Sister Chromatid Exchange Dynamics in Genomic Stability

Sister chromatid exchanges (SCEs) occur when identical chromatids swap segments during or after DNA replication, serving as sensitive markers of DNA repair and chromosomal integrity. These reciprocal exchanges reflect the activity of homologous recombination pathways that resolve replication‐induced lesions and restart stalled forks. Under normal conditions, SCE frequency is low and tightly regulated, but it increases in response to endogenous stressors such as reactive oxygen species or replication impediments, and to exogenous agents including radiomimetics or chemical mutagens. High SCE rates are observed in disorders of genome maintenance, including Bloom syndrome and certain cancers, where defective helicases or repair factors permit excessive recombination events. Advances in single‐cell sequencing and high‐resolution imaging now permit precise mapping of SCE sites, revealing non-random distributions that correlate with late-replicating regions, common fragile sites and repetitive DNA elements. By integrating cytogenetic assays with molecular profiling, researchers are delineating how cell type, developmental stage and environmental exposures shape SCE dynamics. As both a mechanistic probe and a biomarker, SCE analysis informs cancer risk assessment, fertility evaluations in livestock and humans, and the development of genotoxicity assays for novel compounds. Understanding the balance between necessary recombination for genome stability and pathological over‐exchange remains central to elucidating chromosomal maintenance in health and disease.

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Sister Chromatid Exchange Dynamics in Genomic Stability publication trend

The graph below shows the total number of articles in sister chromatid exchange dynamics in genomic stability across all publications each year (not limited to Nature Index journals).

Technical terms

Sister chromatid exchange (SCE): A reciprocal recombination event between identical sister chromatids during or after DNA replication, used as a cytogenetic marker of genome instability.

Bromodeoxyuridine (BrdU): A thymidine analogue incorporated into DNA during replication, traditionally used to differentially label sister chromatids for SCE detection.

5-Ethynyl-2'-deoxyuridine (EdU): A thymidine analogue detected via click chemistry, enabling non-radioactive, fluorescence-based labelling of newly synthesised DNA strands.

Fragile site (FS): Specific chromosomal loci prone to forming gaps or breaks under replication stress, often co-localising with regions of high SCE frequency.

Comet assay (single-cell gel electrophoresis): A technique measuring DNA strand breaks at the single-cell level, used alongside SCE assays to assess genomic damage.

References

1. Bromodeoxyuridine does not contribute to sister chromatid exchange events in normal or Bloom syndrome cells. Nucleic Acids Research (2016).
2. Effect of Selected Micro- and Macroelements and Vitamins on the Genome Stability of Bovine Embryo Transfer Recipients following In Vitro Fertilization. Animals (2023).
3. EdU-Based Step-by-Step Method for the Detection of Sister Chromatid Exchanges for Application in Plant Genotoxicity Assessment. Frontiers in Plant Science (2020).