Frequency of chromosome aberrations in residents of the Semipalatinsk Oblast]

Cytogenetic analysis of the population of the Beskaragai district of the Semipalatinsk oblast adjacent to the territory of the nuclear test site was conducted by means of an ecological genetic questionnaire and cytogenetic examination of metaphase chromosomes. An increase in the total mutation level in the region was observed. The frequency of chromosome aberrations among the population of the Beskaragai district (3.2%) was statistically significantly (about 1.5 times) higher than the background levels in the clear regions (from 1 to 2%). Furthermore, the frequency of aberrations in adolescents was comparable with that in the adults. The spectrum of chromosome aberrations pointed to a significant contribution of radiation component to the mutagenesis.     

Evidence for genetic etiology of heteroploidy in embryos of the Japanese quail (Coturnix coturnix japonica).

The Japanese quail was used as an experimental system to detect the effects of genes that affect chromosome behavior and distribution. From a random-bred population, three inbred generations were produced by full-sib matings in 36 families. The expectation from such a breeding scheme was that embryos bearing aberrations induced by recessive mutant genes would cluster within families and recur in particular lineages. Chromosomal aberrations caused by errors during fertilization, cleavage mitosis, and gametogenesis were scored in 2,037 16- to 18-h embryos from 107 families. Comparisons of the observed frequencies among families and lineages and pedigree analysis indicated that four types of chromosome aberrations had a genetic basis: (1) triploidy and triploid chimerism; (2) haploidy and haploid chimerism; (3) diploid/tetraploid mosaicism; and (4) a new aberration, referred to as "atypical mitotic metaphase." Analysis of the sex-chromosome complements of the embryos indicated that triploidy resulted predominantly from diploid ova, haploid cell lines originated from supernumerary sperm nuclei, and tetraploid cell lines resulted from endoreduplication or failure of cytokinesis. Clustering of triploidy in particular lineages was due to dispermy or recurrent suppression of one or both meiotic divisions during oogenesis.     

Mitotic chromosomal abnormalities and DNA polymorphism in the Nile tilapia (Oreochromis niloticus,Linnaeus, 1758) as a biomarker for water pollution by heavy metals

Mitotic chromosomal aberrations and DNA polymorphism (RAPD marker) were carried out on the Nile tilapia Oreochromis niloticus collected from five sites in Minia governorate, Egypt to test their applicability as biomonitors for heavy metal contaminants of water. The diploid chromosome number of O. niloticus population was 2 n = 44. Different types of chromosomal aberrations were recorded (e.g., deletion, ring, centromeric attenuation, end-to-end association, dicentric chromosome, stickiness chromosomes, endomitosis, fragments and chromatid gap). The chromosomal aberrations varied between O. niloticus population collected from five sites, and the most common type was ring (R) chromosomes. Samples obtained from Bahr Yousef and Irrigation drain exhibited the highest aberration frequency. The frequency of chromosomal aberration was positively correlated with the concentration of heavy metals where their concentration in the surface water of Irrigation drain and Bahr Yousef exceeded the limits defined by WHO as well as the concentration of Pb in muscles. The RAPD marker was also used to identify genetic variation among Nile tilapia samples collected from five different water sources. It created polymorphic and unique bands that can be used as genetic markers to track DNA variations. The dendrogram also revealed that exposure to heavy metal pollution causes gradual accumulation of variance, whereas areas subjected to environmental stress showed higher genetic variation and clustered together.     

Sister-chromatid exchanges and chromosomal aberrations in a population exposed to pesticides

Sister-chromatid exchanges (SCE) and chromosomal aberrations were studied in a population of floriculturists occupationally exposed to organophosphorus, carbamate and organochlorine pesticides. Blood samples from 36 individuals from a community of 154 persons of asiatic origin were obtained. Among the group sampled, 21 individuals exhibited at least one symptom of chronic intoxication. SCE analysis was performed in 14 symptomatic and 13 asymptomatic persons. The asymptomatic group showed a SCE frequency of 5.47 +/- 1.03 and the symptomatic group a frequency of 6.45 +/- 1.19. Comparison between both groups with the Mann-Whitney 'U' test revealed a significant difference (p 0.0409). Case-control analysis of 9 pairs matched by sex and age also showed significant differences between both groups (p 0.0104). In contrast, the frequencies of chromosomal aberrations were not correlated with intoxication symptomatology, though a significant increment of exchange-type aberrations in relation to a group of non floriculturists was observed in the population studied.     

