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Recombinational DNA double-strand breaks in mice precede synapsis.
S K Mahadevaiah1, J M Turner, F Baudat
1Division of Developmental Genetics, National Institute for Medical Research, London, UK.
Nature Genetics
|March 10, 2001
Summary
Meiotic recombination in mice begins with Spo11-dependent double-strand breaks (DSBs) during leptotene. The loss of gamma-H2AX staining, marking DSB sites, correlates with synapsis, even non-homologous pairing.
Area of Science:
- Reproductive Biology
- Genetics
- Molecular Biology
Background:
- Meiotic recombination initiates via Spo11-dependent double-strand breaks (DSBs) in yeast, preceding homologous synapsis.
- Understanding DSB dynamics in mammals is crucial for reproductive health and genetic diversity.
Purpose of the Study:
- To investigate the timing, distribution, and Spo11-dependence of meiotic DSBs in the mouse.
- To characterize the role of gamma-H2AX as a marker for DSBs during mouse meiosis.
Main Methods:
- Utilized an antibody specific for phosphorylated histone gamma-H2AX to identify DSB sites.
- Examined the temporal and spatial correlation between gamma-H2AX staining and synapsis.
- Assessed the Spo11-dependence of DSB formation.
Main Results:
- Confirmed that meiotic DSBs in mice are Spo11-dependent and occur during leptotene, similar to yeast.
- Demonstrated that loss of gamma-H2AX staining is temporally and spatially linked with synapsis.
- Observed this correlation even in cases of non-homologous synapsis.
Conclusions:
- Meiotic recombination in mice is initiated by Spo11-dependent DSBs during leptotene.
- Gamma-H2AX serves as a reliable marker for DSBs and their repair dynamics during mouse meiosis.
- DSB repair and synapsis are coordinated processes, irrespective of homologous pairing.