Features of Prooxidant and Antioxidant Systems of Greater Plantain <Emphasis Type="Italic">Plantago major</Emphasis> Growing for a Long Time under Conditions of Radioactive Contamination

The viability and state of the prooxidant and antioxidant systems of Plantago major seed progeny from cenopopulations growing for a long time at the East-Ural Radioactive Trace (EURT) has been estimated. Radiation doses of maternal plants have been calculated using our empirical data in ERICA Tool. The absorbed dose rates for plantain in the EURT zone varied from 19 to 157 μGy/h, which is 178–1455 times higher than the background values. These relatively low levels of chronic irradiation did not cause a significant decrease in the survival rate of P. major seed progeny; the rate of root and leaf growth decreased only in seedlings from the most polluted cenopopulation. A prooxidant shift was revealed in seedlings from the EURT zone. Given the same regime of enzyme protection (SOD, CAT, and POX) against active oxygen forms, the average rate of accumulation of secondary products of lipid peroxidation (MDA) was 3.3 times higher in impact samples than in background samples. The level of prooxidant shift in impact samples is not linearly related to dose rates that are classified as low doses.     

Intrapopulation variation in the quality of dandelion seed progeny in zones of chemical and radioactive contamination

Interfamilial variation in metal tolerance and radioresistance of seed progeny from F ₁ plants was studied in the dandelion from cenopopulations growing over several decades in gradients of radioactive or chemical contamination. The progeny from the impact zone of the Eastern Ural Radioactive Trace (EURT) proved to be highly viable but had latent injuries that accounted for a high sensitivity to additional technogenic impact. In the F ₁ generation from the zone of chemical contamination, high seed viability was combined with increased tolerance to additional impact of radiation and heavy metals. No significant differences between responses to challenge with habitual and new factors were revealed in samples from either zone.     

Variation in the seed progeny of smooth brome grass,Bromus inermis Leyss., under conditions of chronic irradiation in the zone of the Eastern Ural Radioactive Trace

Long-term studies have been performed on the seed progeny of B. inermis from test plots established along the radioactive contamination gradient in the zone of the Eastern Ural Radioactive Trace (EURT), where dose loads on maternal plants and embryos of seeds from chronically irradiated cenopopulations (with natural background radiation taken into account) exceed control values by factors of 2 to 107. Interannual and individual variation in the viability, mutability, and radiosensitivity of the seed progeny has been revealed. Against the background of high interpopulation variation in test parameters in the EURT zone, weather conditions appear to have no significant effect on seed quality, while such effects are appreciable in background cenopopulations. It has been shown that a positive correlation exist between the initial viability of the seed progeny and their radioresistance. Chronic irradiation in a wide dose range induces an increased frequency of different mutations and morphological modifications. The contents of low-molecular antioxidants in seedlings from impact cenopopulations proved to be higher than in the background sample. The results obtained characterize the potential of protective and restorative mechanisms acquired in the course of evolution that allow plants to survive in the changing environment under exposure to technogenic stress.     

Adaptation of greater plantain, <Emphasis Type="Italic">Plantago major</Emphasis> L., to long-term radiation and chemical exposure

A comparative study of the greater plantain seed progeny was performed with samples from cenopopulations growing for a long time under conditions of radioactive contamination (in the Eastern Ural Radioactive Trace, EURT) or chemical pollution (in the impact zone of the Nizhny Tagil Iron and Steel Works, NTMK). The progeny of plants from the NTMK zone had low viability but proved to be resistant to the additional impact of a “new” factor (acute γ-irradiation) as well as of the “habitual” factor (heavy metal toxicity). Plantain seeds from the EURT area showed high viability and low heavy metal and radiation resistance; i.e., no preadaptation effect was revealed. In experiments on growing plants from different cenopopulations in plot culture, samples from the EURT zone were characterized mainly by morphoses of generative organs, while samples from the NTMK area, by morphoses of vegetative organs.     

Pathways of adaptation of common dandelion cenopopulations to long-term chemical and radiation influences

A comparative study of the seed progeny of dandelions was performed with samples from cenopopulations growing for a long time under conditions of radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT) or chemical pollution (the impact zone of the Nizhnii Tagil Metallurgical Plant, NTMP). The viability of seeds proved to decrease in a similar way along with an increase in technogenic pressure, irrespective of its nature. Experiments on acute exposure to heavy metals and γ-irradiation made it possible to reveal the adaptive capacities of the seed progeny from each cenopopulation. The background sample (formed beyond the zone of any impact) was relatively resistant to irradiation and very sensitive to heavy metals. The cenopopulations from the EURT and NTMP zones manifested nonspecific responses to the effects of both habitual and new factors.     

