[Structural and cytochemical aspects of Brassica rapa embryogenesis under conditions of clinorotation].

The results of study of embryo development in B. rapa plants, as well as the rate and the character of nutrient substances accumulation in their cells under slow horizontal clinorotation and laboratory control are presented. Significant similarity of the peculiarities of embryo differentiation and character of nutrient substance accumulation in both variants was shown. The cases of different deviations during embryo differentiation, and rate and quantity of reserve nutrient substances in their cells are revealed under clinorotation compared to the laboratory control.

[Development of Brassica rapa L. embryos under conditions of microgravity].

Results of comparative studies of the embryos of identical age formed under microgravity and ground laboratory control are presented. Significant similarity of a rate of embryo development and degree of their differentiation in both variants has been shown. The single cases of the disturbances in embryo formation, and also a certain acceleration of endosperm development at the early stages of seed formation in microgravity are revealed.

[Localization of callose in microspores and pollen grains of Sium latifolium plants under different water regimes].

Results of study of callose content and its topography in mother cells of microspores, microspores and pollen grains in terrestrial and air-aquatic S. latifolium plants growing under different water regimes are presented. The increased content of callose in the microspore walls at tetrad stage and pollen grains is revealed on the basis of fluorescence intensity and quantitative luminescent analysis of terrestrial S. latifolium plants. It is connected, probably, first of all, with the protective role of callose for preservation of water in these cells under water deficiency.

[Structural changes of chloroplasts and galactolipid contents in Chlorella cells during clinorotation].

Research of chloroplast ultrastructure in Chlorella cells grown during long-term period under clinorotation has been carried out. Different changes of the chloroplast structure, concerning both the amount of starch grains and stroma electron density as well as membrane system have been revealed. Occurrence of more significant bends of the thylakoids compared to the control and more loose arrangement of the thylakoids in a bunch were noted. The most significant changes were observed in a membrane system, in particular, appearance of the non-uniform expansions of the inter- and intrathylakoid spaces in Chlorella chloroplasts. Taking into account the role of galactolipids as important components of the photosynthetic membranes, the content of general galactolipids, monogalactosyldiacylglycerol and digalactosyldiacylglicerol in Chlorella cells was determined. It was assumed that statistically significant increase of the galactolipid content, especially of MDG, can probably be one of the reasons of membrane system reorganizations in Chlorella cells under altered gravity.

Comparative characteristic of mitochondria ultrastructural organization in Chlorella cells under altered gravity conditions.

Results from experiments that used cells from the unicellular alga Chlorella vulgaris (strain Larg-1) grown on a clinostat, demonstrated the occurrence of rearrangements in cellular organelles, including changes in the mitochondrial ultrastructure compared to controls. Changes in mitochondrial structure were observed in auto- and heterotrophic regimes of cells grown in altered gravity conditions, especially in long-term experiments. The mitochondrial rearrangements become apparent during cell proliferation, which resulted in an increase in the relative volume of mitochondria per cell: up to 2.7 +/- 0.3% in short-term clino-rotation (2.2 +/- 0.1% in the control) and up to 5.3 +/- 0.4% and 5.1 +/- 0.4% in long-term clinorotation (2.3 +/- 0.2% in the control). The size of the mitochondria and their cristae increased in cells grown under long-time clinorotation. In addition, hypertrophied organelles, not typical for this strain, were observed. These changes in the cells were accompanied by increased electron density of the matrix and a well-ordered topography of the cristae. To examine the separation of oxidative phosphorylation and respiration, an inhibitory agent 2,4-dinitrophenol (2,4-DNP) was applied to cells which resulted in insignificant volume changes of the mitochondria (2.5 +/- 0.4% versus 2.1 +/- 0.2% in the control). The increase of mitochondrial size with regularly arranged cristae, with more condensed matrix and extension of cristae areas of clino-rotated cells, may demonstrate higher functional activity of the mitochondria under altered gravity conditions. Changes observed early in clinorotated cells, in particular the increased level of respiration, adenylate content (especially ATP) and more intensive electron-cytochemical reactions of Mg2(+)-ATPase and succinate [correction of succinat] dehydrogenase (SDH) in mitochondria (including hypertrophic organelles), also suggest increased activity of mitochondria from cells grown under altered gravity conditions compared to controls.

