title: Retinoic acid signalling links left-right asymmetric patterning and bilaterally symmetric somitogenesis in the zebrafish embryo.
abstract: During embryogenesis, cells are spatially patterned as a result of highly coordinated and stereotyped morphogenetic events. In the vertebrate embryo, information on laterality is conveyed to the node, and subsequently to the lateral plate mesoderm, by a complex cascade of epigenetic and genetic events, eventually leading to a left-right asymmetric body plan. At the same time, the paraxial mesoderm is patterned along the anterior-posterior axis in metameric units, or somites, in a bilaterally symmetric fashion. Here we characterize a cascade of laterality information in the zebrafish embryo and show that blocking the early steps of this cascade (before it reaches the lateral plate mesoderm) results in random left-right asymmetric somitogenesis. We also uncover a mechanism mediated by retinoic acid signalling that is crucial in buffering the influence of the flow of laterality information on the left-right progression of somite formation, and thus in ensuring bilaterally symmetric somitogenesis.
authors.affiliation: Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Angel
authors.initials: A
authors.lastname: Raya
authors.forename: R Marina
authors.initials: RM
authors.lastname: Raya
authors.forename: Concepción
authors.initials: C
authors.lastname: Rodríguez-Esteban
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Izpisúa Belmonte
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002923:Cilia / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D015398:Signal Transduction; D019170:Somites / Q000166:cytology / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D014212:Tretinoin