Selection and analysis of mitotic crossovers in Saccharomyces cerevisiae Public Deposited

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  • March 22, 2019
  • Barbera, Maria Antonia
    • Affiliation: School of Medicine, Curriculum in Genetics and Molecular Biology
  • Mitotic recombination is an important mechanism of DNA repair in eukaryotic cells. I have developed a novel system that allows the selection of the reciprocal products resulting from spontaneous mitotic crossovers in the yeast Saccharomyces cerevisiae. A number of other types of genetic events, including chromosome loss, can be monitored with this system. For a 120 kb chromosome interval on chromosome V (CEN5 - CAN1), the rate of mitotic crossovers was 4 x 10-5 per division, a rate approximately 25,000-fold lower than the meiotic rate of crossovers. We found no suppression of mitotic crossovers near the centromere of chromosome V, unlike the suppression observed for meiotic exchanges. A tract of trinucleotide repeats, (CTG)115, did not stimulate mitotic recombination or chromosome loss. The rate of reciprocal crossovers was substantially (38-fold) elevated by treatment of cells with hydroxyurea, a drug that reduces nucleotide pools and slows DNA replication. When cells were irradiated with 20 J/m2 UV-light, a dose that results in 90% survival of the cells, mitotic crossovers were stimulated 175-fold. The effect of the mating-type alleles on spontaneous and induced recombination was also examined. Although the analysis with this system was limited to one genetic interval on chromosome V, the same approach can be extended to any region of the yeast genome.
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  • In Copyright
  • Petes, Thomas D.
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  • University of North Carolina at Chapel Hill
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