Fig. 9.

Inhibition of Wnt/β-catenin signalling converts the midgut to hindgut. a Fluorescent in situ hybridization of gut marker genes. b Quantification of the effect of activation/inhibition of Wnt/β-catenin pathway on the expression of these genes by assignment of all individuals to phenotypic classes. Pdu-Subtilisin-1 (first row, red), Pdu-Subtilisin-2 (second row, magenta), Pdu-α-Amylase (third row, cyan) = midgut marker genes, the darker the colour in the graph, the higher the expression. All three midgut marker genes show remarkably lower or no expression when Wnt/β-catenin signalling is inhibited (JW55 or IWR-1-endo). No pronounced effect was observed for activation of the pathway (CHIR99021). Pdu-Legumain (fourth row, yellow) = hindgut marker gene is normally highly expressed in the hindgut but only in very low levels in the midgut, which is also the case in the presence of activator, but it expands to midgut upon Wnt/β-catenin inhibition. Moreover, stronger inhibition (IWR-1-endo) causes it to be expressed outside the digestive tract in nephridia and other cells