Cytogenetic perspective of ageing and longevity in men and women

Analysis of relationships between the ageing cell phenotype and the age of cell donors is one of the ways towards understanding the link between cellular and organismal ageing. Cytogenetically, ageing is associated with a number of gross cellular changes, including altered size and morphology, genomic instability, and changes in expression and proliferation. Genomic instability can be easily assessed by analyzing the level of cytogenetic aberrations. In this review, we focus on the differences in the level and profile of cytogenetic aberrations observed in donors of different age and gender. Centenarians are a small fraction of the population at the extreme of human longevity. Their inclusion in such studies may shed light on one of the basic questions: whether genome stability is better maintained in successfully aged individuals compared to the rest of the population. At the same time, comparing the profile of age-related amount of chromosomal aberrations in men and women may help explaining the commonly observed gender differences in longevity.     

Action of Ypenyl [5-bis-(2-chloroethyl)-aminomethyluracil] on the chromosomes ofVicia faba

An investigation was carried out on ability of Ypenyl,i.e. 5-bis-(2-chloroethyl)-aminomethyluracil to induce structural disturbances of chromosomes and changes of mitotic activity of meristematic cells ofVicia faba. The cytostatic employed induced chromosomal aberrations mostly of the chromatide type, the greater part of which were localized in the group of small chromosomes. The frequency of aberrations was proportional to the concentration of the substance used as well as to the duration of treatment. After a 24 hour treatment with 0·01mm solution of Ypenyl the maximum incidence of aberrations was found after 8 hour recovery in water. Longer recovery periods resulted in a gradual decrease in the number of aberrant post-metaphases in the cell population studied. Increasing concentration of Ypenyl led to the decrease in mitotic activity. Short recovery periods caused a considerable decrease in the mitotic index, which was compensated as late as 16 hours after treatment with the cytostatic.     

Chromosomal analysis in mouse eggs fertilized in vitro with sperm exposed to ultraviolet light (UV) and methyl and ethyl methanesulfonate (MMS and EMS)

Chromosome aberrations were analyzed at the first-cleavage metaphase of mouse eggs fertilized in vitro with sperm exposed to ultraviolet light (UV) as well as to methyl and ethyl methanesulfonate (MMS and EMS). The frequencies of chromosome aberrations markedly increased with dose of UV as well as with concentration of MMS and EMS. In the UV-irradiation group, the frequency of chromosome-type aberrations was much higher than that of chromatid-type aberrations. About 90% of chromosome aberrations observed in the eggs following MMS and EMS treatment to sperm were chromosome type in which the frequency of chromosome fragments was the highest. The effects of UV on the induction of chromosome aberrations were clearly potentiated by post-treatment incubation of fertilized eggs in the presence of Ara-C or caffeine, but the effects of MMS and EMS were not pronounced by post-treatment of Ara-C or caffeine. The results indicate a possibility that UV damage induced in mouse sperm DNA is reparable in the eggs during the period between the entry of sperm into the egg cytoplasm and the first-cleavage metaphase.     

The effects of increasing dosages of X-radiation on the chromosomes of the central mudminnow, Umbra limi (Kirtland) (Salmoniformes: Umbridae)

Fish subjected to 350 R, 660 R and 990 R of X-radiation showed chromosomal aberrations such as chromatid breaks and gaps, and chromatid exchanges between several chromosomes. The frequency of aberrations/metaphase increased with radiation dosage. Likewise, the percentage of aberrant cells increased with increased irradiation. The countable metaphases fish was lower for higher doses of radiation. At lower doses single chromatid breaks accounted for most of the aberrations whereas complex aberrations involving the breakage and exchange of fragments between several chromosomes were more frequent in fish subjected to 990 R. Gill tissue yielded three times as many countable metaphases as did spleen tissue.     

The distribution of chromosome aberrations after gamma and neutron irradiation among cells in various stages of the mitotic cycle in a human lymphocyte culture

Distribution of chromosome aberrations among cells depending on radiation dose, stage of mitotic cycle of human lymphocyte culture, time of cell fixation under the effect of 6 MeV neutrons and their combination with postirradiation hyperthermia has been investigated. The regularities in the distribution of aberrations within cells are similar with both neutron- and gamma-radiation. In experiments with both types of radiation delivered at the S stage and fixation 52 h after the onset of incubation, distribution of aberrations follows Poisson formula whereas with 62-hour fixation, the correlation is disturbed. This is due to the presence of cells dividing for the second time after irradiation which makes the data obtained with delayed fixation scantily informative. Additional hyperthermia does not affect substantially the structure of cell population with both radiation types.     

