title: Chimeric evolution of the 2-microns genome in Saccharomyces cerevisiae.
abstract: We compared the nucleotide substitution pattern over the entire genome of two unique variants of the 6,300-bp selfish DNA (2 microns) plasmid in Saccharomyces cerevisiae. The DNA sequence of the left-unique region is identical among 2-microns variants, while the right-unique region shows substantial divergence. This chimeric pattern cannot be explained by neutral or Darwinian selection models. We propose that horizontal transmission of the 2-microns plasmid coupled with a directed, polarized gene conversion maintains the DNA sequence of the left-unique region, whereas the right-unique region is subject to random drift and Darwinian selection.
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Xie
authors.forename: L E
authors.initials: LE
authors.lastname: Pelcher
authors.forename: G H
authors.initials: GH
authors.lastname: Rank
mesh_terms: D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics*; D014644:Genetic Variation; D016681:Genome, Fungal; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal