The cell lysis mutant is a temperature-sensitive allele of .

The mutants designated (cell lysis) cause cell lysis at elevated temperatures. The mutation, previously localized to an 80 kilobase region between and on the right arm of chromosome VII, has been used for mutation mapping and in recombination assays, but its genetic identity has remained unknown. Whole genome sequencing of mutant and wild-type strains revealed four missense mutations specific to the mutant strain in the - interval, three of these missense mutations affected essential genes. The mutation, but not the two other missense mutations, recapitulated the temperature-sensitive growth, the cell lysis phenotype, and recessive nature of the mutation. The gene encodes separase and is required for normal chromosome segregation during mitosis. Shifting cells containing the mutation to the non-permissive temperature caused chromosome missegregation based on the analysis of DNA content by flow cytometry analysis. Taken together, these results indicate that the temperature-sensitive mutation is an allele of the essential gene.