Biological monitoring of workers in the rubber industry. I. Chromosomal aberrations and sister-chromatid exchanges in lymphocytes of vulcanizers

To evaluate the possible genetic consequences of the industrial exposure among the vulcanizers of a rubber plant we measured the in vivo levels of chromosomal aberrations and sister-chromatid exchanges in peripheral lymphocytes of 34 vulcanizers and in an adequate control population. The observed chromosomal aberration frequencies were 1.9 +/- 1.4 aberrations/100 cells in the exposed group and 2.1 +/- 1.5 aberrations/100 cells in the controls. No difference was found between the two groups for the mean value of sister-chromatid exchanges (5.2 +/- 1.3 in the exposed, 5.2 +/- 0.7 in the control group). Cigarette-smoking was clearly associated with increased sister-chromatid exchange frequencies both in the exposed and in the control groups, while chromosomal aberration frequencies were not correlated with smoking habits.     

Chromosome aberrations in relation to radiation dose following partial-body exposures in three populations

Structural chromosome aberrations were evaluated in peripheral blood samples obtained from three populations exposed to partial-body irradiation. These included 143 persons who received radiotherapy for enlarged thymus glands during infancy and 50 sibling controls; 79 persons irradiated for enlarged tonsils and 81 persons surgically treated for the same condition during childhood; and 77 women frequently exposed as young adults to fluoroscopic chest X rays during lung collapse treatment for tuberculosis (TB) and 66 women of similar ages treated for TB with other therapies. Radiation exposures occurred 30 and more years before blood was drawn. Doses to active bone marrow averaged over the entire body were 21, 6, and 14 cGy for the exposed thymic, tonsil, and TB subjects, respectively. Two hundred metaphases were scored for each subject, and the frequencies of symmetrical (stable) and asymmetrical (unstable) chromosome aberrations were quantified in 97,200 metaphases. Cells with stable aberrations were detected with greater frequency in the irradiated subjects compared with nonirradiated subjects in all three populations, and an overall test for an association between stable aberrations and partial-body ionizing radiation was highly significant (P less than 0.001). We found no evidence that radiation-induced aberrations varied by age at exposure. These data show that exposure of children or young adults to partial-body fractionated radiation can result in detectable increased frequencies of stable chromosome aberrations in circulating lymphocytes 30 years later, and that these aberrations appear to be informative as biological markers of population exposure.     

Use of unstable chromosome aberrations for biological dosimetry after the first postirradiation mitosis

The loss of unstable chromosome aberrations after the first postirradiation mitosis makes their use difficult in radiation dosimetry. We describe here a method which, in a cell population observed at this stage, allows retrospective estimation of the frequencies of the unstable aberrations induced at the time of irradiation, and their use as a dosimeter. The laws controlling the behavior of unstable aberrations during mitosis were defined from a large-scale experiment on irradiated human lymphocytes. For cells undergoing the first, second, or third mitosis after irradiation, relationships were determined between the frequency, at irradiation time, of acentric fragments not arising from formation of dicentrics or rings, and the ratio of dicentrics and centric rings appearing without acentric fragments to the total number of dicentrics plus rings. On the basis of this ratio, the method described here provides an assessment of the postirradiation mitotic activity in a cell population. This assessment permitted estimation of the cell distribution and frequency of dicentrics plus centric rings, and of the frequency of acentric fragments at the time of irradiation. The use of this method for retrospective dosimetry after whole-body irradiation under various conditions of exposure is illustrated.     

Aberrant pollen in southern African Oxalis (Oxalidaceae)

The formation of aberrant pollen is a well‐known phenomenon reported in various angiosperm families.The presence and range of aberrant pollen grains among southern African members of Oxalis L. were studied by SEM analysis. Seven categories of grain aberrations and two successiform series were identified. Grain aberrations were most frequently found amongst pollen with supra‐areolate exine structures and always affected the number and arrangement of the colpi. The exine structure is never altered. No distinct correlation could be detected between grain aberrations and ploidy levels.     

The state of gametes and the type of maturation of follicular oocytes in rats neonatally androgenized by LH-RH-induced ovulation

The character of follicular oocyte maturation and the state of gametes in androgenized rats was studied after LH-RH stimulation. The induction of ovulation with LH-RH has been shown to increase the number of rats with nonovulatory follicules and reduce the number of oocytes maturing prior to the onset of metaphase II. After the induction of ovulation the rate of chromosomal aberrations became higher than in intact animals. Ovulated oocyte population was characterized by the increased number of degenerated gametes. This increase was paralleled by decreased incidence of chromosomal aberrations in ovulated cells.     

