DNA-length polymorphisms of chromosome III in the yeast Saccharomyces cerevisiae

Yeast strains which form velum on the surface of Sherry wine during the aging process have been isolated and characterized. According to their metabolic and molecular features most of the yeasts that were isolated belong to different races of Saccharomyces cerevisiae (beticus, cheresiensis, montuliensis and rouxii). Due to the conditions under which these yeasts were isolated, all strains have in common the capacity to develop a film as an adaptive mechanism which allows them to grow and survive in 15.5% vol. ethanol. All strains were prototrophs for amino acids and most vitamins but they gave different responses to the killer factor. However, whereas their physiological features were similar, they showed a great heterogeneity with regards to the nuclear and mitochondrial genome (mtDNA): DNA content per cell was quite variable (1.3 to 2n), electrophoretic karyotypes of nuclear genomes indicated a main pattern with some variations, and polymorphism shown by the mtDNA was very high. Under extreme conditions such as Sherry wine with 15.5% vol. ethanol, no fermentable sugar and an exclusively oxidative metabolism, cells hardly grow and the maintenance of a live population depends on survival and respiration, which in turn depend on the mtDNA. At the same time these environmental conditions are mutagenic for the mtDNA, causing an increase in variation. Thus, the polymorphism observed might reflect the enormous variability induced by the ethanol followed by the selection of those mtDNA sequences which make the mitochondria metabolically active under these conditions.

Section: Discussionmentioning

confidence: 99%

Physiological and molecular characterization of flor yeasts: Polymorphism of flor yeast populations

Martínez¹,

Codón

Pérez³

et al. 1995

“…The flor yeasts analysed in this study share very different chromosome constitutions than euploid laboratory strains and exhibit a greater relative chromosome polymorphism than sherry flor yeast strains. Since our wine strains sporulate, this additional chromosome polymorphism (which is restricted to a few specific chromosomes) may be generated during meiosis or sporulation, physiological events which can lead to chromosome size variation (Yoda et al, 1993).…”

Section: Chromosome Markermentioning

confidence: 99%

Determination of the Relative Ploidy in DifferentSaccharomyces cerevisiae Strains used for Fermentation and ‘Flor’ Film Ageing of Dry Sherry-type Wines

Guijo

Mauricio

Salmon

et al. 1997

The full chromosomal karyotype of six enological Saccharomyces cerevisiae strains used for fermentation and biological ageing of sherry‐type wines was studied. A genetic method based on the analysis of segregation frequencies of auxotrophic markers, among random spore progeny of hybrids, constructed between laboratory and industrial wine strains (Bakalinsky and Snow, 1990) was used. This method was combined with the analysis of strains by pulsed‐field gel electrophoresis. The results obtained clearly indicate the presence of two, three or four copies of a chromosome in the industrial strains examined, and thus confirm that aneuploidy/polyploidy is not uncommon in these strains. In all strains examined, chromosome XIII polysomy is observed. This chromosome contains the ADH2 and ADH3 loci, that code for the ADHII and ADHIII isoenzymes of alcohol dehydrogenase, which are involved in ethanol oxidative utilization during biological ageing of wines. Tetrad analysis for the ‘flor formation’ character suggests two possibilities: this character is either regulated by at least a digenic system, or by only one gene present on a chromosome which is, at least, disomic.© 1997 John Wiley & Sons, Ltd.

“…However, we can rationalize that the inverted orientation is the key for the maintenance of the duplicated fragments. Note that in the case of tandem repeats, the degree of redundancy readily changes during meiosis and mitosis (Yoda et al, 1993). It should be remembered that recombination between inversely duplicated segments does not alter the genetic information at all and that an illegitimate recombination between homologous chromosomes results in production of null-and di-centric chromosomes, which eventually leads to the loss of these chromosomes.…”

Section: Discussionmentioning

confidence: 99%

Inverted repeat of a large segment unveiled on the right arm of Saccharomyces cerevisiae chromosome II

Ohnishi

Ono

2005

By means of gene disruption analyses, Saccharomyces cerevisiae strain YPH499 was shown to have two, and only two, copies of ATP3 that encodes the γ -subunit of H + -dependent ATP synthase and locates on the right arm of chromosome II. Linkage analyses of the two distinguishably marked copies of ATP3 indicated that the distance between them was about 43 cM. Since YBR030W, an ORF proximal to ATP3 by a distance of 17 kbp, was also found to be duplicated, we marked them with two distinguishable nutritional markers, which were also distinguishable from those used for marking the two copies of ATP3, and achieved four-point linkage analyses; CEN2 marked with an appropriate nutritional marker gene was included as a reference point. And, the following linkage map was deduced: CEN2-[11 cM]-YBR030Wa-[8 cM]-ATP3a-[47 cM]-ATP3b-[55 cM]-YBR030Wb. From this map, we suspected that a segment spanning at least YBR030W-ATP3 would be inversely duplicated on the right arm of chromosome II. We then carried out chromosome fragmentation analyses, using several laboratory strains including YPH499, and obtained data in accord with our speculation for all strains, although the distance between the two copies of ATP3 varied from 48 kbp to 192 kbp among the strains examined.