Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887.

The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

[Recombination in Drosophila in space flight]. / Rekombinatsiia u drozofily v usloviiakh kosmicheskogo poleta.

An experiment with Drosophila melanogaster males was performed aboard the Artificial Satellite "Kosmos-1667". Mutagenic effects of a 7-day space flight on intergene recombination in chromosome 2 were studied. The space flight factors decreased the frequency of recombination. A model experiment on a laboratory centrifuge demonstrated insignificant increase in recombination frequency caused by acceleration.

[Experiments with growing plants on orbital stations Saliut-5, Saliut-6 and Saliut-7]. / Eksperimenty s razvivaiushchimisia rasteniiami na orbital'nykh stantsiiakh "Saliut-5", "Saliut-6" i "Saliut-7".

The experiments with air-dry Crepis capillaris seeds flown on the spacecraft Soyuz-16 and orbital stations Salyut-5, Salyut-6 and Salyut-7 showed that the number of aberrant cells in the seedlings grown during flight (experimental) and after flight (flight control) was higher than that in the ground-based control. This number was greater in the experimental seedlings than in the flight controls. The plants Arabidopsis thaliana grew from cotyledons to flowers during flight. The seeds developed postflight exhibited a lower fertility and a higher frequency of recessive mutants (Experiment Svetoblock-1). The greater number of mutants persisted in the progeny of plants that completed their developmental cycle (Experiment Phyton-3). Inhibited viability of germs manifested as a reduced germination rate of flown seeds and a premature death of seedlings. In the first postflight generation the lesions produced by large chromosome aberrations were eliminated and the lesions caused by gene mutations and micro-aberrations were retained.

[Frequency of chromosome recombination, nondisjunction and breaks in Drosophila melanogaster males exposed during space flight]. / Chastota rekombinatsii, neraskhozhdeniia i razryvov khromosom u samtsov Drosophila melanogaster, éksponirovannykh v orbital'nom polete.

Effects of space flight factors on chromosomal nondisjunctions, breaks and mitotic recombination in Drosophila melanogaster males were studied. It was shown that space flight conditions increased the frequencies of nondisjunctions, breaks and mitotic recombination in chromosomes. It was established that the vibration and acceleration effects could not serve to explain the data obtained. On the basis of these data, it may be suggested that weightlessness and cosmic radiation are the main factors which are responsible for the effects observed.

Experiments with air-dried seeds of Arabidopsis thaliana (L) Heynh. and Crepis capillaris (L) Wallr., aboard Salyut 6.

Space flight factors resulted in the accumulation of genetic damage in embryonic meristem cells of seeds of Arabidopsis thaliana and Crepis capillaris in flights of different duration (49, 226, 408 and 827 days) aboard the orbital station Salyut 6. As a result, the viability of seeds and seedlings was reduced, and the sterility of plants grown from seeds exposed on Salyut 6 was increased. The effect depended upon the flight duration. The data obtained suggest an acceleration of seed aging under flight conditions.

Some results of the effect of space flight factors on Drosophila melanogaster.

Two experiments with Drosophila melanogaster males were performed aboard the Salyut 6 orbital station. Mutagenic effects of a 8 day space flight on sex chromosome nondisjunction and intergene recombination in chromosome II were studied. The space flight factors (SFF) increased the frequency of chromosome nondisjunction and recombination. The model experiments showed that the combined effects of vibration and acceleration do not cover the whole spectrum of space flight mutagenic factors. These data suggest that heavy space ions are mainly responsible for the observed effect.

The role of weightlessness in the genetic damage from preflight gamma-irradiation of organisms in experiments aboard the Salyut 6 orbital station.

