title: High qualitative and quantitative conservation of alternative splicing in Caenorhabditis elegans and Caenorhabditis briggsae.
abstract: Alternative splicing (AS) is an important contributor to proteome diversity and is regarded as an explanatory factor for the relatively low number of human genes compared with less complex animals. To assess the evolutionary conservation of AS and its developmental regulation, we have investigated the qualitative and quantitative expression of 21 orthologous alternative splice events through the development of 2 nematode species separated by 85-110 Myr of evolutionary time. We demonstrate that most of these alternative splice events present in Caenorhabditis elegans are conserved in Caenorhabditis briggsae. Moreover, we find that relative isoform expression levels vary significantly during development for 78% of the AS events and that this quantitative variation is highly conserved between the 2 species. Our results suggest that AS is generally tightly regulated through development and that the regulatory mechanisms controlling AS are to a large extent conserved during the evolution of Caenorhabditis. This strong conservation indicates that both major and minor splice forms have important functional roles and that the relative quantities in which they are expressed are crucial. Our results therefore suggest that the quantitative regulation of isoform expression levels is an intrinsic part of most AS events. Moreover, our results indicate that AS contributes little to transcript variation in Caenorhabditis genes and that gene duplication may be the major evolutionary mechanism for the origin of novel transcripts in these 2 species.
authors.affiliation: Molecular Evolution Group, Department of Molecular Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark. jlrukov@bi.ku.dk
authors.forename: Jakob Lewin
authors.initials: JL
authors.lastname: Rukov
authors.forename: Manuel
authors.initials: M
authors.lastname: Irimia
authors.forename: Søren
authors.initials: S
authors.lastname: Mørk
authors.forename: Viktor Karlovich
authors.initials: VK
authors.lastname: Lund
authors.forename: Jeppe
authors.initials: J
authors.lastname: Vinther
authors.forename: Peter
authors.initials: P
authors.lastname: Arctander
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D002107:Caenorhabditis / Q000235:genetics* / Q000254:growth & development; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth / Q000235:genetics; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D029742:Caenorhabditis elegans Proteins; D018076:DNA, Complementary; D020033:Protein Isoforms