High Frequency Of Chromosomal Aberrations Research Articles

P XVI B.1 - P XVI B.1 A high frequency of chromosomal aberrations in peripheral blood lymphocytes in healthy subjects predicts cancer

P XVI B.1 - P XVI B.1 A high frequency of chromosomal aberrations in peripheral blood lymphocytes in healthy subjects predicts cancer

Selenium salts and chromosome damage

Sodium selenite and sodium selenate, fed by gavaging to age-matched male Swiss albino mice and observed after 24 h following a colchicine-fixative-air drying-Giemsa schedule, were found to induce chromosome breaks and spindle disturbances in bone marrow cells. The four concentrations used were fractions of LD 50 and the effects were directly proportionate to the concentration of the chemical. Sodium selenite induced a slightly higher frequency of chromosomal aberrations than sodium selenate.

Cycloactive, aneugenic and clastogenic effects ofParacoccidioides brasiliensisexoantigen in human lymphocyte cultures

The in vitro effect of Paracoccidioides brasiliensis exoantigen on the human lymphocytes cell cycle and chromosomes was studied. Human peripheral blood lymphocyte cultures from ten healthy, white, non-smoking, non-related adult males (mean age 31.3 +/- 8.2 years) were studied. Blood cultures were treated with three exoantigen concentrations (0.25, 2.50 and 10.00 micrograms ml-1). At least 1000 metaphases were analysed at each concentration, for evaluation of numerical and structural chromosome aberrations (CA) and 30,000 for mitotic index (MI). Among the treated cultures, statistically significant differences in the frequencies of MI and CA were not observed. Nevertheless, when compared with control cultures, they all showed a significantly lower frequency of MI and higher frequency of CA. It is suggested that the detected alterations were caused by the exoantigen, its fractions or its metabolites.

Induction of chromosome aberrations and micronuclei in pulmonary alveolar macrophages of rats following inhalation of mosquito coil smoke

The genotoxic potential of inhalation of mosquito coil (MC) smoke was evaluated by using metaphase chromosome aberration and micronucleus assays in pulmonary alveolar macrophages (PAMs) of rats following short-term as well as long-term whole body intermittent exposure. For short-term exposure, the animals were exposed for 15 min/h, 8 h/day to smoke collected for 1, 5 or 10 min, and they were killed 16 or 24 h after the final exposure. For long-term exposure, they were exposed for 15 min/h, 8 h/day, 7 days/week to smoke collected for 10 min and then they were killed 24 h after the final exposure. Each time before exposure, fresh smoke was collected by burning a mosquito coil. Pulmonary lavage was collected, and conventional flame-drying preparation was done for metaphase chromosome analysis and micronuclei (MN) were analyzed from smear preparations. Significantly higher frequencies of chromosome aberrations, including as well as excluding gaps, and micronucleated PAMs in smoke-exposed animals, compared to controls, indicated genotoxic capacity of MC smoke. The increases significantly correlated with the “concentration” of the gas. Mitotic indices also showed a significant and concentration-dependent increase. The frequencies of chromosome aberrations and MN following 7-day exposure were very similar to those for 1-day exposure. This was probably due to the transient nature of PAMs. A post-exposure gap of 24 h, compared to the 16-h gap, yielded a higher incidence of both mitoses and chromosome aberrations.

Biomonitoring of genotoxic exposure among stainless steel welders

A biosurvey in the Danish metal industry measured the genotoxic exposure from stainless steel welding. The study comprised measurements of chromosomal aberrations (CA), sister-chromatid exchanges (SCE), unscheduled DNA synthesis (UDS) in peripheral lymphocytes and serum immunoglobulin G. Environmental monitoring of welding fumes and selected metal oxides, biomonitoring of chromium and nickel in serum and urine and mutagenic activity in urine, and evaluation of semen quality were also done. Manual metal arc (MMA) welding and tungsten inert gas (TIG) welding were the dominant welding processes. A higher frequency of chromosomal aberrations, classified as translocations, double minutes, exchanges and rings, was observed in stainless steel welders than in non-welders. SCE was lower in welders working with both MMA and TIG welding than in reference persons. N-Acetoxy- N-acetylaminofluorene (NA-AAF)-induced UDS was lower in 23 never-smoking welders than in 19 unexposed never-smokers. Smoking was a confounding factor resulting in significantly higher CA, SCE, NA-AAF binding to DNA and mutagenic activity in urine. Age was also a confounder: CA, SCE, NA-AAF binding to DNA and UDS increased significantly with age. No significant correlation between SCE and CA or between CA and UDS was found. UDS decreased significantly with increasing lymphocyte count and a higher lymphocyte count was seen in MMA welders than in reference persons and in smokers than in non-smokers. Differences in the composition among lymphocytes in exposed persons compared with non-exposed are suggested. MMA welding gave the highest exposure to chromium, an increased number of chromosomal aberrations and a decrease in SCE when compared with TIG welding. Consequently improvements in the occupational practice of stainless steel welding with MMA is recommended.

