Alternative splicing: A missing piece in the puzzle of intron gain

• DOI: 10.1073/pnas.0802941105
• Publication Date: 2008-05-08T01:10:30Z
• Authors: Rosa Tarrío; Francisco J. Ayala; Francisco Rodrígu...
• Keywords: Group II intron; Minor spliceosome

Spliceosomal introns, a hallmark of eukaryotic gene organization, were an unexpected discovery. After three decades, crucial issues such as when and how introns first appeared in evolution remain unsettled. An issue yet to be answered is intron positions arise de novo. Phylogenetic investigations concur that continue emerge, at least some lineages. Yet genomic scans for the sources occupying new have been fruitless. Two alternative solutions this paradox are: (i) formation halted before recent past (ii) it continues occur, but through processes different from those generally assumed. One process dismissed sliding--the relocation preexisting over short distances--because supposed associated deleterious effects. The puzzle gain arises owing pervasive operational definition which sees them precisely demarcated segments genome separated neighboring nonintronic DNA by unmovable limits. Intron homology defined position homology. Recent studies pre-mRNA processing indicate assumption needs revised. We incorporate advances on evolutionarily frequent splicing, exons primary transcripts are spliced patterns, into model sliding accounts diversity positions. posit positional driven two overlapping processes: background continuous spurts extensive gain/loss sequences.