Chimeric types of chromosome X in bottom-fermenting yeasts

Abstract

Aim: To determine the structure of the chimeric chromosome X of bottom‐fermenting yeasts. Methods and Results: Eight cosmid clones carrying DNA from chromosome X of bottom‐fermenting yeasts were selected by end‐sequencing. Four of the cosmid clones had Saccharomyces cerevisiae (SC)‐type and Saccharomyces bayanus (SB)‐type chimeric ends, two had SC‐type ends and two had SB‐type ends. Sequencing revealed that the bottom‐fermenting yeast strains in this study had four types of chromosome X: SC–SC, SC–SB, SB–SC and SB–SB. The translocation site in the chimeric chromosome is conserved among bottom‐fermenting yeast strains, and was created by homologous recombination within a region of high sequence identity between the SC‐type sequence and the SB‐type sequence. Conclusions: Existing bottom‐fermenting yeast strains share a common ancestor in which the chimeric chromosome X was generated. Significance and Impact of the Study: The knowledge gained in this study sheds light on the evolution of bottom‐fermenting yeasts.

Isolation of Meiotic Segregants from a Bottom Fermenting Yeast

“…At any rate, it is obvious that array-CGH showed that the genotypes of meiotic segregants possessing both Lg-FLO1 and ILF1 had an increased copy number of the right end of SC-type chromosome VIII. Previous studies 1,2,12 reported that aneuploidy was also observed among bottom fermenting yeast strains. Most meiotic segregants have wort fermentability and are therefore valuable for the brewing industry.…”

“…The reason why signals of the SBtype Chromosome XI left arm of Weihenstephan34/70-1A were missing, seemed to be that SB-type Chromosome XI was missed from the Weihenstephan34/70-1A genome, while chimera-type Chromosome XI (SC left arm -SB right arm) remained. It has been reported that some bottom fermenting yeast strains possess a chimera-type Chromosome Xs (SC left arm -SB right arm, SB left arm -SC right arm) 9,12 . Thus, the reason why the signal of the SC-type Chromosome X right arm of Weihenstephan 34/70-1A was decreased appears to be similar in the case of Chromosome XIs.…”

Aneuploidy, copy number variation and unique chromosomal structures in bottom-fermenting yeast revealed by array-CGH

“…Some previous studies have used DNA microarray analysis to document aneuploidy in yeast (12)(13)(14)(15)(16)(17). While draft wholegenome sequences of some strains of S. bayanus have been reported (18,19), these S. bayanus sequences are not perfectly identical to the SB-type sequence present in bottomfermenting yeast.…”

“…Some previous studies have used DNA microarray analysis to document aneuploidy in yeast . While draft whole‐genome sequences of some strains of S .…”