Effect of chromosome loss in diploid strains of Saccharomyces cerevisiae on the growth of the resultant aneuploid cells - Note

Aneuploid (2n-1) strains of Saccharomyces cerevisiae which had lost any one of their chromosomes formed smaller colonies than did their parental diploid (2n) strains, and the colony size varied depending upon which chromosome was lost. For further analyses of these phenomena, two different 2n-1 strains which had lost any one of 14 chromosomes were constructed by using a DNA cassette designed for the specific chromosome loss. Comparison of colony sizes and growth rates indicated that the 2n-1 strains grew more slowly as the size of their lost chromosomes increased. The viability of growing 2n-1 cells was more than 99%, but the population of cells with large buds al the log phase was much higher in the 2n-1 strains than in the 2n strain, and the ratio of cells with large buds increased with increasing size of lost chromosomes. Since most of the large daughter cells had their own nucleus, slower growth of the 2n-1 strains is possibly caused by some delay al a certain step after the disjunction of nuclei.