Related Experiment Video
Updated: Oct 4, 2026

Electrophoretic Analysis of Replication Through Structure-Prone DNA Repeats Within the SV40-Based Human Episome
Published on: September 13, 2024
Spontaneous and ultraviolet light-induced direct repeat recombination in mammalian cells frequently results in repeat
1Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, Albuquerque, NM 87131, USA.
Abstract:
Recombination is enhanced by transcription and by DNA damage caused by ultraviolet light (UV). Recombination between direct repeats can occur by gene conversion without an associated crossover, which maintains the gross repeat structure. There are several possible mechanisms that delete one repeat and the intervening sequences (gene conversion associated with a crossover, unequal sister chromatid exchange, and single-strand annealing). We examined transcription-enhanced spontaneous recombination, and UV-induced recombination between neomycin (neo) direct repeats. One neo gene was driven by the inducible MMTV promoter. Multiple (silent) markers in the second neo gene were used to map conversion tracts. These markers are thought to inhibit spontaneous recombination, and our data suggest that this inhibition is partially overcome by high level transcription. Recombination was stimulated by transcription and by UV doses of 6-12J/m(2), but not by 18J/m(2). About 70% of spontaneous and UV-induced products were deletions. In contrast, only 3% of DSB-induced products were deletions. We propose that these product spectra differ because spontaneous and UV-induced recombination is replication-dependent, whereas DSB-induced recombination is replication-independent.
More Related Videos
06:44Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging
Published on: April 28, 2021
08:18Application of Laser Micro-irradiation for Examination of Single and Double Strand Break Repair in Mammalian Cells
Published on: September 5, 2017
Related Concept Videos
Spontaneous and Induced Mutations
Fixing Double-strand Breaks
Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Mutations
Nucleotide Excision Repair
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Nucleotide Excision Repair