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Updated: May 18, 2026
06:18
Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
Published on: July 11, 2025
Preaching about the converted: how meiotic gene conversion influences genomic diversity
Francesca Cole1, Scott Keeney, Maria Jasin
1Developmental Biology Program, Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA. ColeF@mskcc.org
Annals of the New York Academy of Sciences
|September 8, 2012
Summary
Noncrossovers (NCOs) drive most meiotic recombination and gene conversion, significantly impacting genomic diversity and transmission distortion more than crossovers (COs). This highlights NCOs
Area of Science:
- Molecular Biology
- Genetics
- Evolutionary Biology
Background:
- Meiotic recombination generates genomic diversity through crossovers (COs) and independent assortment.
- Gene conversion, often linked to COs, involves unidirectional transfer of genetic information.
- The role of noncrossovers (NCOs) in gene conversion and their impact on diversity were previously underestimated.
Purpose of the Study:
- To comprehensively analyze meiotic recombination events at a mouse hotspot.
- To quantify the relative contributions of COs and NCOs to gene conversion and transmission distortion.
- To assess the impact of NCO characteristics on mammalian evolution and genomic diversity.
Main Methods:
- Analysis of recombination at a highly polymorphic mouse hotspot.
- Distinguishing between crossover (CO) and noncrossover (NCO) recombination events.
- Estimating gene conversion and transmission distortion contributions based on preferential recombination initiation.
Main Results:
- Noncrossovers (NCOs) constitute approximately 90% of observed meiotic recombination events.
- NCO gene conversion, despite shorter tracts, contributes twice as much to allelic shuffling and transmission distortion as CO gene conversion.
- Preferential initiation on one chromosome enabled estimation of NCO and CO contributions to transmission distortion.
Conclusions:
- Noncrossovers (NCOs) are the predominant form of meiotic recombination and a major driver of gene conversion.
- NCOs significantly influence allelic diversity and transmission distortion, impacting population genetics.
- The characteristics of mammalian NCOs warrant further investigation for their evolutionary implications.
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Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
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01:34Crossing Over
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The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
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