| Evolutionary origin and development of snake fangs. | |
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MedLine Citation:
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PMID: 18668106 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Many advanced snakes use fangs-specialized teeth associated with a venom gland-to introduce venom into prey or attacker. Various front- and rear-fanged groups are recognized, according to whether their fangs are positioned anterior (for example cobras and vipers) or posterior (for example grass snakes) in the upper jaw. A fundamental controversy in snake evolution is whether or not front and rear fangs share the same evolutionary and developmental origin. Resolving this controversy could identify a major evolutionary transition underlying the massive radiation of advanced snakes, and the associated developmental events. Here we examine this issue by visualizing the tooth-forming epithelium in the upper jaw of 96 snake embryos, covering eight species. We use the sonic hedgehog gene as a marker, and three-dimensionally reconstruct the development in 41 of the embryos. We show that front fangs develop from the posterior end of the upper jaw, and are strikingly similar in morphogenesis to rear fangs. This is consistent with their being homologous. In front-fanged snakes, the anterior part of the upper jaw lacks sonic hedgehog expression, and ontogenetic allometry displaces the fang from its posterior developmental origin to its adult front position-consistent with an ancestral posterior position of the front fang. In rear-fanged snakes, the fangs develop from an independent posterior dental lamina and retain their posterior position. In light of our findings, we put forward a new model for the evolution of snake fangs: a posterior subregion of the tooth-forming epithelium became developmentally uncoupled from the remaining dentition, which allowed the posterior teeth to evolve independently and in close association with the venom gland, becoming highly modified in different lineages. This developmental event could have facilitated the massive radiation of advanced snakes in the Cenozoic era, resulting in the spectacular diversity of snakes seen today. |
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Authors:
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Freek J Vonk; Jeroen F Admiraal; Kate Jackson; Ram Reshef; Merijn A G de Bakker; Kim Vanderschoot; Iris van den Berge; Marit van Atten; Erik Burgerhout; Andrew Beck; Peter J Mirtschin; Elazar Kochva; Frans Witte; Bryan G Fry; Anthony E Woods; Michael K Richardson |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Nature Volume: 454 ISSN: 1476-4687 ISO Abbreviation: Nature Publication Date: 2008 Jul |
Date Detail:
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Created Date: 2008-07-31 Completed Date: 2008-08-11 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0410462 Medline TA: Nature Country: England |
Other Details:
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Languages: eng Pagination: 630-3 Citation Subset: IM |
Affiliation:
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Institute of Biology, Leiden University, Kaiserstraat 63, PO Box 9516, 2300 RA, Leiden, The Netherlands. |
| Data Bank Information | |
Bank Name/Acc. No.:
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GENBANK/EU236145 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Gene Expression Regulation, Developmental Hedgehog Proteins / genetics, metabolism In Situ Hybridization Molecular Sequence Data Phylogeny* Snakes / anatomy & histology, classification, embryology*, genetics Tooth / anatomy & histology, embryology* |
| Chemical | |
Reg. No./Substance:
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0/Hedgehog Proteins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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