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MBE Advance Access originally published online on February 23, 2005
Molecular Biology and Evolution 2005 22(5):1290-1298; doi:10.1093/molbev/msi117
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© The Author 2005. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oupjournals.org

Research Article

Adaptive Evolution of the Insulin Gene in Caviomorph Rodents

Juan C. Opazo*,{dagger},1, R. Eduardo Palma*,{dagger}, Francisco Melo{dagger},{ddagger} and Enrique P. Lessa§

* Center for Advanced Studies in Ecology and Biodiversity, Departamento de Ecología, {dagger} Facultad de Ciencias Biológicas, and {ddagger} Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago, Chile; and § Laboratorio de Evolución, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay

E-mail: jopazo{at}genetics.wayne.edu.

Insulin is a conservative molecule among mammals, maintaining both its structure and function. Rodents that belong to the Suborder Hystricognathi represent an exception, having a very divergent molecule with unusual physiological properties. In this work, we analyzed the evolutionary pattern of the insulin gene in caviomorph rodents (South American hystricomorph rodents). We found that these rodents have higher rates of nonsynonymous:synonymous substitutions (dN/dS) than nonhystricomorph rodents and that values are heterogeneous inside the group. We estimated codons under positive selection, specifically the second binding site (A13 and B17) and others related with hexamerization (B18, B20, and B22). In the monomer structure, all selected sites formed a single patch around the second binding site. In the hexamer structure, these amino acids were grouped into three major patches. In this structure, contacts between B chains involved all selected sites (except B18), and between faces in the center of the molecule, all contacts were among selected sites. While there is no clear hypothesis regarding the cause of this drastic change, experimental evidence does show that this group of rodents has some peculiarities in growth function, and, whether coincidental or not, these changes appeared together with important changes in life-history traits.

Key Words: insulin • caviomorph • adaptive evolution • life-history traits • Hystricognathi


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This article has been cited by other articles:


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[Abstract] [Full Text] [PDF]


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