Altered expression of mRNAs implicated in osteogenesis under conditions of simulated microgravity is regulated by CD200:CD200R

Mouse calvarial cells grown under simulated microgravity conditions (neutral buoyancy) show preferential differentiation towards the osteoclast lineage, as defined by surrogate mRNAs, bone nodule growth and TRAP⁺ cells, when compared with cells cultured under normal gravity conditions. This effect was suppressed in cultures which contained the immunoregulatory molecule CD200, and conversely enhanced by anti-CD200 mAb. Concomitant increases occur in expression of inflammatory cytokines, and their mRNAs, under simulated microgravity conditions. Again cultures containing exogenous CD200 showed suppressed cytokine and cytokine mRNA expression. Further alterations in osteoclastogenesis were seen using cells isolated from cytokine-receptor knockout mice. We conclude that, as assessed by altered expression of mRNAs associated with osteoblast differentiation, CD200:CD200R interactions play an important regulatory role in the enhanced osteoclastogenesis seen under simulated microgravity conditions, with changes in cytokine expression further modulating this effect.     

Fluid transport in capillary systems under microgravity

The wetting kinetics of model tubes of different geometries has been investigated experimentally and theoretically under conditions of simulated zero-gravity and microgravity. Numerical calculations of meniscus configurations and the rise of the menisci in tubes of different shape are compared with photographic pictures obtained from sounding rocket experiments (TEXUS-Programme). It is demonstrated that menisci under microgravity conditions are essentially different from those of simulated zero-g-experiments. These results, together with observed streamline patterns, yield valuable information with respect to the hydrodynamic deformation of phase interfaces and dynamic contact angles.     

The relative role of visual and non-visual cues in determining the perceived direction of "up": experiments in parabolic flight

In order to measure the perceived direction of "up", subjects judged the three-dimensional shape of disks shaded to be compatible with illumination from particular directions. By finding which shaded disk appeared most convex, we were able to infer the perceived direction of illumination. This provides an indirect measure of the subject's perception of the direction of "up". The different cues contributing to this percept were separated by varying the orientation of the subject and the orientation of the visual background relative to gravity. We also measured the effect of decreasing or increasing gravity by making these shape judgements throughout all the phases of parabolic flight (0 g, 2 g and 1 g during level flight). The perceived up direction was modeled by a simple vector sum of "up" defined by vision, the body and gravity. In this model, the weighting of the visual cue became negligible under microgravity and hypergravity conditions.     

微重力下热薄材料燃烧特性的窄通道实验研究

利用高度分别为10 mm,12 mm和14 mm的水平窄通道对微重力环境下热薄材料表面的火焰传     

Human thermohomeostasis onboard "Mir" and in simulated microgravity studies.

Significant changes of thermogomeostatic parameters was obtained by thermotopometric method using the techniques simulate of microgravity effects: bed rest, pressurized isolation, suit immersion (SI). However, each of ground models made rectal temperature (T) trend downward. The autothermometric study (24 and 12 sessions, 2-13th and 6-174th flight days) was carried out onboard "Mir" by two flight engineers who had preliminary tested at SI (1-2 days). Studies of German investigators onboard "Mir" confirmed: rectal T must be higher in space flight as compared to the normal environment (n=4). Comparative studies suggest that microgravity is a key factor for the human body surface T raise and abolishment of the external/internal T-gradient. T-homeostasis was not really changing during missions and could be regarded as acute effect of microgravity. After delineation of changes in body surface T--by Carnot's thermodynamic law--rectal T raise should have been anticipated. Facts pointing to the excess entropy of human body must not be passed over.     