The ultrastructure of Chlorella mitochondria and their energetic state under altered gravity.

This study looks at the predominance of the participation of the mitochondria in the energy supply of Chlorella cells. The localization of the Mg(2+)-activated ATPases were studied during the culture development under the geterotrophic conditions, and with an investigation of the mitochndria ultrastructure at the various stages of the culture development under clinorotation. It was found that the activity level of this enzyme is one main indice of the energy state of these organelles.

Effect of altered gravity on the mitochondria ultrastructure, activity and fractional composition succinatedehydrogenase in Chlorella cells.

We have earlier demonstrated an essential changeability of the mitochondria concerning of their size, form and matrix density, as well as quantity, size and topography of cristae in Chlorella cells, growing in spaceflight. The likeness of much depositions of the mitochondria rearrangements was revealed under clinorotation. The data about the changes of an intensity respiration of the plants in clinorotation and spaceflight conditions arc present. Dehydrogenases in particular succinatedehydrogenase (SDH), take part in an oxygen metabolism and is the index of an aerobic respiration. It is data, that the mitochondria ultrastructure to a certain degree may be a manifest of their metabolic activity, because SDH was associated with the membranes of the mitochondria cristae. Taking into account above-mentioned information, we have been studying the effect of clinorotation on mitochondria ultrastructure, set of multiple molecular form (MMF) and total activity of SDH during the logarithmic and stationary stages of the culture growth.

Changes in plant mitochondria ultrastructure and respiration intensity in altered gravity.

Analysis of experimental results involving both animals and plants showed that cell mitochondria considerably changed regarding organelles shape, matrix density, number and size of cristae. However, oxidative-reductive enzymes did not lose their activity (2). Moreover, there are some data concerning an increase in respiration intensity of plants grown on a horizontal clinostat (3) and in seedlings being on board of Biosatellite-11 (4). Similar rearrangements in mitochondria are also observed during clinorotation (5). Taking into account that energy supply of cells during their adaptation to various factors considerably depends on the functional activity of these organelles along with ultrastructure the activity of some enzymes of energetic and oxidative metabolism as well as the level of cell respiration in altered gravity was studied.

[The characteristics of the structural organization of Chlorella cells cultured over 1 year under space flight conditions]. / Osobennosti strukturnoi organizatsii kletok Chlorella, kul'tiviruemykh v techenie goda v usloviiakh kosmicheskogo poleta.

Ultrastructure of Chlorella cells grown in individual colonies for 12 months on board of the orbital station "Mir" was studied. A number of differences in submicroscopic organization of cell organelles of the experimental population was detected in comparison with the control. Besides, the spectrum of ultrastructural rearrangements of cell organelles was broader, then in our previous experiments that lasted from 4.5 to 30 days.

Energetic metabolism response in algae and higher plant species from simulation experiments with the clinostat.

Adenylate state is acknowledged to be among the most convenient approaches in the study of physiological changes in plant cells under simulation of altered gravity condition with the clinostat. Adenylate levels and the ATP/ADP ratio in cytoplasmic and mitochondrial extracts of cultivated cells of Haplopappus gracilis and algae cells of Chlorella vulgaris under initial stages of the fast-rotating and slow-rotating clinorotation, as well as the long-term clinorotation, have been investigated. For analysis of ATP and ADP levels in the plant cells under the clinorotation, we applied a high-sensitive bioluminescence method using the luciferase and piruvate kinase enzyme systems. It has been shown that the adenylate ratio is already increased during at the start of clinorotation with the different speed of rotation in the biological material tested. The considerable changes in mitochondrial ultrastructure of Chlorella cells, as well as the rising ATP level and dropping of the ATP/ADP ratio appear after long-duration clinorotation if compared to control material. It is probably connected with the distinctions in ATP-synthetase functioning in mitochondria of the cells under the clinorotation conditions.

Peculiarities of ultrastructure of Chlorella cells growing aboard the Bion-10 during 12 days.

