Why Genes are in Pieces? A Genomics Perspective

초록

Three decades after their discovery, both the biological function and evolutionary origin of introns still remain topics of considerable debate. Sequencing of complete genomes continues to provide key genetic insights into the elusive introns. Although supportive evidence exists both for an 'introns-early' as well as an 'introns-late' model of origin, neither theory is sufficient to account for the presence of both ancient and new introns in current eukaryotic genes; instead, a synthetic theory merging the two models may be valid. Insights into the biological role of introns are also available from genomics and experimental data sets. Introns regulate gene expression by means of a nonsense-mediated decay of mRNAs. Genome diversity generated by recombination between introns of paralogs, and proteome diversity generated by alternative intron splicing, would have been beneficial for the fitness of organisms. In gene families, intron gain or loss followed by gene duplication would have contributed to gene family divergence, and subsequently to species diversity and differentiation.

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