Fig. 4

Hydra Wnt signalling targets regulate genes that play a crucial role in dorsoventral patterning. Upregulation of Wnt signalling results in negative regulation of bilaterian-specific ventral markers. To test the role of Wnt/β-catenin targets in dorsoventral patterning we have used a heterologous model system, zebrafish. Hydra Margin and HvOtp1 genes were selected and in vitro synthesized capped mRNAs were injected into one-cell stage zebrafish embryos. a Heatmap displays the significantly differential regulated TGF-β family members upon activation of Wnt signalling. Red and blue colours denote significantly up- and down- regulated genes with log₂ fold change cut-off of ±0.58 with a p value of 0.01 respectively. b Morphological changes upon injections of Margin and HvOtp1 mRNA. Embryos were imaged at 30 hpf (lateral view, anterior to the left) and further classified based on the extent of phenotypic changes into three sub-classes. c Percentage of total embryos observed with different classes of phenotypic changes (N = 3). d Expression levels of axis determining genes upon injections of Hydra Margin and HvOtp1 mRNAs are represented as fold change with respect to antisense mRNA-injected control embryos at 75% epiboly stage. N = 3; Students two-tailed t-test was performed; *p value < 0.03; **p value < 0.002. e Whole-mount in situ hybridization analysis of dorsal organizer gene chordin (dorsal view).