The ultrastructure of Chlorella cells grown in darkness on a solid agar medium with organic additions aboard the Bion-10 biosatellite was studied. Certain differences in submicroscopic organization of organelles in the experimental cells were revealed compared to the Earth control. The changes are registered mainly in ultrastructure of energetic organelles--mitochondria and plastids of the experimental cells, in particular, an increase of mitochondria and their cristae size, as well as an increase of the total volume of mitochondrion per cell were established. The decrease of the starch amount in the plastid stroma and the electron density of the latter was also observed. In many experimental cells, the increase of condensed chromatin in the nuclei has been noted. Ultrastructural rearrangements in cells after laboratory experiment realized according to the thermogram registered aboard the Bion-10 were insignificant compared to the flight experiment. Data obtained are compared to results of space flight experiments carried out aboard the Bion-9 (polycomponent aquatic system) and the orbital station Mir (solid agar medium).

[Ultrastructure of chloroplasts and activity of amylases in Chlorella cells during space flight]. / Ul'trastruktura khloroplastov i aktivnost' amilaz kletok Chlorella v usloviiakh kosmicheskogo poleta.

Ultrastructure of Chlorella cells grown in space flight was studied. Some differences in cell organells, chloroplasts in particular, were found in experimental cells in comparison to control. The considerable reduction in the number of reserve polysaccharides in chloroplasts and some decrease in stroma electron density were detected. Specific activity of amylases enhanced because of an increase in concentrations of mono- and disaccharides. The rearrangements of chloroplast ultrastructure, predominantly a decrease in reserve polysaccharides, are probably due to an increase of hydrolytic processes under microgravity.

Peculiarities of the submicroscopic organization of Chlorella cells cultivated on a solid medium in microgravity.

The submicroscopic organization of Chlorella vulgaris cells (strain LARG-1) growing over 30 days on a solid agarized medium aboard the orbital station "Mir" was studied. A number of differences in the ultrastructure of cells of the experimental population compared to the control has been revealed. Thus, changes in the membrane system of plastids, in particular, appearance of numerous vesicles of different diameter and outgrowths of the plastids and their contact with the plasmalemma as well as a considerable decrease of reserve polysaccharide number in the plastids. Moreover, an increase in the size of mitochondria, their cristae and lipid drops in cytoplasm, the formation of more complicated configuration folding of plasmalemma and appearance of small-granular material of mean electron density in the periplasmic space of Chlorella cells grown during space flight, are demonstrated. Comparative cytological analysis has revealed general regularities of rearrangements of the submicroscopic organization in Chlorella cells cultivated on both solid and semiliquid agarized nutrient media.

Ultrastructural and growth indices of Chlorella culture in multicomponent aquatic systems under space flight conditions.

Submicroscopic organization of Chlorella cells cultivated under space flight conditions in three-component aquatic system has been studied. Comparison of the experimental cells with that of the controls revealed certain rearrangements of cell organelles particularly, a reduction in the amount of reserve polysaccharides in chloroplasts, increase of cell vacuolization and mitochondrion volume, complication configuration of plasmalemma evaginations and invaginations, and also disturbances in the process of cytokinesis. More over an increase in the number of Chlorella cells infected by bacteria was shown in the experimental variant. No considerable differences were established in the growth characteristics of the experimental and control populations. A comparative cytological analysis revealed general regularities of organelles in Chlorella cells cultivated under space flight condition in the uni- and multicomponent systems.

Prospects of autotrophic link functioning in biological life-support systems based on cell biology studies.

On the basis of using of modern methods of cytological analysis the cell growth peculiarities, reproduction and structure of plant cells of different level organisation (unicellular algae, mosses, angiosperms, cell cultures of higher factors--weightlessness, hypogravity, magnetic fields of various intensity, vibration and acceleration were cleared. It is shown that many discovered biological effects of space flight are connected with the degree of complexity of the object organisation and intensified with the increasing duration of influence.

Changes in symbiotic and associative interrelations in a higher plant-bacterial system during space flight.

The miniature cenosis consisting of the water fern Azolla with its associated symbiotic nitrogen-fixing cyanobacterium Anabaena and the concomitant bacteria was investigated. Ecological closure was shown to produce sharp quantitative and qualitative changes in the number and type of concomitant bacteria. Changes in the distribution of bacterial types grown on beef-extract broth after space flight were recorded. Anabaena azollae underwent the most significant changes under spaceflight conditions. Its cell number per Azolla biomass unit increased substantially. Thus closure of cenosis resulted in a weakening of control over microbial development by Azolla. This tendency was augmented by spaceflight factors. Reduction in control exerted by macro-organisms over development of associated micro-organisms must be taken into account in constructing closed ecological systems in the state of weightlessness.

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.