Mitomycin C (MC) is a chemically reactive antibiotic derived from Streptomyces caespitosus. The drug selectively inhibits DNA synthesis (2, 15, 29, 34, 39, 40, 43, 44, 49) and degrades cellular DNA but does not affect the synthesis of R N A or protein (31, 33, 40). MC induces bacteriophage production in lysogenic bacteria (23, 29), increases the rate of genetic recombination among mutant forms ...

Although the pathogenesis of hepatocellular carcinoma (HCC) remains poorly understood, hepatitis B virus and dietary aflatoxin exposures are established etiological factors for this disease. We conducted a pilot study of 28 patients with HCC and 110 healthy controls matched for age, sex, and ethnicity to determine whether constitutional genetic instability, based on the quantification of mutage...

Using numerical simulations of pairs of long polymeric chains confined in microscopic cylinders, we investigate consequences of double-strand DNA breaks occurring in independent topological domains, such as these constituting bacterial chromosomes. Our simulations show a transition between segregated and mixed state upon linearization of one of the modelled topological domains. Our results expl...

In recombinational DNA double-strand break repair a homologous template for gene conversion may be located at several different genomic positions: on the homologous chromosome in diploid organisms, on the sister chromatid after DNA replication, or at an ectopic position. The use of the homologous chromosome in mitotic gene conversion is thought to be limited in the yeast Saccharomyces cerevisia...

Mutagen sensitivity, measured by quantifying the chromatid breaks induced by mutagens in short-term cultures of peripheral blood lymphocytes, has been used as an indirect measure of DNA repair capacity. Numerous epidemiologic studies have suggested that mutagen sensitivity is a cancer susceptibility factor for a variety of epithelial cancers. A recent classic twin study examined systematically ...

Meiosis is a specialized cell division that halves the genome complement, producing haploid gametes/spores from diploid cells. Proper separation of homologous chromosomes at the first meiotic division requires the production of physical connections (chiasmata) between homologs through recombinational exchange of chromosome arms after sister-chromatid cohesion is established but before chromosom...

Replicated sister chromatids are held together until mitosis by cohesin, a conserved multisubunit complex comprised of Smc1, Smc3, Scc1, and Scc3, which in vertebrate cells exists as two closely related homologues (SA1 and SA2). Here, we show that cohesin(SA1) and cohesin(SA2) are differentially required for telomere and centromere cohesion, respectively. Cells deficient in SA1 are unable to es...

The terminal t-loop structure adopted by mammalian telomeres is thought to prevent telomeres from being recognized as double-stranded DNA breaks by sequestering the 3' single-stranded G-rich overhang from exposure to the DNA damage machinery. The POT1 (protection of telomeres) protein binds the single-stranded overhang and is required for both chromosomal end protection and telomere length regu...

Maintaining genomic stability is critical for the prevention of disease. Numerous DNA repair pathways help to maintain genomic stability by correcting potentially lethal or disease-causing lesions to our genomes. Mounting evidence suggests that the post-translational modification sumoylation plays an important regulatory role in several aspects of DNA repair. The E3 SUMO ligase MMS21/NSE2 has g...