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Biomedical subjects

M G Tairbekov

Publications and source records attributed to M G Tairbekov.

At least 19 recordsLinked to original sources
PubMed2003

[Problems of exobiology: the origin of life on Earth].

The basic problem of exobiology is origin and evolution of life as a space phenomenon. Consideration is given to the facts for the space origin, spreading in the interstellar space of and invasion of the surface of planets by organic compounds, constituents of archetypes of living systems. The authors bring up to discussion the issues of life development under the conditions of Earth, and formation of the main properties of the living organisms differing in the level of organization. Outlined are some international projects on exobiological research in experiments with bio-objects on space platforms.

Biological Evolution↗
PubMed2002

[Evolution of the interaction fo living systems with the environment].

Basic principles of interaction of living systems with environmental factors and different phases of the organic evolution are presented. The general strategy of adaptation of living systems on various levels of organization to changes in the environment is considered. It is shown that in the course of evolutionary adaptation the living systems not only altered their morphophysiological status but also actively adjusted the environment modifying its physical/chemical parameters. Special attention is given to the hereditary and external factors in of structural and functional evolution living organisms. Environmental factors are shown to gain significance in structural/functional and behavioral formation of living organisms as the organic world has evolved.

Biological Evolution↗
PubMed2001

Cytogenetic characteristic of osteogenic cells in vitro as perspective predictors of osteopenia under microgravity.

Mechanical stimulation of bone tissue determined by earth gravity is one of the main factors mediating the nature, rate and direction of functional adaptation of the bone system in the process of onto- and phylogenesis. Theoretically expected losses of bone mass under condition of mechanical load deficit under microgravity (osteopenia, osteoporosis) may become a factor that limits the duration of space flights. As a result of long-term studies some properties and regularities of change in human tissue after prolonged space flights (for 5-7 months) were established.

Animals↗
PubMed2000

[The cell as a gravity-dependent biomechanic system].

In the period of 1995-1997 experimental and theoretical studies with various biomechanic objects, i.e. individual cells and cell associations, were performed under changed gravity (0.00001-5 g). Experimental investigations were conducted using clinostats and centrifuges to model effects of hypo- and hypergravity, and aboard space vehicles in real microgravity. Cell cultures in vitro including fibroblasts and osteoblasts on a solid glass or plastic substrate served as objects of the studies. Changes in value and direction of the gravity vector were found to modify the morphophysiological characteristics of cells: structural organization (spatial rearrangement of the intracell component, changes in forms, sizes and quantity of cells) and functional activity (alterations in energy expenditure and intensity of intracellular metabolism). The data suggest that there should be mechanisms of gravitational sensitivity in living systems on the cellular level. As was stated, sensitivity of unicellular free-living organisms to gravity is mostly defined by the motor activity determined by the level of general metabolism. Morphological characteristics (form, size and mass) are of secondary importance. Theoretical analysis resulted in correction of one of the principle postulates of gravitational biology stating a direct link between size (mass) and gravitational sensitivity of organism. Described were consistent patterns of growth, development, and behavior of unicellular cultures in gravitational fields. Strengthening of the force of gravity (hypergravity) leads to eventual deceleration of cell growth and diminution of biomass gain. On the other hand, the spaceflight environment (microgravity) stimulates growth mechanisms. In our opinion, behind these gravitational effects are altered levels of energy spent by cells to overcome the force of gravity. Opposite trends were observed in experiments with cell cultures in vitro. During space microgravity, fibroblast cultures on the solid substrate decreased the growth rate, and inhibited cell division and migration within the substrate. Compared to the Earth's gravity, under elevated gravity these parameters were noticeably higher. It was demonstrated that the main cause of the unfavorable effects of space microgravity on the cellular level is decay in the adherence of cells to the substrate. Explored were also the most probable mechanisms of the effects of changed gravity on the cell as a biomechanic structure. Specialized and non-specialized graviceptors of various types of cells were crypt-analyzed and classified. In future, investigations should be angled for elucidation of the role of intracellular components in perception and implementation of the gravitational stimulus, and description of quantitative characteristics of energy exchange and metabolism in cells as a function of gravity force and direction.

Biomechanical Phenomena↗
PubMed1999

[The growth movements of moss protonemata under clinostatic and microgravity conditions].

Populations of dark-grown protonemata of moss Ceratodon purpureus wt-4 (Germany) and wt-U (Ukraine) were rotated on clinostat or flown in space (experiment "Protonema" aboard Bion-11, December 24, 1996-January 7, 1997) to determine the effects of altered gravity on orientation of protonemata growing filaments. Protonemata had been cultivated 8 days in vertical stationary position at dark to be transported to microgravity or placed in clinostat for the period of 14 days. In the ground control, protonemata demonstrated the negatively gravitropic growth (straight upwards in a bundle of compact filaments). The horizontal or circular rotation in clinostat and exposure to microgravity made filaments grow every each way within the substrate plane but with an apparent trend to rightward curling resulting in "spiral galaxies".

