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Related Concept Videos

Gene Conversion02:08

Gene 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...
Gene Conversion02:08

Gene 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...
Fixing Double-strand Breaks02:04

Fixing Double-strand Breaks

The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
Fixing Double-strand Breaks02:04

Fixing Double-strand Breaks

The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
Homologous Recombination02:31

Homologous Recombination

The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
Homologous Recombination02:31

Homologous Recombination

The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...

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Related Experiment Video

Updated: May 12, 2026

Using Next Generation Sequencing to Identify Mutations Associated with Repair of a CAS9-induced Double Strand Break Near the CD4 Promoter
06:59

Using Next Generation Sequencing to Identify Mutations Associated with Repair of a CAS9-induced Double Strand Break Near the CD4 Promoter

Published on: March 31, 2022

Alternative end-joining mechanisms: a historical perspective.

Anabelle Decottignies1

  • 1Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Faculty of Pharmacy and Biomedical Sciences, Catholic University of Louvain Brussels, Belgium.

Frontiers in Genetics
|April 9, 2013
PubMed
Summary
This summary is machine-generated.

Alternative DNA repair pathways, distinct from non-homologous end-joining (NHEJ) and homologous recombination (HR), can repair DNA double-strand breaks (DSBs) but are highly mutagenic, potentially causing cancer. Further research is needed to understand these mechanisms.

Keywords:
Ku70/Ku80alternative end-joiningchromosomal translocationdouble-strand breakmicrohomology-mediated end-joiningnon-homologous end-joiningsingle-strand annealingtelomere fusion

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Quantitation and Analysis of the Formation of HO-Endonuclease Stimulated Chromosomal Translocations by Single-Strand Annealing in Saccharomyces cerevisiae
09:40

Quantitation and Analysis of the Formation of HO-Endonuclease Stimulated Chromosomal Translocations by Single-Strand Annealing in Saccharomyces cerevisiae

Published on: September 23, 2011

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae
07:55

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Published on: September 11, 2022

Related Experiment Videos

Last Updated: May 12, 2026

Using Next Generation Sequencing to Identify Mutations Associated with Repair of a CAS9-induced Double Strand Break Near the CD4 Promoter
06:59

Using Next Generation Sequencing to Identify Mutations Associated with Repair of a CAS9-induced Double Strand Break Near the CD4 Promoter

Published on: March 31, 2022

Quantitation and Analysis of the Formation of HO-Endonuclease Stimulated Chromosomal Translocations by Single-Strand Annealing in Saccharomyces cerevisiae
09:40

Quantitation and Analysis of the Formation of HO-Endonuclease Stimulated Chromosomal Translocations by Single-Strand Annealing in Saccharomyces cerevisiae

Published on: September 23, 2011

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae
07:55

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Published on: September 11, 2022

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • DNA double-strand breaks (DSBs) are primarily repaired by non-homologous end-joining (NHEJ) and homologous recombination (HR) to prevent chromosomal aberrations.
  • NHEJ-deficient cells exhibit alternative DNA end-joining activities, operating across species and chromosomal contexts.

Purpose of the Study:

  • To investigate alternative DNA end-joining mechanisms beyond canonical NHEJ and HR.
  • To characterize the mutagenic potential and genetic requirements of these alternative pathways.

Main Methods:

  • Analysis of DNA repair activities in NHEJ-deficient cells.
  • Investigation of microhomology usage and involvement of specific DNA ligases (Ligase III and Ligase I).
  • Assessment of mutagenic outcomes, including telomere fusions and chromosomal translocations in mouse models.

Main Results:

  • Alternative end-joining often involves microhomologous sequences, requiring DNA end resection and utilizing HR single-strand annealing enzymes and DNA Ligase III.
  • A distinct alternative pathway, potentially involving DNA Ligase I, may operate without pre-existing microhomologies.
  • Both microhomology-dependent and independent alternative pathways are mutagenic, driving genomic instability and cancer-associated translocations.

Conclusions:

  • Alternative DNA end-joining mechanisms represent a significant source of mutagenicity, contributing to genomic instability and oncogenesis.
  • Understanding the genetic factors governing these pathways is crucial for future therapeutic strategies targeting cancer and other diseases involving DNA repair defects.