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The effect of a pulsed magnetic field (PMF) on meristem cells of onion seedlings was compared with the effects of acute gamma irradiation using the allium test. It was found that a PMF with a carrier frequency of 1.8 MHz, a pulse repetition rate of 28 kHz, and a magnetic field induction of 75 mT per pulse leads to an increase in the mitotic index, mainly due to an increase in the proportion of cells in the prophase and an increase in the frequency of cells with chromosome aberrations in the ana-telophase and does not affect the frequency of cells with micronuclei. It has been suggested that a PMF causes nonspecific oxidative stress in plant cells, accompanied by a delay in the cell cycle at the check point (G2/M) and induction of DNA damage. According to these indicators, the PMF resembles the effect of ionizing radiation in doses of 0.05–0.5 Gy. [ABSTRACT FROM AUTHOR]

Chromosome aberrations are an example of the mutation process that happens at the chromosome level of DNA packaging. The occurrence of inversions and complex translocations has not been studied well enough due to the complexity of their detection using the conventional methods of differential staining. It is well-known that ionizing radiation is one of the factors that increases the frequency of chromosomal rearrangements. The objective of this pilot research was to study the frequency of inversions involving telomere regions of the chromosomes and complex translocations in T-cells of 25 chronically exposed residents of the Southern Urals. Inversions were studied in the group of 12 exposed individuals (one man, 11 women, exposure doses ranging from 0.001 to 2.9 Gy) using the Q-FISH method. Complex translocations were analyzed in the group of 13 people (nine women, four men, exposure dose ranging from 0.5 to 3.1 Gy) with the help of M-FISH method. The groups did not overlap. As a result of this analysis, it has been revealed that complex translocations occur six times less frequently than simple ones (р < 0.001). Chromatid variants of inversions predominated as compared to chromosomal ones (9 : 0.17 per 100 cells, p < 0.001). No dependence of the studied parameters on the exposure dose to red bone marrow was noted. [ABSTRACT FROM AUTHOR]

The article discusses possible approaches to cytogenetic homeostasis assessment in natural populations. Various cytogenetic methods, their advantages, disadvantages, and limitations related to the study of animals in their natural habitat are considered. For a reliable characterization of environmental quality, it is recommended to supplement the data obtained in natural populations with laboratory experiments using a test object. Due to a number of features, it is proposed to use the short-living fish Nothobranchius rachovii. [ABSTRACT FROM AUTHOR]

Long after chronic radiation exposure mainly of red bone marrow (mean exposure dose was 0.98 ± 0.05 Gy, individual dose range was 0.08–2.14 Gy), changes in the T-cell immunity such as a decrease in the relative number of CD3+ lymphocytes and a decreased absolute number of CD4+ cells, which did not depend on the maximum dose rate and the absorbed dose on red bone marrow and soft tissues, were observed in peripheral blood lymphocytes of individuals with increased levels of chromosomal aberrations (mainly dicentrics and translocations). The concomitant increase in the relative number of CD19+ lymphocytes, which was mainly determined by the dose rate and absorbed dose on soft tissues, indicated a shift in the immunological balance in the direction of the humoral immune response. [ABSTRACT FROM AUTHOR]

Evaluation of the frequency of chromosome translocations in peripheral blood T-lymphocytes is a generally accepted method of retrospective biodosimetry. Accidental contamination of the Techa River (Chelyabinsk Oblast) in 1950s with bone-seeking long-lived strontium-90 gave an opportunity to evaluate the effect of local red bone marrow (RBM) exposure on translocation formation in the peripheral T-lymphocytes of local inhabitants. The studies of the inhabitants using fluorescent in situ hybridization (FISH) showed that RBM doses calculated based on FISH results were lower than those estimated based on 90Sr body burden measurements. The current study presents analytical review of the published data dealing with the most important processes of the T-lymphocyte development and formation of chromosome aberrations: characteristics of the main compartments where the exposure of T-cell occurs; assessment of the time spent by T-lymphocytes and their progenitors in these compartments; analysis of the dynamics of T-cell populations (proliferation and death); age-related aspects. The paper presents a concept of T-cell Genus (TG) united all the progeny of T progenitor with inheritable specific aberrations that could have developed in bone marrow. [ABSTRACT FROM AUTHOR]

Abstract—The results of a study of delayed changes in the frequency of unstable chromosomal aberrations and the CNA- and LOH-genetic landscape of blood leukocytes in healthy employees at the main facilities of the Siberian Group of Chemical Enterprises exposed to external irradiation are presented. In 2014, 11 persons with de novo induced mosaic deletions and amplifications associated with dicentric and/or ring chromosomes (markers for individual radiosensitivity) were detected. Three years later, the frequency levels of chromosomal aberrations were compared. In 2017 the frequency of aberrant cells had increased by 1.7 times compared to 2014, the frequency of the chromosomal type aberrations had doubled, the frequency of pair fragments had a more than fourfold increase, and the frequency of dicentrics had almost doubled. The mosaic deletion in employee no. 1490 (3q12.3–13.11) identified in 2014 persisted until 2017. Mosaic amplifications identified in 2014 were preserved in five out of six employees (nos. 178, 203, 450, 1620, and 1792). Moreover, we identified that the CNstate in employee no. 450 had increased 1.5 times by 2017. The mosaic amplification of the short arm of the third chromosome in employee no. 278 had been eliminated by 2017. Other changes in the CNA and LOH-genetic landscape were not detected. Thus, these data indicate the formation of self-sustained bone marrow clones, whose descendants produce a population of aberrant cells in the blood of irradiated individuals. Further research into the preservation of chromosomal aberrations and CNA is needed, as well as studies aimed at detecting the clones of aberrant cells in the bone marrow. [ABSTRACT FROM AUTHOR]