Participation of the lipid peroxidation processes in the adaptation mechanism of Muridae like rodents to the radioactive contamination of the Chernobyl NPP zone

Results of the comparative analysis of the complex investigation of rodent population state caught at areas with different levels of contamination in the accident zone of the Chernobyl NPP during 1986-1993 and 2007, at areas with a practically normal radiation background in the neighborhood of the Kiev City in 1993 and at areas with the normal and increased radiation background in Ukhta region of Komi Republic in 1993-2008 are presented. It is shown that the absence of the linear dependence in changes of the lipid peroxidation (LPO) regulatory system parameters in rodent tissues on the dose of the external gamma-radiation at areas of their trap persists for a long time. Different ability to normalization of the studied indices and nonlinearity of their dose dependences allow us to suggest that changes of the scale and direction of interrelations between the reciprocal parameters of the LPO regulatory system in norm in tissues of rodents which were caught in the accident zone and at areas with an increased radiation background should be the information signal determining selection of the strategy of adaptation to the chronic radiation factor action.     

Monitoring of tundra vole (Microtus oeconomus Pall.) population inhabiting areas with increased radiation background

The data of complex examinations of morphophysiological state of Tundra vole (Microtus oeconomus Pall.), the lipid peroxidation (LPO) processes and the energy exchange in their organs, the cytogenetic analysis of marrow cells and the process of multiplication in populations inhabiting areas with increased natural radiation background more 50 years are generalized. The data obtained support the existence of qualitative differences of Tundra vole subpopulations inhabiting control and radioactive nuclide contaminating areas. They allow to suppose that the process of adaptation to chronic low intensity radiation effect of Tundra vole in natural conditions involves the transition of the LPO and another regulatory systems to different level of function and is directed on population survival and homeostasis maintenance in changing radioecological conditions.     

The structural-functional disorders in the liver of wild rodents from areas of the accident at the Chernobyl Atomic Electric Power Station]

A study was made of the morphological status of hepatocytes, the antioxidant activity of lipids and composition of phospholipids, and dehydrogenase activity in the liver of field mice taken from seven regions of the Chernobyl A.P.S. zone with different levels of contamination in 1987. There observed multiple types of destructive damages to the organ; depletion of liver lipids by antioxidants; diminution of phospholipids within the total lipid level; considerable increase in the phosphatidyl choline/phosphatidyl ethanolamine ratio and in the relative content of phospholipid lysoforms; and inhibition of dehydration processes. In the absence of a strict correlation between the changes in the biophysical and biochemical parameters or between the severity of degenerative changes in hepatocytes and the level of external irradiation, certain relationship was followed up between liver lipid depletion by antioxidants, inhibition of dehydration processes and the number of wild rodents which developed dystrophic changes in the organ. These structural and functional changes were found in the liver of wild rodents taken from all the regions: this indicated a considerable sensitivity of the parameters of the regulatory cell systems and hepatocytes to the effect of technogenic contamination.     

The parameters of antioxidant status of tissues in the offspring of tundra vole (Microtus oeconomus Pall.) inhabiting areas with increased natural radioactivity

The parameters of the lipid peroxidation regulatory system (the antioxidative and antiperoxidant activities, the peroxide content, the lipid peroxidation intensity) in the tissues and the activities of the antioxidative defence enzymes (the peroxidase activity in blood, the superoxide dismutase activity in the blood erythrocytes) are studied in progeny of tundra vole which are reproduced from parent inhabiting areas with different radioecological environment during a long time. The progeny had the preservation of the changed antioxidant status. The scale of the changing of the investigating parameters depend on the state of radionucleoids contamination of areas where tundra voles are caught, sex of rodents, the content of antioxidants in lipids of tissues of parents.     

Dependence of response reaction of root voles to low-intensity irradiation on the initial state of the tissue antioxidant system

There has been studied the response of antioxidant (AO) reaction of the tissue system of the root voles Microtus oeconomus Pall. whose parents belonged to the populations long inhabiting the Republic Komi regions with different degrees of radioactive contamination on an additional radiation action at low doses. Differences have been revealed in the phospholipid content, activities of AO defense, intensities of processes of lipid peroxidation (LPO) in tissues of the vole offspring caught in the control and contaminated regions. It has been revealed that direction and degree of changes in the offspring tissues after the additional action are determined by the parameter value in the non-irradiated animal group. Intensity of the LPO processes in liver and brain was leveled after the long low-intensity irradiation. The obtained data and analysis of literature indicate that at predicting effects of chronic action of low doses of a damaging factor both in experiment and in the natural habitation, it is necessary to take into account initial characteristics of biological objects.     

