title: her1 and the notch pathway function within the oscillator mechanism that regulates zebrafish somitogenesis.
abstract: Somite formation is thought to be regulated by an unknown oscillator mechanism that causes the cells of the presomitic mesoderm to activate and then repress the transcription of specific genes in a cyclical fashion. These oscillations create stripes/waves of gene expression that repeatedly pass through the presomitic mesoderm in a posterior-to-anterior direction. In both the mouse and the zebrafish, it has been shown that the notch pathway is required to create the stripes/waves of gene expression. However, it is not clear if the notch pathway comprises part of the oscillator mechanism or if the notch pathway simply coordinates the activity of the oscillator among neighboring cells. In the zebrafish, oscillations in the expression of a hairy-related transcription factor, her1 and the notch ligand deltaC precede somite formation. Our study focuses on how the oscillations in the expression of these two genes is affected in the mutants aei/deltaD and des/notch1, in 'morpholino knockdowns' of deltaC and her1 and in double 'mutant' combinations. This analysis indicates that these oscillations in gene expression are created by a genetic circuit comprised of the notch pathway and the notch target gene her1. We also show that a later function of the notch pathway can create a segmental pattern even in the absence of prior oscillations in her1 and deltaC expression.
authors.affiliation: Max Planck-Institut für Entwicklungsbiologie, Tübingen, Germany. scott.holley@yale.edu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Holley
authors.forename: Dörthe
authors.initials: D
authors.lastname: Jülich
authors.forename: Gerd-Jörg
authors.initials: GJ
authors.lastname: Rauch
authors.forename: Robert
authors.initials: R
authors.lastname: Geisler
authors.forename: Christiane
authors.initials: C
authors.lastname: Nüsslein-Volhard
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D001683:Biological Clocks / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction; D019170:Somites / Q000502:physiology*; D014157:Transcription Factors; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D012097:Repressor Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C405694:Hairy, HRT1 protein; C064045:delta protein; C437805:notch1a protein, zebrafish