Journal of Molecular Evolution

, Volume 71, Issue 5, pp 364–373

Evaluation of Models of the Mechanisms Underlying Intron Loss and Gain in Aspergillus Fungi

Article

DOI: 10.1007/s00239-010-9391-6

Cite this article as:
Zhang, LY., Yang, YF. & Niu, DK. J Mol Evol (2010) 71: 364. doi:10.1007/s00239-010-9391-6

Abstract

Although intron loss and gain have been widely observed, their mechanisms are still to be determined. In four Aspergillus genomes, we found 204 cases of intron loss and 84 cases of intron gain. Using this data, we tested common hypotheses of intron loss or gain. Statistical analysis showed that adjacent introns tend to be lost simultaneously and small introns were preferentially lost, supporting the model of mRNA-mediated intron loss. The lost introns reside in internal regions of genes, which is inconsistent with the traditional version of the model (partial length cDNAs are reverse transcribed from 3′ ends of mRNAs), but consistent with an alternate version (partial length cDNAs are produced by self-primed reverse transcription). The latter version was not supported by examination of the abundance of T-rich segments in mRNAs. Preferential loss of internal introns might be explained by highly efficient recombination at internal regions of genes. Among the 84 cases of intron gain, we found a significantly higher frequency of short direct repeats near exon–intron boundary than in conserved introns, supporting the double-strand break repair model. We also found possible source sequences for two cases of intron gain, one by gene conversion and one by insertion of a mitochondrial sequence during double-strand break repair. Source sequences for most gained introns could not be identified and the possible reasons were discussed. In the four Aspergillus genomes studied, we did not find evidence of frequent parallel intron gains.

Keywords

Aspergillus mRNA-mediated intron loss Parallel intron gain Orthologous genes Double-strand break repair Self-primed reverse transcription 

Supplementary material

239_2010_9391_MOESM1_ESM.txt (883 kb)
Supplementary material 1 (TXT 883 kb)
239_2010_9391_MOESM2_ESM.txt (251 kb)
Supplementary material 2 (TXT 250 kb)
239_2010_9391_MOESM3_ESM.doc (38 kb)
Supplementary material 3 (DOC 38 kb)

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.MOE Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life SciencesBeijing Normal UniversityBeijingChina

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