Genotoxic agents induce chromosomal alterations, such as aberrations, micronuclei, and sister chromatid exchanges as well as mutations both in vivo and in vitro. Ionizing radiation and typical radiomimmetic agents such as bleomycin are very efficient inducers of chromosomal aberrations. The type of aberrations induced by these agents are cell-cycle dependent, i.e., chromosome type in pre-replic...

Exposure to particulate matter (PM) is a major world health concern, which may damage various cellular components, including the nuclear genetic material. To assess the impact of PM on nuclear genetic integrity, structural chromosomal aberrations are scored in the metaphase spreads of mouse RAW264.7 macrophage cells. PM is collected from ambient air with a high volume total suspended particles ...

We have previously isolated the hpttg proto-oncogene, which is expressed in normal tissues containing proliferating cells and in several kinds of tumors. In fact, expression of hPTTG correlates with cell proliferation in a cell cycle-dependent manner. Recently it was reported that PTTG is a vertebrate analog of the yeast securins Pds1 and Cut2, which are involved in sister chromatid separation....

DNA double-strand break (DSB) repair mechanisms differ in their requirements for a homologous repair template and in the accuracy of the result. We aimed to quantify the outcome of repair of a single targeted DSB in somatic cells of young barley (Hordeum vulgare) plants. Amplicon sequencing of three reporter constructs revealed 47 to 58% of reads as repaired via nonhomologous end-joining (NHEJ)...

BACKGROUND Homologous recombination promotes proper segregation of chromosomes during meiosis. Programmed double-strand breaks (DSBs) initiate recombination and are repaired preferentially using the homolog rather than the sister chromatid template. In yeast, activation of Mek1 kinase upholds this bias. Mek1 is also a proposed effector kinase in the recombination checkpoint that responds to abe...

Mutagen sensitivity, measuring the extent of chromosome damage induced by an in vitro treatment of peripheral lymphocytes with bleomycin, has been associated with an increased risk of various human cancers. Sensitivity to bleomycin appears to have high heritability and is usually considered to reflect individual capacity to repair DNA lesions. Another potential contributor to variation in bleom...

The ERCC1 protein is essential for nucleotide excision repair in mammalian cells and is also believed to be involved in mitotic recombination. ERCC1-deficient mice, with their extreme runting and polyploid hepatocyte nuclei, have a phenotype that is more reminiscent of a cell cycle arrest/premature ageing disorder than the classic DNA repair deficiency disease, xeroderma pigmentosum. To underst...

During meiosis there is an imperative to create sufficient crossovers for homologue segregation. This can be achieved during repair of programmed DNA double-strand breaks (DSBs), which are biased towards using a homologue rather than sister chromatid as a repair template. Various proteins contribute to this bias, one of which is a meiosis specific kinase Mek1. It has been proposed that Mek1 est...

Telomeres protect chromosome ends from being viewed as double-strand breaks and from eliciting a DNA damage response. Deprotection of chromosome ends occurs when telomeres become critically short because of replicative attrition or inhibition of TRF2. In this study, we report a novel form of deprotection that occurs exclusively after DNA replication in S/G2 phase of the cell cycle. In cells def...

In mammalian cells, ionizing radiation (IR)-induced DNA double-strand breaks (DSBs) are repaired in all phases of the cell cycle predominantly by classical, DNA-PK-dependent nonhomologous end joining (D-NHEJ). Homologous recombination repair (HRR) is functional during the S- and G2-phases, when a sister chromatid becomes available. An error-prone, alternative form of end joining, operating as b...