Related Experiment Video
Updated: Jun 20, 2026
06:18
Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
Published on: July 11, 2025
Condensins regulate meiotic DNA break distribution, thus crossover frequency, by controlling chromosome structure
David G Mets1, Barbara J Meyer
1Howard Hughes Medical Institute, University of California-Berkeley, Berkeley, CA 94720-3204, USA.
Cell
|September 29, 2009
Summary
A novel condensin complex regulates meiotic crossover (CO) distribution by controlling DNA double-strand break (DSB) formation. This finding reveals how chromosome structure influences CO recombination and evolution.
Area of Science:
- Genetics
- Molecular Biology
- Evolutionary Biology
Background:
- Meiotic crossover (CO) recombination is essential for accurate chromosome segregation and evolution.
- CO distribution is tightly regulated, with specific patterns like nonrandom spacing and preference for hotspots.
- Understanding the molecular mechanisms controlling CO distribution is crucial for comprehending genome stability and evolution.
Purpose of the Study:
- To identify the molecular machinery that regulates the number and distribution of meiotic crossovers (COs) on a chromosome-wide scale.
- To investigate the role of chromosome structure in the regulation of CO recombination.
- To provide a model for the evolution of CO hotspots.
Main Methods:
- Utilized a C. elegans model system.
- Investigated the function of a novel condensin complex composed of subunits from the dosage compensation complex and mitotic condensin II.
- Analyzed DNA double-strand break (DSB) formation and distribution.
- Examined meiotic chromosome axis length.
- Performed genetic disruption experiments and cosuppression analysis.
Main Results:
- Identified a condensin complex controlling CO number and distribution at the level of DNA double-strand break (DSB) formation.
- Disruption of any subunit of this CO-controlling condensin altered DSB distribution, affecting COs and extending meiotic chromosome axes.
- These phenotypes were partially rescued by disrupting a chromosome axis element, suggesting a link between chromosome structure and CO regulation.
- Demonstrated that higher-order chromosome structure plays a role in regulating CO recombination.
Conclusions:
- A specific condensin complex regulates meiotic CO distribution by influencing DSB formation.
- This regulation is linked to higher-order chromosome structure.
- The findings offer a model for the rapid evolution of CO hotspots and highlight how molecular part shuffling can create distinct functional machines.
Related Concept Videos
02:15Condensins
Condensins are large protein complexes that use ATP to fuel the assembly of chromosomes during mitosis. They transform the tangled, shapeless mass of post-interphase DNA into individualized chromosomes by compacting, organizing, and segregating chromosomal DNA.
The plant and animal cells contain two types of condensin complexes—condensin I and condensin II. Both complexes have five subunits: two SMC (Structural Maintenance of Chromosomes) subunits, a kleisin subunit, and two HEAT-repeat...
The plant and animal cells contain two types of condensin complexes—condensin I and condensin II. Both complexes have five subunits: two SMC (Structural Maintenance of Chromosomes) subunits, a kleisin subunit, and two HEAT-repeat...
02:15Condensins
Condensins are large protein complexes that use ATP to fuel the assembly of chromosomes during mitosis. They transform the tangled, shapeless mass of post-interphase DNA into individualized chromosomes by compacting, organizing, and segregating chromosomal DNA.
The plant and animal cells contain two types of condensin complexes—condensin I and condensin II. Both complexes have five subunits: two SMC (Structural Maintenance of Chromosomes) subunits, a kleisin subunit, and two HEAT-repeat...
The plant and animal cells contain two types of condensin complexes—condensin I and condensin II. Both complexes have five subunits: two SMC (Structural Maintenance of Chromosomes) subunits, a kleisin subunit, and two HEAT-repeat...
01:34Crossing Over
Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
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...
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...
01:30Crossing Over
Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...
02:08Gene Conversion
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...
02:20Cohesins
Cohesin protein complexes are a molecular glue that holds two sister chromatids together. They play an important role both in mitosis and meiosis. In mitosis, all cohesin complexes present on the chromosomes are removed before the start of the anaphase stage.
Cohesin complexes in Meiotic Division
Meiosis involves two distinct rounds of chromosomal segregation and cell divisions— Meiosis I followed by Meiosis II – producing four daughter cells. Meiosis I includes the separation of homologous...
Cohesin complexes in Meiotic Division
Meiosis involves two distinct rounds of chromosomal segregation and cell divisions— Meiosis I followed by Meiosis II – producing four daughter cells. Meiosis I includes the separation of homologous...