Fig. 5. Overexpression of HOW(L) reduces the Spalt domain non-autonomously and represses dpp mRNA expression. (A-H) Wing imaginal discs carrying sd-gal4 (A-D) or dpp-gal4 (E-H) and either UAS-GFP alone (A,B,E,F) or together with the repressor isoform UAS-HOW(L) (C,D,G,H) stained for Spalt (Sal, red). The merged images of GFP and Spalt are shown (B,D,F,H). (I) Quantification of the Spalt domain width in wild type (WT) and in wing imaginal discs overexpressing HOW(L) in the dpp domain is given as the ratio between Spalt domain width and the wing imaginal disc width (calculated as detailed in Fig. 2). (J,K) In situ hybridization with the DIG-labeled dpp antisense probe of wing imaginal discs carrying sd-gal4 (J), or overexpressing HOW(L) driven by the sd-gal4 driver (K). Arrowheads indicate the wing imaginal disc pouch domain.