title: Variability in minimal genomes: analysis of tandem repeats in the microsporidia Encephalitozoon intestinalis.
abstract: Microsporidia are ubiquitous fungi with genomes that have undergone a strong reduction to the extreme cases of Encephalitozoon cuniculi and Encephalitozoon intestinalis. Genetic variability within species of the Encephalitozoon genus has been reported, with most of the studies based on the internal transcribed spacer (ITS) of the rDNA. However, in contrast to the picture of E. cuniculi and Encephalitozoon hellem, where different strains have been identified, no genetic variability has yet been observed in E. intestinalis. We have analysed tandem repeats included in putative coding sequences which could be used as polymorphic markers in E. intestinalis. Eight candidate loci (M2, M2A, M3, M5, M7, M7A, M8 and PTP1) were established and 9 E. intestinalis cultured strains from North America, South America and Europe were analysed. M2, M7 and PTP1 nucleotide sequences were identical among the different strains and the GenBank sequence. In contrast, we observed variants in 4 markers (M2A, M3, M7A and M8) which did not correspond to their respective reference sequences. The most noticeable finding was that with the M5 marker two genotypes were defined among the different strains studied, demonstrating genotypic variability of E. intestinalis. Although the diversity described is certainly not high, which can be explained by a lower chance of genetic variability in its minimal genome, we have demonstrated that polymorphisms actually exist in E. intestinalis. Epidemiological studies using this genetic marker should now be conducted to elucidate the genetic variability in E. intestinalis and improve our knowledge of the epidemiology of this microsporidia.
authors.affiliation: Laboratorio de Parasitología, Facultad de Farmacia, Universidad San Pablo CEU, Urbanización Montepríncipe, CP 28668, Boadilla del Monte, Madrid, Spain; Escuela de Microbiología, Grupo de Parasitología, Universidad de Antioquia, Calle 67 No. 53-108, Medellín, Colombia. Electronic address: agalvandiaz@yahoo.com.
authors.forename: Ana
authors.initials: A
authors.lastname: Galván
authors.forename: Angela
authors.initials: A
authors.lastname: Magnet
authors.forename: Fernando
authors.initials: F
authors.lastname: Izquierdo
authors.forename: Soledad
authors.initials: S
authors.lastname: Fenoy
authors.forename: Nuno
authors.initials: N
authors.lastname: Henriques-Gil
authors.forename: Carmen
authors.initials: C
authors.lastname: del Aguila
mesh_terms: D000818:Animals; D001483:Base Sequence; D004271:DNA, Fungal / Q000235:genetics*; D016819:Encephalitozoon / Q000145:classification / Q000235:genetics*; D016890:Encephalitozoonosis / Q000469:parasitology; D005656:Fungal Proteins / Q000235:genetics; D005819:Genetic Markers; D014644:Genetic Variation; D016681:Genome, Fungal / Q000235:genetics; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D020080:Tandem Repeat Sequences / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D005819:Genetic Markers
keywords: Encephalitozoon intestinalis; Genetic variability; Genotype; Microsporidia