| 1. |
- Beck, Halfdan, et al.
(författare)
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Saccharomyces kluyveri as a model organism to study pyrimidine degradation.
- 2008
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 8:8, s. 1209-1213
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The yeast Saccharomyces kluyveri (Lachancea kluyveri), a far relative of Saccharomyces cerevisiae, is not a widely studied organism in the laboratory. However, significant contributions to the understanding of nucleic acid precursors degradation in eukaryotes have been made using this model organism. Here we review eukaryotic pyrimidine degradation with emphasis on the contributions made with S. kluyveri and how this increases our understanding of human disease. Additionally, we discuss the possibilities and limitations of this nonconventional yeast as a laboratory organism.
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| 2. |
- Fekete, Veronika, et al.
(författare)
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Transition of the ability to generate petites in the Saccharomyces/Kluyveromyces complex
- 2007
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 7:8, s. 1237-1247
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Tidskriftsartikel (refereegranskat)abstract
- Petite-positivity - the ability to tolerate the loss of mtDNA - was examined after the treatment with ethidium bromide (EB) in over hundred isolates from the Saccharomyces/Kluyveromyces complex. The identity of petite mutants was confirmed by the loss of specific mtDNA DAPI staining patterns. Besides unequivocal petite-positive and petite-negative phenotypes, a few species exhibited temperature sensitive petite positive phenotype and petiteness of a few other species could be observed only at the elevated EB concentrations. Several yeast species displayed a mixed 'moot' phenotype, where a major part of the population did not tolerate the loss of mtDNA but several cells did. The genera from postwhole-genome duplication lineages (Saccharomyces, Kazachstania, Naumovia, Nakaseomyces) were invariably petite-positive. However, petite-positive traits could also be observed among the prewhole-genome duplication species.
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| 3. |
- Fonseca, Alvaro, et al.
(författare)
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Professor Isabel Spencer-Martins 1951-2008 OBITUARY
- 2008
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 8:7, s. 1208-1208
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Logg, Katarina, 1979, et al.
(författare)
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Investigations on light-induced stress in fluorescence microscopy using nuclear localization of the transcription factor Msn2p as a reporter
- 2009
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 9:6, s. 875-884
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Tidskriftsartikel (refereegranskat)abstract
- We utilized the nuclear localization of a stress-sensitive transcription factor, Msn2p, to study light-induced stress caused by time-lapse fluorescence imaging of green fluorescent protein (GFP) in budding yeast Saccharomyces cerevisiae. A range of exposure times, light intensities and intervals between exposures were tested in order to provide guidelines for noninvasive imaging. We found that the cellular response, revealed as an enhanced nuclear shuttling of Msn2p-GFP, is induced at significantly lower light exposures than those causing observable changes in cell morphology or cell growth. However, no stress induction was observed if the accumulated photon energy per area unit used to obtain an image was maintained at 0.16 J cm−2 or below. Above this 'safe' level, the stress response is determined by both the intensity and the exposure time. In particular, for a given accumulated photon energy per area unit, a high intensity applied during a short exposure causes more stress than vice versa. Interestingly, no correlation was found between the degree of stress and the absolute fluorescence signal, indicating that light-induced cellular stress in the studied system is not specifically related to GFP excitation.
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| 5. |
- Merico, Annamaria, et al.
(författare)
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The oxygen level determines the fermentation pattern in Kluyveromyces lactis
- 2009
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 9:5, s. 749-756
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Tidskriftsartikel (refereegranskat)abstract
- Yeasts belonging to the lineage that underwent whole-genome duplication (WGD) possess a good fermentative potential and can proliferate in the absence of oxygen. In this study, we analyzed the pre-WGD yeast Kluyveromyces lactis and its ability to grow under oxygen-limited conditions. Under these conditions, K. lactis starts to increase the glucose metabolism and accumulates ethanol and glycerol. However, under more limited conditions, the fermentative metabolism decreases, causing a slow growth rate. In contrast, Saccharomyces cerevisiae and Saccharomyces kluyveri in anaerobiosis exhibit almost the same growth rate as in aerobiosis. In this work, we showed that in K. lactis, under oxygen-limited conditions, a decreased expression of RAG1 occurred. The activity of glucose-6-phosphate dehydrogenase also decreased, likely causing a reduced flux in the pentose phosphate pathway. Comparison of related and characterized yeasts suggests that the behavior observed in K. lactis could reflect the lack of an efficient mechanism to maintain a high glycolytic flux and to balance the redox homeostasis under hypoxic conditions. This could be a consequence of a recent specialization of K. lactis toward living in a niche where the ethanol accumulation at high oxygen concentrations and the ability to survive at a low oxygen concentration do not represent an advantage.
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| 6. |
- Rhodin, Jenny, et al.
