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Molecular footprinting of skeletal tissues in the catshark Scyliorhinus canicula and the clawed frog Xenopus tropicalis identifies conserved and derived features of vertebrate calcification.

Enault S, Muñoz DN, Silva WT, Borday-Birraux V, Bonade M, Oulion S, Ventéo S, Marcellini S, Debiais-Thibaud M - Front Genet (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Institut des Sciences de l'Evolution de Montpellier, UMR5554, Université Montpellier, Centre National de la Recherche Scientifique, IRD, EPHE Montpellier, France.

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.

No MeSH data available.


Related in: MedlinePlus

Skeletal expression patterns the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 during Xenopus tropicalis vertebrae development. Transverse sections of stage NF54 (A–F) and NF57 (G–L) vertebrae processed for in situ hybridizations using the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 probes, as indicated. Black arrowheads show loose (A,B) or perichondral (D–F) cells. White arrowheads in (C,I) show Xt-Col2a1 positive epithelial non-vacuolated cells of the notochord. Arrows point at osteoblasts expressing Xt-Col1a1(G,J), Xt-Col1a2(H,K), or Xt-Col2a1(I,L). In (I,L), calcified, Alizarin red-positive cartilaginous regions are marked by an asterisk and the dotted lines demarcates expression boundaries between Xt-Col2a1 positive and Xt-Col2a1negative chondrocytes. In situ hybridization signal is light to dark blue. Brown endogenous X.t. pigment cells are also visible in the vicinity of the dorsal neural arch (D–F, J–L). Scale bar in (A) represents 50 μm in (A–F); scale bar in (G) represents 50 μm in (G–L).
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Figure 5: Skeletal expression patterns the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 during Xenopus tropicalis vertebrae development. Transverse sections of stage NF54 (A–F) and NF57 (G–L) vertebrae processed for in situ hybridizations using the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 probes, as indicated. Black arrowheads show loose (A,B) or perichondral (D–F) cells. White arrowheads in (C,I) show Xt-Col2a1 positive epithelial non-vacuolated cells of the notochord. Arrows point at osteoblasts expressing Xt-Col1a1(G,J), Xt-Col1a2(H,K), or Xt-Col2a1(I,L). In (I,L), calcified, Alizarin red-positive cartilaginous regions are marked by an asterisk and the dotted lines demarcates expression boundaries between Xt-Col2a1 positive and Xt-Col2a1negative chondrocytes. In situ hybridization signal is light to dark blue. Brown endogenous X.t. pigment cells are also visible in the vicinity of the dorsal neural arch (D–F, J–L). Scale bar in (A) represents 50 μm in (A–F); scale bar in (G) represents 50 μm in (G–L).

Mentions: Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 expression patterns were examined in the lateral and dorsal neural arch regions of the vertebrae (see Figures 4E,F,H,I,O,P,U,V). At stage NF54, Xt-Col1a1, and Xt-Col1a2 are expressed in scattered cells of mesenchymal appearance located in the vicinity of the cartilage (Figures 5A,B), as well as in a thin layer of perichondrium surrounding the dorsal neural arch (Figures 5D,E). At this early stage, Xt-Col2a1 is expressed in all chondrocytes and is also evident in the perichondrium of the dorsal neural arch (Figures 5C,F). At stage NF57, Xt-Col1a1, and Xt-Col1a2 are robustly expressed in osteoblasts lying onto the calcified bone matrix of the vertebrae (arrows in Figures 5G,H,J,K). These osteoblasts also express Xt-Col2a1, albeit more weakly than hypertrophic chondrocytes (Figures 5I,L). In chondrocytes, Xt-Col2a1 is excluded from the Alizarin red-positive regions (asterisk in Figures 5I,L), forming sharp expression boundaries between calcified and non-calcified cartilage (dotted line in Figures 4P,V, 5I,L). In addition, at stages NF54 and NF57, we detected a strong Xt-Col2a1 staining in the epithelial non-vacuolated cells of the notochord (arrowheads in Figures 5C,I), a known site of Col2a1 expression in cyclostomes and teleosts (Ota and Kuratani, 2010; Yamamoto et al., 2010).


