Chromosomal Aberrations in Blood Lymphocytes of the Residents of 30-km Chornobyl NPP Exclusion Zone

Title: Chromosomal Aberrations in Blood Lymphocytes of the Residents of 30-km Chornobyl NPP Exclusion Zone

Author: Larysa BEZDROBNA, Tetyana TSYGANOK, Olena ROMANOVA, Larysa TARASENKO, Volodymyr TRYSHYN and Ludmila KLIMKINA

Reference: Institute for Nuclear Research, National Academy of Science of Ukraine

Keywords: lymphocytes, Chernobyl exclusion zone, chromosomal aberrations, Ukraine

Abstract: A comparative сytogenetic examination of 33 self-settlers in the 30 km ChNPP Exclusion Zone and 31 residents in villages of Yahotyn district, Kyiv region was carried out in 1998-99.

ＵＲＬ：http://www.rri.kyoto-u.ac.jp/NSRG/reports/kr79/kr79pdf/Bezdrobna.pdf

Analysis of Chromosome Aberrations in Human Lymphocytes after Accidental Exposure to Ionizing Radiation

Title: Analysis of Chromosome Aberrations in Human Lymphocytes after Accidental Exposure to Ionizing Radiation

Author: Galina SNIGIRYOVA and Vladimir SHEVCHENKO

Reference: Russian Scientific Center of Roentgeno-Radiology, MOH RF, N.I. Vavilov Institute of General Genetics, RAS

Keywords: chromosomes, ionizing radiation, liquidators

Abstract: Analysis of the results of cytogenetic examination and reconstruction of irradiation doses by the frequency of chromosome aberrations in the liquidators of the consequences of the Chernobyl NPP accident.

URL：http://www.rri.kyoto-u.ac.jp/NSRG/reports/kr79/kr79pdf/Snigiryova.pdf

Nucleotide variation in the p53 tumor-suppressor gene of voles from Chernobyl, Ukraine.

Title: Nucleotide variation in the p53 tumor-suppressor gene of voles from Chernobyl, Ukraine.

Author: DeWoody JA.

Reference: Mutat Res. 1999 Feb 2;439(1):25-36.

Keywords:

Abstract: The 1986 Chernobyl disaster contaminated vast regions of Ukraine and Belarus with a variety of radioactive isotopes and heavy metals. While over 90% of the radioactive isotopes have decayed into stable compounds, radiation levels in contaminated areas are still extraordinarily high. In fact, some rodents living near the reactor have internal 134,137Cs concentrations approaching 80 000 Bq/g. Several recent genetic analyses of vertebrates have illustrated that mutation rates of organisms exposed to radiation from Chernobyl are higher than in control groups, but none have studied DNA sequences. Nucleotide sequences of rodent mitochondrial genes were originally reported to have been hypervariable, but those results were subsequently retracted. Herein, I report the results of a pilot study to determine the extent of nucleotide variation at the p53 gene in four species of rodents (voles) from Chernobyl and from control sites. I sequenced a 788 bp region (coding and non-coding) of p53 in 30 different mice comprising four different species of Microtus. Nucleotide variation at the population level was due to deletions and substitutions; both were limited to introns. There were no significant differences between the number of haplotypes in radioactive and control populations (p=0.60). Rare or private alleles might have arisen due to unique mutational pressures at Chernobyl. Alternatively, natural selection might have favored one allele over others (i.e., a selective sweep). Neither scenario is strongly supported by these data. Thus, no apparent genetic effects of the Chernobyl disaster on the p53 gene of resident voles were revealed; more extensive surveys will be necessary to determine if mutation rates are indeed elevated in mice from Chernobyl. However, two salient points emerge; the first involves the utility of introns as markers for mutations in coding regions and the second considers the relative merits of cloning in mutation detection studies.

ＵＲＬ：http://www.ncbi.nlm.nih.gov/pubmed/10029670

High level of genetic change in rodents of Chernobyl

Title: High level of genetic change in rodents of Chernobyl

Author: Robert J. Baker, Ronald A. Van Den Bussche, Amanda J. Wright, Lara E. Wiggins, Meredith J. Hamilton, Erin P. Reat, Michael H. Smith, Michael D. Lomakin and Ronald K. Chesser

Reference: Nature. 1996 Apr 25;380(6576):707-8.

Keywords:

Abstract: Base-pair substitution rates for the mitochondrial cytochrome beta gene of free-living, native populations of voles collected next to reactor 4 at Chernobyl, Ukraine, were estimated by two independent methods to be in excess of 10(-4) nucleotides per site per generation. These estimates are hundreds of times greater than those typically found in mitochondria of vertebrates, suggesting that the environment resulting from this nuclear power plant disaster is having a measurable genetic impact on the organisms of that region. Despite these DNA changes, vole populations thrive and reproduce in the radioactive regions around the Chernobyl reactor.