Mechanisms responsible for the limited lifespan and immortal phenotypes in cultured mammalian cells

Normal mammalian cells have a limited lifespan in culture and hypotheses explaining cellular senescence usually fall into one of two categories. One of these postulates that random errors or damage accumulate in essential macromolecules and eventually outstrip the cell's capacity for resynthesis and repair. The second considers the changes when immortal clones are produced from normal cells and in particular the lifespans of hybrids when cells of differing growth potentials are fused. These data can be explained by postulating that the mortal phenotype is dominant and that trans-acting growth inhibitors are involved in limiting lifespan. But the results do not indicate if the inhibitors are the primary cause of senescence or a secondary effect induced by quite different initial events. We suggest that normal cells possess proof-reading mechanisms which monitor the accuracy of chromosome segregation and replication and which can induce the synthesis of growth inhibitors when they detect major errors in chromosome metabolism. It is further postulated that random damage accumulates during the growth of normal cells and eventually leads to detectable chromosome changes and the synthesis of inhibitors. Our hypothesis predicts that the emergence of immortal clones will be linked to the absence of active inhibitors and therefore to a loss in the fidelity of chromosome metabolism. Data are quoted which show that in contrast to normal cells, immortal clones have highly irregular karyotypes, amplify segments of their chromosomes, integrate exogenous DNA efficiently, maintain a constant level of 5-methylcytosine residues and have high frequencies of chromosomal aberrations. The mechanism of the proof-reading is unknown, but it may monitor changes in the patterns by which chromosome domains are attached to the nuclear matrix.

Chromosome instability in bladder carcinoma patients

The relationship between the presence of a high frequency of chromosome aberrations and a predisposition to cancer has been well established in the so-called chromosome instability syndromes. Chromosome instability is also present in a variety of patients affected by cancer, and sometimes in their healthy relatives. We present a cytogenetic study carried out in lymphocytes from 13 untreated bladder carcinoma patients (only four of them had a history of occupational exposure to mutagens). Percentages of aberrant metaphases were significantly higher in cancer patients than in controls. Of the total number of chromosome aberrations in cancer patients, 67.16% corresponded to major structural chromosome abnormalities, while 25.37% were gaps or breaks. Numerical abnormalities represented 7.46% of the total. The bands more frequently involved in chromosome rearrangements were 5q31 and 1q32. Our results tentatively indicate that a significant proportion of patients with bladder carcinoma may have an underlying inherent chromosome instability. An age effect cannot be excluded, but we did not find significant differences between patients over 50 years of age and patients under 50 years of age.

Enhanced mutability at the tk locus in the radiosensitive double-strand break repair mutant xrs5

The thymidine kinase locus (tk) has been utilised as the target locus to measure the induced mutation frequency following X-irradiation in the X-ray-sensitive xrs5 mutant and its parent CHO K1 line of Chinese hamster cells. Mutations of tk − cells were measured by plating cells in selective medium containing trifluorothymidine after a post-irradiation expression time of 4 days. Our results show that the mutation frequency was 3–4 times higher in the xrs5 mutant than in the CHo K1 cell line. This enhanced mutation frequency in xrs5 is though to result from the deficiency in DNA double-strand repair in this cell line which also results in the enhanced cell killing and higher frequencies of chromosomal aberrations in respnose to X-irradiation. The findings of the present study suggest that DNA double-strand break is a critical lesion leading to mutations in irradiated cells.