Immunological approach to assessing the health of the environment

The article sums up 10 years of experience in assessing the quality of the environment based on the parameters of the immune system. The studies were conducted on rodents caught in areas with different levels of radioactive or chemical contamination, under the influence of electromagnetic fields of the radio range, and also in laboratory conditions. The most revealing results were obtained when evaluating the proliferative activity of lymphoid cells. A formula has been proposed that allows one to evaluate the degree of anthropogenic impact on the state of an organism in points based on an analysis of the level of spontaneous and mito-gen-induced proliferation of lymphocytes.     

Effect of oxidative processes in lipids on the formation of the biological response during combined exposure to X-rays and chemical agents

It shown that the preliminary administration of the low toxic surfactant (Tween 80) and of acetone at low doses increases the action of the acute X-rays with sublethal and lethal doses on the living organisms. The absence of the linear dependence between the biochemical changes of the lipid peroxidation (LPO) regulatory system and initial levels of parameters of this system was found. The gain of the effect of the action on the LPO intensity in tissues and the changes in the scale and direction of the interrelation between the antioxidative status parameters in murine liver under combined exposure of the damaging factors of the chemical and physical nature was found.     

Dependence of response reaction of root voles to low-intensity irradiation on initial state of the tissue antioxidant system

There has been studied the response of antioxidant (AO) reaction of the tissue system of the root voles Microtus oeconomus Pall., whose parents belonged to the populations long inhabiting the Republic Komi regions with different degrees of radioactive contamination, on an additional irradiation at low doses. Differences have been revealed in the phospholipid content, activity of AO defense, intensity of processes of lipid peroxidation (LPO) in tissues of the offspring of voles caught in the control and contaminated regions. It has been revealed that direction and degree of changes in the offspring tissues after the additional action are determined by the parameter value in the non-irradiated animal group. Intensity of the LPO processes in liver and brain was leveled after the long low-intensity irradiation. The obtained data and analysis of literature indicate that at predicting effects of chronic action of low doses of a damaging factor both in experiment and in the natural habitation, it is necessary to take into account initial characteristics of biological objects.     

Mutagenesis in Muridae from regions with increased radiation level

Genetic monitoring of wild populations of mouse-like rodents has been carried out since 1992 in areas with the increased radioactivity in the south of the Bryansk region. The radioactive background ranged from 0.20 to 2.20 mkGy/h. Over 400 rodents of different species have been examined. Bank vole constituted more than a half of the examined animals. The genetic effect of radiation was estimated by the frequency of micronuclei in normochromatic erythrocytes of peripheral blood and by the frequency of abnormal sperm heads. In house mice the frequency of reciprocal translocations and the level of embryo mortality were studied in the progeny of the caught male mice mated with intact laboratory females. The data obtained demonstrate that the yield of induced genetic disorders by all tests was relatively low and only in a few cases the frequency of disturbances tended to increase with an increase in the level of radionuclide contamination in the examined areas.     

Migrations of Rodents in the Zone of Local Radioactive Contamination at Different Phases of Population Dynamics and Their Consequences

Migrations of rodents in the zone of local radioactive contamination (East Urals Radioactive Trace, Southern Urals) at different phases of population dynamics are analyzed for the first time. The absence of any isolation of the rodents in the zone of this radioactive trace is convincingly demonstrated and the migration distances are estimated. As is shown, migration decreases the probability for transfer and fixation of adaptations in the chain of generations in vagile rodent species and increases the within-population genetic diversity of animals in adjacent regions. The need to consider the migration factor in a wide range of studies on assessment of biological effects in the zones of local technogenic contamination is confirmed.     

The distribution of labelled iodine in the tissues of wild and laboratory animals with differing functional activity of the thyroid

The dynamics of radioactive iodine accumulation in some organs and tissues of experimental and wild rodent has been studied. The data obtained indicate the seasonal changes in accumulation investigated. These changes correlate with the dynamics of thyroid gland functional state.     

The phospholipid composition of the liver in root voles living under different radioecological conditions

The effect of the increased natural radiation background (within some areas in Komi Republic) and man-caused radioactive contamination in the Chernobyl NPP accident zone on the composition of liver phospholipids in Microtus oeconomus inhabiting these areas was studied. The significant changes in the liver lipid composition in rodents inhabiting both the Chernobyl accident zone and the areas with the increased natural radiation background were found. The maximal changes in the liver phospholipid composition were revealed during the first year after the accident. The reverse dependence between the phosphatidyl choline/phosphatidyl ethanolamine ratio and the ratio between the sum of more readily oxidizable phospholipids and the sum of more poorly oxidizable ones was found. However, the slope of corresponding curves significantly depends on the radioactive state in the area of the population inhabitance. The conclusion about high sensitivity of the lipid composition of hepatocytes in Microtus oeconomus both to the impact of the man-caused radioactive contamination and the increased level of the natural radioactivity was drawn.     

