The cytogenetic consequences of chronic irradiation in rodent populations inhabiting the Eastern Urals Radioactive Trace zone

In bone marrow cells of rodents (Apodemus (Sylvaemus) uralensis Pall., 1811, Apodemus agrarius Pall., 1771) inhabiting the Eastern Urals Radioactive Trace (EURT) zone (Kyshtym radiation accident 1957) and adjacent areas of Urals, the chromosome instability and 90Sr accumulation in bones were investigated. Intensive mutagenic process in both species from impact plots (the soil pollution by 90Sr 2322-16690 kBq/m2) was found. Significant positive correlation of aberrant cells frequencies and 90Sr was shown. Possible causes of the lack of resistance to long-term mutagenic factor (over 100 generations since 50 years from the accident) such as migration of animals and specific configuration of the EURT zone (narrow extended territory with sharply falling gradient of radionuclide pollution), which considerably decrease the probability that certain changes will be fixed and inherited in a series of generations of rodents, are discussed.     

Cytogenetic results of irradiation of Southern Ural residents

The paper summarizes the results of studies of 85 individuals exposed in the Southern Ural region. The spontaneous frequency of the cells with micronuclei (MN) in a population of human blood lymphocytes after PHA stimulation and cytokinetic block with cytochalasin B has been determined. The sensitivity of lymphocytes to the irradiation at the dose of 1.0 Gy and the adaptive response (AR) after the irradiation at the low adaptive dose of 0.05 Gy, and the challenge dose of 1.0 Gy 5 h later have been studied too. It was shown that the peculiarity of the Urals population consists in a higher individual variability of the frequency of cells with MN in all groups have been investigated (spontaneous, after acute irradiation in the dose 1.0 Gy) in comparison with Moscow people. The proportion of persons with a significant AR in the Urals groups was considerably lower than that identified among Moscow residents, and the number of persons with enhanced radiosensitivity increased following low-dose irradiation. We can suppose that prolonged action of low level radiation with another ecological factors, living in the contaminated regions result in the enhancement of the sensitivity to the genotoxic agents in the separate individuals.     

Analysis of microsatellite DNA in rodents from Eastern Urals Radioactive Trace zone and contiguous territories

The variability of four microsatellite loci of rodents, caught from the head part of Eastern Urals Radioactive Trace (EURT), along with the rodents inhabiting contiguous zone with background radiation level and distant reference territory, was analyzed for the first time. Differences in the parameters of genetic diversity between northern red-backed voles from the EURT zone and from the reference population were detected. An increase in some indices of genetic diversity in animals from a contiguous to the EURT zone was found; this is probably associated with animal migration and configuration of the area of pollution. A transfer of radiation-induced effects to the contiguous territories and a decrease in the possibility of fixation of adaptations in a series of generations of mobile rodent species in the area of local radioactive pollution are consequences of migrations. The results of the study make it possible to recommend microsatellite markers for the analysis of radiation-induced effects in rodents as model objects of radioecological monitoring.     

Cytogenetic effects in plant populations from the East Urals Radioactive Track

Mutation dynamics in generations was studied in natural populations of plants from the East Ural Radioactive Track (EURT, Kyshtym accident). The experiments were aimed at the investigation of the formation of genetic load in natural plant populations under conditions of prolonged radiation exposure. The main approach used in the study was the analysis of cytogenetic alteration, chlorophyll and gene mutations in plants exposed for more than 40 years to chronic beta-irradiation and in their progeny.     

Some radiobiological effects in higher plants growing on the territory of the East Ural Radioactive Trace

The spontaneous level of cytogenetic damage in three plant species (Achyrophorus maculatus (Scop.) L.; Plantago lanceolata L.; and Plantago media L.) growing on the territory of the East Ural Radioactive Trace is studied. The radiation resistance of plants from radioactive and control nonpolluted sites is determined. The effects of additional fractionated irradiation at different doses and the role of antioxidant systems in the formation of the radioprotector effect are examined. It is shown that the level of the mutation process in the plant population growing at the radiation polluted sites is increased compared to the control populations from nonpolluted territories. Additional acute γ irradiation of seeds collected from polluted and nonpolluted territories demonstrates improved radiation resistance of the plants from the polluted territory. In the control population of A. maculatus in the versions with a one-hour interval between fractions, the radiation effect follows the additivity principle; at the same time, at a one-day interval between fractions, a highly significant radioprotective effect is manifested clearly in the experimental population. For higher plants, the enhanced effectiveness of the functioning of the antioxidant systems in plants growing on territories contaminated with radiation is shown for the first time. Thus, the radioprotector mechanisms of low-dose chronic and preliminary irradiation are similar and one of these mechanisms is activation of the antioxidant systems in plants growing under conditions of chronic low-intensity irradiation for long periods of time.     

The ecology-genetic consequences of chronic irradiation for the populations of the plants and animals

The modem presentations are considered in the review about the consequences for the genotype of animals and of plants of the chronic action of factors of low intensity. Inoffer is spoken about possible dug the chronic irradiation in small doses in microevolution events.     

