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Updated: Oct 9, 2026

Microscopy of Fission Yeast Sexual Lifecycle
07:47

Microscopy of Fission Yeast Sexual Lifecycle

Published on: March 9, 2016

Fate of mat1 DNA strands during mating-type switching in fission yeast

B Arcangioli1

  • 1Unité des Virus Oncogènes, URA 1644 du CNRS, Département des Biotechnologies, Institut Pasteur, Paris, France. barcan@pasteur.fr

EMBO Reports
|March 27, 2001
PubMed

Insights

Fission yeast mating-type switching involves a unique DNA replication process where one-fourth of mat1 DNA is synthesized de novo, not semi-conservatively. This mechanism, involving gene conversion and DNA breaks, links molecular events to the switching phenotype.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • Mating-type switching in Schizosaccharomyces pombe is a precisely regulated process.
  • This switching occurs over two asymmetric cell divisions, yielding one switched cell from four progeny.

Purpose of the Study:

  • To elucidate the molecular mechanism of DNA replication during mating-type switching in fission yeast.
  • To investigate the role of DNA breaks and gene conversion in the mat1 locus.

Main Methods:

  • DNA density-gradient centrifugation was employed to analyze DNA replication patterns.
  • Site- and strand-specific DNA breaks (SSBs) were investigated in the mat1 locus.

Main Results:

  • One-fourth of mat1 DNA replication proceeds via de novo synthesis, deviating from the semi-conservative model.
  • Evidence suggests a gene conversion event initiated by a site- and strand-specific DNA break.
  • The nick present in the switched mat1 chromatid is reintroduced during lagging strand synthesis in the sister chromatid.

Conclusions:

  • The study establishes a molecular link between DNA replication anomalies and the asymmetric mating-type switching phenotype.
  • The findings provide a detailed molecular understanding of a unique DNA repair and replication process in fission yeast.

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