The effect of weightlessness on chromosomal aberration frequency in preflight irradiated Crepis capillaris seeds, on the viability, fertility and mutation frequency in Arabidopsis thaliana, and on the frequency of nondisjunction and loss of X chromosomes in pre-flight irradiated Drosophila melanogaster gametes was studied aboard the Salyut 6 orbital station. The following effects were observed: a flight-time dependent amplification of the effects of preflight gamma-irradiation in A. thaliana with respect to all the parameters studied; unequal effects in seeds and seedlings Crepis capillaris; and a significant increase in the frequency of nondisjunction and loss of chromosomes during meiosis in Drosophila females. These observations are discussed in terms of the data of ground-based model experiments and flight experiments with a different time of exposure of objects to weightlessness. An attempt is made to elucidate the role of weightlessness in the modification of ionizing radiation effects.

Biological studies of Chlorella pyrenoidosa (strain LARG-1) cultures grown under space flight conditions.

This paper reports data from an electron microscopic analysis of Chlorella pyrenoidosa (LARG-1) cultures after five days of growth in the dark on a semiliquid mineral/glucose medium in the IFS-2 device on board the Soyuz 27-Salyut 6-Soyuz 28 orbital research complex (Soviet-Czechoslovak experiment "Chlorella-1"). For space flight of five days duration the ultrastructural cellular organization of the flight and control cultures were similar. This testifies to normal cell function.

Development of higher fungi under weightlessness.

The development of Polyporus brumalis basidomycete cultures, both in the dark and in the light, was studied in the 17 day experiment on the orbital station Salyut 5 and in the 20 day experiment on the orbital station Salyut 6. In the first experiment the test tube cultures were exposed to weightlessness beginning from the stage of the fruiting body primordium. In the second experiment the culture was exposed in large containers at the stage of mycelium growth. In the first experiment fruiting bodies that had formed in light had stems and caps approximating the appearance and anatomical structure of the control culture. The fruiting bodies and caps were oriented towards the light. Some structural changes in the hymenophore were observed. Fruiting bodies developed in the dark had twisted stems and no caps. In the second experiment no fruiting bodies were formed in the dark. Light-optical and electron-microscopic studies of Polyporus brumalis growth under weightlessness were carried out.

The action of space flight factors on the radiation effects of additional gamma-irradiation of seeds.

The action of space flight factors (SFF) on radiosensitivity and the effects of preflight irradiation of air-dried Crepis capillaris (L) Wallr and Arabidopsis thaliana (L) Heynh seeds aboard the spaceships of the Cosmos, Soyuz and Salyut series was studied. The results have shown that vibration and linear acceleration (VA) cause damage of the meristematic embryonic cells and simultaneously decrease the radiosensitivity of seeds. SFF enhance the effect of preflight gamma-irradiation of seeds with respect to a number of characteristics. This can be explained partly by the action of VA. The basis of all observed effects is chromosomal aberrations which are expressed in a series of successive cell divisions and which decrease the survival and fertility of plants that grow from flight-exposed seeds.

Biological investigations on the orbital station "Salyut-5".

Genetic and embryological investigations were continued on the orbital station Salyut-5. The effect of space flight factors on dry Crepis capillaris (L) Wallr seeds and seedlings, dry Arabidopsis thaliana (L) Heynh seeds, Polyporus brumalis Pers. ex. Fries culture as well as on spawn development and fish behaviour was studied. Space flight factors are shown to have adverse effects with respect to some characteristics in seeds and seedlings, and to change the morphology of the fungus. Fishes appear to adapt themselves to weightlessness.

[Effect of cadmium ions on cell division in the root meristem of Crepis capillaris (L.) Wallr]. / Vliianie ionov kadmiia na delenie kletok kornevoi meristemy Crepis capillaries (L.) Wallr.

Germination of seeds in cadmium chloride solution resulted in certain disturbances in nuclear division and stopped cytokinesis. Cystein added to cadmium chloride solution decreased the number of these disturbances. The effect of cadmium ions is supposed to be associated with the SH-groups blocking in contractile proteins of cellular spindle or in enzymes responsible for mitosis.

Biological investigations of higher and lower plants aboard Soyuz 19.