Cytogenetic studies on the effect of chronic gamma irradiation onVicia faba

Vicia faba seeds (cv. Giza 1) were planted in the Inshas gamma radiation field where they were chronically irradiated during the whole life of the plant. The percentage of the induced abnormal P.M.Cs, as well as the frequency of abnormal P.M.Cs in the different meiotic stages were proportional with the given doses. The main types of chromosome aberrations were anaphase and telophase bridges, fragmentation and lagging chromosomes. The nearest plants to the source showed an inhibition of shoot growth, flower and seed sterility and irregular branching. At the dosage levels used irradiation had no effect on pollen fertility. Seeds of the 1st filial generation were used for both mitotic and meiotic studies. The percentage of the mitotic abnormalities was proportional with the doses. The most dominant type of anomaly was the presence of micronuclei in the different stages of mitosis and in the resting cells. Irradiation affected also other types of anomaliese.g. lagging chromosomes, fragments, bridges...etc. Meiosis, and pollen fertility (2nd generation) were normal.     

Accumulation of 90Sr in the bone tissue of the northern mole vole, living in the head part of the East Ural Radioactive Trace

Deposition of 90Sr in a bone tissue of the northern mole-vole (Ellobius talpinus Pallas, 1770) living in the head part of the East Ural Radioactive Trace (EURT) (density of pollution by 90Sr 37 MBq/m2 - 1000 Ci/km2) was investigated. Features of the rodent are digging (underground) way of life, family organization of settlements and weak migratory activity. Authentic (p < 0.01) interfamily distinctions in concentration 90Sr are revealed on the background of absence of sexual and are features of accumulation the radionuclides inside separate families, thus individual parameters differ in 7 times. It is established, that the level of accumilation of 90Sr is comparable with that in other species of small mammals in this territory. Age inversion of accumulation of 90Sr earlier found out in other species of mammals on the EURT is confirmed.     

Differentiation of the mitochondrial subhaplogroup U4 in the populations of Eastern Europe, Ural, and Western Siberia: implication to the genetic history of the Uralic populations

Phylogenetic relationships between the sequences of the mitochondrial DNA (mtDNA) hypervariable segment 1, belonging to subhaplogroup U4, were examined in the populations of Eastern Europe, Ural, and Northwest Siberia. It was shown that the frequency of subhaplogroup U4, as well as its proportion in the U-component of the gene pools, increased eastwards, reaching maximum values in the populations of Northwest Siberia. Phylogenetic analysis it was showed that the appearance of specific U4-lineage (16113C-16356-16362) in the ancestors of Mansi was most likely caused by its divergence from the East European cluster 16356-16362 in the Late Upper Paleolithic (18566 +/- 12915 years before present). Other U4 mtDNA lineages (16189-16356 and 16311-16356), typical mostly of the indigenous populations of Northwest Siberia (Mansi, Nganasans, and Kets) may have formed during the Neolithic-early Bronze Age (6055 +/- 3599 years before present, on average). It seems likely that the isolation of ancient populations inhabiting the region between the Ob' and Yenisei rivers was the key factor, providing the appearance of the unique Caucasoid mtDNA lineages in their gene pools. These results were consistent with the traditional point of view on the mixed origin of the Finno-Ugric populations of the Volga-Ural region and West Siberia, resulted from the genetic relationships between the populations of Europe and Asia.     

Ecological and genetic monitoring of muridae from populations undergone to the chronic irradiation

In work the data of long-term researches of consequences of chronic irradiation and radioactive pollution on a population of muridaea living in a zone of failure on the Chernobyl atomic power station and in territory of Northern radioecological station are resulted. It is shown, that chronic influence by investigated factors leads to authentically significant change of size of the genetic load determined on a level cytogenetic damages, intensity of reproduction, fertility.     

Genetic effects of acute and chronic ionizing irradiation on Pinus sylvestris L., inhabiting the Chernobyl' meltdown area]

The main results of the 12-year radiation-genetic monitoring of radiobiological, cytogenetic, and genetic parameters in Pinus sylvestris forest plantation from the Chernobyl meltdown area are presented. The acute ionizing irradiation at doses > 1 Gy was shown to induce formation of morphoses and depressed growth; at doses > 2 Gy, the reproductive ability of the trees declined. The radiobiological parameters showed a linear or close to linear dose-dependence relationship. The acute irradiation at a dose of 0.5 Gy induced cytogenetic and genetic effects that were significantly higher than the corresponding control values. The relationship between the cytogenetic effects and the absorbed dose was exponential. The dependence of the mutation frequency at specific loci on the absorbed dose was described by a nonlinear curve. The results of cytogenetic analysis of seedlings obtained from seeds annually collected in zones of slight, moderate, and strong damage of Pinus sylvestris L. are presented.     

Cytogenetic and population effects in oligochaeta from the Chernobyl zone

Research on intensity and character of reproduction of Oligochaeta (Dero obtusa, Nais pseudobtusa and Nais pardalis) was carried out in 1995-1996 in two water-bodies: a) in the Chernobyl NPP zone near Yanov Village, with a dose rate of 14 microGy h-1 on the surface of the bottom sediment; b) at the Uzh River area (the control water-body). The changes in both intensity and reproduction type were observed in worms at the radioactively polluted water-body. Stimulation of paratomic division in D. obtusa as well as activation of sexual reproduction in two other species were found out along with increasing of amount of cytogenetic damages in somatic cells.     

