Spontaneous mutagenesis in haploid and diploid Saccharomyces cerevisiae

Gaku Ohnishi, Kingo Endo, Akiko Doi, Atsushige Fujita, Yasukazu Daigaku, Tatsuo Nunoshiba, Kazuo Yamamoto

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


To obtain insights into the mechanisms of spontaneous mutations in Saccharomyces cerevisiae, we have characterized the genetic alterations that inactivate either the CAN1 gene in haploid cells or heterozygously situated in diploid cells. The mutation rate in haploid cells was 9.08 × 10 -7, 100-fold lower than that in diploid cells (1.03 × 10 -4). In haploid cells, among 69 independent CAN1 mutations, 75% were base substitutions and 22% frameshifts. The base substitutions were both transitions (33%) and transversions (42%), with G:C → A:T and G:C → T:A dominating. Minus frameshifts (12%) and plus frameshifts (10%) were also observed at run and non-run bases, and at A:T and G:C pairs with almost equal efficiency. An analysis of chromosome structure in diploid yeast cells indicated that allelic crossover was the predominant event followed by gene conversion and chromosome loss. We argued that genetic alterations leading to spontaneous phenotypic changes in wild-type diploid yeast cells occurred through two steps; replication-dependent alterations of bases in either allele then recombination-dependent transfer of the mutated allele to the intact one.

Original languageEnglish
Pages (from-to)928-933
Number of pages6
JournalBiochemical and biophysical research communications
Issue number3
Publication statusPublished - 2004 Dec 17
Externally publishedYes


  • CAN1 gene
  • Diploid
  • Haploid
  • Loss of heterozygosity
  • Saccharomyces cerevisiae
  • Spontaneous mutagenesis

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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