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Cyclin B-cdk activity stimulates meiotic rereplication in budding yeast
Randy Strich1, Michael J Mallory, Michal Jarnik
1Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA. randy.strich@fccc.edu
Genetics
|September 3, 2004
Summary
Budding yeast can undergo extra DNA replication rounds during meiosis when cyclin B/cyclin-dependent kinase is activated. This unexpected rereplication still results in viable, haploid spores, challenging existing models of meiotic regulation.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- Meiosis involves one DNA replication (meiS) followed by two divisions to produce haploid gametes.
- Understanding the regulation of DNA replication during meiosis is crucial for reproductive success.
Purpose of the Study:
- To investigate the effects of ectopic cyclin B/cyclin-dependent kinase activation on DNA replication during meiosis in budding yeast.
- To determine if DNA rereplication during meiosis impacts spore viability and ploidy.
Main Methods:
- Ectopic activation of cyclin B/cyclin-dependent kinase in budding yeast.
- Microscopy and genetic analysis to assess DNA content, nuclear divisions, and spore viability.
- Investigating the role of synaptonemal complex formation and recombination.
Main Results:
- Ectopic cyclin B/CDK activation induced one to three additional rounds of meiS in up to 30% of meiotic cells.
- Overreplicated cells produced viable, haploid spores with Mendelian segregation, indicating successful meiosis I.
- Interference with synaptonemal complex or recombination enhanced rereplication efficiency.
Conclusions:
- The block to DNA rereplication differs significantly between meiotic and mitotic cells.
- Recombination machinery may negatively regulate meiotic DNA rereplication.
- Cells appear to count replication cycles, not chromosome content, to determine nuclear divisions.