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Research Article

Insights from Amphioxus into the Evolution of Vertebrate Cartilage

  • Daniel Meulemans mail,

    To whom correspondence should be addressed. E-mail: dm@caltech.edu

    Affiliation: Division of Biology, California Institute of Technology, Pasadena, California, United States of America

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  • Marianne Bronner-Fraser

    Affiliation: Division of Biology, California Institute of Technology, Pasadena, California, United States of America

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  • Published: August 29, 2007
  • DOI: 10.1371/journal.pone.0000787
  • Published in PLOS ONE

Reader Comments (3)

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Cooption of differentiation potential

Posted by Heather on 30 Aug 2007 at 14:45 GMT

"Most other amphioxus orthologs of vertebrate CNC and cartilage markers were expressed in mesodermal derivatives, while relatively few genes mark epidermal, neural, or endodermal cells (Figure 1B). Similar expression of vertebrate chondrogenic neural crest markers in mesodermal derivatives suggests that most components of the vertebrate neural crest cartilage program operated primitively in mesoderm. This is consistent with the overlapping developmental potentials of cranial neural crest cells and mesoderm to generate connective tissue, muscle, and cartilage."

I am convinced by this data, which adds itself to a body of other literature about the potential of cranial neural crest and the potential of vascular pericytes and so-called mesenchymal stem cells to give rise to the same derivatives under the right circumstances.

What I would be interested in, is the identification of the signaling cocktail from the endoderm, that I presume may itself be conserved, that patterns the overlying naive progenitor population from the competent cephalic mesoderm (in lower chordates) OR the cephalic neural crest (in vertebrates) to become cartilage. I suspect that the crest was indeed a true vertebrate innovation, from ancestral precursors in the dorsal neural tube. However, it was their plasticity once mesenchymal, that made them respond to the same signals the cephalic mesoderm used to in the pharynx and develop into cartilage with some of the same collagens and other components previously expressed by that mesoderm in that given location.