Cell type and regulatory analysis in amphioxus illuminates evolutionary origin of the vertebrate head

To shed light on the enigmatic origin of the vertebrate head, our study employs an integrated approach that combines single-cell transcriptomics, perturbations in signalling pathways, and cis-regulatory analysis in amphioxus, a close relative of chordate common ancestor. Through cell type characterization, we identified the presence of a prechordal plate, pre-migratory and migratory neural crest-like cell populations in the developing amphioxus embryo. Functional analysis established conserved roles of the Nodal and Hedgehog signalling pathways in prechordal plate, and of Wnt signalling pathway in neural crest development. Furthermore, the trans-species transgenic experiments provided evidence of cis-regulatory level homology within the chordate lineage. Our findings provide evidence that the key features of vertebrate head development can be traced back to the common ancestor of all chordates. One Sentence SummaryCell populations forming the vertebrate head are present in the close relative of chordate common ancestor.