title: Early chordate origins of the vertebrate second heart field.
abstract: The vertebrate heart is formed from diverse embryonic territories, including the first and second heart fields. The second heart field (SHF) gives rise to the right ventricle and outflow tract, yet its evolutionary origins are unclear. We found that heart progenitor cells of the simple chordate Ciona intestinalis also generate precursors of the atrial siphon muscles (ASMs). These precursors express Islet and Tbx1/10, evocative of the splanchnic mesoderm that produces the lower jaw muscles and SHF of vertebrates. Evidence is presented that the transcription factor COE is a critical determinant of ASM fate. We propose that the last common ancestor of tunicates and vertebrates possessed multipotent cardiopharyngeal muscle precursors, and that their reallocation might have contributed to the emergence of the SHF.
authors.affiliation: Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Stolfi
authors.forename: T Blair
authors.initials: TB
authors.lastname: Gainous
authors.forename: John J
authors.initials: JJ
authors.lastname: Young
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mori
authors.forename: Michael
authors.initials: M
authors.lastname: Levine
authors.forename: Lionel
authors.initials: L
authors.lastname: Christiaen
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002465:Cell Movement; D002938:Ciona intestinalis / Q000196:embryology* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism / Q000502:physiology*; D047108:Embryonic Development; D006321:Heart / Q000196:embryology*; D007568:Jaw; D008648:Mesoderm / Q000196:embryology; D008675:Metamorphosis, Biological; D018482:Muscle, Skeletal / Q000196:embryology; D009132:Muscles / Q000196:embryology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D010609:Pharyngeal Muscles / Q000166:cytology / Q000196:embryology; D013234:Stem Cells / Q000166:cytology / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014714:Vertebrates / Q000196:embryology*; D014981:Xenopus
chemical_list: D014157:Transcription Factors