Bryopsida↗
PubMed1996

The role of signal systems in cell gravisensitivity.

Reception of physical environmental signals caused by alteration of the gravitation field leads to the shift of morpho-physiological cell characteristics. The gravity influence on a cell may be direct or non direct, its extent varying in dependence of the cell model applied. Direct influences are more pronounced in vitro, while non direct influences are usually expressed in the community of unicellular organisms (in vivo). Gravity affects morphogenesis processes, such as locomotion, adhesion, intercellular contacts, etc. At the same time, all the processes named are under control of cell integral systems of the signal transduction. Minor disturbances in this system coming from the environment, due to amplification, may provide significant modulations of the signals. So, studies of this system at the level of molecular cell reception is of great interest. Results of flight and model experiments are discussed in the present manuscript.

Animals↗
PubMed1996

Physico-chemical characteristics of biomembranes and cell gravisensitivity.

The resistance of living systems to the action of environmental factors is known to be largely determined by molecular organization of biomembranes constituting the basis of the cell per se and of all intracellular organelles. Gravity as one of the environmental factors, plays a definite role in the vital activity of organisms. Therefore, the problem of altered gravity impact on biological objects should be considered in close relation to the functional state of membranes and contractible elements of cytoskeleton. Moreover, the involvement of membrane structures and cytoskeleton in the processes of reception and realization of gravitational stimulus allows us to evaluate the extent of the direct or indirect influence of gravity on cell functioning in the gravitational field. The results of experimental studies having been conducted up to this time on a variety of cells and cell organelles under altered gravity conditions demonstrated noticeable alterations in the molecular organization of the membranes.

Animals↗
PubMed1995

[Effects of altered gravity on the culture of unicellular eucaryotic organisms, Bursaria truncatella (Ciliophora)].

The paper reports the results of experiments with centrifugation and clinostating. Growth rate, cellular division and several morphofunctional characteristics of unicellular organisms of infusoria Bursaria truncatella in culture were studied under normal (1 g), elevated (hypergravity at 2 and 5 g), and compensated gravity. The data point to certain changes in the functional activity and morphology of cells consequent to long-time cultivation under these conditions. The observed regularities in the dynamics of B.truncatella growth and shifts in its physiology and morphology due to hypergravity or compensated gravity support our earlier proposed working hypothesis about the dominance of functional activity over morphological properties in sensitivity of unicellular organisms to perception and realization of the gravitational stimulus.

Animals↗
PubMed1995

[Biomechanical aspects of the process of formation of food vacuoles in the infusoria Bursaria truncatella under changed gravity].

Results from clinostatic and centrifugal laboratory experiments in which there has been evaluated an activity of digestive process in infusoria Bursaria truncatella by the content of vacuole numbers and its change in the cell under changed gravity are presented. It is indicated that the extended clinostatic exposure of infusoria stimulates their digestive activity and an increased gravity (centrifugation 2 g, 5 g) inhibits this process. In these examinations, an effort was made to explain the obtained results started from the propositions of cell biomechanics and bioenergetics. The mechanisms of gravity influence on this process have been proposed.

Animals↗
PubMed1992

Biological role of gravity: hypotheses and results of experiments on "Cosmos" biosatellites.

In order to reveal the biological significance of gravity, microgravity effects have been studied at the cellular, organism and population levels. The following questions arise. Do any gravity-dependent processes exist in a cell? Is cell adaptation to weightlessness possible; if so, what role may cytoskeleton, the genetic apparatus play in it? What are the consequences of the lack of convection in weightlessness for the performance of morphogenesis? Do the integral characteristics of living beings change in weightlessness? Is there any change in "biological capacity" of space, its resistance to expansion of life? What are the direction and intensity of microgravity action as a factor of natural selection, the driving force of evolution? These problems are discussed from a theoretical point of view, and in the light of results obtained in experiments from aboard biosatellites "Cosmos".

Adaptation, Physiological↗
PubMed1992

Structural and functional organisation of regenerated plant protoplasts exposed to microgravity on Biokosmos 9.

Preparatory experiments for the IML-1 mission using plant protoplasts, were flown on a 14-day flight on Biokosmos 9 in September 1989. Thirty-six hours before launch of the biosatellite, protoplasts were isolated from hypocotyl cells of rapeseed (Brassica napus) and suspension cultures of carrot (Daucus carota). Ultrastructural and fluorescence analysis of cell aggregates from these protoplasts, cultured under microgravity conditions, have been performed. In the flight samples as well as in the ground controls, a portion of the total number of protoplasts regenerated cell walls. The processes of cell differentiation and proliferation under micro-g did not differ significantly from those under normal gravity conditions. However, in micro-g differences were observed in the ultrastructure of some organelles such as plastids and mitochondria. There was also an increase in the frequency of the occurrence of folds formed by the plasmalemma together with an increase in the degree of complexity of these folds. In cell cultures developed under micro-g conditions, the calcium content tends to decrease, compared to the ground control. Different aspects of using isolated protoplasts for clarifying the mechanisms of biological effects of microgravity are discussed.

