Agrobacterium tumefaciens-mediated genetic transformation involves transfer of a single-stranded T-DNA molecule (T strand) into the host cell, followed by its integration into the plant genome. The molecular mechanism of T-DNA integration, the culmination point of the entire transformation process, remains largely obscure. Here, we studied the roles of double-stranded breaks (DSBs) and double-s...

In bacteria, double-strand break (DSB) repair via homologous recombination is thought to be initiated through the bi-directional degradation and resection of DNA ends by a helicase-nuclease complex such as AddAB. The activity of AddAB has been well-studied in vitro, with translocation speeds between 400-2000 bp/s on linear DNA suggesting that a large section of DNA around a break site is proces...

Radiation lethality is largely attributed to radiation-induced DNA double-strand breaks (DSBs). A range of structural complexity is predicted for radiation-induced DSBs. However, this lesion has never been analyzed in isolation at the molecular level. To address this problem, we have created authentic site-specific radiation-induced DSBs in plasmid DNA by triplex-forming oligonucleotide-targete...

We studied the relation between initial DNA double-strand breaks (DNA-DSB) and the rejoining kinetics of the strand breaks, as well as the OER (oxygen enhancement ratio) after low- and high-LET (linear energy transfer) radiations. CHO cells were exposed to 200 kVp X-rays or 80 keV/microm carbon ions under oxic and hypoxic conditions. DNA-DSB in the cells were analyzed by a static-field gel elec...

Repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) in haploid cells is generally restricted to S/G2 cell cycle phases, when DNA has been replicated and a sister chromatid is available as a repair template. This cell cycle specificity depends on cyclin-dependent protein kinases (Cdk1 in Saccharomyces cerevisiae), which initiate HR by promoting 5'-3' nucleolytic degradatio...

The repair of chromosomal double-strand breaks (DSBs) can be accomplished through homologous recombination in most organisms. We report here that exogenous oligonucleotides can efficiently target for repair a single DSB induced in a chromosome of yeast. The efficiency of recombinational targeting leading to a desired DNA change can be as high as 20% of cells. The DSB was generated either by a r...

Various lines of evidence indicate the involvement of DNA strand breaks (DSB) in the regulation of physiological states of cells, especially in cell death. Currently, cell death is divided into two categories, apoptosis and necrosis. As lysosomal integrity is maintained in apoptosis, while disrupted in necrosis, it is possible to assume that necrotic chromatin is exposed to digestion by various...

Unless efficiently and faithfully repaired, DNA double-strand breaks (DSBs) cause genome instability. We implicate a Schizosaccharomyces pombe nuclear envelope-spanning linker of nucleoskeleton and cytoskeleton (LINC) complex, composed of the Sad1/Unc84 protein Sad1 and Klarsicht/Anc1/SYNE1 homology protein Kms1, in the repair of DSBs. An induced DSB associates with Sad1 and Kms1 in S/G2 phases...

DNA double-strand breaks (DSBs) are a major threat to genome integrity. Proteins involved in DNA damage checkpoint signaling and DSB repair often relocalize and concentrate at DSBs. Here, we used an ORFeome library of the fission yeast Schizosaccharomyces pombe to systematically identify proteins targeted to DSBs. We found 51 proteins that, when expressed from a strong exogenous promoter on the...

A hospital-based unmatched case-control study was performed in order to determine the relation of DNA single (ssb) and double (dsb) strand breaks in women with and without cervical neoplasia. Cervical epithelial cells of 30 women: 10 with low grade squamous intraepithelial lesions (LG-SIL), 10 with high-grade SIL (HG-SIL), and 10 without cervical lesions were evaluated using alkaline and neutra...