Abnormally high levels of spontaneous and mitomycin C or diepoxybutane induced chromosome breakage were observed in lymphocytes from eight out of nine previously undescribed patients clinically diagnosed as having Fanconi's anaemia. The results suggest that the combination of spontaneous and induced chromosome breakage is a good aid in the differential diagnosis and we suggest that increased ch...

Elevated frequencies of chromosomal aberrations have been observed in the lymphocytes of benzene-exposed workers. Similar changes occurring in the bone marrow may play an important role in the development of leukemia. The objective of this research has been to characterize chromosomal alterations induced by benzene in mice and humans and to investigate the potential role of inhibition of topois...

The effects of 13 mutagen-sensitive (mus) mutants (representing seven loci) on mitotic chromosome stability in nonmutagenized cells have been examined genetically. To do this, mus-bearing flies heterozygous for the recessive somatic-cell marker, multiple wing hairs (mwh), were examined for increased frequencies of mwh clones in the wing blade. Mutants at the mus-103, mus-104 and mus-106 loci do...

E A R L Y in radiation genetic investigations it was reported that X-ray-induced sex-linked recessive lethals were not homogeneous in composition. Instead they included: ( 1 ) apparent intragenic changes without observable cytological abnormalities (point mutations) ; (2) deficiencies; and (3) changes associated with and, for the most part, inseparable from chromosome rearrangements (OLIVER 193...

background helicobacter pylori (h. pylori) is recognized as the causative agent of peptic and duodenal ulcers, gastric adenocarcinoma, and low-grade mucosa-associated lymphoid tissue (malt) lymphoma . in the present study, we investigate the genotoxic damage of lysates of h. pylori in human b lymphocytes. materials and methodsâ  human b lymphocytes were treated with 0, 10, 20, and 30 âµg/ l of ...

DNA double-strand break (DSB) repair and checkpoint control represent distinct mechanisms to reduce chromosomal instability. Ataxia telangiectasia (A-T) cells have checkpoint arrest and DSB repair defects. We examine the efficiency and interplay of ATM's G2 checkpoint and repair functions. Artemis cells manifest a repair defect identical and epistatic to A-T but show proficient checkpoint respo...

The transposable element Tam3 of Antirrhinum majus is capable of causing large-scale chromosomal restructuring. It induced a large deletion at the nivea locus, to produce the allele niv-:529. The deletion removed the entire nivea coding region while the element remains intact with the potential to induce further rearrangements. Genetic experiments showed that the endpoint of the deletion (calle...

In Saccharomyces cerevisiae, absence of the checkpoint kinase Mec1 (ATR) is viable upon mutations that increase the activity of the ribonucleotide reductase (RNR) complex. Whether this pathway is conserved in mammals remains unknown. Here we show that cells from mice carrying extra alleles of the RNR regulatory subunit RRM2 (Rrm2(TG)) present supraphysiological RNR activity and reduced chromoso...

The clinical, cytogenetic and dermatoglyphic findings in a patient with a ring chromosome 21 are presented. This anomaly acts as a deletion of chromosomal material and results in specific congenital defects. A comparison is made with 24 cases of deletions involving chromosome 21 described in the literature. Six of these have been studied by means of recently developed chromosome banding techniq...

PURPOSE To model intrachromosomal clustering of DSB (DNA double strand breaks) induced by ionizing radiation. That DSB are located non-randomly along chromosomes after high LET irradiation, with clustering even at extremely large scales, has been confirmed by recent pulsed field gel electrophoresis data for size distributions of DNA fragments. We therefore extend the standard random-breakage mo...