Figure 1.

Wg is upregulated in esg^+ve cells in response to damage in the adult Drosophila midgut. (A–C″′) Control midguts (A–A″′) and midguts subject to wg knockdown in the visceral muscle (VM) only (how^ts>wg-IR) (B, B″′) or in VM and ISCs/EBs (esg; how^ts>wg-IR) (C–C″′) and stained with anti-Wg (red), DAPI (blue) and Phalloidin (green; A″, A″′, B″, B″′) or anti-GFP (C″). Posterior of the midgut is to the right. Panels (A, A′, B, B′, C, C′) show apical confocal sections of the VM and (A″, A″′, B″, B″′, C″, C″′) represent cross-sections of the intestinal tube. Note the loss of Wg staining in the VM after RNAi for Wg (arrows in A, A′, B, B′, C, C′ and arrowheads in remaining panels). Arrows in (A″, A″′, B″, B″′, C″, C″′) point to cells within the midgut epithelium, which either show detectable Wg staining (Wg^+ve cells) (A″, A″′, B″, B″′; red) or express esg>gfp (esg^+ve cells) (C″; green). Note that Wg^+ve cells are still detectable in how^ts>wg-IR (B″, B″′; compare with A″, A″′) but not in esg; how^ts>wg-IR midguts (C″, C″′; compare with B″, B″′). (D–L) Wg staining (red) from midguts of the indicated genotypes, treated with Sucrose (Suc, D, D′, J), infected with the bacteria Pseudomonas entomophila (Pe) (E, E′, G, G′, I, K, L), or treated with Dextran sodium sulphate (DSS) (F, F′, H, H′). Note the induction of Wg levels during regeneration (compare E′, F′, I with D′ and K with J). RNAi for Wg suppressed Wg upregulation when expressed in the esg^+ve lineage (compare G′, H′ with E′, F′, respectively) but not when expressed in the VM (compare I with E′) or in enterocytes (ECs) (compare L with K). Except otherwise noted posterior midguts were analysed in all cases, and posterior is up in all panels. Scale bars: 40 μm.