Modeled microgravity increases filamentation, biofilm formation, phenotypic switching, and antimicrobial resistance in Candida albicans

Candida albicans is an opportunistic fungal pathogen responsible for a variety of cutaneous and systemic human infections. Virulence of C. albicans increases upon exposure to some environmental stresses; therefore, we explored phenotypic responses of C. albicans following exposure to the environmental stress of low-shear modeled microgravity. Upon long-term (12-day) exposure to low-shear modeled microgravity, C. albicans transitioned from yeast to filamentous forms at a higher rate than observed under control conditions. Consistently, genes associated with cellular morphology were differentially expressed in a time-dependent manner. Biofilm communities, credited with enhanced resistance to environmental stress, formed in the modeled microgravity bioreactor and had a more complex structure than those formed in control conditions. In addition, cells exposed to low-shear modeled microgravity displayed phenotypic switching, observed as a near complete transition from smooth to "hyper" irregular wrinkle colony morphology. Consistent with the presence of biofilm communities and increased rates of phenotypic switching, cells exposed to modeled microgravity were significantly more resistant to the antifungal agent Amphotericin B. Together, these data indicate that C. albicans adapts to the environmental stress of low-shear modeled microgravity by demonstrating virulence-associated phenotypes.     

Response and adaptation of bone cells to simulated microgravity

Bone loss induced by microgravity during space flight is one of the most deleterious factors on astronaut’s health and is mainly attributed to an unbalance in the process of bone remodeling. Studies from the space microgravity have demonstrated that the disruption of bone remodeling is associated with the changes of four main functional bone cells, including osteoblast, osteoclast, osteocyte, and mesenchymal stem cells. For the limited availability, expensive costs and confined experiment conditions for conducting space microgravity studies, the mechanism of bone cells response and adaptation to microgravity is still unclear. Therefore, some ground-based simulated microgravity methods have been developed to investigate the bioeffects of microgravity and the mechanisms. Here, based on our studies and others, we review how bone cells (osteoblasts, osteoclasts, osteocytes and mesenchymal stem cells) respond and adapt to simulated microgravity.     

Survival of Bacillus pumilus spores for a prolonged period of time in real space conditions

To prevent forward contamination and maintain the scientific integrity of future life-detection missions, it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated surfaces, spores of Bacillus pumilus SAFR-032 exhibited unusually high resistance to decontamination techniques such as UV radiation and peroxide treatment. Subsequently, B. pumilus SAFR-032 was flown to the International Space Station (ISS) and exposed to a variety of space conditions via the European Technology Exposure Facility (EuTEF). After 18 months of exposure in the EXPOSE facility of the European Space Agency (ESA) on EuTEF under dark space conditions, SAFR-032 spores showed 10-40% survivability, whereas a survival rate of 85-100% was observed when these spores were kept aboard the ISS under dark simulated martian atmospheric conditions. In contrast, when UV (>110?nm) was applied on SAFR-032 spores for the same time period and under the same conditions used in EXPOSE, a ～7-log reduction in viability was observed. A parallel experiment was conducted on Earth with identical samples under simulated space conditions. Spores exposed to ground simulations showed less of a reduction in viability when compared with the "real space" exposed spores (～3-log reduction in viability for "UV-Mars," and ～4-log reduction in viability for "UV-Space"). A comparative proteomics analysis indicated that proteins conferring resistant traits (superoxide dismutase) were present in higher concentration in space-exposed spores when compared to controls. Also, the first-generation cells and spores derived from space-exposed samples exhibited elevated UVC resistance when compared with their ground control counterparts. The data generated are important for calculating the probability and mechanisms of microbial survival in space conditions and assessing microbial contaminants as risks for forward contamination and in situ life detection.     

The first "space" vegetables have been grown in the "SVET" greenhouse using controlled environmental conditions

The paper describes the "SVET" project--a new generation of space greenhouse with small dimensions. Through the use of a minicomputer, "SVET" is fully capable of automatically operating and controlling environmental systems for higher plant growth. A number of preliminary studies have shown the radish and cabbage to be potentially important crops for CELSS (Closed Environmental Life Support System). The "SVET" space greenhouse was mounted on the "CRYSTAL" technological module docked to the Mir orbital space station on 10 June 1990. Soviet cosmonauts Balandin and Solovyov started the first experiments with the greenhouse on 15 June 1990. Preliminary results of seed cultivation over an initial 54-day period in "SVET" are presented. Morphometrical characteristics of plants brought back to Earth are given. Alteration in plant characteristics, such as growth and developmental changes, or morphological contents were noted. A crop of radish plants was harvested under microgravity conditions. Characteristics of plant environmental control parameters and an estimation of functional properties of control and regulation systems of the "SVET" greenhouse in space flight as received via telemetry data is reported.     

