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The ecological half-life of 137Cs was calculated individually for four symbiotrophic fungi species (Boletus edulis, Imleria badia, Suillus luteus, Paxillus involutus) at 10 sampling sites in the Chornobyl exclusion zone and in the Kyiv region. It was found that the maximum rate of excretion of 137Cs from the fungi organisms is characteristic for the territory with the maximum levels of soil contamination, i.e., for a zone near Chornobyl Nuclear Power Plant. In areas with low 137Cs content, a slowing down of the excretion rate predominates. These results reveal different fungal response to the distinct concentration levels of 137Cs in forest ecosystems. This observation further suggests that radiocaesium can be selectively accumulated by fungi and used in their life processes. Presence of this 137Cs retention mechanism in fungi leads to a longer contamination of woody plants-symbionts. [ABSTRACT FROM AUTHOR]

Studies of the 137Cs content in fruit bodies of Suillus luteus in the territory of the Chornobyl exclusion zone and Kyiv region outside the zone were carried out during the period 1986 - 2020. It was found that the dynamics of 137Cs activity in the mushroom can be described as a two-stage process. The first stage since 1986 was characterized by the annual increase in levels of specific activity of 137Cs for the following 10 - 12 yrs. During the second stage, there has been a gradual decrease in concentrations of 137Cs. The ecological half-life of 137Cs in the mushroom at the second stage differs for different sampling sites. Its minimum values were noted at Yaniv and Novo-Shepelychy sampling sites inside the exclusion zone. The maximum of 137Cs ecological half-life in Suillus luteus was observed on the Rzhyshchiv sampling site, which is the most remote from the Chornobyl Nuclear Power Plant outside the exclusion zone. [ABSTRACT FROM AUTHOR]

Objective. Determination of the peculiarities of ultrastructural changes and metabolism of reactive forms of oxy& gen and nitrogen in the tissues of the myocardium, aorta and portal vein of the radiosensitive BALB/c mice due long&term exposure to the complex of radionuclides of Chоrnobyl fallout (ejection) and low&intensity low&dose γ& irradiation. Materials and methods. Experimental studies were performed on 60 mice&female radiosensitive lines BALB/c with a body weight of 20-22 g, which were divided into 3 groups: I group (control) & animals age 6-9 months which were born and lived their lives in Kyiv vivarium under conditions natural radioactive background; ІІ - animals age 6 months, which were born and lived in the Chornobyl exclusion zone throughout their lives; ІІІ - animals, which from 3 months of age for 6 months were constantly located in cages with flat ionizing radiation sources and exposed to external γ&irradiation in a total dose of 0.43 Sv. Animals of II and III groups were kept in the vivarium of the Institute for Safety Problems of Nuclear Power Plants of the National Academy of Sciences of Ukraine (Chornobyl). Mice of the BALB/c lines are sensitive to radiation: for males LD 50/30 < 5.7 Gy, for females - 5.85 Gy. Results and conclusions. The peculiarities of structural and functional changes in the organs of the cardiovascular system (CVS) and mechanisms of the development of oxidative and nitrosatitative stress due long&term exposure to the complex of radionuclides of the Chornobyl fallout (ejection) and low&intensity low&dose γ&radiation based on the study of ultrastructural organization and metabolism of reactive oxygen species (ROS) and nitrogen (NRS) of the atri& al cardiomyocytes (CMC), the aortic endothelium and portal vein of the BALB/c mice. Found that the permanent expo& sure to low doses of radiation changes occur, including the dominant mechanism is to run a CMC apoptosis and endothelial cells of the aorta and portal vein. It is shown that the development of oxidative stress accompanied by increased activity of ROS metabolism that occurs due to activation of nucleotide and lipid superoxide generators. Found that under these conditions the development of nitrosative stress is due to the activation of inducible NO syn& thesis enzyme iNOS and inhibit its synthesis constitutive eNOS enzyme. High levels of simultaneous generation of superoxide and NO, bindting, lead to the formation of toxic peroxynitrite, which initiates the process of apoptosis. [ABSTRACT FROM AUTHOR]

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