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Small chromosomes among Danish Candida glabrata isolates originated through different mechanisms.

Ahmad KM, Ishchuk OP, Hellborg L, Jørgensen G, Skvarc M, Stenderup J, Jørck-Ramberg D, Polakova S, Piškur J - Antonie Van Leeuwenhoek (2013)

Bottom Line: 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).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".

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden. khadija_mohamed.ahmad@biol.lu.se

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".

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Electrophoretic karyotyping of 25 C. glabrata clinical isolates belonging to the same phylogenetic sub-group KA002574 which is arrowed in Fig. 2. Five groups of chromosomes (according to the CBS 138 nomenclature, see also Supplementary materials Fig. S1) are shown on the left, and the chromosome sizes on the right. The number of chromosome bands ranges from ten to thirteen but KA002870 (Y663) has fourteen chromosome bands because of its small chromosome (arrowed as a). The large chromosome group (K-L-M) shows a clear variation, from one band as in KA005064 to three bands, as in KA003250, or even four bands, as in KA005129. KA004709 and KA004773, arrowed as b and c, were isolated in 1997 from the same hospital but have clearly different karyotypes. In b we can see only ten bands but the third smallest chromosome (located in the C-D-E group) is likely a double band, while in c there are 12 bands
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Fig3: Electrophoretic karyotyping of 25 C. glabrata clinical isolates belonging to the same phylogenetic sub-group KA002574 which is arrowed in Fig. 2. Five groups of chromosomes (according to the CBS 138 nomenclature, see also Supplementary materials Fig. S1) are shown on the left, and the chromosome sizes on the right. The number of chromosome bands ranges from ten to thirteen but KA002870 (Y663) has fourteen chromosome bands because of its small chromosome (arrowed as a). The large chromosome group (K-L-M) shows a clear variation, from one band as in KA005064 to three bands, as in KA003250, or even four bands, as in KA005129. KA004709 and KA004773, arrowed as b and c, were isolated in 1997 from the same hospital but have clearly different karyotypes. In b we can see only ten bands but the third smallest chromosome (located in the C-D-E group) is likely a double band, while in c there are 12 bands

Mentions: Phylogenetic relationship, as deduced by Neighbor-joining method, based on the IGS region located between the CDH1 and EPR6 genes. 35 (plus CBS 138) different haplotypes (representing isolate sequences which had the available 474 positions) were deduced. The strain numbers correspond to the museum numbers of the initial collection and can be found in Supplementary materials Table 1. The names of the strains with small chromosomes are followed by a capital letter pointing out which CBS 138 chromosome is related to the small chromosome. Among the analyzed strains several sequences belonged to the same haplotype. The appearance of each haplotype, in addition to the shown strain (and if different from 1), is written in the brackets following the strain/sequence designation. The strains belonging to each of these haplotypes can be found in Supplementary methods Table S1. The group 002574 (analyzed for their karyotypes in Fig. 3) is arrowed. The bootstrap values are shown on some branches and the tree is not rooted


Small chromosomes among Danish Candida glabrata isolates originated through different mechanisms.

Ahmad KM, Ishchuk OP, Hellborg L, Jørgensen G, Skvarc M, Stenderup J, Jørck-Ramberg D, Polakova S, Piškur J - Antonie Van Leeuwenhoek (2013)

Electrophoretic karyotyping of 25 C. glabrata clinical isolates belonging to the same phylogenetic sub-group KA002574 which is arrowed in Fig. 2. Five groups of chromosomes (according to the CBS 138 nomenclature, see also Supplementary materials Fig. S1) are shown on the left, and the chromosome sizes on the right. The number of chromosome bands ranges from ten to thirteen but KA002870 (Y663) has fourteen chromosome bands because of its small chromosome (arrowed as a). The large chromosome group (K-L-M) shows a clear variation, from one band as in KA005064 to three bands, as in KA003250, or even four bands, as in KA005129. KA004709 and KA004773, arrowed as b and c, were isolated in 1997 from the same hospital but have clearly different karyotypes. In b we can see only ten bands but the third smallest chromosome (located in the C-D-E group) is likely a double band, while in c there are 12 bands
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672514&req=5

Fig3: Electrophoretic karyotyping of 25 C. glabrata clinical isolates belonging to the same phylogenetic sub-group KA002574 which is arrowed in Fig. 2. Five groups of chromosomes (according to the CBS 138 nomenclature, see also Supplementary materials Fig. S1) are shown on the left, and the chromosome sizes on the right. The number of chromosome bands ranges from ten to thirteen but KA002870 (Y663) has fourteen chromosome bands because of its small chromosome (arrowed as a). The large chromosome group (K-L-M) shows a clear variation, from one band as in KA005064 to three bands, as in KA003250, or even four bands, as in KA005129. KA004709 and KA004773, arrowed as b and c, were isolated in 1997 from the same hospital but have clearly different karyotypes. In b we can see only ten bands but the third smallest chromosome (located in the C-D-E group) is likely a double band, while in c there are 12 bands
Mentions: Phylogenetic relationship, as deduced by Neighbor-joining method, based on the IGS region located between the CDH1 and EPR6 genes. 35 (plus CBS 138) different haplotypes (representing isolate sequences which had the available 474 positions) were deduced. The strain numbers correspond to the museum numbers of the initial collection and can be found in Supplementary materials Table 1. The names of the strains with small chromosomes are followed by a capital letter pointing out which CBS 138 chromosome is related to the small chromosome. Among the analyzed strains several sequences belonged to the same haplotype. The appearance of each haplotype, in addition to the shown strain (and if different from 1), is written in the brackets following the strain/sequence designation. The strains belonging to each of these haplotypes can be found in Supplementary methods Table S1. The group 002574 (analyzed for their karyotypes in Fig. 3) is arrowed. The bootstrap values are shown on some branches and the tree is not rooted

Bottom Line: 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).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".

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden. khadija_mohamed.ahmad@biol.lu.se

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".

Show MeSH
Related in: MedlinePlus