Loss of heterozygosity in yeast can occur by ultraviolet irradiation during the S phase of the cell cycle

Yasukazu Daigaku, Satsuki Mashiko, Keiichiro Mishiba, Saburo Yamamura, Ayako Ui, Takemi Enomoto, Kazuo Yamamoto

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


A CAN1/can1Δ heterozygous allele that determines loss of heterozygosity (LOH) was used to study recombination in Saccharomyces cerevisiae cells exposed to ultraviolet (UV) light at different points in the cell cycle. With this allele, recombination events can be detected as canavanine-resistant mutations after exposure of cells to UV radiation, since a significant fraction of LOH events appear to arise from recombination between homologous chromosomes. The radiation caused a higher level of LOH in cells that were in the S phase of the cell cycle relative to either cells at other points in the cell cycle or unsynchronized cells. In contrast, the inactivation of nucleotide excision repair abolished the cell cycle-specific induction by UV of LOH. We hypothesize that DNA lesions, if not repaired, were converted into double-strand breaks during stalled replication and these breaks could be repaired through recombination using a non-sister chromatid and probably also the sister chromatid. We argue that LOH may be an outcome used by yeast cells to recover from stalled replication at a lesion.

Original languageEnglish
Pages (from-to)177-183
Number of pages7
JournalMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Issue number1-2
Publication statusPublished - 2006 Aug 30


  • Canavanine-resistance
  • Cell cycle
  • Loss of heterozygosity
  • Saccharomyces cerevisiae
  • Ultraviolet light

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Health, Toxicology and Mutagenesis


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