Literaturdatenbank
Literaturdatenbank |
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Cebra-Thomas, J. A., Tan, F., Sistla, S., Estes, E., Bender, G., & Kim, C., et al. (2005). How the turtle forms its shell: A paracrine hypothesis of carapace formation. Journal of Experimental Zoology Part B Molecular and Developmental Evolution, 304b(6), 558–569.
Added by: Sarina Wunderlich (23 Dec 2008 22:36:30 UTC) Last edited by: Sarina Wunderlich (23 Dec 2008 22:42:52 UTC) |
| Resource type: Journal Article DOI: 10.1002/jez.b.21059. BibTeX citation key: CebraThomas2005a View all bibliographic details  |
Categories: General Keywords: Schildkröten = turtles + tortoises Creators: Bender, Cebra-Thomas, Estes, Gilbert, Kim, Ricco, Sistla, Tan Collection: Journal of Experimental Zoology Part B Molecular and Developmental Evolution |
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| URLs http://www.swarthm ... EZTurtlehypoth.pdf |
| Abstract |
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We propose a two-step model for the evolutionary origin of the turtle shell. We show here that the carapacial ridge (CR) is critical for the entry of the ribs into the dorsal dermis. Moreover, we demonstrate that the maintenance of the CR and its ability to attract the migrating rib precursor cells depend upon fibroblast growth factor (FGF) signaling. Inhibitors of FGF allow the CR to degenerate, with the consequent migration of ribs along the ventral body wall. Beads containing FGF10 can rearrange rib migration in the chick, suggesting that the CR FGF10 plays an important role in attracting the rib rudiments. The co-ordinated growth of the carapacial plate and the ribs may be a positive feedback loop (similar to that of the limbs) caused by the induction of Fgf8 in the distal tips of the ribs by the FGF10-secreting mesenchyme of the CR. Once in the dermis, the ribs undergo endochrondral ossification. We provide evidence that the ribs act as signaling centers for the dermal ossification and that this ossification is due to bone morphogenetic proteins secreted by the rib. Thus, once the ribs are within the dermis, the ossification of the dermis is not difficult to achieve. This relatively rapid means of carapace formation would allow for the appearance of turtles in the fossil record without obvious intermediates.
Added by: Sarina Wunderlich Last edited by: Sarina Wunderlich |
| Notes |
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WIF
Added by: Sarina Wunderlich Last edited by: Sarina Wunderlich |