Developmental genetic bases behind the independent origin of the tympanic membrane in mammals and diapsids
The amniote middle ear is a classical example of the evolutionary novelty. Although paleontological evidence supports the view that mammals and diapsids (modern reptiles and birds) independently acquired the middle ear after divergence from their common ancestor, the developmental bases of these tra...
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Published in | Nature communications Vol. 6; no. 1; p. 6853 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
22.04.2015
Nature Publishing Group Nature Pub. Group |
Subjects | |
Online Access | Get full text |
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Summary: | The amniote middle ear is a classical example of the evolutionary novelty. Although paleontological evidence supports the view that mammals and diapsids (modern reptiles and birds) independently acquired the middle ear after divergence from their common ancestor, the developmental bases of these transformations remain unknown. Here we show that lower-to-upper jaw transformation induced by inactivation of the Endothelin1-Dlx5/6 cascade involving
Goosecoid
results in loss of the tympanic membrane in mouse, but causes duplication of the tympanic membrane in chicken. Detailed anatomical analysis indicates that the relative positions of the primary jaw joint and first pharyngeal pouch led to the coupling of tympanic membrane formation with the lower jaw in mammals, but with the upper jaw in diapsids. We propose that differences in connection and release by various pharyngeal skeletal elements resulted in structural diversity, leading to the acquisition of the tympanic membrane in two distinct manners during amniote evolution.
The evolution of the amniote middle ear remains unclear. Here, the authors show that inactivation of the Edn1-Dlx5/6 cascade during development results in loss of the tympanic membrane in mouse and duplication in chicken, which suggests independent evolution of the tympanic membrane in different amniotes. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 These authors contributed equally to this work Present address: Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan |
ISSN: | 2041-1723 2041-1723 |
DOI: | 10.1038/ncomms7853 |