title: Pre-bilaterian origin of the blastoporal axial organizer.
abstract: The startling capacity of the amphibian Spemann organizer to induce naïve cells to form a Siamese twin embryo with a second set of body axes is one of the hallmarks of developmental biology. However, the axis-inducing potential of the blastopore-associated tissue is commonly regarded as a chordate feature. Here we show that the blastopore lip of a non-bilaterian metazoan, the anthozoan cnidarian Nematostella vectensis, possesses the same capacity and uses the same molecular mechanism for inducing extra axes as chordates: Wnt/β-catenin signaling. We also demonstrate that the establishment of the secondary, directive axis in Nematostella by BMP signaling is sensitive to an initial Wnt signal, but once established the directive axis becomes Wnt-independent. By combining molecular analysis with experimental embryology, we provide evidence that the emergence of the Wnt/β-catenin driven blastopore-associated axial organizer predated the cnidarian-bilaterian split over 600 million years ago.
authors.affiliation: Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria.|Department of Evolutionary Biology, Biological Faculty, Moscow State University, Leninskiye gory 1/12, Moscow 119234, Russia.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Kraus
authors.affiliation: Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria.
authors.forename: Andy
authors.initials: A
authors.lastname: Aman
authors.affiliation: Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria.
authors.forename: Ulrich
authors.identifier: 0000-0003-4472-8258
authors.initials: U
authors.lastname: Technau
authors.affiliation: Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria.
authors.forename: Grigory
authors.initials: G
authors.lastname: Genikhovich
mesh_terms: D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics*; D064113:CRISPR-Cas Systems; D005775:Gastrula / Q000196:embryology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D016296:Mutagenesis; D020897:Organizers, Embryonic / Q000196:embryology / Q000378:metabolism*; D012615:Sea Anemones / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000235:genetics; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D051176:beta Catenin