Table of Contents
International Journal of Evolutionary Biology
Volume 2012, Article ID 278981, 7 pages
http://dx.doi.org/10.1155/2012/278981
Review Article

What Can Domesticated Genes Tell Us about the Intron Gain in Mammals?

Department of Molecular and Biomedical Sciences, Josef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia

Received 26 January 2012; Accepted 6 April 2012

Academic Editor: Frédéric Brunet

Copyright © 2012 Dušan Kordiš and Janez Kokošar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Domesticated genes, originating from retroelements or from DNA-transposons, constitute an ideal system for testing the hypothesis on the absence of intron gain in mammals. Since single-copy domesticated genes originated from the intronless multicopy transposable elements, the ancestral intron state for domesticated genes is zero. A phylogenomic approach has been used to analyse all domesticated genes in mammals and chordates that originated from the coding parts of transposable elements. A significant amount of intron gain was found only in domesticated genes of placental mammals, where more than 70 cases were identified. De novo gained introns show clear positional bias, since they are distributed mainly in 5′ UTR and coding regions, while 3′ UTR introns are very rare. In the coding regions of some domesticated genes up to 8 de novo gained introns have been found. Surprisingly, the majority of intron gains have occurred in the ancestor of placental mammals. Domesticated genes could constitute an excellent system on which to analyse the mechanisms of intron gain. This paper summarizes the current understanding of intron gain in mammals.