title: The molecular nature of the zebrafish tail organizer.
abstract: Based on grafting experiments, Mangold and Spemann showed the dorsal blastopore lip of an amphibian gastrula to be able to induce a secondary body axis. The equivalent of this organizer region has been identified in different vertebrates including teleosts. However, whereas the graft can induce ectopic head and trunk, endogenous and ectopic axes fuse in the posterior part of the body, raising the question of whether a distinct organizer region is necessary for tail development. Here we reveal, by isochronic and heterochronic transplantation, the existence of a tail organizer deriving from the ventral margin of the zebrafish embryo, which is independent of the dorsal Spemann organizer. Loss-of-function experiments reveal that bone morphogenetic protein (BMP), Nodal and Wnt8 signalling pathways are required for tail development. Moreover, stimulation of naive cells by a combination of BMP, Nodal and Wnt8 mimics the tail-organizing activity of the ventral margin and induces surrounding tissues to become tail. In contrast to induction of the vertebrate head, known to result from the triple inhibition of BMP, Nodal and Wnt, here we show that induction of the tail results from the triple stimulation of BMP, Nodal and Wnt8 signalling pathways.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR 7104, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP10142, CU de Strasbourg, 67404 Illkirch Cedex, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Agathon
authors.forename: Christine
authors.initials: C
authors.lastname: Thisse
authors.forename: Bernard
authors.initials: B
authors.lastname: Thisse
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D003598:Cytoskeletal Proteins; D004627:Embryonic Induction / Q000187:drug effects; D055457:Nodal Protein; D020897:Organizers, Embryonic / Q000502:physiology*; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013623:Tail / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology; D051153:Wnt Proteins; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology
chemical_list: D019485:Bone Morphogenetic Proteins; D003598:Cytoskeletal Proteins; D055457:Nodal Protein; D011506:Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C094521:wnt8a protein, zebrafish