ＵＲＬ：http://www.ncbi.nlm.nih.gov/pubmed/8614463

Frequencies of micronuclei in bank voles from zones of high radiation at Chornobyl, Ukraine

Title: Frequencies of micronuclei in bank voles from zones of high radiation at Chornobyl, Ukraine

Author: Brenda E. Rodgers, Robert J. Baker

Reference: Environmental Toxicology and Chemistry, Volume 19, Issue 6, pages 1644–1648, June 2000

DOI: 10.1002/etc.5620190623

Keywords: Micronucleus test; Chornobyl; Radiation; Clethrionomys glareolus; Genotoxicology

Abstract: A population of Clethrionomys glareolus (bank vole) from a highly radioactive area within the Chornobyl, Ukraine exclusion zone was sampled in June 1997 and in June and October 1998. Internal radiation doses from radiocesium were estimated to be as high as 8 rads/d. Total dose, which takes into account the internal dose from radiostrontium and the surrounding environment, was estimated to be 15 to 20 rads/d. In contrast, individuals from a reference population lying outside of the exclusion zone registered negligible levels of contamination. We used the micronucleus test in a double-blind study to analyze blood samples from 58 individuals. We scored more than 600,000 polychromatic erythrocytes (PCEs) but could not reject the null hypothesis that the frequency of micronucleated PCEs in voles exposed to radiation was equal to the frequency in unexposed voles. Results of our study stand in sharp contrast to earlier reports of increased frequencies of micronuclei in rodents exposed to fallout of the Chornobyl accident, but with radiation doses that were orders of magnitude lower than those reported here. Radioresistance and experimental methods are possible explanations for these differences in the results.

ＵＲＬ：http://onlinelibrary.wiley.com/doi/10.1002/etc.5620190623/abstract

Genetic diversity of Clethrionomys glareolus populations from highly contaminated sites in the Chornobyl region, Ukraine

Title: Genetic diversity of Clethrionomys glareolus populations from highly contaminated sites in the Chornobyl region, Ukraine

Author: Cole W. Matson, Brenda E. Rodgers, Ronald K. Chesser, Robert J. Baker

Reference: Environmental Toxicology and Chemistry, Volume 19, Issue 8, pages 2130–2135, August 2000

DOI: 10.1002/etc.5620190824

Keywords: Population genetics; Clethrionomys; Radiation; Chornobyl; Evolutionary toxicology

Abstract: At radioactive sites, at least two mechanisms may affect the genetic diversity of populations of a given species. Increased mutation rates due to radiation exposure may increase the amount of genetic diversity in a population. Alternatively, population bottlenecks exacerbated by environmental degradation may lead to a reduction of diversity. The relationship between these two contradictory forces is complex. To explore this relationship, long-term monitoring of a genetic marker within a population is needed. To provide baseline data on the population genetics of the bank vole (Clethrionomys glareolus) living in the most contaminated regions at Chornobyl, Ukraine, we have sequenced 291 base pairs of the mitochondrial DNA control region. Bank voles were chosen as a model system because they have the highest levels of internal dose of cesium-134, cesium-137, and strontium-90 within the Chornobyl exclusion zone. We sampled three geographic sites, which were Oranoe, a reference site with virtually no radioactive contamination (<2 Ci/km²), and two highly contaminated sites, Glyboke Lake and the Red Forest (both 1,000 Ci/km²). Genetic diversity in the population from Red Forest (0.722 ± 0.024) was significantly greater than at the Oranoe reference site (0.615 ± 0.039), while genetic diversity at Glyboke Lake (0.677 ± 0.068) was intermediate. It is concluded that long-term studies of historical and demographic characteristics for experimental and reference populations are required in order to employ population genetics to understand the biological impact of environmental contaminants on the genetics of natural populations.

ＵＲＬ：http://onlinelibrary.wiley.com/doi/10.1002/etc.5620190824/abstract

X-rays induce distinct patterns of somatic mutation in fetal versus adult hematopoietic cells

Title: X-rays induce distinct patterns of somatic mutation in fetal versus adult hematopoietic cells

Author: Li Liang, Li Deng, Marc S. Mendonca, Yanping Chen, Betty Zheng, Peter J. Stambrook, Changshun Shao, Jay A. Tischfield

Reference: DNA Repair, Volume 6, Issue 9, 1 September 2007, Pages 1380–1385

DOI: http://dx.doi.org/10.1016/j.dnarep.2007.04.005

Keywords: Ionizing radiation; Prenatal exposure; Mitotic recombination; Base excision repair; Developmental stage