Recent Levels of Radionuclide Contamination in the Eastern Ural Radioactive Trace and Biological Effects in Local Populations of <Emphasis Type="Italic">Plantago major</Emphasis> L.

The results of the study have shown that the stocks of ⁹⁰Sr and ¹³⁷Cs in the frontal part of the EURT are 6700–15000 and 200–400 kBq/m², respectively. The coefficients of their accumulation in different herbaceous plant species in this impact zone are lower than in other areas. The accumulative capability of plants has probably decreased in the course of selection as an adaptation to the effect of radiation. The viability and growth parameters of Plantago major L. seeds from the EURT zone are similar to those of seeds from the background sample. Cenopopulations chronically exposed to radiation are characterized by a higher mutation rate in the progeny and an unstable response to additional acute irradiation in most characters studied. A high level of inbreeding is observed in all P. major cenopopulations of plantain. The cenopopulation of the impact zone is characterized by a lower variation of allozyme loci, which may be a result of stringent selection for individuals better adapted to the complex of conditions existing in its habitat.     

Intraspecific variation in Melandrium album along a radioactive contamination gradient at the Eastern Ural radioactive trace

Specific ecogenetic features of plants and parameters of seed progeny have been studied in Melandrium album cenopopulations from test plots established along the radioactive contamination gradient in the zone of the Eastern Ural Radioactive Trace (EURT), where absorbed radiation doses in buffer and impact plots exceeded the background level by factors of 2–18 and 330–418, respectively. It has been shown that interannual variation in parameters characterizing the viability of seed progeny largely depends on fluctuations of weather conditions. This dependence is more distinct in cenopopulations from the EURT than in control samples, which is indicative of interaction between radiation and other relevant ecological factors. The radioresistance of seed progeny is contingent on its viability, being independent of radiation load at the sites of maternal plant growth. Hermaphrodite plants occur only in irradiated M. album cenopopulations. This character is inherited: all F ₁ descendants of such plants grown in a vegetation experiment had hermaphrodite flowers. The mutability of seed progeny formed in the EURT zone exceeds the background level. The occurrence and frequencies of recorded anomalies has proved to vary by years and, therefore, can be interpreted as nonheritable modifications.     

Assessment of biological effects in <Emphasis Type="Italic">Plantago major</Emphasis> L. Seed progeny in the zone of impact from a Copper Smelter

The quality of seed progeny was studied in Plantago major from populations growing for a long time in the gradient of chemical pollution around the Karabash Copper Smelter (KCS). The results showed that the range of variation in seed germination and seedling survival rates was wider in background than in impact populations. The lowest values of growth parameters (the number of seedlings with a true leaf and root length) were recorded in the sample from the most polluted plot. Challenging exposure to toxic elements (seed germination in soils from polluted plots) was found to stimulate, to different extents, the rate of leaf formation and suppress root growth in the seedlings. It cannot be stated from these results that the adaptive potential of plants grown in the zone of impact from the KCS is altered, compared to that in other samples. Evaluation of the prooxidant and antioxidant status of seedlings from this zone revealed a decrease in superoxide dismutase and catalase activities (to 60 and 33% of background values, respectively) and an increase in peroxidase activity (to 122%). The prooxidant status of seedlings in samples from the KCS zone was found to be increased, except for the sample from the most polluted plot.     

Variability of biochemical parameters and radiation resistance of the seed progeny of <Emphasis Type="Italic">Descurainia sophia</Emphasis> and <Emphasis Type="Italic">Lepidium apetalum</Emphasis> under exposure to various factors

The physiological and biochemical characteristics of seedlings of Descurainia sophia (Fisch.) and Lepidium apetalum Wild. have been used as examples to demonstrate that long-term exposure of plant populations to environmental stress factors causes adaptive changes in antioxidant and genomic systems that may considerably affect the radioresistance of seed progeny. The resistance to additional acute irradiation of seed progeny of wild plants adapted to different environmental conditions has been found to be determined not only by the combination of antioxidant and DNA-repair protection systems and the vulnerability of the functioning genome, but also by their variability. The data on the relationship of the radioresistance of wild plant populations with physiological and biochemical characteristics and their variability may be used for expert environmental assessment of the state of the biota and prediction of its viability under exposure to abiotic environmental factors.     

