Fig. 6. hh regulates gastric caecum development through dpp expression regulation. (A,D,F,G,I,J,L) Guts dissected at 25 AEL stained with phalloidin-FITC. Arrows indicate gastric caecum evaginations; asterisks indicate eliminated gastric caeca. Compare the gastric caecum size using the vertical broken line as a measure. (B,E,H,K) dpp RNA expression in stage 13 embryos with HH signaling defects. Large arrowheads indicate dpp expression in VM-PS3. dpp expression in VM-PS6,7 serves as an internal control (small arrowheads). (A-C) The wild-type embryo possesses four long evaginations of gastric caecum with similar size. In wild type, VM-PS3 dpp (red) expression almost overlapped that of VM-hh-lacZ (green) (inset in B). (C) The dorsal view of a wild-type stage 14 embryo stained for Dwnt4 RNA (red) and VM-hh-lacZ (green). Arrowheads indicate VM-PS3 gastric caecum primordia with hh expression. In hh^ts embryos shifted-up during mid-stage 11 to late stage 12 (6.3-9.3 AEL), gastric caeca were shortened or eliminated (D,F) and VM-PS3 dpp expression was significantly reduced in area and intensity (E). In embryos with 48Y-GAL4-driven UAS-ciNZn, gastric caecum was always short (G) and VM-PS3 dpp expression was reduced (H). (I) bap-GAL4/+; UAS-ciNZn/+ embryo. In hh^13C (J) or twi-GAL4/+:UAS-ciNZn embryos (L), gastric caecum evagination was barely detectable. In these embryos, dpp expression in VM-PS3 was abolished (K; data not shown).

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