The effects of radiation on sperm swimming behavior depend on plasma oxidative status in the barn swallow (Hirundo rustica)

Sperm are highly susceptible to reactive oxygen species (ROS) that can damage sperm DNA and structure, resulting in reduced fertilizing capacity. Exposure to radioactive contamination can also impair sperm swimming behavior and fertilizing ability, both through a reduction of sperm DNA integrity and via an increased generation of reactive oxygen species (ROS). However, the relationship between individual oxidative status and sperm swimming behavior has never been investigated in any wild population of animals exposed to radioactive contamination. We studied the motility of sperm collected from barn swallows, Hirundo rustica, breeding under different levels of radioactive contamination following the Chernobyl accident in 1986, in relation to individual oxidative status. We tested the hypothesis that the degree of impairment of sperm swimming behavior by radioactive contamination depended on plasma antioxidant capacity, the level of reactive oxygen metabolites (ROMs) and oxidative stress (sensu Costantini et al. 2006), a better oxidative status being associated with higher sperm motility. Sperm behavior parameters were subjected to principal component (PC) analysis, which extracted four PCs explaining 86% of the variance in sperm motility. PC2, representing sperm with high track velocity and ample lateral head displacement, was significantly predicted by the interaction between radiation level and either oxidative damage or oxidative stress. Contrary to our predictions, the highest values of PC2 were associated with relatively high radiation levels, particularly for high levels of either ROMs or oxidative stress. In addition, there was a tendency for values of PC3 (representing the percent of motile sperm) and PC4 (representing slow sperm with high beat cross frequency) to depend on the interaction between radiation level and total plasma antioxidant protection. Our results confirm the importance of oxidative status in determining the genetic and physiological outcome of exposure to radioactive contamination, complementing previous studies relating sperm abnormality to circulating levels of specific antioxidants. Our results also complement previous evidence that oxidative damage of sperm was negatively related to sperm motility, thus indicating a possible trade-off in quenching pro-oxidant compounds in the plasma and the seminal fluid.     

Assessment of radiation exposure of murine rodents at the EURT territories

The study provides data on contemporary levels of radiation exposure of organs and tissues of murine rodents (several species of mice and voles) inhabiting the East-Ural Radioactive Trace. The estimation procedure involves the most advanced approach based on application of appropriate voxel phantom and biokinetic model. Input data for dose assessment are the results of measurements of skeletal ⁹⁰Sr activity concentration. Maximal internal dose to skeleton, accumulated during 45 days, is 303 mGy. Median internal dose rates on the last day before trapping were 0.83, 0.092 and 0.023 mGy/day for animals trapped at the sites with initial (1957) ⁹⁰Sr surface contamination >37 MBq/m², 18.5–37 MBq/m² and 0.074–18.5 MBq/m² respectively. Taking to account internal and external exposures, upper boundary of the ICRP Derived Consideration Reference Level (DCRL) is exceeded on the territory with maximal level of the initial ⁹⁰Sr surface contamination. On the territory with 18.5–37 MBq/m², whole body mean dose rates to murine rodents exceed the lower boundary of DCRL. On the areas with lower level of surface contamination, even the 90-th percentile of dose rate is below the DCRL.     

The influence of chromium chloride consumption on lipid peroxidation and activity of the antioxidant defense in rat tissues

The effect of food supplementation with chromium (CrCl₃ · 6H₂O) on intensity of peroxide processes and activity of antioxidant enzymes has been investigated in some rat tissues. Food supplementation with 200 μg/kg CrCl₃ · 6H₂O for 30 days resulted in the increase of tissue chromium. The tissue chromium content of chromium-treated rats decreased in the following order: spleen, heart, kidney, lung, brain, liver, skeletal muscles. All organs and tissues (except skeletal muscles) of chromium-treated rats were characterized by decreased content of lipid peroxidation (LPO) products: hydroperoxides and thiobarbituric acid reactive substances (TBARS). The maximal reduction in LPO products was observed in spleen, kidney, liver, and lung. Treatment with chromium also caused an increase in the activity of glutathione peroxidase, glutathione reductase, and calatase in all tissues and organs studied. In the brain and kidney an increase in the content of reduced glutathione was observed. Superoxide dismutase activity was higher in myocardium and skeletal muscles, basically equal in lung and liver, while in other organs (brain, kidney, spleen) of experimental animals it was lower than in control animals. Results of this study suggest that chromium exhibits tissue/organ-specific regulatory effects on enzymes of the antioxidant defense     