Chromosomal aberrations in V79 hamster cells induced by hyperosmotic solutions of NaCl

In this study V79 hamster cells were treated with hypertonic NaCl solutions. A pulse treatment of 30 min made it possible to use hypertonic solutions of up to 1500 mM. Hypertonic treatment induced high frequencies of chromosomal aberrations and the aberration pattern led to the conclusion that hypertonicity acts similarly to S-phase-independent mutagens. We also tested the influence of several parameters on aberration induction and tried to standardize the experimental protocol. The mechanisms involved in aberration production after hypertornic treatment are unknown, we discuss a change in chromatin structure, inhibition of repair processes or protein damage responsible for chromosomal aberrations.

A unique human mutant B-lymphoblastoid cell line (ataxia telangiectasia) which exhibits increased siste-chromatid exchange retaining hypersensitivity to neocarzinostatin and bleomycin

Chromosome aberrations and sister-chromatid exchanges (SCEs) were examined in 4 ataxia telangiectasia (AT)-derived B-lymphoblastoid cell lines (B-LCLs) (AT-S, AT-SHI, AT-SHI B13A and AsHa) following treatments with neocarzinostatin (NCS) and bleomycin. All of these cell lines exhibited extremely high frequencies of chromosome aberrations with the NCS and bleomycin treatments. Among them, AsHa, a mutant B-LCL originating from an AT patient, showed high frequencies of SCEs under high bromodeoxyuridine (BrdU) concentrations retaining hypersensitivity to NCS and bleomycin with regard to chromosome aberrations. A clear BrdU dose-dependent increase in SCEs (9.85 SCEs/cell at 40 μg/ml, 36.65 SCEs/cell at 100 μg/ml on average) in this mutant was observed. When AsHa mutant cells were treated with NCS (0.02 μg/ml) and/or bleomycin (5.0 μg/ml) under 40 μg/ml BrdU (minimum BrdU concentration for sister-chromatid differential staining), SCE levels increased from 9.85 (baseline level) to 21.1 with NCS and 20.5 with bleomycin, in a dose-dependent manner. These observations indicate that AsHa is a unique AT-derived mutant cell clone with a high SCE character retaining the original hypersensitivity to bleomycin and NCS.

Chromosome aberrations and urinary thioethers in smokers

Chromosome aberrations, classified as chromosome- and chromatid-type aberrations, were evaluated in 94 individuals. The concentration of thioethers in the urine was also determined. The sample consisted of 41 non-smokers (control group) and 53 smokers, 25 smoked 10–20 cigarettes/day (subgroup IIA) and 28 smoked more than 20 cigarettes/day (subgroup IIB). Our aim was to perform internal dosimetry on smokers using a cytogenetic test, and a test for urinary excretion of thioethers, in order to determine the relation between these 2 methods of dosimetry. Our results show a higher frequency of chromosome aberrations ( p < 0.0001) and a higher excretion of urinary thioethers ( p < 0.0001) in smokers as compared to non-smokers. However, linear regression between these parameters was not statistically significant. In view of the variation between different individuals with regard to the amount of urinary thioethers, it seems more accurate to perform the biomonitoring of smoking by analyzing chromosome aberrations.

Induction of sister chromatid exchanges with hypotonic treatment

Hypotonic NaCl solutions and diluted culture medium were tested for induction of sister chromatid exchanges (SCEs) and chromosomal aberrations (CA). Hypotonic treatment conditions were found to induce high frequencies of CA and SCEs. However, an increase in SCEs was observed only in cells that also had CA. Possible lesions and mechanisms leading to SCEs and CA are discussed.

X-ray- and mitomycin C (MMC)-induced chromosome aberrations in spermiogenic germ cells and the repair capacity of mouse eggs for the X-ray and MMC damage

