Fig. 7

Wnt/β-catenin pathway is active in the larval gut and is affected by chemical manipulation. a Maximal projections and orthogonal virtual sections on the level of midgut and hindgut of a fluorescent confocal z-stacks of β-catenin protein immunostaining (green) on 7 dpf larvae done to confirm the chemical treatment’s efficacy. The larvae shown here come from the same batch as those used for in situ hybridization in Fig. 9. High levels of β-catenin were observed especially in the midgut. While the activation by CHIR99021 did not cause any dramatic increase in β-catenin levels, the inhibition of Wnt/β-catenin signalling by either of the inhibitors, JW55 or IWR-1-endo led to the complete absence of such high levels of β-catenin in the gut. b Fluorescent in situ hybridization of a putative Wnt target gene, Pdu-Axin (yellow) and quantification of the phenotype classes (c) shows no effect for the activator (CHIR99021) and mild effects of both Wnt/β-catenin inhibitors on axin expression. These larvae come from the same batch as those used for in situ hybridization in Fig. 10. d The fluorescent signal from the microinjected Wnt reporter construct SuperTOPFlash-tdTomato with 8 Tcf/LEF binding sites can be observed in the endoderm of 7 dpf transient transgenic larvae. This indicates that the Wnt/β-catenin signalling is active in the gut. e The effect of chemical manipulation of Wnt/β-catenin signalling on the expression of Pdu-Tcf