Fig. 4

Gene expression pattern of the duplicated HEs in Xenopus frogs. A Phylogenetic tree of amphibian HEs constructed using the maximum likelihood method, with the amniote HEs as the outgroup (HECUB2 indicate HE genes having two CUB domain structures at the C-terminal side). Genes colored in red are genes whose expression in hatching gland cells has been confirmed in previous studies or this study. Genes that are colored blue (XlHE13 and XtHE14) were expressed at the caudal fin. The numbers at the nodes indicate the bootstrap values (> 50%). Whole mount in situ hybridization of HEs in hatching gland cells (B) and of XlHE13 genes in fins (C) and XlHE13 expression on the sections of caudal fins (D) in X. laevis. E–H Spatiotemporal reanalysis of XtHE1 and XtHE14 using t-distributed stochastic neighbor embedding with public data on the single-cell transcriptome of Western clawed frog (E developmental stages; F cell lineages; G and G’, expression of XtHE1; H and H’, expression of XtHE14) indicates different expression patterns in these genes. I Cell-fate tree of hatching gland and posterior fin estimated from the single-cell transcriptome. Each cell lineage was derived from the same origin, non-neural ectoderm