title: Use of ribosomal introns as new markers of genetic diversity in Exophiala dermatitidis.
abstract: Exophiala dermatitidis is one of the prevalent black yeasts found as opportunistic pathogens or colonizers in humans. In the tropics its natural habitat is thought to be fruit surfaces and it is also found in the digestive system of fruit-eating animals. However, it has recently been abundantly isolated from human-made environments (steam baths, railway ties, dishwashers) in tropical and temperate climates. Two genotypes have been distinguished within this species: genotype A, mostly corresponding to strains isolated from patients, and genotype B, to strains isolated from the natural environment. In human-made environments, both genotypes A and B occur. A previous study suggested that one genotype had been selected for in the human host. In our study, the distribution of ribosomal insertions agrees with an ecological specialization of E. dermatitidis genotypes by showing a significantly higher frequency of ribosomal insertions in clinical strains in comparison to environmental ones. The characterization of these insertions shows that they correspond to introns of group IC or IE, the most frequent types within the fungal kingdom. These ribosomal group I introns could be used as new markers for populations of E. dermatitidis.
authors.affiliation: Service de Parasitologie-Mycologie, CHU de Brabois, Vandoeuvre-les-Nancy, France. m.machouart@chu-nancy.fr
authors.forename: Marie
authors.initials: M
authors.lastname: Machouart
authors.forename: Cécile
authors.initials: C
authors.lastname: Gueidan
authors.forename: Arnaud
authors.initials: A
authors.lastname: Khemisti
authors.forename: Rémy
authors.initials: R
authors.lastname: Dulongcourty
authors.forename: Montarop
authors.initials: M
authors.lastname: Sudhadham
authors.forename: G Sybren
authors.initials: GS
authors.lastname: de Hoog
mesh_terms: D000818:Animals; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics*; D004783:Environmental Microbiology; D005093:Exophiala / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D005819:Genetic Markers; D014644:Genetic Variation; D006801:Humans; D007438:Introns; D016533:Mycological Typing Techniques / Q000379:methods*; D009690:Nucleic Acid Conformation; D060446:Phaeohyphomycosis / Q000382:microbiology* / Q000662:veterinary*
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D005819:Genetic Markers