Chinese hamster DON cells with 5-bromodeoxyuridine (BrdU)-substituted chromosomes were ultraviolet (UV)-exposed and processed for in situ detection of induced DNA breaks under electron microscopy. For this purpose, UV-induced breaks were amplified by an exonuclease III digestion to obtain single stranded DNA motifs which could hybridize with oligonucleotides of random sequences. These reannealed motifs could be used as primers which were extended by the Klenow polymerase, incorporating biotinylated-dUTP that was detected by a gold-tagged streptavidin. After processing, the chromatid whose DNA was BrdU-substituted in one strand showed a higher electron density than the chromatid substituted in both strands. In contrast, the unifilarly substituted chromatid showed about twice the labelling of DNA breaks as the bifilarly substituted one. This result could be the consequence of a greater loss of chromatin tracts in the bifilarly substituted chromatid, as implied by an X-ray microanalysis which showed that the amount of phosphorous lost by the bifilarly substituted chromatid was higher than that of the unifilarly substituted chromatid.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1016/0248-4900(94)90063-9 | DOI Listing |
NAR Cancer
June 2024
Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA.
Extrachromosomal circular DNAs (eccDNAs) are produced from all regions of the eucaryotic genome. We used inverse PCR of non-B microsatellites capable of forming hairpin, triplex, quadruplex and AT-rich structures integrated at a common ectopic chromosomal site to show that these non-B DNAs generate highly mutagenized eccDNAs by replication-dependent mechanisms. Mutagenesis occurs within the non-B DNAs and extends several kilobases bidirectionally into flanking and nonallelic DNA.
View Article and Find Full Text PDFExtrachromosomal circular DNAs (eccDNAs) are produced from all regions of the eucaryotic genome. In tumors, highly transcribed eccDNAs have been implicated in oncogenesis, neoantigen production and resistance to chemotherapy. Here we show that unstable microsatellites capable of forming hairpin, triplex, quadruplex and AT-rich structures generate eccDNAs when integrated at a common ectopic site in human cells.
View Article and Find Full Text PDFPLoS One
June 2023
Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI, United States of America.
Bloom syndrome helicase (BLM) is a RecQ-family helicase implicated in a variety of cellular processes, including DNA replication, DNA repair, and telomere maintenance. Mutations in human BLM cause Bloom syndrome (BS), an autosomal recessive disorder that leads to myriad negative health impacts including a predisposition to cancer. BS-causing mutations in BLM often negatively impact BLM ATPase and helicase activity.
View Article and Find Full Text PDFGenes Dev
April 2023
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
The evolutionarily conserved cohesin complex mediates sister chromatid cohesion and facilitates mitotic chromosome condensation, DNA repair, and transcription regulation. These biological functions require cohesin's two ATPases, formed by the Smc1p and Smc3p subunits. Cohesin's ATPase activity is stimulated by the Scc2p auxiliary factor.
View Article and Find Full Text PDFbioRxiv
January 2023
Department of Biomolecular Chemistry, University of Wisconsin, Madison WI 53706.
Bloom syndrome helicase (BLM) is a RecQ-family helicase implicated in a variety of cellular processes, including DNA replication, DNA repair, and telomere maintenance. Mutations in human cause Bloom syndrome (BS), an autosomal recessive disorder that leads to myriad negative health impacts including a predisposition to cancer. BS-causing mutations in often negatively impact BLM ATPase and helicase activity.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!