type wing. (N and N') Wing vein expansion is also observed in the pep1-misexpressioin clone. The misexpression clone is identified by the presence of GFP (N') and the clone boundary is marked by black dash lines in (N).