title: Molecular footprinting of skeletal tissues in the catshark Scyliorhinus canicula and the clawed frog Xenopus tropicalis identifies conserved and derived features of vertebrate calcification.
abstract: Understanding the evolutionary emergence and subsequent diversification of the vertebrate skeleton requires a comprehensive view of the diverse skeletal cell types found in distinct developmental contexts, tissues, and species. To date, our knowledge of the molecular nature of the shark calcified extracellular matrix, and its relationships with osteichthyan skeletal tissues, remain scarce. Here, based on specific combinations of expression patterns of the Col1a1, Col1a2, and Col2a1 fibrillar collagen genes, we compare the molecular footprint of endoskeletal elements from the chondrichthyan Scyliorhinus canicula and the tetrapod Xenopus tropicalis. We find that, depending on the anatomical location, Scyliorhinus skeletal calcification is associated to cell types expressing different subsets of fibrillar collagen genes, such as high levels of Col1a1 and Col1a2 in the neural arches, high levels of Col2a1 in the tesserae, or associated to a drastic Col2a1 downregulation in the centrum. We detect low Col2a1 levels in Xenopus osteoblasts, thereby revealing that the osteoblastic expression of this gene was significantly reduced in the tetrapod lineage. Finally, we uncover a striking parallel, from a molecular and histological perspective, between the vertebral cartilage calcification of both species and discuss the evolutionary origin of endochondral ossification.
authors.affiliation: Institut des Sciences de l'Evolution de Montpellier, UMR5554, Université Montpellier, Centre National de la Recherche Scientifique, IRD, EPHE Montpellier, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Enault
authors.affiliation: Laboratory of Development and Evolution, Department of Cell Biology, Faculty of Biological Sciences, Universidad de Concepción Concepción, Chile.
authors.forename: David N
authors.initials: DN
authors.lastname: Muñoz
authors.affiliation: Institut des Sciences de l'Evolution de Montpellier, UMR5554, Université Montpellier, Centre National de la Recherche Scientifique, IRD, EPHE Montpellier, France.
authors.forename: Willian T A F
authors.initials: WT
authors.lastname: Silva
authors.affiliation: Laboratoire EGCE UMR Centre National de la Recherche Scientifique 9191, IRD247, Université Paris Sud Gif-sur-Yvette, France ; Université Paris Diderot, Sorbonne Paris Cité Paris, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Borday-Birraux
authors.affiliation: Laboratoire EGCE UMR Centre National de la Recherche Scientifique 9191, IRD247, Université Paris Sud Gif-sur-Yvette, France.
authors.forename: Morgane
authors.initials: M
authors.lastname: Bonade
authors.affiliation: Institut des Sciences de l'Evolution de Montpellier, UMR5554, Université Montpellier, Centre National de la Recherche Scientifique, IRD, EPHE Montpellier, France.
authors.forename: Silvan
authors.initials: S
authors.lastname: Oulion
authors.affiliation: Institute for Neurosciences of Montpellier, Institut National de la Santé et de la Recherche Médicale U1051 Montpellier, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Ventéo
authors.affiliation: Laboratory of Development and Evolution, Department of Cell Biology, Faculty of Biological Sciences, Universidad de Concepción Concepción, Chile.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Marcellini
authors.affiliation: Institut des Sciences de l'Evolution de Montpellier, UMR5554, Université Montpellier, Centre National de la Recherche Scientifique, IRD, EPHE Montpellier, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Debiais-Thibaud
keywords: Scyliorhinus canicula; Xenopus tropicalis; bone; cartilage; fibrillar collagens; vertebrate skeletogenesis