Brassica↗
PubMed1992

The effect of exposure to microgravity on the development and structural organisation of plant protoplasts flown on Biokosmos 9.

Preparatory experiments for the IML-1 (International Microgravity Laboratory) mission to be flown on the Space Shuttle in January, 1992, were performed on a 14 day flight on Biokosmos 9 (Kosmos 2044) in September 1989. The purpose of the experiment was to study the effect of weightlessness on protoplast regeneration. Problems with late access to the space vehicle meant that the newly isolated protoplasts from hypocotyl cells of rapeseed (Brassica napus L. cv Niklas) and suspension cultures of carrot (Daucus carota L, cv Nobo) had to be stored at 4 degrees C for 36 h prior to the launch of the biosatellite, in order to delay cell wall regeneration until the samples were in orbit. In the flight samples and the ground controls, a portion of the total number of protoplasts regenerated cell walls. The growth of flight rapeseed cells was only 56% compared to the ground control; the respective growth of carrot cells in orbit was 82% of the ground control. Analysis demonstrated that the peroxidase activity and the amount of protein was lower in the flight samples than in the ground controls. The number of different isoenzymes was also decreased in the flight samples. A 54% decrease in the production of cellulose was found in rapeseed, and a 71% decrease in carrot. Hemicellulose production was also decreased in the flight samples compared to the ground controls. Ultrastructural analysis of the cell aggregates from the protoplasts cultured in orbit, demonstrated that hydrolysis and disappearance of reserve starch occurred in the flight cell plastids. The mitochondria were more varied in appearance in the flight samples than in the ground control cells. An increased frequency of the occurrence of folds formed by the plasmalemma together with an increase in the degree of complexity of these folds was also observed. Fluorescence analysis showed a decrease of the calcium content in cell cultures under space flight compared to the ground controls. One general effect of the stay onboard the space vehicle was a retardation of the regeneration processes. Callus cultures obtained from the flight samples grew very slowly compared to callus regenerated from the ground controls, and two years after the Biokosmos 9 flight there appears to be no further growth in the samples exposed to microgravity. Callus cultures from the ground controls, however, continue to grow well. A simulation experiment for IML-l performed in January 1990 at ESTEC (European Space Technology Center), The Netherlands, has resulted in regenerated plants. These observations are discussed and compared to the results obtained on Biokosmos 9.

Bioreactors↗
PubMed1989

[The effect of space flight conditions on the rate of multiplication, morphology of cells, DNA and protein content in the ciliate Tetrahymena pyriformis].

The conditions of a space flight and, in particular, the weightlessness promote an increased density of the ciliate culture, an enhanced reproduction rate, and an elevated ratio of dividing cells. The condition of weightlessness brings about some decrease in the bulk protein content of the cells determined by cytophotometry of Naphthol-yellow stained ciliates. The quantity of DNA in macronuclei was measured following the routine Feulgen procedure (its "cold" variant). The DNA content was found to remain unchanged. Some changes in the shape and size of the cells were noticed under flight conditions: ciliates that had developed in weightlessness appeared more spherical than control ones, due presumably to a decrease in the body length and to some extension in the body width. The conditions of space flight, including the weightlessness, induce changes in the physiological status of unicellular organisms. A decrease in the gravitation force may lead to a decrease in the energy expenditures for maintenance of the cell positional homeostasis.

Animals↗
PubMed1983

Experimental and theoretical analysis of the influence of gravity at the cellular level: a review.

The present paper is a review of the experimental investigations published in the literature and performed by the authors on space vehicles. The paper also gives an analysis of theoretical concepts concerning gravitational effects on the cell. Taking this into account, the authors put forth a hypothesis that free-living unicellular organisms are indifferent to variations in the magnitude and direction of the gravitational field.

Animals↗
PubMed1981

Biological investigations aboard the biosatellite Cosmos-1129.

Experiments on insects, higher plants and lower fungi were carried out aboard the biological satellite Cosmos-l129, in Earth orbit, from 25 September to 14 October 1979. The main objective of these experiments was to gain more profound knowledge of the effect of weightlessness on living organisms and to study the mechanisms by which these various organisms with different life cycles can adjust and develop in weightlessness. Experiments on insects (Drosophila melanogaster) were made with a view towards understanding gravitational preference in flies, the life cycle of which took place on board the biosatellite under conditions of artificial gravity. Experiments on higher plants (Zea mays, Arabidopsis thaliana, Lycopersicum esculentum) and lower fungi (Physarum polycephalum) were performed.

Animals↗