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

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

Conclusion

- Phase distribution of spliceosomal introns: implications for intron origin

The debate surrounding introns-early versus introns-late remains vigorous [23,24]. We previously provided two lines of support for the introns-late view: there is no general trend over evolution toward decreasing intron density [[22], but also see ref. [25]]; and there was no clear case of intron position conservation in a set of 25 cytoplasmic RP genes of archaeal origin and mitochondrial RP genes of bacterial origin, which are thought to have diverged at the progenote [26]. In this paper, we have provided two more lines of support for introns-late from analyses of intron phase distribution: the current excess of phase-0 introns is due to the excess of phase-0 among gained introns and not to the remnants of minigenes; and the all-pattern intron insertion model can explain the observed intron phase distributions in various species. These results should help to resolve the long-standing but important debate about the origin of spliceosomal introns.