Radiation biology. Radioecology

Cosmonauts and astronauts, as well as pilots, are regarded as occupational groups exposed to permanent exposure to cosmic radiation, including low LET radiation and dense ionizing particles. The data from Table II of Reynolds R.J. et al., 2014, USA, in terms of Standardized mortality ratio (SMR) from all causes for cosmonauts compared with the USSR/Russia general population and with US astronauts (1960–2013) were analysed. The data on the mortality of cosmonauts were taken by the authors from the site ‘USSR/Russian cosmonaut biographies’, and the source of information on mortality rates for the population of the USSR/Russia is not indicated. R.J. Reynolds and co-authors, firstly, claim a 9–10-fold decrease in the overall mortality of cosmonauts compared to the general population of the USSR/Russia, although a similar value in terms of the ‘healthy worker effect’ is unknown for any other types of employment in developed countries. Secondly, when recalculating the SMR of astronauts in comparison with the population of the USSR/Russia, the value of SMR begins to amount to negligible, indicating an allegedly 17–29 times lower mortality (life expectancy is inversely proportional to SMR). Thirdly, based on the SMR index for astronauts compared to the general population of the United States (Reynolds R.J., Day S.M., 2010), which was 0.59, when recalculating the SMR for cosmonauts to the general population of the United States SMR = 1.1–1.7 times. That is, compared to the US population, Soviet/Russian cosmonauts allegedly have a life expectancy reduced by up to 1.7 times, although a similar level of SMR is shown only in a few studies of asbestos and chemical production. In your summary Reynolds R.J. et al., 2014 includes data on increased SMRs of cosmonauts compared to astronauts, but no other details. It is concluded that, due to the stated absurd data, the study of cosmonaut SMR performed in the USA cannot be considered correct and should not be used for citation, as well as for professional or social comparisons or conclusions.

AMP-activated protein kinase as a universal metabolic sensor regulates the processes of anabolism and catabolism in the body. Activation of AMP-activated protein kinase occurs with a decrease in ATP content in the cell, which occurs under the influence of stress of various etiologies: with fasting, acute hypoxia, physical exertion, with radiation lesions and many other pathophysiological conditions of the body. The increase in its activity can be initiated pharmacologically through G-protein-coupled receptors, including ala1-adrenoagonists, exhibiting unique radioprotective properties on the example of indralin. AMP-activated protein kinase takes part through succinate dehydrogenase (respiratory chain complex II). in enhancing cellular respiration and ATP synthesis. According to the existing hypothesis, with excessive stimulation of AMP-activated protein kinase by alpha1-adrenoagonists, acute cellular hypoxemia develops, which is one of the main mechanisms for the implementation of their action. Under these conditions, the reduction of cell death from acute hypoxia with the stimulation of AMP-activated protein kinase and the participation of nitric monoxide is carried out by the transition to aerobic glycosis. The second important mechanism of protection by alpha1-agonists at large doses of radiation implements an anti-apoptic effect through the PPAR-AMPK-PGC-1α axis, maintaining the functional state of mitochondria. When stimulated with alpha1-adrenoagonists, sirtuin 1 provides an increase NAD+ in the cell, and through PGC-1α mitochondrial biogenesis is carried out, the required intensity of metabolism, cellular respiration and ATP synthesis. These processes may be facilitated by a closely related alpha-1-adrenoagonist cell cycle arrest associated with AMP-protein kinase, which favors affected DNA repair. The potential anti-apoptic properties of the alpha1-adrenoagonist igralin may contribute to the development of high radioprotective properties of the radriorotector at ultra-lethal doses of radiation.

According to the clinical assessment, 85–95% of patients undergoing standard radiation therapy develop such a side effect of radiation dermatitis (RD). Currently, the study of the problem of RD moves away from the classification of the main symptoms towards the development of high-tech methods of diagnosis and treatment, which are associated with the use of bioactive substances of different nature, targeted and cellular therapy, and also nanotechnology. However, there is currently no worldwide standard treatment for RD. This review presents a retrospective of the formation and development of this problem, the current state and possible ways of further development of studies.

The effect of γ-irradiation (⁶⁰Co) in the dose range from 2 to 50 Gy on the morphological (length of the sprout, length of the main root) and biochemical parameters (the content of photosynthetic pigments – chlorophyll a, chlorophyll b, carotenoids) of sprouts of irradiated seeds of common barley variety Vityaz was studied.

Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 led to extensive environmental contamination by several radionuclides, particularly ¹³⁴Cs (half-life Т_1/2=2.06 years) and ¹³⁷Cs (Т_1/2=30.17 years). This has rekindled the interest in the behavior of radiocesium in the environment, particularly given the geoclimatic conditions of Japan. This review paper summarizes key findings of post-Fukushima studies of radiocesium fate and transport in soil-water environment and challenges for the future. The studies after the Fukushima accident have clearly demonstrated that behaviour of accidentally released radiocesium in the environment is governed by speciation in fallout and site-specific environmental characteristics. The Fukushima-derived ¹³⁷Cs is found to be strongly bound to soil and sediment particles, which reduces the potential bioavailability of this radionuclide. Up to 80% of the deposited ¹³⁷Cs on the soil of the contaminated area were reported to be incorporated in hot glassy microparticles (CsMPs) insoluble in water. These particles decompose in the environment very slowly, and long-term radiocesium leaching from these particles is a challenge for future studies. In Fukushima contaminated areas the high annual precipitation and steep slopes are conducive to significant erosion and intensive r-Cs wash-off especially during devastating typhoons. Typhoons Etou in 2015 and Hagibis in 2019 demonstrated a pronounced redistribution of ¹³⁷Cs on river watersheds and floodplains, and natural self-decontamination occurred in some cases. Understanding mechanisms and prediction of radiocesium long-term dynamics and seasonality in water bodies, as well as its remobilization from river-transported sediments at the interface between freshwater and marine water in estuaries is important challenge for contemporary radioecology.

Firstly, polymorphism of gene cytochrome b’(cytb) fragment of mitochondrial DNA (mtDNA ) and migratory activity of red-backed voles (Myodes rutilus Pallas, 1779) at zone of local radioactive pollution – Eastern-Urals radioactive trace zone (EURT) are investigated. More high haplotype diversity in both samples from EURT zone and adjacent background territory (9–10 km) as compared with the reference one (220 kms) was found. Moreover nucleotide diversity and average number of pair distinctions between haplotypes were greatest in voles from contiguous site with background radiation level. Our hypothesis about association genetic diversity with rodents’ migrations from EURT zone were verified in field experiments employing group marking of population by biomarker rhodamine B. Migrants (males and females) of different functional status at background sites were revealed. Long-distance movements (9500 m) are maximal known for M. rutilus. EURT zone is a source of genetic diversity in rodents populations on adjacent territories due to interpopulation gene flows patterns (radiation-induced effects) carrying by migrants. MtDNA can be served as an effective biomarker of radionuclide exposure in natural environment. Сombining usage of ecological and molecular biomarkers is expediently for monitoring in rodents inhabiting zones of local radionuclides pollution.