Both size and GC-content of minimal introns are selected in human populations

PLoS One. 2011 Mar 17;6(3):e17945. doi: 10.1371/journal.pone.0017945.


Background: We previously have studied the insertion and deletion polymorphism by sequencing no more than one hundred introns in a mixed human population and found that the minimal introns tended to maintain length at an optimal size. Here we analyzed re-sequenced 179 individual genomes (from African, European, and Asian populations) from the data released by the 1000 Genome Project to study the size dynamics of minimal introns.

Principal findings: We not only confirmed that minimal introns in human populations are selected but also found two major effects in minimal intron evolution: (i) Size-effect: minimal introns longer than an optimal size (87 nt) tend to have a higher ratio of deletion to insertion than those that are shorter than the optimal size; (ii) GC-effect: minimal introns with lower GC content tend to be more frequently deleted than those with higher GC content. The GC-effect results in a higher GC content in minimal introns than their flanking exons as opposed to larger introns (≥125 nt) that always have a lower GC content than that of their flanking exons. We also observed that the two effects are distinguishable but not completely separable within and between populations.

Conclusions: We validated the unique mutation dynamics of minimal introns in keeping their near-optimal size and GC content, and our observations suggest potentially important functions of human minimal introns in transcript processing and gene regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Composition / genetics*
  • Base Pairing / genetics*
  • Base Sequence
  • Evolution, Molecular
  • Genetics, Population*
  • Humans
  • INDEL Mutation
  • Introns / genetics*
  • Selection, Genetic*