Chromosome aberrations induced at the first-cleavage metaphase of eggs fertilized with sperm recovered from spermiogenic cells which had been X-irradiated and treated with mitomycin C (MMC) at various stages were observed using in vitro fertilization and embryo culture technique. Furthermore, the repair capacity of the fertilized eggs for X-ray- and MMC-induced DNA damage which was induced in the spermiogenic cells and retained in the sperm until fertilization was investigated by analysis of the potentiation effects of 2 repair inhibitors, 3-aminobenzamide (3AB) and caffeine on the yield of chromosome aberrations. The frequency of chromosome aberrations observed in the eggs fertilized with sperm recovered from the early spermatid to late spermatocyte stage with X-irradiation of 4 Gy (16–20 days after X-irradiation) was markedly higher than that in the eggs fertilized with sperm recovered from spermatozoa to late spermatid stage (0–8 days after X-irradiation). The induced chromosome aberrations predominantly consisted of chromosome-type aberrations, the main type being chromosome fragment followed by chromosome exchange through all the spermiogenic stages. On the other hand, a high frequency of chromosome aberrations was not induced through all the stages with MMC treatment of 5 mg/kg. The remarkable potentiation effects of 3AB and caffeine were found in the eggs fertilized with sperm recovered from almost all the spermiogenic stages after X-irradiation. In the MMC treatment, a remarkable caffeine effect was observed limitedly in mid-early spermatids to late spermatocytes where a large amount of MMC damage could be induced. These results suggest that the large amount of DNA lesions induced in spermiogenic cells by X-rays and MMC persist as reparable damage until sperm maturation and are effectively repaired in the cytoplasm of the fertilized eggs.

Induction of chromosomal aberrations by hypotonic culture conditions is independent of the S-phase in V79 hamster cells.

A deviation from physiological osmolality (300 mOsm/kg H2O) can lead to genotoxic effects. A 30-min treatment of V79 hamster cells with hypotonic sodium chloride of 60 mOsm/kg H2O or with diluted culture medium of the same osmolality induces extraordinarily high frequencies of chromosomal aberrations. In this study, multiple fixation times over a 24-hr period were used to identify cells in various stages of the cell cycle at the time of treatment and to find out whether or not hypotonic conditions are able to induce aberrations in all cell cycle stages. Because of the aberration pattern observed, it is suggested that hypotonic treatment acts as an S-independent agent, like X-rays or restriction endonucleases. Whether the aberrations originate from directly induced DNA damage or from a release of DNase after lysosomal breakdown is discussed.

Petrochemical-related DNA damage in wild rodents detected by flow cytometry.

The need for quick, reliable, in situ tests of environmental mutagenicity is evidenced by increasing public concern about potential health effects of pollutants. Conventional tests of clastogenicity usually involve treatment of laboratory test systems with pure samples of suspect compounds followed by scoring numerous metaphase cells for chromosome aberrations. There are at least two shortcomings of these test protocols. They are very time consumptive and are generally restricted to controlled laboratory situations which may not realistically indicate the effects of environmental pollution. The use of flow cytometry to study resident rodent species as bioindicators provides a system by which cytogenetic effects of environmental pollutants upon exposed organisms rapidly and accurately can be ascertained. The authors found that two species of wild rodents (Peromyscus leucopus and Sigmodon hispidus) living at a dump site polluted with a complex mixture of oil, grease, polychlorinated biphenols, hexachlorobenzene, zinc, manganese, cadmium, chromium, copper, and lead had significantly higher frequencies of chromosomal aberrations than did animals from two unpolluted control sites. These data suggest that resident small mammals may be useful as in situ monitors of the presence and action of mutagenic pollutants in the environment. This study was conducted to determine if changes in patternsmore » of DNA content indicative of the action of mutagens could be detected by flow cytometric analysis of tissues from these same animals.« less

Genetic effects of ethanol

Alcoholics have a higher frequency of chromosomal aberrations and sister-chromatid exchanges (SCEs) in their peripheral lymphocytes. In human and mammalian cells in vitro, ethanol generally does not induce genetic damage, but it induces SCEs in the presence of an exogenous metabolic system. In human lymphocytes in vitro, ethanol induces SCEs in the presence of alcohol dehydrogenase. In animals in vivo, ethanol induces a variety of genetic effects, including SCEs, micronuclei, dominant lethal mutations and aneuploidy in mouse eggs. There is some indication that ethanol may lead to genetic damage in sperm. In bacteria, ethanol is at best marginally active. Ethanol leads to anomalous chromosome segregation in Aspergillus, to mutations in yeast, to chromosomal aberrations and SCEs in plant root tips and to disturbances of meiosis and micronuclei in tetrads in Zea and Tradescantia respectively. The first metabolite of ethanol, acetaldehyde is mutagenic in a variety of test systems. The mutagenic activity of acetaldehyde in bacteria is questionable, but there is no doubt of its mutagenic activity in a variety of eukaryotic test systems in vitro as well as in vivo.

