The Mre11/Rad50/Nbs1 complex is involved in many aspects of chromosome metabolism. Aberrant function of the complex is associated with defects in the DNA checkpoint, double-strand break repair, meiosis, and telomere maintenance. In this article, we report the consequences of Mre11 dysfunction for the stability of mitotic and meiotic chromosomes in Arabidopsis thaliana. Although plants homozygou...

Dose estimates for the assessment of future risks, following accidental exposure to radiation, for certain diseases such as cancer usually rely on both physical and biological quantitative analyses. A traditional biological method of choice is the measurement of chromosome aberration frequencies in peripheral-blood lymphocytes. However, thorough examination of large sample populations is time a...

Chromosomal analysLs of peripheral leukocytes in patients being treated with nitrogen mustard, 6-mercaptopurine, and A649 demonstrated an increase in i>olyploidy, including cells show ing endoreduplication. With nitrogen mustard, up to 15% of cells cultured were polyploids; with 6-mercaptopurine, 9% polyploidy was evident; anrl when A-649 was used, up to 14% polyploidy was seen. Chromosomal dam...

The Smt3 (SUMO) protein is conjugated to substrate proteins through a cascade of E1, E2, and E3 enzymes. In budding yeast, the E3 step in sumoylation is largely controlled by Siz1p and Siz2p. Analysis of Siz- cells shows that SUMO E3 is required for minichromosome segregation and thus has a positive role in maintaining the fidelity of mitotic transmission of genetic information. Sumoylation of ...

The majority of human tumour cells are aneuploid owing to an underlying chromosome instability phenotype. While the genetic lesions that cause chromosome instability remain undefined, mouse ES cells harbouring homozygous adenomatous polyposis coli (APC) mutations are frequently tetraploid. In addition, colon cancer cells with APC mutations have weakened kinetochore-microtubule interactions. Fur...

DNA replication errors at certain sites in the genome initiate chromosome instability that ultimately leads to stable genomic rearrangements. Where instability begins is often unclear. And, early instability may form unstable chromosome intermediates whose transient nature also hinders mechanistic understanding. We report here a budding yeast model that reveals the genetic ontogeny of genome re...

The most popular and 'gold standard' phenomenon in Biological dosimetry is the appearance of dicentric chromosomes in metaphase in white blood cells. The metaphase finder is a tool for biological dosimetry that finds metaphase cells on slide glasses. The author and a software company were using new special software that was faster than conventional systems. A Nikon Eclipse Ni-E microscope with ...

The aim of this study was to evaluate the genotoxic effects of ionizing radiation in vivo in exposed Bulgarian nuclear power plant workers by using classical cytogenetic and molecular cytogenetic analyses of peripheral lymphocytes. Chromosome analysis using fluorescence in situ hybrydization (FISH) and Giemsa techniques was undertaken on 63 workers and 45 administrative staff controls from the ...

Breakage-fusion-bridge (BFB) cycle is a series of chromosome breaks and duplications that could lead to the increased copy number of a genomic segment (gene amplification). A critical step of BFB cycles leading to gene amplification is a palindromic fusion of sister chromatids following the rupture of a dicentric chromosome during mitosis. It is currently unknown how sister chromatid fusion is ...