In eukaryotes, the number and rough organization of chromosomes is well preserved within isolates of the same species. Novel chromosomes and loss of chromosomes are infrequent and usually associated with pathological events. Here, we analyzed 40 pathogenic isolates of a haploid and asexual yeast, Candida glabrata, for their genome structure and stability. This organism has recently become the second most prevalent yeast pathogen in humans. Although the gene sequences were well conserved among different strains, their chromosome structures differed drastically. The most frequent events reshaping chromosomes were translocations of chromosomal arms. However, also larger segmental duplications were frequent and occasionally we observed novel chromosomes. Apparently, this yeast can generate a new chromosome by duplication of chromosome segments carrying a centromere and subsequently adding novel telomeric ends. We show that the observed genome plasticity is connected with antifungal drug resistance and it is likely an advantage in the human body, where environmental conditions fluctuate a lot.chromosome rearrangements ͉ evolution ͉ genome stability ͉ pathogenicity ͉ segmental duplications

A one‐year examination of mammary secretions (n = 2,896) from Danish cattle with clinical or subclinical mastitis revealed 45 strains of fungi and algae. The strains originated from 44 mammary secretions of 42 cows in 40 herds. The following species of fungi were identified: Candida catenulata (n = 2), Candida kefyr (n = 6), Candida krusei (n=17), Candida rugosa (n = 6), Candida tropicalis (n = 3), Candida valida (n=1), Geotrichum capitatum (n = 5). The algal species Prototheca zopfii was demonstrated in five samples.

No abstract

Dual fungal and Streptococcus sanguis endocarditis is reported in a 63-year-old woman 7 months after placement of a porcine aortic valve prosthesis. Both microorganisms were isolated by blood cultures, and the patient succumbed after a full course of antibacterial chemotherapy without having received antifungal chemotherapy. The best possible designation of the fungus was Phialemonium aft. curvatum W. Gams & W. B. Cooke, as represented by CBS 331.93. At autopsy hyphae were revealed in the porcine valve tissue by conventional staining. A hyperimmune rabbit antiserum raised towards strain CBS 331.93 and extensively absorbed with heterologous fungal antigens reacted strongly with hyphae in the valve tissue by indirect immunofluorescence technique. We consider it most likely that the Phialemonium infection evolved insidiously from the time of open heart surgery and led to a haematogenous streptococcal infection of a more fulminant course.

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”.Electronic supplementary materialThe online version of this article (doi:10.1007/s10482-013-9931-3) contains supplementary material, which is available to authorized users.