T lymphocyte function is strongly depressed in vitro and in vivo under low-g conditions in space as well as simulated in clinostat. Here we describe the effect of a food supplement based on yeast plasmolysate on T cells activated in vitro with Concanavalin A and cultured in a random positioning machine. The mitotic index was measured by ³H-thymidine incorporation into DNA, the expression of activation markers CD25, CD69 and HLA-DR on the cell surface by cytofluorimetry and the secretion of the IL-2R by an enzyme immunoassay. Our data indicate that the food supplement used is capable to modulate T lymphocyte function. The addition of the food supplement increased the expression of activation markers in activated and non-activated cells. Cultivation under low-gravity conditions reduced the expression of the activation markers, but this expression was partly restored or even increased upon addition of yeast plasmolysate. On the other hand, cell proliferation and secretion of soluble IL-2 receptor was reduced after addition of the food supplement in all samples.

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It is necessary to establish a suitable experimental design for the determination of auxin (indole-3-acetic acid: IAA) polar transport in space using a spacecraft in concerning with the role of gravity. Problems in space experiments are as follows: I) Selection of suitable plant species; II) Preservation of integrity of plant segments for activities of auxin polar transport; III) Stop of auxin polar transport of the segments after the transport experiment in space. Segments of etiolated pea epicotyls and etiolated maize coleoptiles showed relatively high activities of auxin polar transport among dicotyledonous and monocotyledonous plants tested, respectively. The activities decreased dramatically when the segments were pre-stored at 25 °C only for 1 day. On the other hand, the storage at low temperature (5 °C) in the presence of antioxidants or chelating agents, especially EGTA, maintained relatively high activities of auxin polar transport in pea epicotyl segments. Low temperature (5 °C) substantially inhibited the activity of auxin polar transport. Based on the results in this study, a suitable experimental design for the space experiment of auxin polar transport using a spacecraft is also proposed.

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The survival conditions of microorganisms under extremely severe environment are of interest in various areas of biology, sterilization, and space engineering, especially where resistance to microorganisms is concerned. Despite the interest, the resistance to microorganisms under extremely severe environment such as space environment or other planetary environment is not known well. In order to investigate survival conditions of microorganisms under extremely severe environment, surviving fractions for spores and vegetative cells of Bacillus subtilis were surveyed in various chemical species of atmosphere at various pressures and various temperatures, and the dependence on time for surviving fractions was examined. The results show: (i) Surviving fractions depend on chemical species of atmosphere. (ii) At high pressure and high temperature, surviving fractions are low and the resistance of spores is stronger than that of vegetative cells. (iii) Surviving fractions decrease as first-order reaction along with time elapsed.

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The Amphibia bridge the phyletic gap between the aquatic fishes and the terrestrial vertebrates. This transition has involved many interesting changes of metabolisms. In this short review, we have attempted to summarize the kidney structure and functions on the osmoregulations in the Amphibia. Amphibians excrete the water absorbed through their skin as a dilute urine. Pronephros of tadpoles may start to work in the hatching stages and metanephros is well developed and functions. Glomerular filtration rate is relatively large and glomerular intermittency is important to regulate urine production. The proximal tubule reabsorbs approximately 20-45% of filtered water and sodium. Absorption is driven by the basolateral Na⁺, K⁺-ATPase common to all tubular cells. The diluting segment, early parts of distal nephron, highly develops basolateral interdigitation and reabsorbs approximately 40% of filtered Na⁺, K⁺, and Cl^-, but is impermeable to water, thus this part results in the formation of hypo-osmotic tubular fluid. In the late distal tubule, the primary mechanism of reabsorption may be via a luminal NaCl synporter, driven by the ubiquitous Na⁺, K⁺-ATPase on basolateral membrane. In collecting tubule, there are two types of cells, the principal cells and the intercalated cells. Many hormonal and nervous regulations are involved in the glomerular filtration rate and reabsorptions in the amphibian nephrons.

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