A medico-genetic study of isolates in Uzbekistan. III. Results of a cytogenetic study]

The cytogenetic examination of the population of the villages of Karakent and Ishan consisted of two directions: the study on the frequency of chromosome aberrations in the culture of lymphocytes and the diagnostics of anomalies and variants of karyotype. The frequency of chromosome aberrations of 40 individuals was studied. It is shown that the frequency of cells with chromosome aberrations of the individuals in different villages does not differ and on the average is 1,4%. The distribution of lymphocyte culture according to the number of aberrations corresponds to that of theoretical Puassonian. Chromatide breaks are the main type of the aberrations. Among 250 karyotypically examined individuals no evident structure reformations were found. In the caryotype of a 7-year old girl trisomia of the 21st autosome was detected. On the basis of differential staining of chromosomes by Hiemse's dye 18 individuals (7,2%) were diagnosed to have insignificant changes in morphology of some chromosomes, considered as variants of caryotype. In the majority of cases these changes were of a family nature. On the medical examination mnay individuals were diagnosed to have different pathological features, though we did not succeed in revealing any correlation between a certain microanomaly of chromosomes and a pathological feature.     

Studies on the salivary gland chromosomes of an isolated population of Anopheles stephensi (Diptera, Culicidae)

The salivary gland chromosomes of Anopheles stephensi from a local wild population in Nadasahib (Haryana) have been studied. The banding pattern is compared with the standard pattern of Anopheles stephensi (NICD strain). Differences in the free ends of the X-chromosome and the autosomal arms have been seen. These differences are both in the shape and the banding pattern of the free ends. The impact of ecogeographic isolation on genetic variability between the two species is also discussed. The Nadasahib population is free from natural chromosomal polymorphism, whereas 32 different types of aberrations have been seen in the NICD strain.     

Mitotic cycle kinetics of root meristems of isolated barley embryos and intact seedlings. Labelling of nuclei by3H- thymidine and its cytogenetic consequences

The duration of the mitotic cycle and its individual phases was estimated in root meristems of isolated barley embryos and intact barley seedlings by means of pulse labelling with³H-thymidine and construction of labelled mitoses curve. The duration of the whole mitotic cycle in the cell population of root meristems of isolated barley embryos cultivated in the aerated liquid complete medium is 12.2 h. The mitotic cycle time of root meristems of intact barley seedlings, oultived in Petri dishes on wet blotting paper is 9.2 h. Most of root meristem cells belong to the fraction of rapidly proliferating cells, but this fraction exerts a high degree of variability by itself. Pulse treatment by³H-thymidine in our experimental conditions (74 kBq ml^-1 - or 2 μCi ml^-1, exposure 0.5 h) did not induoe any chromosomal aberrations in unlabelled cells and only a very low frequency of chromosomal aberrations in labelled cells. Measuring the cell population kinetics by pulse labelling with³H-thymidine can be used simultaneously with the study of induction of ohromosomal aberrations by mutagens.     

Chromosome-damaging action of isoniazid and thiacetazone on human lymphocyte cultures in vivo

Summary Antitubercular drugs in general are given in various combinations, one being isoniazid and thiacetazone. In the present study, was evaluated the in vivo chromosome-damaging effects of a combination of these two drugs in 72 h lymphocyte cultures.Chromosome aberrations were significantly increased in the patients treated with INH and thiacetazone as compared with two types of controls: (1) tuberculosis patients before starting the drug treatment and (2) individuals from the general population. The most frequently observed aberrations were chromatid breaks and gaps.It has been shown that individually, isoniazid may not be clastogenic on human chromosomes in therapeutic doses. The effects of thiacetazone on human chromosomes are not known. Consequently, the enhancement in chromosomal aberrations in the drug-exposed patients may be due to a synergistic effect of isoniazid and thiacetazone or to the clastogenic effects of thiacetazone alone.     

四种杀虫剂对白纹伊蚊(Aedes albopictus)细胞株(C6/36)的细胞遗传学效应

本文研究了四种杀虫剂:敌敌畏乳剂,灭害灵,甲基对硫磷,叶蝉散对白纹伊蚊细胞株（C6/36）染色体畸变和姐妹染色单体互换（SCE）的影响。结果表明:0.1％和0.01％浓度的敌敌畏,可使（SCE）频率明显增加,而染色体畸变率只在0.1％浓度有显著增加;0.5％的灭害灵,可使SCE频率明显增加,而染色体畸变增加不明显;甲基对硫磷和叶蝉散的实验结果表明,无论是染色体畸变和SCE频率均没有明显增加。