Research on the Biological Effects of Ionizing Radiations

with Different Physical Characteristics

Participating countries and international organizations:

Armenia, Belarus, Bulgaria, Cuba, Egypt, Italy, Mongolia, Romania, Russia, Serbia, Slovakia, South Africa, Uzbekistan, Vietnam.

The problem under study and the main purpose of the research:

Theoretical and experimental research on the biological effects of heavy charged particles of different energies at JINR's basic facilities.

Brief annotation and scientific rationale:

The aim of the research is to study the molecular, genetic and organismal effects of ionizing radiation with different physical characteristics. The use of ionizing radiation of a wide range of linear energy transfer in radiobiological experiments allows obtaining unique information on the nature of the damage to the DNA structure of cells after irradiation, the mechanisms of the induction of gene and structural mutations in cells with different levels of genome organization, and the action of particle radiation on tumor during radiation therapy. Within the framework of the Theme, fundamental and applied problems of modern radiation biology will be addressed: the formation and repair of cluster DNA damage in normal and tumor cells following exposure to accelerated charged particles; the study of the radiosensitizing effect of the DNA repair modifier AraC in combination with various molecular biological complexes during irradiation of tumor cells and tissues; the study of the induction of gene and structural mutations in normal and tumor cells following exposure to charged particles; investigation of acute and long-term morphological and functional changes in the mammalian central nervous system following exposure to radiation with different physical characteristics.

When organizing radiobiological experiments with charged particle beams, it is extremely important to improve physico-dosimetric complexes, provide precision dosimetry, and conduct computer simulation of radiation-induced effects. In this regard, the urgent tasks are: the need for experimental modeling of the energy and spectral composition of cosmic and other types of ionizing radiation; the search for methods for non-destructive analysis of unique samples; and automated processing of biological experiment data. In the course of the research, it is planned to develop new setups and dosimetry systems for irradiating biological samples; introduce methods for non-destructive analysis of unique samples, develop and test systems for automated computer processing of biological data; formulate new mathematical models and computational approaches for radiobiology, bioinformatics and radiation medicine; and identify mechanisms and pathways of catalytic synthesis of prebiotic compounds under the action of radiation.

Expected results upon completion of the project:

1. To study clustered DNA DSB formation after exposure to accelerated charged particles of different energies in the nuclei of human skin fibroblasts, tumor cells, and neurons of different parts of the central nervous system of irradiated animals.

2. To study the repair kinetics of clustered DNA DSB in the post-irradiation period in the nuclei of human skin fibroblasts and radioresistant tumor cells.

3. To study mechanisms of the radiosensitizing effect of cytosine arabinoside in combination with various molecular biological complexes on normal and tumor cells after exposure to radiation with different LET.

4. To study quantitatively the survival of normal and tumor cells after radiation exposure in the presence of a combination of DNA repair modifiers.

5. To continue investigation of point and structural mutation induction in Saccharomyces cerevisiae yeast cells by radiation with different LET.

6. To study the influence of heterogeneity of cell population in haploid yeast on the radiation-induced mutagenesis; estimate mutagenesis in different phases of cell cycle.

7. To study the influence of respiratory impairment as the result of mitochondrial DNA damage on the sensitivity to the mutagenic effect of radiation.

8. To study the mechanism of radioresistance and its effect on radiation-induced mutagenesis in yeast mutants.

9. To continue the study of radiation-induced mutagenesis and to compare the yield of chromosomal aberrations in Chinese hamster cells at the highest and lowest mutagenesis levels depending on the time of expression and LET of accelerated ions.

10. To analyse structural disorders in the hprt gene and their projection on disorders in the chromosome machinery of cells.

11. To finalise the mFISH study of the biological effectiveness of proton beams.

12. To study the biological effectiveness of low-energy X-rays following in vitro irradiation of human blood lymphocytes using the mFISH method.

13. To evaluate the contribution of complex chromosome aberrations to the biological effectiveness of densely ionizing radiations following irradiation of human normal and tumour cells in vitro.

14. To study the induction and kinetics of chromatin break repair by premature chromatin condensation in normal and tumour human cells exposed to sparsely and densely ionizing radiation.

15. To continue the study of primary and late morphological and functional changes in the central nervous system of rats following exposure to ionizing radiation with different physical characteristics.

