| 1. |
- Naumov, Gennadi I., et al.
(författare)
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Genetic characterization of the nonconventional yeast Hansenula anomala
- 2001
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Ingår i: Research in Microbiology. - : Elsevier. - 0923-2508 .- 1769-7123. ; 152:6, s. 551-562
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Tidskriftsartikel (refereegranskat)abstract
- We describe genetic, molecular and taxonomic characteristics of the yeast Hansenula anomala. Pulsed-field gel electrophoresis of chromosomal DNAs from 19 H. anomala strains and related species indicated that H. anomala had a clearly different karyotype. Chromosome length polymorphism of the H. anomala strains was independent of their geographic origin and source of isolation. The strains were classified into four groups of similar karyotypes and one strain showed a unique profile. The sizes of chromosomes ranged from 850 to 3500 kb in different strains. The haploid chromosome number of H. anomala is at least nine. We have found RAPD primers discriminating at both the species and strain levels. All the primers tested except the M13 core sequence generated unique patterns with most strains. The results indicate the usefulness of PCR analysis with primer M13 for identification of the H. anomala species. Screening of the CBS (Utrecht) collection strains of H. anomala showed that they are rather difficult objects for genetic hybridization analysis. The strains have low fertility, viz. very poor sporulation, low mating type activities and, as a rule, nonviable ascospores. The majority of the hybrids obtained are polyploid, probably tetraploid, as judged by the segregation of control auxotrophic markers. Nevertheless, some monosporic cultures of the strains studied, including the biocontrol yeast J121, formed diploid hybrids with regular meiotic segregation of control auxotrophic markers. As a rule, H. anomala isolates are homothallic, showing delayed self-diploidization. Rare stable heterothallic strains of H. anomala also occur.
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| 2. |
- Tellini, Nicolo, et al.
(författare)
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Ancient and recent origins of shared polymorphisms in yeast
- 2024
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Ingår i: NATURE ECOLOGY & EVOLUTION. - 2397-334X. ; 8, s. 761-776
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Tidskriftsartikel (refereegranskat)abstract
- Shared genetic polymorphisms between populations and species can be ascribed to ancestral variation or to more recent gene flow. Here, we mapped shared polymorphisms in Saccharomyces cerevisiae and its sister species Saccharomyces paradoxus, which diverged 4-6 million years ago. We used a dense map of single-nucleotide diagnostic markers (mean distance 15.6 base pairs) in 1,673 sequenced S. cerevisiae isolates to catalogue 3,852 sequence blocks (>= 5 consecutive markers) introgressed from S. paradoxus, with most being recent and clade-specific. The highly diverged wild Chinese S. cerevisiae lineages were depleted of introgressed blocks but retained an excess of individual ancestral polymorphisms derived from incomplete lineage sorting, perhaps due to less dramatic population bottlenecks. In the non-Chinese S. cerevisiae lineages, we inferred major hybridization events and detected cases of overlapping introgressed blocks across distinct clades due to either shared histories or convergent evolution. We experimentally engineered, in otherwise isogenic backgrounds, the introgressed PAD1-FDC1 gene pair that independently arose in two S. cerevisiae clades and revealed that it increases resistance against diverse antifungal drugs. Overall, our study retraces the histories of divergence and secondary contacts across S. cerevisiae and S. paradoxus populations and unveils a functional outcome. Analysis of 1,673 sequenced Saccharomyces cerevisiae isolates identifies 3,852 sequence blocks introgressed from Saccharomyces paradoxus, most of which are recent and clade-specific. By contrast, divergent Chinese strains of S. cerevisiae show little evidence of introgression but do share ancient polymorphisms with S. paradoxus due to incomplete lineage sorting.
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