Jesús Ambrona

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Wine Saccharomyces cerevisiae strains producing a new killer toxin (Klus) were isolated. They killed all the previously known S. cerevisiae killer strains, in addition to other yeast species, including Kluyveromyces lactis and Candida albicans. The Klus phenotype is conferred by a medium-size double-stranded RNA (dsRNA) virus, Saccharomyces cerevisiae virus(More)
Genetic instability and genome renewal may cause loss of heterozygosity (LOH) in homothallic wine yeasts (Saccharomyces cerevisiae), leading to the elimination of the recessive lethal or deleterious alleles that decrease yeast fitness. LOH was not detected in genetically stable wine yeasts during must fermentation. However, after sporulation, the(More)
We describe a genetic instability found in natural wine yeasts but not in the common laboratory strains of Saccharomyces cerevisiae. Spontaneous cyh2(R)/cyh2(R) mutants resistant to high levels of cycloheximide can be directly isolated from cyh2(S)/cyh2(S) wine yeasts. Heterozygous cyh2(R)/cyh2(S) hybrid clones vary in genetic instability as measured by(More)
Winemaking with selected yeasts requires simple techniques to monitor the inoculated yeast. New high-concentration rhodamine-resistant mutants and low-concentration rhodamine-pink mutants, easy to detect by replica-plate assay, were obtained from selected wine yeasts. The rhodamine-pink mutations were dominant and were located at the pdr5 locus that encodes(More)
Genetic instability causes very rapid asymmetrical loss of heterozygosity (LOH) at the cyh2 locus and loss of killer K2 phenotype in some wine yeasts under the usual laboratory propagation conditions or after long freeze-storage. The direction of this asymmetrical evolution in heterozygous cyh2(R)/CYH2(S) hybrids is determined by the mechanism of(More)
Winemaking with selected yeasts requires simple and cheap techniques to monitor the yeast population dynamics. We obtained new sulfometuron (smr) resistant mutants, easy to detect by replica-plate assay, from selected wine yeasts. The mutations were dominant and were located at the ilv2 locus that encodes for acetolactate synthase enzyme. The mutants were(More)
The use of new transgenic yeasts in industry carries a potential environmental risk because their dispersal, introducing new artificial genetic combinations into nature, could have unpredictable consequences. This risk could be avoided by using sterile transgenic yeasts that are unable to sporulate and mate with wild yeasts. These sterile yeasts would not(More)
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