title: Complete genome sequences from three genetically distinct strains reveal high intraspecies genetic diversity in the microsporidian Encephalitozoon cuniculi.
abstract: Microsporidia from the Encephalitozoonidae are obligate intracellular parasites with highly conserved and compacted nuclear genomes: they have few introns, short intergenic regions, and almost identical gene complements and chromosome arrangements. Comparative genomics of Encephalitozoon and microsporidia in general have focused largely on the genomic diversity between different species, and we know very little about the levels of genetic diversity within species. Polymorphism studies with Encephalitozoon are so far restricted to a small number of genes, and a few genetically distinct strains have been identified; most notably, three genotypes (ECI, ECII, and ECIII) of the model species E. cuniculi have been identified based on variable repeats in the rRNA internal transcribed spacer (ITS). To determine if E. cuniculi genotypes are genetically distinct lineages across the entire genome and at the same time to examine the question of intraspecies genetic diversity in microsporidia in general, we sequenced de novo genomes from each of the three genotypes and analyzed patterns of single nucleotide polymorphisms (SNPs) and insertions/deletions across the genomes. Although the strains have almost identical gene contents, they harbor large numbers of SNPs, including numerous nonsynonymous changes, indicating massive intraspecies variation within the Encephalitozoonidae. Based on this diversity, we conclude that the recognized genotypes are genetically distinct and propose new molecular markers for microsporidian genotyping.
authors.affiliation: Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Pombert
authors.forename: Jinshan
authors.initials: J
authors.lastname: Xu
authors.forename: David R
authors.initials: DR
authors.lastname: Smith
authors.forename: David
authors.initials: D
authors.lastname: Heiman
authors.forename: Sarah
authors.initials: S
authors.lastname: Young
authors.forename: Christina A
authors.initials: CA
authors.lastname: Cuomo
authors.forename: Louis M
authors.initials: LM
authors.lastname: Weiss
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Keeling
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D021901:DNA, Intergenic / Q000235:genetics*; D009670:Encephalitozoon cuniculi / Q000145:classification / Q000235:genetics*; D005819:Genetic Markers; D016681:Genome, Fungal; D005838:Genotype; D060005:Genotyping Techniques; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion
chemical_list: D021901:DNA, Intergenic; D005819:Genetic Markers