16. To conduct studies of pharmacological protection agents' action under ionizing radiation exposure.

17. To continue the investigation of the activation of microglial cells in cell culture and inflammatory markers in the brain of mice following exposure to ionizing radiation of different quality.

18. To investigate the possibility to modulate the activation of microglial cells in irradiated culture and neuroinflammation in the brain of irradiated mice by using inhibitors to the receptors of signalling pathways involved in these processes.

19. To study in vivo the radiosensitizing effect of cytosine arabinoside in combination with other molecular biological complexes on melanoma tumor growth in mice following the combined exposure to these agents and proton radiation.

20. To evaluate the influence of the combined action of AraC and other molecular biological complexes on the survival of different normal and tumor cell lines based on clonogenic survival criterion upon X-ray and proton irradiation.

21. To study the kinetics of the formation and elimination of DNA damage in U87 glioblastoma and other radioresistant cell cultures after proton and X-ray exposure in the presence of AraC and other molecular biological complexes.

22. To study DNA DSB formation in different components of the central nervous system after in vivo irradiation with protons and X-rays in the presence of a combination of radiomodifiers.

Expected results of the project in the current year:

1. To continue the analysis of the formation and repair of clustered DNA double-strand breaks after exposure to accelerated charged particles and photon radiation in the nuclei of human fibroblasts, tumor cells (U87, B16), and neurons of different parts of the central nervous system (CNS) of animals.

2. To continue the analysis of the formation and structure of complex clustered DNA lesions by immunocytochemical staining of repair proteins γH2AX, 53BP1, OGG1, and XRCC1 in human fibroblast nuclei and tumor cells (U87, B16) after exposure to accelerated charged particles and photon radiation.

3. To continue studying apoptosis induction in human skin fibroblasts, tumor cells (U87, B16), and mammalian CNS neurons after exposure to accelerated charged particles and photon radiation.

4. To study mechanisms of the radiosensitizing effect of cytosine arabinoside (AraC) in combination with various molecular biological complexes on the survival of, and the formation and elimination of DNA damage in, normal and tumor cells in vivo and in vitro after exposure to accelerated charged particles and photon radiation.

5. To continue research on the induction of structural rearrangements in yeast cells by radiation with different LET.

6. To study the influence of yeast cell population heterogeneity on the sensitivity to the lethal and mutagenic effects of ionizing radiation.

7. To study the effect of different repair pathways on radiation-induced mutagenesis in lower eukaryotes.

8. To continue studying the effect of mitochondrial DNA damage on radiosensitivity and mutagenesis in unicellular eukaryotes.

9. To continue the analysis of chromosomal aberrations detected in radiation-induced mutants in the long term after irradiation of a mammalian cell culture.

10. To compare the yield of structural abnormalities and the level of HPRT mutagenesis in V79 Chinese hamster cells after exposure to ionizing radiation with different physical characteristics.

11. To continue the metaphase and mFISH analysis of chromosomal aberrations induced in peripheral blood lymphocytes of monkeys (Macaca mulatta) by ionizing radiation with different physical characteristics.

12. To continue the mFISH study of the induction of complex aberrations in human normal and tumor cells by ionizing radiation with different physical characteristics.

13. To continue the study of long-term memory and learning disorders in rats in the Morris test after whole-body proton irradiation.

14. To study demyelination and morphological changes in the CNS of rats after whole-body proton irradiation.

15. To develop a method for assessing radiation-induced cell death in intestinal crypts and conduct pilot experiments with X-rays alone and in combination with AraC.

16. To study the electroencephalogram, behavioral reactions, and morphological changes after local irradiation of the brain of laboratory animals at the SARRP facility.

17. To carry out pilot experiments on computer tomography and local X-ray irradiation of tumors in laboratory animals at the SARRP facility.

18. To develop a method for the evaluation of AraC and other radiomodifiers' content in blood plasma, tissues, and tumors of laboratory animals using liquid chromatography in order to study the pharmacokinetics and metabolism of these compounds.

 
Brief annotation and scientific rationale:

A wide range of JINR's ionizing radiation sources, especially heavy ion beams of various energies, offer a unique opportunity to solve a number of fundamental problems of radiobiology and astrobiology, as well as practical problems related to space exploration and the development of radiation medicine.

