Fig. 6. Signaling activity of Hh, HhN and Hhc85s. (A) A wing imaginal disc with the posterior P compartment cells expressing Hh (green) and the anterior A compartment cell expressing Ptc (red) in response to Hh. The red frame indicates the territory represented in the adjacent panel, showing the real staining of the wing disc with Hh (green) and Ptc (red) antibodies. The right panel shows the expression of different Hh target genes in A compartment cells. (B) The different thresholds of Hh signaling required for the activation of the different targets. Ectopic Hh-GFP (C-F), HhN-GFP (G-J) and Hhc85s-GFP (K-N) clones induce activation of En (C,G,K), Ptc (D,H,L), Dpp (E,I,M) and Iro (F,J,N) in the anterior compartment (labeled in red). Hh-expressing cells are marked by b-Gal (blue) in most of the panels, with the exception of panels E, I and M, where they are labeled by the absence of CD2 (blue). Arrows indicate the autonomous response and arrowheads indicate the non-autonomous response to various forms of Hh. (O-Q) The activation of Hh targets by ectopic Hh-GFP (O), HhN-GFP (P) and Hhc85s-GFP (Q) clones in the A compartment. Light green represents the levels and graded distribution of Hh protein and the dark green represents the signaling activity of wild-type Hh, HhN-GFP and Hhc85s-GFP. In O, but not in P and Q, Hh protein distribution is the same as its signaling activity gradient.