Cytogenetic mechanism and genetic consequences of thelytoky in the wasp Trichogramma cacoeciae

In Hymenoptera, complete parthenogenesis, that is thelytoky, is a common phenomenon where virgin females produce only daughters. Thelytoky is often induced by bacteria of the genus Wolbachia, but can also be genetically determined by the insect itself, as in the genus Trichogramma where both forms exist. In order to compare these two forms of thelytoky, chromosome behaviour analysis in young eggs and genetic analysis of microsatellite markers were carried out in the wasp Trichogramma cacoeciae, where thelytoky is genetically determined. Microscopic studies revealed that during female gamete formation meiotic cells undergo only a single equational division followed by the expulsion of a single polar body. This absence of meiotic recombination and reduction corresponds well with the high levels of heterozygosity observed in females collected from the field and a nonsegregation pattern in the offspring of heterozygous females. We therefore concluded that diploidy in T. cacoeciae is maintained through an apomictic cloning mechanism and that the incidence of thelytoky under genetic control of the wasp differs entirely from the mechanism induced by Wolbachia infection, where thelytoky is restored through gamete duplication.     

Adaptation of the gymnosperms to the conditions of irradiation in the Chernobyl zone: from morphological abnormalities to the molecular genetic consequences

The most suitable plant indicator targets for radiation pollution biomonitoring are conifers, because they have high radiosensitivity. Previously accumulated information about the genetic nature of morphological abnormalities in gymnosperms, induced by acute and chronic irradiation in the exclusion zone of the Chernobyl nuclear power plant, are briefly considered in this review. Since an additional number of important research results appeared in the last decade that are dedicated to the analysis of molecular biological and molecular genetic effects of chronic irradiation on the coniferous plants growing in the exclusion zone of the Chernobyl disaster, all these data are also analyzed in the current review.     

Iodine concentration by the fungus Penicillium chrysogenum inhabiting soils of the nonchernozem zone

The iodine accumulation by strains of microscopic fungi Penecillium chrysogenum isolated from soddy-middle podzolic soils of Kirov region has been studied. It has been shown that fungi are able to accumulate from 5,0 X 10(-5) to 10,2% of iodine depending upon the medium iodine content and the degree of the organisms' tolerance to its high concentrations.     

Radiation and genetic consequences of ionizing irradiation on population of Pinus sylvestris L. within the zone of the Chernobyl NPP

Main results of the nineteen year radiation-genetic monitoring of radiobiological, of cytogenetic, and of genetic parameters of Pinus sylvestris L. of forest plantation from the Chernobyl meltdown area are presented. The acute ionizing irradiation at doses >1 Gy induces the formation of morphoses and of depressed growth; at doses >2 Gy, the reproductive ability of the trees declined. The radiobiological parameters shown linear or close to it dose-dependence relationship. The acute irradiation at dose of 0.5 Gy induces cytogenetic and genetic effects that were significantly higher than the corresponding control values. The relationship between the cytogenetic effects and the absorbed dose was exponential. The dependence of mutation frequency at specific loci on the absorbed dose was described by a nonlinear curve. The results of the cytogenetic analysis of seedlings obtained from seeds annually collected in zones of slight, of moderate, and of strong damage of Pinus sylvestris L. are presented.     

Cytogenetic screening of livestock populations in Europe: an overview

Clinical animal cytogenetics development began in the 1960's, almost at the same time as human cytogenetics. However, the development of the two disciplines has been very different during the last four decades. Clinical animal cytogenetics reached its 'Golden Age' at the end of the 1980's. The majority of the laboratories, as well as the main screening programs in farm animal species, presented in this review, were implemented during that period, under the guidance of some historical leaders, the first of whom was Ingemar Gustavsson. Over the past 40 years, hundreds of scientific publications reporting original chromosomal abnormalities generally associated with clinical disorders (mainly fertility impairment) have been published. Since the 1980's, the number of scientists involved in clinical animal cytogenetics has drastically decreased for different reasons and the activities in that field are now concentrated in only a few laboratories (10 to 15, mainly in Europe), some of which have become highly specialized. Currently between 8,000 and 10,000 chromosomal analyses are carried out each year worldwide, mainly in cattle, pigs, and horses. About half of these analyses are performed in one French laboratory. Accurate estimates of the prevalence of chromosomal abnormalities in some populations are now available. For instance, one phenotypically normal pig in 200 controlled in France carries a structural chromosomal rearrangement. The frequency of the widespread 1;29 Robertsonian translocation in cattle has greatly decreased in most countries, but remains rather high in certain breeds (up to 20-25% in large beef cattle populations, even higher in some local breeds). The continuation, and in some instances the development of the chromosomal screening programs in farm animal populations allowed the implementation of new and original scientific projects, aimed at exploring some basic questions in the fields of chromosome and/or cell biology, thanks to easier access to interesting biological materials (germ cells, gametes, embryos ...).