title: Delta-Notch signaling induces hypochord development in zebrafish.
abstract: Different cell types that occupy the midline of vertebrate embryos originate within the Spemann-Mangold or gastrula organizer. One such cell type is hypochord, which lies ventral to notochord in anamniote embryos. We show that hypochord precursors arise from the lateral edges of the organizer in zebrafish. During gastrulation, hypochord precursors are closely associated with no tail-expressing midline precursors and paraxial mesoderm, which expresses deltaC and deltaD. Loss-of-function experiments revealed that deltaC and deltaD were required for her4 expression in presumptive hypochord precursors and for hypochord development. Conversely, ectopic, unregulated Notch activity blocked no tail expression and promoted her4 expression. We propose that Delta signaling from paraxial mesoderm diversifies midline cell fate by inducing a subset of neighboring midline precursors to develop as hypochord, rather than as notochord.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Latimer
authors.forename: Xinhong
authors.initials: X
authors.lastname: Dong
authors.forename: Youlia
authors.initials: Y
authors.lastname: Markov
authors.forename: Bruce
authors.initials: B
authors.lastname: Appel
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D008648:Mesoderm / Q000502:physiology; D009024:Morphogenesis / Q000502:physiology*; D009672:Notochord / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology; D051880:Receptors, Notch; D015398:Signal Transduction; D015027:Zebrafish / Q000196:embryology*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; C064045:delta protein