Molecular footprinting of skeletal tissues in the catshark Scyliorhinus canicula and the clawed frog Xenopus tropicalis identifies conserved and derived features of vertebrate calcification.

Enault S, Muñoz DN, Silva WT, Borday-Birraux V, Bonade M, Oulion S, Ventéo S, Marcellini S, Debiais-Thibaud M - Front Genet (2015)

Skeletal expression patterns the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 during Xenopus tropicalis vertebrae development. Transverse sections of stage NF54 (A–F) and NF57 (G–L) vertebrae processed for in situ hybridizations using the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 probes, as indicated. Black arrowheads show loose (A,B) or perichondral (D–F) cells. White arrowheads in (C,I) show Xt-Col2a1 positive epithelial non-vacuolated cells of the notochord. Arrows point at osteoblasts expressing Xt-Col1a1(G,J), Xt-Col1a2(H,K), or Xt-Col2a1(I,L). In (I,L), calcified, Alizarin red-positive cartilaginous regions are marked by an asterisk and the dotted lines demarcates expression boundaries between Xt-Col2a1 positive and Xt-Col2a1negative chondrocytes. In situ hybridization signal is light to dark blue. Brown endogenous X.t. pigment cells are also visible in the vicinity of the dorsal neural arch (D–F, J–L). Scale bar in (A) represents 50 μm in (A–F); scale bar in (G) represents 50 μm in (G–L).
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Figure 5: Skeletal expression patterns the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 during Xenopus tropicalis vertebrae development. Transverse sections of stage NF54 (A–F) and NF57 (G–L) vertebrae processed for in situ hybridizations using the Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 probes, as indicated. Black arrowheads show loose (A,B) or perichondral (D–F) cells. White arrowheads in (C,I) show Xt-Col2a1 positive epithelial non-vacuolated cells of the notochord. Arrows point at osteoblasts expressing Xt-Col1a1(G,J), Xt-Col1a2(H,K), or Xt-Col2a1(I,L). In (I,L), calcified, Alizarin red-positive cartilaginous regions are marked by an asterisk and the dotted lines demarcates expression boundaries between Xt-Col2a1 positive and Xt-Col2a1negative chondrocytes. In situ hybridization signal is light to dark blue. Brown endogenous X.t. pigment cells are also visible in the vicinity of the dorsal neural arch (D–F, J–L). Scale bar in (A) represents 50 μm in (A–F); scale bar in (G) represents 50 μm in (G–L).
Mentions: Xt-Col1a1, Xt-Col1a2, and Xt-Col2a1 expression patterns were examined in the lateral and dorsal neural arch regions of the vertebrae (see Figures 4E,F,H,I,O,P,U,V). At stage NF54, Xt-Col1a1, and Xt-Col1a2 are expressed in scattered cells of mesenchymal appearance located in the vicinity of the cartilage (Figures 5A,B), as well as in a thin layer of perichondrium surrounding the dorsal neural arch (Figures 5D,E). At this early stage, Xt-Col2a1 is expressed in all chondrocytes and is also evident in the perichondrium of the dorsal neural arch (Figures 5C,F). At stage NF57, Xt-Col1a1, and Xt-Col1a2 are robustly expressed in osteoblasts lying onto the calcified bone matrix of the vertebrae (arrows in Figures 5G,H,J,K). These osteoblasts also express Xt-Col2a1, albeit more weakly than hypertrophic chondrocytes (Figures 5I,L). In chondrocytes, Xt-Col2a1 is excluded from the Alizarin red-positive regions (asterisk in Figures 5I,L), forming sharp expression boundaries between calcified and non-calcified cartilage (dotted line in Figures 4P,V, 5I,L). In addition, at stages NF54 and NF57, we detected a strong Xt-Col2a1 staining in the epithelial non-vacuolated cells of the notochord (arrowheads in Figures 5C,I), a known site of Col2a1 expression in cyclostomes and teleosts (Ota and Kuratani, 2010; Yamamoto et al., 2010).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Institut des Sciences de l'Evolution de Montpellier, UMR5554, Université Montpellier, Centre National de la Recherche Scientifique, IRD, EPHE Montpellier, France.

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.

No MeSH data available.


Related in: MedlinePlus