Intron Loss and Gain


Introns, the nonprotein coding regions of genes that are interspersed between protein‐coding exons are present in all eukaryotes' genomes. The variation in intron abundance in eukaryotic genomes signifies that intron loss and intron gain have occurred at varying degrees during the evolution of eukaryotes. Intron gain or loss events have been rare in human and other mammalian genomes, but intron loss in other eukaryotes is starting to be understood in terms of the biology of genomes.

Keywords: introns; evolution; genome; eukaryotes

Figure 1.

Schematic illustration of the suggested mechanisms for intron gain and loss discussed in the article. Intron loss shown in light grey box, all other boxes concern intron gain. DNA is shown as grey bars. Reverse transcribed extra‐chromosomal DNA is labelled ‘cDNA’, all other DNA sequences are genomic. White bars denote RNA. Introns are shown as black lines regardless whether they are DNA or RNA. See text for detailed description of intron gain and loss mechanisms.



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Further Reading

Collins L and Penny D (2005) Complex spliceosomal organization ancestral to extant eukaryotes. Molecular Biology and Evolution 22: 1053–1066.

Jeffares DC, Mourier T and Penny D (2006) The biology of intron gain and loss. Trends in Genetics 22: 16–22.

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Rogozin IB, Wolf YI, Sorokin AV, Mirkin BG and Koonin EV (2003) Remarkable interkingdom conservation of intron positions and massive, lineage‐specific intron loss and gain in eukaryotic evolution. Current Biology 13: 1512–1517.

Roy SW and Gilbert W (2005) Complex early genes. Proceedings of the National Academy of Sciences of the USA 102: 1986–1991.

Roy SW and Gilbert W (2006) The evolution of spliceosomal introns: patterns, puzzles and progress. Nature Reviews Genetics 7: 211–221.

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How to Cite close
Mourier, Tobias, and Jeffares, Daniel C(Dec 2007) Intron Loss and Gain. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0020785]