Biological investigations carried out aboard Soyuz 19 consisted of three independent complex experiments. All biological materials aboard the spacecraft were kept in "Biocat" thermostats which maintained the required temperature. The objective of the experiment "Genetic investigations" was to determine the effect of space flight factors on the heredity of lower (Chlamydomonas reinhardi Dang) and higher (Crepis capillaris (L) Wallr and Arabidopsis thaliana (L) Heynh) plants, and on the radiosensitivity of plant seeds and the radiation effect of prior gamma-irradiation. The space flight factors decreased the survival of Chlamydomonas cells and A. thaliana plants of the first generation. They decreased the germination of seeds, increased the rate of chlorophyll mutations and embryonal lethals, produced no effect on the rate of visible mutations in unicellular algae, increased the rate of chromosome aberrations in root meristem cells C. capillaris, induced disturbances in mitosis of unicellular algae and modified the effect of prior gamma-irradiation. The experiment "Growth of micro-organisms" was conducted with a culture of Proteus vulgaris in a growth chamber. After return to the laboratory the experimental and control variants were studied for twenty-two tests. The control and experimental material differed in the average cell size, biomass distribution, the character of haemotaxis, the rate of cell migration over the substratum surface, dehydrogenase activity, ribosomal aggregation, and ultrastructural peculiarities of cells. The experiment "Embryological investigations" was carried out to study the effect of space flight factors on embryogenesis of the bony fish Brachyodanio rerio. No abnormalities were noted in the course or rate of the development of spawn cultivated in a special thermostat.

Biological experiments on the orbital station Salyut 4.

Two series of experiments were carried out on the orbital station Salyut 4: one series consisted of two experiments (30 and 62 days respectively) designed to study the effect of space-flight factors on the growth and development of Drosophila melanogaster, strain D-32, and the second series consisted of two experiments (24-33 days) designed to study the effect of space-flight factors on the growth and development of the dwarf pea, variety "Pioneer". Analysis of the progeny from flies exposed to space flight showed an increase in the rate of visible mutations for y, ct, w and vg loci over those observed in the earth control. Space flight factors produced no noticeable effect on the first growth stages of pea plants. Later on growth stopped and most of the plants died under weightless conditions at the age of 2-3 weeks. Possible causes of their death during flight are discussed on the basis of anatomo-morphological, cytological and biochemical analyses of experimental and control plants.

The evolutionary role of gravity.

Analysis of the part played by gravity in development in the organic world shows that this factor has had an impact on evolution. All terrestrial organisms, including man, have adapted themselves to gravity by developing a number of important features of their composition and functions. Variations of gravitational field in any direction bring about numerous changes in organisms, ranging from metabolism to changes in more conservative systems which also include hereditary structures. Gravitational forces determine the form and the size of organisms, the development of skeletal supporting organs, and energetics. The study of the role of gravity in the variability of the organic world will be of great importance for long-term systems of life support and for work on space orbital stations or at bases on the moon and planets where gravitational forces may differ greatly those from on the earth.

Cytogenetic analysis of seeds of Crepis capillaris (L) Wallr. exposed on board the earth artificial satellite Cosmos 613.

We studied the effect of space flight factors on air-dry seeds of Crepis capillaris (L) Wallr. and on radiation injury of seeds exposed to gamma-radiation (3 kr, 525 r/min) before and after the flight on the satellite Cosmos 613. Space flight factors induced little increase (which was statistically insignificant) in the rate of chromosome aberrations in cells of the root meristem of Crepis capillaris sprouts, but they enhanced the effect of preliminary irradiation of seeds and decreased their radiosensitivity. The modification of radiation injury was statistically significant.

[Experiment with a physiologically active culture of Chlorella on "Soiuz-9" spacecraft]. / Eksperiment s fiziologicheski aktivnoi kul'turoi khlorelly na kosmicheskom korable "Soiuz-9"

A physiologically-active culture of chlorella was for the first time exhibited on board the "Soyuz-9" spacecraft. The use of a special four-socket container made it possible to investigate in one experiment the effect of the factors of a space flight on the cells of algae developing in illumination during 1, 6 and 14 days. Besides that the effect of the flight conditions was studied on the culture of chlorells. Insignificant change in sensitivity of the cells to the effect of the flight factors depending upon the duration of their exposure in the active condition is shown.