Water and salt disturbances under condition of microgravity

Under conditions of microgravity severe alterations in body fluid composition and volume take place largely as a result of "cardiothoracic pooling" or headward shift of blood. Inappropriate endocrine, renal and cardiovascular responses result from the "misreading" of homeostatic signals by physiological receptors to produce an as yet incompletely defined syndrome under microgravitational conditions.     

星载稀布L阵对地面辐射源的高精度测向研究

在均匀分布和非均匀分布两种情况下,采用二维MUSIC算法研究了星载稀布L阵列的地面辐射源测向精度。对地面辐射源方位估计、小角度辐射源分辨率,以及测向精度的分析和仿真结果表明,星载L型阵列能实现对地面辐射源的高精度二维测向。在相同条件下,非均匀阵的测向性能明显优于均匀阵。     

Early renal changes in 45 degrees HDT rats

Background: Both microgravity and simulated microgravity models, such as the 45HDT (45 degrees head-down tilt), cause a redistribution of body fluids indicating a possible adaptive process to the microgravity stressor. Understanding the physiological processes that occur in microgravity is a first step to developing countermeasures to stop its harmful effects, i.e., (edema, motion sickness) during long-term space flights. Hypothesis: Because of the kidneys' functional role in the regulation of fluid volume in the body, it plays a key role in the body's adaptation to microgravity. Methods: Rats were injected intramuscularly with a radioactive tracer and then lightly anesthetized in order to facilitate their placement in the 45HDT position. They were then placed in the 45HDT position using a specially designed ramp (45HDT group) or prone position (control group) for an experimental time period of 1 h. During this period, the 99mTc-DTPA (technetium-labeled diethylenepentaacetate, MW=492 amu, physical half-life of 6.02 h) radioactive tracer clearance rate was determined by measuring gamma counts per minute. The kidneys were then fixed and sectioned for electron microscopy. A point counting method was used to quantitate intracellular spaces of the kidney proximal tubules. Results: 45HDT animals show a significantly (p=0.0001) increased area in the interstitial space of the proximal tubules. Conclusions: There are significant changes in the kidneys during a 1 h exposure to a simulated microgravity environment that consist primarily of anatomical alterations in the kidney proximal tubules. The kidneys also appear to respond differently to the initial periods of head-down tilt.     

Microgravity measurement assembly (MMA) for spacelab module missions

The microgravity measurement assembly (MMA) is a precision measurement facility for ground and on-orbit disturbance accelerations on board Spacelab, being currently under development by MBB/ERNO under DFVLR contract. MMA is using a new generation of micromechanical acceleration detectors developed by CSEM under ESTEC contract. Small dimensions of the triaxial sensor packages allow for installation very close to scientific experiments; mass is significantly reduced compared to conventional systems. Six or more of these mini-sensor packages are installed at the most g-sensitive experiments of Spacelab Module Missions. Acceleration and housekeeping data are processed in real time by a dedicated microcomputer and transmitted to the ground. Thus, for the first time, synchronized and comparable precision acceleration data are available in real time on ground for on-line judgement of the microgravity environment desired for experiment success, offering the possibility, for example of experiment repetition in case of excessive g-disturbances. Furthermore, MMA allows for immediate feedback to the crew concerning the microgravity effects of their dynamic behavior, with the aim of crew training towards lower disturbances. An additional mobile sensor package can be installed at vibration sources, e.g. pumps, centrifuges etc. or any arbitrary location inside the Spacelab Module. An impact hammer can be used together with MMA in order to measure in-flight structural transfer functions. The MMA on-board system and ground station and its planned utilization for the German Spacelab Mission D-2 is described.     

