title: Myogenic waves and myogenic programs during Xenopus embryonic myogenesis.
abstract: Although Xenopus is a key model organism in developmental biology, little is known about the myotome formation in this species. Here, we assessed the expression of myogenic regulatory factors of the Myod family (MRFs) during embryonic development and revealed distinct MRF programs.
  
  
  RESULTS
  The expression pattern of each MRF during embryonic development highlights three successive myogenic waves. We showed that a first median and lateral myogenesis initiates before dermomyotome formation: the median cell population expresses Myf5, Myod, and Mrf4, whereas the lateral one expresses Myod, moderate levels of Myogenin and Mrf4. The second wave of myoblasts arising from the dermomyotome is characterized by the full MRF program expression, with high levels of Myogenin. The third wave is revealed by Myf5 expression in the myotome and could contribute to the formation of plurinucleated fibers at larval stages. Furthermore, Myf5- or Myod-expressing anlagen are identified in craniofacial myogenesis.
  
  
  CONCLUSIONS
  The first median and lateral myogenesis and their associated MRF programs have probably disappeared in mammals. However, some aspects of Xenopus myogenesis have been conserved such as the development of somitic muscles by successive myogenic waves and the existence of Myf5-dependent and -independent lineages.
authors.affiliation: Centre d'Etude de la Sensori-Motricité, UMR 8194 CNRS, Université Paris Descartes, Centre Universitaire des Saints-Pères, 45 rue des Saints-Pères, Paris, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Della Gaspera
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Armand
authors.forename: Inés
authors.initials: I
authors.lastname: Sequeira
authors.forename: Albert
authors.initials: A
authors.lastname: Chesneau
authors.forename: André
authors.initials: A
authors.lastname: Mazabraud
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lécolle
authors.forename: Frédéric
authors.initials: F
authors.lastname: Charbonnier
authors.forename: Christophe
authors.initials: C
authors.lastname: Chanoine
mesh_terms: D000818:Animals; D018507:Gene Expression Regulation, Developmental; D024510:Muscle Development / Q000235:genetics*; D018482:Muscle, Skeletal / Q000196:embryology* / Q000378:metabolism; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D014981:Xenopus / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C497419:Myf5 protein, Xenopus; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D029867:Xenopus Proteins; C063403:myogenic factor 6