Analysis of Local Dandelion (Taraxacum officinales.l.) Cenopopulations from Radioactively Contaminated Zones

Local dandelion (Taraxacum officinales.l.) populations were studied in the areas of the Eastern Ural Radioactive Trace and the floodplain of the Techa River in its upper reaches. In impact plots, the density of soil and plant cover contamination with ⁹⁰Sr and ¹³⁷Cs exceeded the background level by factors of 13–440 and 2–500, respectively; the radiation load exceeded the background level by factors of 1.5 to 45. The seed progeny of plants from these plots was characterized by a high proportion of abnormal seedlings and an increased level of chromosome aberrations in meristem cells. In some years, variation in the seedling viability, growth rate, and developmental rate in these plots exceeded the reaction norm of plants from the background plot, demonstrating both stimulation and inhibition of growth processes. The response of seeds to acute irradiation at high challenging doses varied depending on the level of background radiation in the plots.     

Analysis of rodent populations in technogenically transformed areas (with reference to <Emphasis Type="Italic">Apodemus</Emphasis> (<Emphasis Type="Italic">S.</Emphasis>) <Emphasis Type="Italic">uralensis</Emphasis> from the EURT zone)

It is shown that the response of rodent populations to acute and chronic irradiation depends on its functional structure, i.e., on specific features of animals with two alternative types of ontogenetic development. Upon acute irradiation, sexually immature young of the year (animals with the second type of ontogeny) are most radioresistant. Exposure to chronic irradiation, as in the zone of the Eastern Ural Radioactive Trace (EURT), leads to an increase in the proportion of mature young of the year (animals with the first type of ontogeny), which are the most radiosensitive part of the population. The abundance and fecundity of mice in the impact zone are consistently higher than in the background zone, which improves the adaptive potential of the population. The role of species ecological specialization and configuration of the contaminated zone in the formation of migrant rodent population is emphasized. It is concluded that a high migration activity allows the pigmy wood mouse (a radiosensitive species) to avoid long-term radiation exposure.     

Relationship between morphological disparity and taxonomic diversity in rodent communities in the zone of influence from the Eastern Ural Radioactive Trace in the Southern Urals

To test the hypothesis that morphological disparity increases while taxonomic diversity decreases in a radioactively contaminated environment, the relationship of these parameters was studied in communities (taxocenes) of rodents living in the Southern Urals in the zone of influence from the Eastern Ural Radioactive Trace (EURT) (2003–2008). Young of the year of six rodent species (98 samples) were examined in the background (control) area (0.2 Ci/km²) and in the impact area polluted with radionuclides from the EURT (750 Ci/km²). The dynamics of morphological disparity (MD), assessed with regard to average values of five exterior characters, was compared between the control and impact taxocenes. Taxonomic (taxocenotic) diversity was estimated with the Shannon index (H). Morphological disparity was found to increase significantly at low rodent abundance (in conditionally unfavorable years) and decrease at high abundance, with the value of MD in the impact taxocene being significantly higher. A negative correlation between MD and H was revealed (r = −0.70), in conformity with the above hypothesis. Discordance (difference in direction) of annual changes in the test parameters, with H increasing while MD decreases (or vice versa) was observed in unfavorable years; it can be used as an indicator of conditions unfavorable for rodent taxocenes.     

Ecogenetic Characteristics of Dandelion (Taraxacum officinale s.l.) Populations from the Techa River Floodplain Ecosystems

This study looks into T. officinale cenopopulations growing in the Techa River floodplain under conditions of chronic low-dose irradiation. It has been shown that the left-bank and right-bank cenopopulations differ from one another, as well as from the control (background) population, in the allozyme structure, viability, and radioresistance of the seed progeny and the mechanisms of antioxidant protection. In nature, cenopopulations differing in their phenogenetic structure may have different strategies of adaptation to the chronic influence of low radiation doses against the background of changing environmental conditions. The consequences of irradiation for such cenopopulations, including the viability and radiosensitivity of their seed progenies, may also differ considerably.     

Phenogenetic Analysis of Pygmy Wood Mouse (Apodemus uralensis Pall.) Populations in the Zone of the Eastern Ural Radioactive Trace (EURT)

Monitoring of A. uralensis populations in Kamenskii raion, Sverdlovsk oblast, in 1992–2002 and in Kaslinskii raion, Chelyabinsk oblast, in 2000–2001 revealed an increase in the proportion and diversity of minor morphogenetic aberrations and abnormalities in the structure of the cranium along the axis of the Eastern Ural Radioactive Trace (EURT). The samples from the southern and northern parts of the EURT (contaminated with ⁹⁰Sr to 500 and 4 Ci/km², respectively) were characterized by directed deviations from the control with respect to the frequencies of phenes of nonmetric cranial traits and an increase in the level of their fluctuating asymmetry in young females, which is indicative of epigenetic rearrangements in populations living in a radioactive environment.     