Separation of bacterial cells by free flow electrophoresis under microgravity: a result of the SpaceLab-Japan project on Space Shuttle flight STS-47

We demonstrated free flow electrophoresis (FFE) of charged cells under microgravity, where gravitational effects are almost eliminated. Separation of a mixture of three bacterial strains (mutants of Salmonella typhimurium LT2) by FFE was conducted on NASA Space Shuttle flight STS-47 (September 1992). The experiment was designed to differentiate three strains having different lipopolysaccharide core structures in the cell membrane. The results were compared to those of ground experiments, in order to examine whether or not FFE in a weightless environment provides distinct advantages. Smooth strain SL1027 and rough strain SL3749 migrated to two separated fractions. The quality (viability) and the yields of the separated samples were sufficient to show the advantage of microgravity. Another rough strain, SL1102, exhibited unexpected electrophoretic behavior, which prevented the complete resolution of the three strains. All the strains were recovered as viable cells after 8 days of flight. The present study suggests that electrophoretic separation of bacterial cells is much more effective under microgravity conditions with relatively good resolution in comparison with the ground operation.     

The properties of alamethicin incorporated into planar lipid bilayers under the influence of microgravity.

During evolution, life on earth had adapted to the gravity of 1g. Due to space flight, in the last decades the question arose what happens to the brain under microgravity on the molecular level. Ion channels among others are the molecular basis of brain function. Therefore, the investigation of ion channel function under microgravity seems to be a promising approach to gather knowledge on brain function during space flight. In a first step, the ion channel forming peptide Alamethicin was used as a model channel in an artificial membrane. It is well suitable for this kind of investigation, since its properties are well described under standard gravity. For that reason, changes due to microgravity can be detected easily. All experiments were performed in the German drop tower at ZARM-FAB, Bremen. A special set-up was constructed based on the bilayer technique introduced by Mueller and Rudin. All functions of this set-up can be observed and controlled remotely. In the first set of experiments, a dramatic change of electrical properties of Alamethicin under microgravity could be observed. Mainly, the pore frequency is significantly reduced.     

The Protein Crystallization Facility (PCF) for EURECA.

Research on the structure of molecules by X-ray diffraction analysis requires large single crystals. However, the dynamic behavior of proteins caused by their high molecular weight prevents the growth of large single crystals if this process is disturbed by thermal convection. For example, protein single crystals grown under terrestrial (1 g) conditions are limited to dimensions in the order of 0.1 mm, whereas the size of crystals, grown under (quasi) space conditions has been 5 times larger (pilot experiment CRYOSTAT, Spacelab). Under EURECA conditions (e.g. no microgravity disturbances), the result in regularity of crystal growth and size is expected to be much better. In this paper an overview is given of the protein crystallization facility which includes Experiment-, Service- and Secondary Cooling Module, and its interfaces to the EURECA Carrier. At the end, there will be presented a short mission profile concerning cooling-, power- and data exchange requirements.     

Spaceflight effects on consecutive generations of peas grown onboard the Russian segment of the International Space Station

In the period from March 2003 to April 2005 we fulfilled five experimental cultivations of genetically marked dwarf pea species in greenhouse Lada installed in the Russian segment (RS) of the International Space Station (ISS). The purpose of this series of experiments was to make morphologic and genetic analysis of pea plants grown in successive generations.According to our results, pea growth and development over the full cycle of ontogenesis (from seed to seed) taking place in space greenhouse Lada were not different as compared with the ground control plants. In addition, four successive pea crops gathered in space flight did not loose their reproductive functions and formed viable seeds.Genetic analysis of the plants grown from the “space” and “ground” seeds produced by the first to fourth successive crops was performed using the methods of chromosomal aberrations count and Random Amplified Polymorphic DNA (molecular method). No genetic polymorphism was found either in the experimental or control crops. This can serve as a sound argument for the supposition that the genetic apparatus of plants is not impacted by exposure of several successive generations to the conditions of space flight.