| 1. |
- Ishchuk, Olena P., et al.
(författare)
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Novel centromeric loci of the wine and beer yeast dekkera bruxellensis CEN1 and CEN2
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- The wine and beer yeast Dekkera bruxellensis thrives in environments that are harsh and limiting, especially in concentrations with low oxygen and high ethanol. Its different strains' chromosomes greatly vary in number (karyotype). This study isolates two novel centromeric loci (CEN1 and CEN2), which support both the yeast's autonomous replication and the stable maintenance of plasmids. In the sequenced genome of the D. bruxellensis strain CBS 2499, CEN1 and CEN2 are each present in one copy. They differ from the known "point" CEN elements, and their biological activity is retained within ~900-1300 bp DNA segments. CEN1 and CEN2 have features of both "point" and "regional" centromeres: They contain conserved DNA elements, ARSs, short repeats, one tRNA gene, and transposon-like elements within less than 1 kb. Our discovery of a miniature inverted-repeat transposable element (MITE) next to CEN2 is the first report of such transposons in yeast. The transformants carrying circular plasmids with cloned CEN1 and CEN2 undergo a phenotypic switch: They form fluffy colonies and produce three times more biofilm. The introduction of extra copies of CEN1 and CEN2 promotes both genome rearrangements and ploidy shifts, with these effects mediated by homologous recombination (between circular plasmid and genome centromere copy) or by chromosome breakage when integrated. Also, the proximity of the MITE-like transposon to CEN2 could translocate CEN2 within the genome or cause chromosomal breaks, so promoting genome dynamics. With extra copies of CEN1 and CEN2, the yeast's enhanced capacities to rearrange its genome and to change its gene expression could increase its abilities for exploiting new and demanding niches.
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| 2. |
- Ishchuk, Olena P., et al.
(författare)
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Simple carbohydrate derivatives diminish the formation of biofilm of the pathogenic yeast candida albicans
- 2020
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Ingår i: Antibiotics. - : MDPI AG. - 2079-6382. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- The opportunistic human fungal pathogen Candida albicans relies on cell morphological transitions to develop biofilm and invade the host. In the current study, we developed new regulatory molecules, which inhibit the morphological transition of C. albicans from yeast-form cells to cells forming hyphae. These compounds, benzyl α-l-fucopyranoside and benzyl β-d-xylopyranoside, inhibit the hyphae formation and adhesion of C. albicans to a polystyrene surface, resulting in a reduced biofilm formation. The addition of cAMP to cells treated with α-l-fucopyranoside restored the yeast-hyphae switch and the biofilm level to that of the untreated control. In the β-d-xylopyranoside treated cells, the biofilm level was only partially restored by the addition of cAMP, and these cells remained mainly as yeast-form cells.
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| 3. |
- Ishchuk, Olena P., et al.
(författare)
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The use of polyhydroxylated carboxylic acids and lactones to diminish biofilm formation of the pathogenic yeast : Candida albicans
- 2019
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 9:19, s. 10983-10989
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Tidskriftsartikel (refereegranskat)abstract
- The vaginal microbiome of healthy women is a diverse and dynamic system of various microorganisms. Any sudden change in microbe composition can increase the vaginal pH and thus lead to vaginal infections, conditions that affect a large percentage of women each year. The most common fungal strains involved in infections belong to the yeast species Candida albicans. The main virulence factor of C. albicans is the ability to transform from planktonic yeast-form cells into a filamentous form (hyphae or pseudohyphae), with the subsequent formation of biofilm. The hyphal form, constituted by filamentous cells, has the ability to invade tissue and induce inflammation. Our hypothesis is that certain polyhydroxylated carboxylic acids, that may serve as an alternative carbohydrate source and at the same time lower the pH, function as an indicator of a nutrient-rich environment for C. albicans, which favors planktonic cells over hyphae, and thus diminish the formation of biofilm. We have shown that the biofilm formation in C. albicans and other Candida species can be significantly reduced by the addition of glucono-δ-lactone (GDL).
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