Due to the high complexity and cost of performing biological experiments at accelerator complexes, it is of paramount importance to improve experimental methods, ensure dosimetry and radiation safety, and perform relevant computer simulations. The most pressing issues here are the need for experimental reproduction of the energy and spectral composition of cosmic and other types of ionizing radiation, the search for methods for non-destructive analysis of unique samples and automated processing of biological experiment data, as well as the high complexity and resource intensity of computer simulation of processes in living systems.

This project is aimed at solving a complex of the above problems arising in radiobiological and astrobiological research. In the course of its implementation, it is planned to develop new stations for irradiation and dosimetry systems; introduce methods for non-destructive analysis of unique samples; develop and test systems for automated computer processing of biological data; formulate new mathematical models and computational approaches for radiobiology, bioinformatics, and radiation medicine; and identify mechanisms and pathways of the catalytic synthesis of prebiotic compounds under radiation exposure.

Expected results upon completion of the project:

1. Provision of dosimetry and irradiation of biological samples at JINR accelerators.

2. Upgrade and commissioning of the Genome-3 facility.

3. Development of a multimodal tomography system for small laboratory animals.

4. Equipping a room for radiobiological experiments using radionuclides.

5. Creation of a prototype space radiation simulator.

6. Development and testing of instruments for neutron dosimetry and spectrometry.

7. Development of an information system for working with experimental data in the form of two-dimensional images, computed tomography data, and video recordings.

8. Development of protocols for labeling two-dimensional images and video materials, formation of a labeled database.

9. Testing the implemented analysis algorithms; development and registration of software designed for automated data processing.

10. Development of mathematical models of the formation and repair of various types of DNA damage and models of the formation of mutations and chromosomal aberrations.

11. Molecular dynamics modeling of structural and functional disorders in mutant and oxidized forms of proteins.

12. Development of mathematical models of radiation-induced death of tumor cells and prediction of tumor growth for promising radiation therapy methods.

13. Theoretical evaluation of radiation-induced disorders of the CNS on the basis of mathematical models of brain neural networks, taking into account damage to synaptic receptors, oxidative stress, and impaired neurogenesis and gliogenesis.

14. Study of possible pathways of, and conditions for, the formation of prebiotic compounds by irradiation of cosmic matter or terrestrial rocks in combination with the simplest organic molecules.

15. Search for and structural analysis of microfossils and organic compounds in various meteorites by nuclear physics methods.
    
    
    

Expected results of the project in the current year:

1. To perform mathematical modeling of DNA damage formation and repair kinetics in different phases of the cell cycle after exposure of mammalian normal and tumor cells to accelerated heavy charged particles of different energies.

2. To continue mathematical modeling of tumor cell population dynamics after exposure to ionizing radiation in the presence of DNA synthesis inhibitors.

3. To continue molecular dynamics modeling of violations of the structure and functions of synaptic receptor proteins and, as a result, the behavior of the neural network of the central nervous system (CNS).

4. To continue mathematical modeling of radiation-induced disorders of neurogenesis and gliogenesis and neuroinflammatory processes in CNS structures.

5. To continue mathematical modeling of the induction of chromosomal aberrations in mammalian and human cells by ionizing radiation with different characteristics.

6. To apply computer vision algorithms to biological data processing, histology, and behavioral experiments.

7. To ensure that radiobiological experiments are carried out at the LRB's X-ray facilities (SARRP, CellRad).

8. To take part in the design and construction of the Genome-3 station at applied beams of the U400M cyclotron.

9. To take part in a model calculation of the radiation fields of the NICA complex in order to provide the radiation protection of personnel.

10. Together with the JINR Department of Radiation Safety, to take part in forecasting the radiation environment and studying the radiation fields of the NICA accelerator complex using the Bonner sphere method during commissioning.

11. To take part in the design and construction of the SIMBO station at the ARIADNA applied beams of the NICA complex.

12. To develop a prototype of a new neutron dosimeter for a wide energy range.

13. To expand the collection of samples of terrestrial rocks and meteorites.

14. To compare the mineral composition of terrestrial rocks and carbonaceous chondrites using SEM.

15. To conduct an elemental analysis of terrestrial biological samples and fossils of different geological periods.

16. To classify and systemize microfossil samples in carbonaceous chondrites.

17. To formulate the problems of terrestrial contamination of meteorites.

18. To analyze the results of experiments on the synthesis of prebiotic compounds from formamide.

Collaboration