Chromosome analysis of human oocytes recovered from preovulatory follicles in stimulated cycles.

To investigate the incidence and types of abnormalities of chromosome number in oocytes, we recovered preovulatory oocytes from 17 women who were undergoing clomiphene stimulation and laparoscopy because of infertility. Twenty-three oocytes were recovered and studied after they had been fixed with a gradual-fixation method: 17 of the oocytes had numbers of chromosomes in the haploid range (19 to 25 second-metaphase chromosomes), 4 had only 1 to 5 chromosomes, 1 was not analyzable, and 1 had 23 chromosome bivalents in the first metaphase. Of the oocytes with chromosome numbers in the haploid range, nine had an apparently normal haploid set of 23 chromosomes. Two had 1 to 2 additional chromosomes, three lacked 2 to 4 chromosomes, and three had totals of chromosomes that were close to 23 but could not be determined with certainty. We conclude that infertile women undergoing clomiphene stimulation have a high proportion (nearly 50 percent) of oocytes with an abnormal karyotype. If this is also true of fertile women, including those not taking clomiphene, it may explain the high frequency of chromosome aberrations occurring in early spontaneous abortion and the low pregnancy rate after in vitro fertilization.

Restriction endonuclease Bam H I induces chromosomal aberrations in Chinese hamster ovary (CHO) cells

Treatment of Chinese hamster ovary (CHO) cells with the restriction endonuclease Bam H I (recognition site: G/GATCC) leads to high frequencies of chromosomal aberrations. Experiments with bromodeoxyuridine-labelled chromosomes show that the aberrations occur nearly exclusively in first post-treatment metaphases. The results are interpreted to mean that only some of the cells take up the enzyme and that these cells are the ones showing the aberrations. Cells which do not take up the enzyme show up as differentially stained metaphases and have no aberrations. Why some cells take up the restriction enzyme and others not is not known, possibly this is dependent on the physiological condition of the cells.

Chapter 29 Instability of Chromosomes and Alkaloid Content in Cell Lines Derived From Single Protoplasts of Cultured Coptis Japonica Cells

Publisher Summary Genetic homogeneity in cultured cell systems is essential for research on plant cells. Such uniformity is particularly important when studying the regeneration of plants with constant chromosome numbers and for stabilizing the production of useful compounds in cultured cells. Deus and Zenk suggested that the different rates of alkaloid production that they found in the cell lines of Catharanthus roseus were related to a high frequency of chromosome aberrations. Chromosome instability as an aspect of genetic variation in cultured cells, however, is a common phenomenon in many plant species. Yet there have been only a few reports that describe chromosome stabilization in plant cell cultures. Cloning of single protoplasts or single cells can be used to reduce the genetic heterogeneity of cell populations and to obtain cell lines that produce useful compounds. Studies of chromosome stability in the root tips of some plant species derived from protoplasts have been reported. Both normal and abnormal chromosome numbers were found in these regenerated plants. But little information is available on chromosome numbers in callus tissue derived from single protoplasts. This chapter presents the cytogenetic evidence that a variation in chromosome number occurred in one of the cell clones (derived from 27 single protoplast-derived cell lines of Coptis japonica Makino that are characterized by their various chromosomal traits) after 6 months of subculture. It also discusses the fact that there seems to be no correlation among this variation in chromosome number and the production of berberine in the cell.

ACNU-resistant mutants of 9L rat glioma cell line. Isolation and preliminary characterization of these subclones.

Three ACNU-resistant subclones were isolated and characterized from a wild-typed 9L rat glioma cell line in culture. At an early stage after cloning, these ACNU-resistant subclones showed a high frequency of chromosomal aberrations compared with nonresistant 9L cells. These ACNU-resistant subclones revealed a cross resistance to BCNU, CCNU, methyl CCNU, nitrogen mustard, cyclophosphamide, and cis-platinum, which are alkylating agents. Further studies are necessary to clarify the mechanisms of ACNU-resistance from the aspect of repair of DNA alkylation damage.