In order to evaluate the applicability of the cytokinesis-block micronucleus cytome assay in routine mutagenicity testing we investigated with this method different chemicals having different mechanisms of action: non-mutagens, direct-acting basealtering mutagens, direct-acting cross-linking mutagens, clastogens including a radiomimeti...

Human fibroblasts whose lifespan in culture has been extended by expression of a viral oncogene eventually undergo a growth crisis marked by failure to proliferate. It has been proposed that telomere shortening in these cells is the property that limits their proliferation. Here we report that ectopic expression of the wild-type reverse transcriptase protein (hTERT) of human telomerase averts c...

Few cases of isochromosomes for the short arm of the X have been reported and all are dicentric with variable portions of the long arms interposed between the two centromeres. This paper reports three cases of complete short arm duplication of one X chromosome in unrelated female patients. All patients also have a 45,X cell line and present with some characteristic features of Turner syndrome. ...

Yeast strains with mutations in both TEL1 and MEC1 have short telomeres and elevated rates of chromosome deletions. By using a PCR assay, we demonstrate that mec1 tel1 strains also have telomere-telomere fusions (T-TFs). T-TFs require Lig4p (a ligase required for nonhomologous end-joining DNA repair). The highest rates of T-TFs are found in strains with combination of mutations that affect telo...

The aim of this study was to investigate radioprotective properties of Echinacea purpurea tablets in vivo. We analysed lymphocyte chromosome aberrations (CA), micronuclei (MN), apoptosis of leukocytes and haematological parameters in a group of radiation workers who were identified as carrying dicentric chromosomes in their lymphocytes. All radiation workers were taking two 275 mg Echinacea tab...

The centromere is a specialized chromosomal region identified as the major constriction, upon which the kinetochore complex is formed, ensuring accurate chromosome orientation and segregation during cell division. The rapid evolution of centromere DNA sequence and the conserved centromere function are two contradictory aspects of centromere biology. Indeed, the sole presence of genetic sequence...

The conserved ATM checkpoint kinase and the Mre11 DNA repair complex play essential and overlapping roles in maintaining genomic integrity. We conducted genetic and cytological studies on Drosophila atm and mre11 knockout mutants and discovered a telomere defect that was more severe than in any of the non-Drosophila systems studied. In mutant mitotic cells, an average of 30% of the chromosome e...

The breakage-fusion-bridge cycle is a classical mechanism of telomere-driven genome instability in which dysfunctional telomeres are fused to other chromosomal extremities, creating dicentric chromosomes that eventually break at mitosis. Here, we uncover a distinct pathway of telomere-driven genome instability, specifically occurring in cells that maintain telomeres with the alternative lengthe...

BACKGROUND In most mammals, sex is determined at the beginning of gestation by the constitution of the sex chromosomes, XY in males and XX in females. CASE Here we report an interesting case characterized by ambiguous genitalia and ovotestis in a newborn carrying an apparently female karyotype (46 XX). Array Comparative Genomic Hybridization (Array-CGH) revealed an unbalanced rearrangement re...

We present a patient with partial monosomy of the short arm of chromosome 18 caused by de novo translocation t(Y;18) and a generalized form of keratosis pilaris (keratosis pilaris affecting the skin follicles of the trunk, limbs and face-ulerythema ophryogenes). Two-color FISH with centromere-specific Y and 18 DNA probes identified the derivative chromosome 18 as a dicentric with breakpoints in...