The Stability of Chromosomes in Yeast

Abstract

Five new genetic loci (chl2, chl3, chl4, chl5 and chl6) controlling transmission of yeast chromosomes in mitosis have been identified. Mutations in these loci lead to chromosome loss (10–100 times more frequently than in wild type strain) and to instability of artificial minichromosomes with different replicators and centromeric loci (cen3, cen4, cens, cen6 and cen 11). The mutations in chl2, chl3, chl4, chl5 and chl6 are nonallelic to yeast mutations described as having a high instability of chromosomes: chl1 (Liras et al. 1978), rad52 (Mortimer et al. 1981), cdc2, cdc6, cdcl4 (Hartwell and Smith 1985). The loss of artificial minichromosomes in one of the mutants obtained — chl6 — is due to nondisjunction. Thus the chl6 gene of S. cerevisiae seems to control the segregation of chromosomes in mitosis. The detailed characteristic of the chl6 mutant as well as other chl mutants will be discussed in the report.