A new approach to assessment of biological consequences of exposure to low-dose radiation

A high sensitivity of characteristics of the lipid metabolism in erythrocytes to exposure to low doses of gamma- and X-rays was found; the changes in lipid peroxidation (LPO) of blood components were persistent, which substantially influenced the development of biological consequences of low doses of radiation. The effect of low doses of radiation on the interrelation between the LPO intensity in blood plasma and the lymphocyte DNA structural integrity or the cell-free DNA content in animal blood plasma was found. Different sensitivity of the examined parameters (neither normalization nor linear dependence on a dose rate was found) implies the transition of the LPO regulatory system to another level of functioning due to scale changes of interrelations between the examined parameters under influence of low doses of radiation. These findings make possible to assess biological consequences of radiation factor for animal groups by the scale changes of interrelations between the examined characteristics in blood plasma.     

Role of the antioxidant system in adaptation of ducks to postnatal development conditions

The peculiarities of antioxidant system functioning of duck organism were exposed in postnatal ontogenesis. The liver tissues and blood plasma of daily ducks are characterized by high LPO level, that leads to changes of superoxide dismutase, catalase, glutathione peroxidase activity. The level of LPO products declines, but disforming of adapt mechanism breaks the coordinating function of enzymes while vitamin A and E provision are deficient sience 7 till 42 days age. In the 8 and 10 ontogenesis weeks the LPO intensification depends on lipid content increase. Perhaps, it is a response on energy need growth of duck organism in forming feather period.     

Yellow-necked mice (<Emphasis Type="Italic">Apodemus flavicollis</Emphasis>) and bank voles (<Emphasis Type="Italic">Myodes glareolus</Emphasis>) as zoomonitors of environmental contamination at a polluted area in Slovakia

Background  

Free-living wild rodents are often used as zoomonitors of environmental contamination. In the present study, accumulation of cadmium (Cd), copper (Cu), iron (Fe), and zinc (Zn) in critical organs of yellow-necked mice (Apodemus flavicollis) and bank voles (Myodes glareolus) trapped in a polluted area in Nováky, Slovakia was investigated.     

Intraspecific directed deterrence by the mustard oil bomb in a desert plant

Plant secondary metabolites (SMs) acting as defensive chemicals in reproductive organs such as fruit tissues play roles in both mutualistic and antagonistic interactions between plants and seed dispersers/predators. The directed-deterrence hypothesis states that SMs in ripe fruits deter seed predators but have little or no effect on seed dispersers. Indeed, studies have demonstrated that birds are able to cope with fruit SMs whereas rodents are deterred by them. However, this mechanism was only demonstrated at the class level, i.e., between birds and mammals, based on differences in the vanilloid receptors. Here we present experimental and behavioral data demonstrating the use of the broad-range, class-independent "mustard oil bomb" mechanism in Ochradenus baccatus fruits to force a behavioral change at an ecological timescale, converting rodents from seed predators to seed dispersers. This is achieved by a unique compartmentalization of the mustard oil bomb, causing activation of the system only upon seed and pulp coconsumption, encouraging seed dispersal via seed spitting by rodents. Our findings demonstrate the power of SMs to shift the animal-plant relationship from predation to mutualism and provide support for the directed-deterrence hypothesis at the intraspecific level, in addition to the interspecific level.     

Experimental adiaspiromycosis of the common vole (Microtus arvalis) and other small wild mammals after intraperitoneal inoculation

After intraperitoneal inoculation ofE. crescens to nine species of wild small mammals, six species of rodents (Apodemus flavicollis, A. sylvaticus, Clethrionomys glareolus, Microtus agrestis, M. arvalis, Mus musculus) developed generalized adiaspiromycosis. The course of experimental infection corresponded to the infections of laboratory animals provoked in the same manner of inoculation. The authors studied the affliction of individual organs, the dynamics of growth of adiaspores in the organs of the abdominal cavity and in the lungs and followed up morphological changes in the adiaspores. In fresh cover glass preparations, the presence of manifestations was demonstrated justifying considerations on the capacity of multiplication of the adiaspiromycosis agent in the host organism.