RT Journal Article SR Electronic T1 Par-Cteno-Genesis or Cteno Par-Genesis JF bioRxiv FD Cold Spring Harbor Laboratory SP 431114 DO 10.1101/431114 A1 Miguel Salinas-Saavedra A1 Mark Q Martindale YR 2018 UL http://biorxiv.org/content/early/2018/09/29/431114.abstract AB In bilaterians and cnidarians, embryonic and epithelial cell-polarity are regulated by the interactions between Par proteins, Wnt/PCP signaling pathway, and cell-cell adhesion. Par proteins are highly conserved across Metazoa, including ctenophores. But strikingly, ctenophore genomes lack components of the Wnt/PCP pathway and cell-cell adhesion complexes; raising the question if ctenophore cells are polarized by mechanisms involving Par proteins. Here, by using immunohistochemistry and live-cell imaging overexpression of specific mRNAs, we describe for the first time the subcellular localization of selected Par proteins in blastomeres and epithelial cells during the embryogenesis of the ctenophore Mnemiopsis leidyi. We show that these proteins distribute differently compared to what has been described for other animals. This differential localization might be related with the emergence of different junctional complexes during Metazoa evolution. Data obtained here challenge the ancestry of the apicobasal cell polarity and raise questions about the homology of epithelial tissue across the Metazoa.