The evolution of spliceosomal introns: patterns, puzzles and progress

  title={The evolution of spliceosomal introns: patterns, puzzles and progress},
  author={Scott William Roy and Walter Gilbert},
  journal={Nature Reviews Genetics},
The origins and importance of spliceosomal introns comprise one of the longest-abiding mysteries of molecular evolution. Considerable debate remains over several aspects of the evolution of spliceosomal introns, including the timing of intron origin and proliferation, the mechanisms by which introns are lost and gained, and the forces that have shaped intron evolution. Recent important progress has been made in each of these areas. Patterns of intron-position correspondence between widely… 

Mystery of intron gain: new data and new models.

Origins and evolution of spliceosomal introns.

Research into the origins of introns is at a critical juncture in the resolution of theories on the evolution of early life (which came first, RNA or DNA?), the identity of LUCA (the last universal

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    Cellular and Molecular Life Sciences
  • 2010
Findings in support of the DNA repair hypothesis that provides a global mechanistic scenario for intron creation are reviewed, which posit that DNA repair processes are a major source of intron formation.

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The wealth of ways in which structures of spliceosomal introns as well as their conservation and change through evolution may be harnessed for evolutionary and genomic analysis are reviewed.

Endogenous mechanisms for the origins of spliceosomal introns.

Two further hypotheses are proposed that are broadly based on central cellular processes: 1) internal gene duplication and 2) the response to aberrant and fortuitously spliced transcripts provide a powerful way to explain the establishment of spliceosomal introns in eukaryotes without invoking an exogenous source.

Three distinct modes of intron dynamics in the evolution of eukaryotes.

A comprehensive probabilistic model to obtain a definitive reconstruction of intron evolution was developed and applied to 391 sets of conserved genes from 19 eukaryotic species, inferring that a relatively high intron density was reached early.

Splicing-Related Features of Introns Serve to Propel Evolution

It is proposed that splicing-related structural features of introns serve as an additional motor to propel evolution and were more prone to sustainable structural changes than DNA sequences without introns due to intron's ability to jump within the genome via unknown mechanisms.

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

It is posited that intron positional diversity is driven by two overlapping processes: (i) background process of continuous relocation of preexisting introns by sliding and (ii) spurts of extensive gain/loss of new intron sequences.

Organization and Evolution of Fibrillarin Gene Introns

Analysis of the intron organization of the fibrillarin gene from the sequenced genomes of twenty-five species showed that more complex, multicellular species had generally larger numbers and lengths of introns, indicating that these introns were present in early eukaryotic ancestors as predicted by the introns-early model.



The evolutionary gain of spliceosomal introns: sequence and phase preferences.

The phase bias of intron gain is sufficient to account quantitatively for the well-known 5:3:2 bias in phase frequencies among extant introns, a conclusion that holds even when taxonomic heterogeneity in phase patterns is considered.

Messenger RNA surveillance and the evolutionary proliferation of introns.

It is suggested that the proliferation of spliceosomal introns was facilitated by the evolution of nonsense-mediated decay, an ancient and intron-dependent mechanism for eliminating aberrant mRNA molecules resulting from errors in transcription and splicing and from mutations at the DNA level.

The recent origins of spliceosomal introns revisited.

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    Current opinion in genetics & development
  • 1998

Eukaryotic evolution: Early origin of canonical introns

Intons from a close relative of Giardia, Carpediemonas membranifera, are described that have boundary sequences of the normal eukaryotic type, indicating that canonical introns are likely to have arisen very early in eukARYotic evolution.

Introns in Gene Evolution

It is argued that the processes central to intron-early (exon shuffling) and introns-late (intron insertion) theories are entirely compatible.

Rates of intron loss and gain: implications for early eukaryotic evolution.

  • S. RoyW. Gilbert
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 2005
The observed rates of intron gain are insufficient to explain the large number of introns estimated to have been present in the plant-animal ancestor, suggesting that introns present in early eukaryotes may have been created by a fundamentally different process than more recently gained introns.

A new Drosophila spliceosomal intron position is common in plants

An intron position is identified that was gained independently in animals and plants in the xanthine dehydrogenase gene and argues strongly for separate gain rather than recurrent loss.

Intron phase correlations and the evolution of the intron/exon structure of genes.

Using a large data base of eukaryotic intron-containing genes, it is found that there are correlations between intron phases leading to an excess of symmetric exons and asymmetric exon sets, which supports the concept that some of the introns were ancient, the exon theory of genes.

The ins and outs of group II introns.