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Biomedical subjects

G P Parfenov

Publications and source records attributed to G P Parfenov.

17 recordsLinked to original sources
PubMed1988

[Weightlessness and elementary biological processes].

This book gives comprehensive review of the role of gravity in fundamental biological processes. The book surveys the results of experiments on precellular and unicellular organisms, plant and animal cultured cells and tissues, fungi and actinomycetes, higher plants, and insects. The book discusses essentially every experiment performed in real flights, including those in which the combined effect of microgravity and ionizing radiation was investigated, as well as many clinostat and centrifuge studies. In orbital flights unicellular organisms exhibited no gravity-dependent processes. The maximum size and basic morphology of unicellular organisms developed obeying the second law of thermodynamics do not therefore depend on space or time. Fungi retained all their properties except for gravitational ordering. Higher plants developed normally through seed-to-seed cycles: from the stage of seed germination to that of maturation of next generation seeds. Plants changed all their gravity-dependent movements. Since plant movements are irreversible, this affected their final shape, although the basic structure and size remained unaltered. The frequency of spontaneous and radiation--induced mutations changed insignificantly. The rotation of generations of plants and animals taken under study developed in a normal way. The morphological, physiological and genetic status of present-day organisms has developed under the effect of the gravity force that plays three different parts: as the creator and transformer of the abiotic environment, as the factor of natural selection, and as the factor of environmental physiology eliciting stable mechanical stresses. The effects of these gravity roles are implemented by different mechanisms and actualized in different time scales. The uneventful development of the basic biological processes in microgravity is an important factor that makes possible long-term space missions. From this point of view, the road to outer space is open to man in terms of his biology.

Animals↗
PubMed1970

Experiments with Drosophila on board the spacecraft Zond-5.

A container with 257 eggs of Drosophila melanogaster of the D-32 line, which is characterized by a very low spontaneous mutability, was placed on board Zond-5. The results of two tests on the frequency of lethal recessive point mutations: a) sex-linked and b) autosomal (in the second chromosome) were studied. A significant increase in the frequency of lethals in the X-chromosome of males, presumably caused by the influence of earth conditions after the return of the spacecraft, was found. No substantial increase of such mutations in the X-chromosome of females was found, but a substantial increase in the frequency of autosomal recessive lethals was discovered. Possible explanations of the causes of these events are discussed.

Animals↗
PubMed1967

The results of biological studies made on board the Voskhod and Voskhod 2 spaceships.

The biological effects of flight and outer space factors were studied on biological specimens of various organization, viz. spiderwort microspores, dry seeds of the pine tree, wheat, onion and of other higher plants as well as on lysogenic bacteria and wine flies. Furthermore, lysogenic bacteria were studied for the effectiveness of a number of well known ray-proof substances (such as mercaptopropylamine, 5-methoxytriptamine, etc.). The specimens were secured in special containers both on board the spaceships and in the hip pockets of the astronaut Leonov's spacesuit. Biological effectiveness of the factors was evaluated by means of cytogenic, genetic and microbiological procedures. The analysis of the data obtained has shown that under the impact of the complex of flight and outer space factors, including ionizing radiation, both qualitative and quantitative changes occurred in the hereditary structures of some of the specimens, viz.: wheat seeds, spiderwort microspores and lysogenic bacteria. These changes were similar to the effects recorded in the flights of Vostok-2, 3, 6. As compared to the controls, an enlargement was found in the cells of wheat sprout radicles, accompanied by chromosome rearrangements (N. L. Deloney et al.). Increased phage production by lysogenic bacteria (N. N. Zhukov-Verezhnikov, N. I. Rybakov et al.) and impairment of the mitosis mechanism in the spiderwort macrospores were demonstrated (N. L. Deloney, etc.). Higher frequency of dominant lethals and more frequent than normal chromosome indivergence in the wine flies were recorded. Quantitatively, the recorded drifts were insignificant (as was the case with the 'Vostok' spaceships' flights). Of interest are the results of the experiments on spiderwort microspores carried out with B. B. Yegorov's participation. The data obtained show that 1) during the mitosis stage spiderwort microspores show differing sensitivity to the space flight factors, and that 2) the mitosis stages support the previous hypothesis that impairment of the mitosis mechanism is due to the state of weightlessness, while chromosome rearrangements are chiefly induced by the effects of the complex of factors related to the take-off and touch-down stages of the flight. (N. L. Deloney et al.). The analysis of beta-mercaptopropylamine and 5-methoxytriptamine tests indicates that these substances significantly reduce the phage producing activities of the lysogenic bacteria not only blocking the induced phage production but reducing the amount of spontaneous phage production as well (N. N. Zhukov-Verezhnikov, N. I. Rybakov et al.). Thus, the results of biological experiments on various specimens with differing degrees of radiosensitivity agree well among themselves and are consistent with the data on the dosage of space radiation.

Bacteria↗
PubMedDate not supplied

[Chromosome aberrations in Crepis capillaris after gamma-irradiation and clinostatism].

The rate of cell division and emergence of spontaneous and radiation chromosomal aberrations in Crepis capillaris exposed to clinostating were determined. The plants were gamma-irradiated with 300 R during clinostating when the primary roots were 1-2 mm long. The velocity of clinostat rotation was 2 rpm. The mitotic index was not affected either by clinostating alone or combined with irradiation. The exposure to clinostating did not change significantly the total frequency of nuclear aberrations or the distribution of the aberrations of the chromosomal and chromatin type as well as aberrations resulting from one or two radiation events. Thus, the effect of clinostating combined with gamma-irradiation can be considered zero.

Cell Count↗
PubMedDate not supplied

[Biological research in space].

The paper presents the results of investigations carried out during the last two decades on various biological objects--microorganisms, plant seeds, insects, higher and lower plants, fish and amphibians--in real and simulation space flights. The paper discusses the current knowledge of the biological role of gravity and possible mechanisms of adaptation to weightlessness as well as the suitability of different biological objects for further space studies. Most experiments conducted in real space flights have lent support to the theoretical studies of the level and limits of weightlessness effects upon biological systems. Analysis of the data obtained in space and ground-bound experiments suggests that molecular processes are indifferent to an altered gravity and that energy metabolism plays an important role in adaptation of biological systems to zero-g.

Adaptation, Physiological↗
PubMedDate not supplied

[Space biology in the 3d decade].

The paper reviews the major results of experiments on microorganisms, plants and animals flown onboard space vehicles during the past two decades. To explain the experimental findings, it is hypothesized that living beings develop an indirect adaptation to gravity effects which has a bearing only on the phylogenetic process.

Adaptation, Biological↗
PubMedDate not supplied

[Reproduction and mutability of the flour beetle in weightlessness (experiments on the Saliut-6 orbital station)].

Experiments with the flour beetle Tribolium castaneus showed that in weightlessness these insects completed their cycle of development--from fertilization to the emergence of mature imago of the next generation--in the normal way. Survival of specimens, densities of cultures, duration of development and frequency of morphoses in flight and control studies were similar. Exposure to weightlessness did not increase the number of genetic changes.

Animals↗
PubMedDate not supplied

Current status of the problem of the mechanism of gravity reception in plants.

Basic work carried out recently on the role of the structural-functional condition of cell organelles in the development of geotropic reaction in higher plants is reviewed. On the basis of analysis of theoretical proposals and experimental investigations of the molecular mechanism of perception and realization of the gravity stimulus, a hypothesis was developed that the key factor in the development of geotropic reaction is an interaction of cell organelles with membranes of the endoplasmic reticulum as a result of their sensing the gravity stimulus.

Aerobiosis↗