Login

Join for Free!
118238 members
table of contents table of contents

This study strongly support the introns-late hypothesis of the origin of spliceosomal …


Biology Articles » Evolutionary Biology » Molecular Evolution » Phase distribution of spliceosomal introns: implications for intron origin

Abstract
- Phase distribution of spliceosomal introns: implications for intron origin

Research article

Phase distribution of spliceosomal introns: implications for intron origin

Hung D Nguyen, Maki Yoshihama and Naoya Kenmochi

Frontier Science Research Center, University of Miyazaki 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan




Background

The origin of spliceosomal introns is the central subject of the introns-early versus introns-late debate. The distribution of intron phases is non-uniform, with an excess of phase-0 introns. Introns-early explains this by speculating that a fraction of present-day introns were present between minigenes in the progenote and therefore must lie in phase-0. In contrast, introns-late predicts that the nonuniformity of intron phase distribution reflects the nonrandomness of intron insertions.

Results

In this paper, we tested the two theories using analyses of intron phase distribution. We inferred the evolution of intron phase distribution from a dataset of 684 gene orthologs from seven eukaryotes using a maximum likelihood method. We also tested whether the observed intron phase distributions from 10 eukaryotes can be explained by intron insertions on a genome-wide scale. In contrast to the prediction of introns-early, the inferred evolution of intron phase distribution showed that the proportion of phase-0 introns increased over evolution. Consistent with introns-late, the observed intron phase distributions matched those predicted by an intron insertion model quite well.

Conclusion

Our results strongly support the introns-late hypothesis of the origin of spliceosomal introns.

Source: BMC Evolutionary Biology 2006, 6:69. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.


rating: 3.00 from 4 votes | updated on: 13 Jul 2007 | views: 5971 |

Rate article:







excellent!bad…