Specific features of the allozyme structure of dandelion populations under conditions of radionuclide and chemical contamination

A study of allozyme spectra has been performed in dandelion cenopopulations growing for a long time under conditions of chemical pollution (the zone of the Nizhnii Tagil Metallurgical Plant, NTMP) or radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT). Cenopopulations from the NTMP and EURT zones and from the background area differ significantly in the qualitative and quantitative composition of allozyme phenes. An analysis of clonal diversity has shown that all cenopopulations are phenogenetically unique. The genesis of each cenopopulation proceeded in a specific way: they had different sets of progenitor plants, whose descendants varied genetically in the course of their reproduction and more or less successful colonization of habitats, undergoing selection under the impact of natural environmental factors and technogenic stress. An increased variability of enzyme systems, compared to the sample from the background area, and, as a consequence, reduced clonal diversity may be regarded as a trait common to populations exposed to chemical or radiation stress.     

Composition of pied flycatcher (<Emphasis Type="Italic">Ficedula hypoleuca</Emphasis> Pall.) nestling diet in industrially polluted area

The composition of pied flycatcher (Ficedula hypoleuca Pall.) nestling diet was studied in the zone of strong pollution with emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast) and in the background area from 2005 to 2007. The results show that diversity of the diet decreases and prevalence in it of one insect taxon (Lepidoptera) increases near the source of emissions. The proportion of uncharacteristic food objects (orthopterans, herpetobiont invertebrates) and variation in the size of invertebrates brought by parents to their nestlings increase, which is explained by degradation of forest habitats in the polluted area. Pied flycatchers provide nestlings with sufficient quantities of food, but its quality in the polluted zone is lower than in the background area.     

Skeletal 90Sr as a marker of migration activity of murine rodents in the zone of the Eastern Ural Radioactive Trace

Analysis and generalization of long-term monitoring data on the accumulation of ⁹⁰Sr in the bone tissue of rodents inhabiting the East-Ural Radioactive Trace and the adjacent control area have shown that the skeletal content of ⁹⁰Sr depends on the level of radionuclide contamination of soil in animal habitats. An assessment of animal migration between contaminated and clean areas by this criterion has shown that the proportion of migrants does not exceed 10%. On this basis, the conclusion is drawn concerning relative isolation of rodent populations in the EURT zone.     

Intraspecific variation in the viability of soredia in <Emphasis Type="Italic">Hypogymnia physodes</Emphasis> (L.) Nyl. (Ascomycota: Lecanorales)

The contribution of morphological features of parent thalli, substrate and climatic factors, and their seasonal fluctuations to variation in the viability of vegetative diaspores has been studied on the model of epiphytic lichen Hypogymnia physodes. Seasonal trends in viability have been revealed only in certain types of biotopes. Hygrothermal conditions and substrate properties in the biotope have proved to have a significant effect on the viability of soredia.     

Assessment of the reproductive capacity of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> trees growing under conditions of chronic exposure to radionuclides of uranium and thorium series

The reproductive capacity of Scots pine (Pinus sylvestris L.) has been estimated in trees from the population growing in an area used to store tailings from uranium ore processing and radium production. Under such conditions, 12- to 15-year-old trees produce seeds of a quality inferior to that in areas with a normal background radiation level. As the weighted absorbed dose rate (at a weighting coefficient of 5) for generative organs increases from 0.002 ± 0.0003 to 0.344 ± 0.059 mGy/day, a proportional increase is observed in the proportion of empty seeds and the frequency of cytogenetic disturbances in the root meristem of seedlings, while the survival rate of seedlings decreases. The minimum absorbed dose rate leading to these changes in the pine population is 0.027 mGy/day, i.e., 12 times as high as the control value.     

Evaluation of DNA damage in the root cells of Allium cepa seeds growing in soil of high background radiation areas of Ramsar – Iran

Plants are unique in their ability to serve as in situ monitors for environmental genotoxins. We have used the alkaline comet assay for detecting induced DNA damage in Allium cepa to estimate the impact of high levels of natural radiation in the soils of inhabited zones of Ramsar. The average specific activity of natural radionuclides measured in the soil samples for ²²⁶Ra was 12,766 Bq kg⁻¹ whereas in the control soils was in the range of 34–60 Bq kg⁻¹. A positive strong significant correlation of the DNA damage in nuclei of the root cells of A. cepa seeds germinated in the soil of high background radiation areas with ²²⁶Ra specific activity of the soil samples was observed. The results showed high genotoxicity of radioactively contaminated soils. Also the linear increase in the DNA damage indicates that activation of repair enzymes is not triggered by exposure to radiation in HBRA.