Exobiology
Exobiology as scientific discipline is one of the areas of space biology. A significant part of the questions of exobiology are invited to unite in the same discipline, defined as “astrobiology” encompassing essentially the most important branches of exobiology (physico-chemical aspects of formation of organic compounds, the origin and evolution of living systems).
Central to exobiology is the problem of life as a cosmic phenomenon. However, exobiology happens to be partly extends beyond biology and is a region associated with a number of other natural Sciences relevant to the question of the origin and spread of life. Exobiology happens to be involved in the theoretical problem of the nature of living as the essence, being different from inanimate matter and in this sense isolated from the environment. This paper reviews the state of the main directions of exobiology – the origin and development of life as a cosmic phenomenon. Discusses data on occurrence in space, propagation in the interstellar space and contacting with the surface of organic compounds, which are material for prototypes of living systems. Discusses the development of life on earth, the emergence of the fundamental properties of living organisms of the various organization levels. Provides information about some of the research projects in the field of exobiology, implemented in experiments aboard spacecrafts.
Problems of exobiology / Проблемы экзобиологии (552.6 KiB)
Gravitational field and living systems
Fundamental researches in the field of gravitational biology share a common goal – to identify the role of gravity as an evolutionary factor, to understand the nature and mechanisms of its influence on various aspects of life, to assess the degree of participation of gravity in the formation of structural and functional organization of living organisms in the process of their development (phylogenesis and ontogenesis).
An extensive experimental material accumulated in gravitational biology suggests that the basis of the regulatory processes aimed at preservation and maintenance of physiological homeostasis in altered gravity are the molecular and cellular mechanisms of adaptation. The results obtained have allowed first of all to formulate a hypothesis about the mechanism of gravity sensitivity of single-celled organisms. The essence of this hypothesis is that gravitational sensitivity (tolerance) of single-celled organism as an individual independent and self-sufficient biological system is a function of its metabolic and physical activity. This means that the main condition for determining the gravitational sensitivity of single-celled organisms are not their form and dimensions, but functional activity. This hypothesis allows to make significant adjustments to one of the fundamental postulates of gravitational biology on the presence of a positive correlation between the weight (size) of organisms and their gravitational sensitivity. These data are of particular practical interest for gravitational and space biology.
One of the evolutionary process vectors is, apparently, reducing the degree of organism dependency from the fluctuations of environmental parameters. In relation to the external temperature, this relative independence was achieved in two different ways in two different directions in the evolution of living systems — homoiotherm and poikilotherm. Despite the fact that the body temperature of the latter is a function of the ambient temperature, the active state of poikilothermal is carried out in a specific, albeit wide, range of natural temperatures. Some types of poikilothermal temperatures in this range are significantly increased with respect to the environment – due to the muscular activity and morphofunctional adaptations. However, there is not yet discussed aspect of the “energy cost” of living systems existence in a gravitational field in relation to the level of the cell both free-living and organism-integrated. Based on the approach of linking temperature range of quasistationarity of cells with the level of functional load we believe that the earth’s gravity in the course of evolution has influenced the formation of physiologically regulated temperature range warm-blooded and their average level of body temperature. Of course, the situation here is quite polysemous (dependence of the intensity of metabolism on body size). However, studies of body temperature of rats and monkeys in “Cosmos” biosatellite program showed the presence of reliable physiologically controlled reduction of body and brain temperatures of animals in flight (microgravity) as compared to control.
Gravity-dependent processes in biological systems of various organization levels (2001-2005) / Гравитационно-зависимые процессы в биологических системах различных уровней организации (2001-2005 гг.) (405.4 KiB)
Research in the field of gravitational biology (2001-2005) /Исследования в области гравитационной биологии (2001-2005 гг.) (369.1 KiB)
Evolution of living systems in Earth's gravitational field (biomechanical and energy aspects) /Эволюция живых систем в гравитационном поле земли (биомеханические и энергетические аспекты) (505.7 KiB)
Gravitational field and the cell
The study of cellular mechanisms of interaction of living systems with environmental factors, including gravity, is a priority direction of fundamental research conducted on living organisms of various complexity, from unicellular to mammals, using a wide range of modern techniques: biophysical, biochemical, physiological. One of the important issues is the clarification of the mechanism of perception and realization of the gravity stimulus in different cell types and cellular associations. The basis of this task are detection, decoding and classification of intracellular sensors of gravity, which is impossible without a clear understanding of the principles of organization and functioning of the cell itself.
According to the theory describing the cell as a chemical reactor of microscopic size, such a system should be indifferent to changes of the gravitational field tension, at least in the range of values from 10-5 to 10g. However, the analysis of a large number of data accumulated so far in the experiments with different types of cells, indicates the presence of structures and processes that are sensitive to changes in the magnitude of the force of gravity. As it is known, cells isolated from organs and tissues of multicellular organisms and cultured in vitro in the laboratory, are free from the influence of regulatory and control mechanisms of higher order (nervous or hormonal) and are deprived of intraorganic, and often, and interstitial relationships. This enables the experimenter to study the effect of the factor acting on cell in pure form, not disguised by system mechanisms of regulation and control.
For the development of this research direction offers a comprehensive program that includes experimental and theoretical studies aimed at clarifying the nature and reactions of living systems at the cellular level in conditions of reduced or increased gravity. As research objects it is expected to use cell culture, cell suspension and isolated tissue cells.
Gravitational sensitivity of microbiomechanical systems / Гравитационная чувствительность микробиомеханических систем (616.1 KiB)
The role of gravity in structural and functional changes of the state of cells / Роль силы тяжести в изменениях структурно- функционального состояния клетки (305.0 KiB)
Probable mechanisms of the of cells gravitational sensitivity /Вероятные механизмы гравитационной чувствительности клеток (412.3 KiB)
Research in the field of cell biology with the unmanned spacecrafts / Исследования в области клеточной биологии в полете автоматических космических аппаратов (637.5 KiB)