Abstract: There are a variety of mechanisms and pathways whereby cells safeguard their genomes in the face of environmental insults that damage DNA. Whether each of these pathways is equally robust at specific developmental stages in mammals and whether they are also modulated in a tissue-specific manner, however, are unclear. Here, we report that ionizing radiation (IR) produces different types of somatic mutations in fetal cells compared with adult cells of the same lineage. While 1 Gy of X-ray significantly induced intragenic point mutations in T cells of adult mice, no point mutational effect was observed when applied to fetuses. Fetal exposure to IR, on the other hand, led to a significant elevation of mitotic recombination in T cells, which was not observed in adults. Base excision repair (BER) activity was significantly lower in fetal hematopoietic cells than in adult cells, due to a low level of DNA polymerase β, the rate-limiting enzyme in BER. In fetal hematopoietic cells, this low BER activity, together with a high rate of proliferation, causes X-ray-induced DNA lesions, such as base damage, single strand breaks and double strand breaks, to be repaired by homologous recombination, which we observe as mitotic recombination. Higher BER activity and a relatively lower rate of cell proliferation likely contribute to the significant induction of DNA point mutations in adults. Thus, the mutational response to IR is at least partly determined by the availability of specific repair pathways and other developmentally regulated phenotypes, such as mitotic index.

ＵＲＬ：http://www.sciencedirect.com/science/article/pii/S1568786407001693

Chromosomal aberration analysis in peripheral lymphocytes of radiation workers

Title: Chromosomal aberration analysis in peripheral lymphocytes of radiation workers

Author: Abbas N. Balasem, Abdul-Sahib K. Ali, Hashim S. Mosa, Khattab O. Hussain

Reference: Mutation Research/Environmental Mutagenesis and Related Subjects, Volume 271, Issue 3, June 1992, Pages 209–211

DOI: http://dx.doi.org/10.1016/0165-1161(92)90015-E

Keywords: Chromosomal aberrations; Biological dosimetry; Cytogenetics; Lymphocytes

Abstract: Chromosomal aberration analyses were performed in two groups of radiation workers and in a group of healthy controls. Although the level of exposure was below the accepted annual limit of 50 mSv, the yields of chromosome fragments and of total aberrations were significantly higher in the radiation workers than in the controls. However, the frequencies of dicentric and ring chromosomes in the radiation workers were not significantly different from those in the control

ＵＲＬ：http://www.sciencedirect.com/science/article/pii/016511619290015E

Cytogenetic study on children living in Southern Urals contaminated areas (nuclear incidents 1948–1967)

Title: Cytogenetic study on children living in Southern Urals contaminated areas (nuclear incidents 1948–1967)

Author: A Testa, L Padovani, F Mauro, M Appolloni, P Anzidei, L Stronati

Reference: Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, Volume 401, Issues 1–2, 5 June 1998, Pages 193–197

DOI: http://dx.doi.org/10.1016/S0027-5107(98)00008-6

Keywords: Southern Urals; Radiation exposure; Cytogenetics; Chromosome aberration

Abstract: As a result of the activities of the first Soviet plutonium production reactor, large territories of the Southern Urals were exposed to radioactive contamination. Three different incidents occurring between 1948 and 1967 lead to major exposure. A total of 280,000 people residing on the contaminated territories were exposed both to external and internal contamination particularly due to the long-lived radionuclides ¹³⁷Cs and ⁹⁰Sr. The highest doses were received by 28,000 people living on the Techa riverside villages. In the present paper 15 presumably exposed children coming from the Muslyumovo village on the Techa river have been analyzed using conventional cytogenetic procedure in order to assess a radiation-induced damage. The data obtained have been compared to a group of matched unexposed controls. The results show a statistical difference between the two cohorts which suggests a possible residual contamination representing a continuous hazard for the new generations.

ＵＲＬ：http://www.sciencedirect.com/science/article/pii/S0027510798000086

An increased frequency of structural chromosome aberrations in persons present in the vicinity of Chernobyl during and after the reactor accident. Is this effect caused by radiation exposure?

Title: An increased frequency of structural chromosome aberrations in persons present in the vicinity of Chernobyl during and after the reactor accident. Is this effect caused by radiation exposure?

Author: G. Stephan, U. Oestreicher

Reference: Mutation Research/Genetic Toxicology, Volume 223, Issue 1, May 1989, Pages 7–12

DOI: http://dx.doi.org/10.1016/0165-1218(89)90057-8

Keywords: Chernobyl; Chromosome aberration; Human; Radiation effect

Abstract: About a week after the reactor accident in Chernobyl, a number of German citizens returned to the Federal Republic of Germany from different places of residence in the U.S.S.R. Chromosome analyses of these individuals show a surprisingly significant increase in dicentric chromosomes in comparison to the laboratory control. Acentrics are nearly twice as frequent as dicentrics. Centric rings are also in evidence. Chromatid breaks do not significantly differ from the control with the exception of 1 place of residence.

The frequency of aberrations is too high to be induced by absorbed doses calculated physically or by modelling techniques. So far, no explanation is available for the discrepancy – a factor of about 100 – between calculated absorbed doses and the measured biological effect.

ＵＲＬ：http://www.sciencedirect.com/science/article/pii/0165121889900578