Disabling mutations in genome maintenance and DNA repair pathways are frequently observed in cancer. These DNA repair defects represent genetic aberrations that are specific to cancer cells and not present in healthy tissues. It is thought that these molecular defects produce a "mutator phenotype," which allows incipient cancer cells to accumulate additional cancer-promoting mutations. In recen...

Heterozygous mutations in the tumor suppressor BRCA2 confer a high risk of breast and other cancers in humans. BRCA2 maintains genome stability in part through the regulation of Rad51-dependent homologous recombination. Much about its precise function in the DNA damage responses is, however, not yet known. We have made null mutations in the Drosophila homolog of BRCA2 and measured the levels of...

We have determined the kinetics of up-regulation of the homologous recombination gene RAD51, one of the genes induced following DNA damage in isogenic haploid DNA repair-deficient mutants of Saccharomyces cerevisiae, using treatment with the DNA crosslinking agent 8-methoxypsoralen. We show that RAD51 is up-regulated concomitantly, although independently, with a shift from the G1 cell cycle pha...

In all cells, genetic recombination is used to repair DNA breaks and, as a result, genetic information is exchanged between homologous DNA molecules. Discontinuities in DNA strands, specifically double-strand DNA breaks and single-strand DNA gaps, attract the enzymes responsible for the initiation of homologous recombination. In wild-type Escherichia coli, two distinct pathways are responsible ...

Homologous recombination plays essential roles in mitotic DNA double strand break (DSB) repair and meiotic genetic recombination. In eukaryotes, RAD51 promotes the central homologous-pairing step during homologous recombination, but is not sufficient to overcome the reaction barrier imposed by nucleosomes. RAD54, a member of the ATP-dependent nucleosome remodeling factor family, is required to ...

Homologous recombination between ectopic sites is rare in higher eukaryotes. To test whether double-strand breaks (DSBs) can induce ectopic recombination, transgenic tobacco plants harboring two unlinked, nonfunctional homologous parts of a kanamycin resistance gene were produced. To induce homologous recombination between the recipient locus (containing an I-SceI site within homologous sequenc...

Disablingmutations in genomemaintenance andDNA repair pathways are frequently observed in cancer. These DNA repair defects represent genetic aberrations that are specific to cancer cells and not present in healthy tissues. It is thought that these molecular defects produce a "mutator phenotype," which allows incipient cancer cells to accumulate additional cancer-promoting mutations. In recent y...

Crossovers (COs) generated through meiotic recombination are important for the correct segregation of homologous chromosomes during meiosis. Several models describing the molecular mechanism of meiotic recombination have been proposed. These models differ in the arrangement of heteroduplex DNA (hDNA) in recombination intermediates. Heterologies in hDNA are usually repaired prior to the recovery...

In spite of its essential role as the carrier of genetic information, DNA is not an inert structure. The genome is susceptible to potentially mutagenic threats of both endogenous and environmental origin. A dramatic threat to the covalent structure of DNA is posed by breaks in the phosphate backbone affecting one or both strands of the Watson–Crick double helix. Ionizing radiation and certain c...