Fig. 4. Combinatorial inputs from Dpp and Wg signaling regulate metameric Dorsocross expression in the dorsolateral ectoderm and mesoderm. (A,B) Doc3 in situ hybridization (green) and anti-PMad antibody staining (red) in wild-type stage 10 embryos seen from lateral (A) or ventral (B) views (only trunk regions are shown in this figure; v, ventral midline). Doc3 expression is activated within the nuclear PMad domain. (C) Ventral extension of the ectodermal PMad domain by ectopic Dpp leads to ventral extension of Doc3 patches. Ectopic Dpp was driven from a UAS-dpp transgene by ZKr-GAL4 in the ectodermal Krüppel domain (Frasch, 1995). (D,E) Wild-type stage 10-11 embryos double-stained with anti-Doc3+2 antibody (green) plus anti-En/Invected (red) (D) and anti-Doc3+2 antibody (green) plus anti-Wg (red) (E). Ectodermal Doc expression is centered around the Wg-stripes and overlaps partially with the En stripes (yellow ectodermal signals). (F) Homozygous wg^CX4 mutant embryo stained as in E. Metameric Doc expression is absent from the ectoderm and mesoderm, although amnioserosa expression is not affected. All images are combined confocal sections within the specified germ layer. Doc-expressing cells flanking the amnioserosa (as) in D, and to lesser extent in E, are mesodermal.