title: Small chromosomes among Danish Candida glabrata isolates originated through different mechanisms.
abstract: We analyzed 192 strains of the pathogenic yeast Candida glabrata from patients, mainly suffering from systemic infection, at Danish hospitals during 1985-1999. Our analysis showed that these strains were closely related but exhibited large karyotype polymorphism. Nine strains contained small chromosomes, which were smaller than 0.5 Mb. Regarding the year, patient and hospital, these C. glabrata strains had independent origin and the analyzed small chromosomes were structurally not related to each other (i.e. they contained different sets of genes). We suggest that at least two mechanisms could participate in their origin: (i) through a segmental duplication which covered the centromeric region, or (ii) by a translocation event moving a larger chromosome arm to another chromosome that leaves the centromere part with the shorter arm. The first type of small chromosomes carrying duplicated genes exhibited mitotic instability, while the second type, which contained the corresponding genes in only one copy in the genome, was mitotically stable. Apparently, in patients C. glabrata chromosomes are frequently reshuffled resulting in new genetic configurations, including appearance of small chromosomes, and some of these resulting "mutant" strains can have increased fitness in a certain patient "environment".
authors.affiliation: Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden. khadija_mohamed.ahmad@biol.lu.se
authors.forename: Khadija Mohamed
authors.initials: KM
authors.lastname: Ahmad
authors.forename: Olena P
authors.initials: OP
authors.lastname: Ishchuk
authors.forename: Linda
authors.initials: L
authors.lastname: Hellborg
authors.forename: Gloria
authors.initials: G
authors.lastname: Jørgensen
authors.forename: Miha
authors.initials: M
authors.lastname: Skvarc
authors.forename: Jørgen
authors.initials: J
authors.lastname: Stenderup
authors.forename: Dorte
authors.initials: D
authors.lastname: Jørck-Ramberg
authors.forename: Silvia
authors.initials: S
authors.lastname: Polakova
authors.forename: Jure
authors.initials: J
authors.lastname: Piškur
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D001483:Base Sequence; D041221:Candida glabrata / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure*; D002177:Candidiasis / Q000382:microbiology; D015825:Chromosomes, Fungal / Q000648:ultrastructure*; D003428:Cross Infection / Q000382:microbiology; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal; D003718:Denmark; D025141:Drug Resistance, Fungal / Q000235:genetics; D019143:Evolution, Molecular; D015725:Fluconazole / Q000494:pharmacology; D016469:Fungemia / Q000382:microbiology; D020440:Gene Duplication; D005800:Genes, Fungal; D042822:Genomic Instability; D006238:Haploidy; D006801:Humans; D007621:Karyotyping; D008969:Molecular Sequence Data; D010802:Phylogeny; D012641:Selection, Genetic; D013045:Species Specificity; D014178:Translocation, Genetic
chemical_list: D000935:Antifungal Agents; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D015725:Fluconazole