title: A glimpse of a putative pre-intron phase of eukaryotic evolution.
abstract: Comparison of the exon-intron structures of ancient eukaryotic paralogs reveals the absence of conserved intron positions in these genes. This is in contrast to the conservation of intron positions in orthologous genes from even the most evolutionarily distant eukaryotes and in more recent paralogs. The lack of conserved intron positions in ancient paralogs probably reflects the origination of these genes during the earliest phase of eukaryotic evolution, which was characterized by concomitant invasion of genes by group II self-splicing elements (which were to become introns in the future) and extensive duplication of genes.
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Sverdlov
authors.forename: Miklos
authors.initials: M
authors.lastname: Csuros
authors.forename: Igor B
authors.initials: IB
authors.lastname: Rogozin
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D020440:Gene Duplication; D006801:Humans; D007438:Introns; D008957:Models, Genetic