(författare)
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Highly sequence-specific binding is retained within the DNA-binding domain of the Saccharomyces castellii Cdc13 telomere-binding protein
- 2008
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 8:8, s. 1289-1302
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Tidskriftsartikel (refereegranskat)abstract
- The essential protein Cdc13p binds the single-stranded telomeric 3' overhangs in Saccharomyces cerevisiae and takes part in the regulation of telomere length. The DNA-binding domain (DBD) of Cdc13p is structurally established by an oligonucleotide/oligosaccharide-binding (OB)-fold domain. The sequence homolog in Saccharomyces castellii (scasCDC13) was characterized previously, and the full-length protein was found to bind telomeric DNA specifically. Here, the DBD of scasCdc13p was defined to the central part (402-658) of the protein. The region necessary for forming the scasCdc13p-DBD is larger than the minimal DBD of S. cerevisiae Cdc13p. Deletion of this extended DBD region from the full-length protein completely abolished the DNA binding, indicating the importance of the extended region for the correct formation of a binding-competent DBD. The scasCdc13p-DBD bound the same 8-mer minimal binding site as the full-length protein, but an extension of the target site in the 3' end increased the stability of the DNA-protein complex. Significantly, scasCdc13p-DBD showed a retained high sequence specific binding, where the four nucleotides of most importance for the sequence specificity are highly conserved in eukaryotic telomeric repeats. Thus, the unique single-stranded DNA-binding properties of the full-length protein are entirely retained within the isolated scasCdc13p-DBD.
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| 7. |
- Gombault, Aurélie, et al.
(författare)
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A phenotypic study of TFS1 mutants differentially altered in the inhibition of Ira2p or CPY.
- 2009
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Ingår i: FEMS yeast research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 9:6, s. 867-74
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Tidskriftsartikel (refereegranskat)abstract
- The Saccharomyces cerevisiae protein Tfs1p is known as a dual protein. On the one hand, it inhibits the carboxypeptidase Y protease, and on the other, it inhibits Ira2p, a GTPase-activating protein of Ras. We managed to dissect precise areas of Tfs1p specifically involved in only one of those functions. Based on these data, specific Tfs1p point mutants affected in only one of these two functions were constructed. In order to obtain insights on the physiological role of these functions, systematic phenotypic tests were performed on strains expressing these specific Tfs1p mutants. The results obtained demonstrate that the inhibition of Ira2p by Tfs1p is the predominant function under the conditions tested.
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| 8. |
- Olstorpe, Matilda, et al.
(författare)
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Screening of yeast strains for phytase activity
- 2009
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Ingår i: FEMS yeast research (Print). - Oxford, United Kingdom : Oxford University Press. - 1567-1356 .- 1567-1364. ; 9:3, s. 478-488
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Tidskriftsartikel (refereegranskat)abstract
- A screening method was developed to elucidate the ability of different yeast strains to utilize phytic acid as sole phosphorus source. The growth test in liquid culture in a microtiter plate with phytic acid as sole phosphorus source was shown to be a reliable, fast and easy-to-use screening method. We tested 122 strains from 61 species with our method and observed growth differences among species and strains that were not detectable on solid medium. Specific phytase activities were measured for 10 yeasts strains, selected due to their strong growth in the liquid medium. Strains of Arxula adeninivorans and Pichia anomala reached the highest volumetric phytase activities. Arxula adeninivorans also displayed the highest intra- and extracellular specific activities. There were large differences in both extra- and intracellular phytase activities among species. Strain-specific extracellular phytase activities were detected in P. anomala. The presence of free phosphate in the media completely suppressed the extracellular phytase activity and also reduced intracellular phytase activity for all tested yeast strains.
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| 9. |
- Passoth, V., et al.
(författare)
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Biotechnology, physiology and genetics of the yeast Pichia anomala
- 2006
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Ingår i: FEMS yeast research (Print). - Oxon, United Kingdom : Blackwell Publishing. - 1567-1356 .- 1567-1364. ; 6:1, s. 3-13
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Forskningsöversikt (refereegranskat)abstract
- The ascomycetous yeast Pichia anomala is frequently associated with food and feed products, either as a production organism or as a spoilage yeast. It belongs to the nonSaccharomyces wine yeasts and contributes to the wine aroma by the production of volatile compounds. The ability to grow in preserved food and feed environments is due to its capacity to grow under low pH, high osmotic pressure and low oxygen tension. A new application of P. anomala is its use as a biocontrol agent, which is based on the potential to inhibit a variety of moulds in different environments. Although classified as a biosafety class-1 organism, cases of P. anomala infections have been reported in immunocompromised patients. On the other hand, P. anomala killer toxins have a potential as antimicrobial agents. The yeast can use a broad range of nitrogen and phosphor sources, which makes it a potential agent to decrease environmental pollution by organic residues from agriculture. However, present knowledge of the physiological basis of its performance is limited. Recently, the first studies have been published dealing with the global regulation of the metabolism of P. anomala under different conditions of oxygenation.
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| 10. |
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