Evolution of exon–intron structure and alternative splicing in fruit flies and malarial mosquito genomes

  1. Dmitry B. Malko1,
  2. Vsevolod J. Makeev1,
  3. Andrey A. Mironov1,2, and
  4. Mikhail S. Gelfand1,2,3,4
  1. 1 State Scientific Center GosNIIgenetika, Moscow 117545, Russia;
  2. 2 Department of Bioengineering and Bioinformatics, Moscow State University, Moscow 119992, Russia;
  3. 3 Institute for Information Transmission Problems RAS, Moscow 127994, Russia

Abstract

Comparative analysis of alternative splicing of orthologous genes from fruit flies (Drosophila melanogaster and Drosophila pseudoobscura) and mosquito (Anopheles gambiae) demonstrated that both in the fruit fly genes and in fruit fly–mosquito comparisons, constitutive exons and splicing sites are more conserved than alternative ones. While >97% of constitutive D. melanogaster exons are conserved in D. pseudoobscura, only ∼80% of alternative exons are conserved. Similarly, 77% of constitutive fruit fly exons are conserved in the mosquito genes, compared with <50% of alternative exons. Internal alternatives are more conserved than terminal ones. Retained introns are the least conserved, alternative acceptor sites are slightly more conserved than donor sites, and mutually exclusive exons are almost as conserved as constitutive exons. Cassette and mutually exclusive exons experience almost no intron insertions. We also observed cases of interconversion of various elementary alternatives, e.g., transformation of cassette exons into alternative sites. These results agree with the observations made earlier in human–mouse comparisons and demonstrate that the phenomenon of relatively low conservation of alternatively spliced regions may be universal, as it has been observed in different taxonomic groups (mammals and insects) and at various evolutionary distances.

Footnotes

  • 4

    4 Corresponding author.

    4 E-mail gelfand{at}iitp.ru; fax +7-095-2090579.

  • [Supplemental material is available online at www.genome.org.]

  • Article published online ahead of print. Article and publication date are at http://www.genome.org/cgi/doi/10.1101/gr.4236606

    • Received October 11, 2005.
    • Accepted January 3, 2006.
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