Development of a CELSS bioreactor: oxygen transfer and micromixing in parabolic flight.

The gas exchange portion of a phase-separated loop bioreactor was tested with respect to oxygen mass transfer and micromixing in accelerations of 0.01g, 1g, and 2g. A plot of the overall mass transfer coefficient versus gravity indicates the rate of oxygen transfer does not change as a function of acceleration. Also, it was determined that the micromixing did not exhibit significant changes in the various gravitational fields. These observations indicate the loop bioreactor should function independent of acceleration.     

Central hemodynamics in a baboon model during microgravity induced by parabolic flight.

We developed a chronically instrumented nonhuman primate model (baboon) to evaluate the central cardiovascular responses to transient microgravity induced by parabolic flight. Instrumentation provided simultaneous recording of high fidelity (Ao) and pulmonary artery (PA) pressures, right and left ventricular and atrial pressures, Ao and PA blood flow velocities and vessel dimensions, ECG and pleural pressures. Four daily flights in 1991 and five in 1992 were flown with forty parabola per flight. Animals flown in 1991 were not controlled for volume status. Animals flown in 1992 were studied in one of three conditions: 1) volume depleted by furosemide (DH), 2) volume expanded by saline infusion (VE), and 3) euvolemic (EU, no intervention, used for echo only). Mean right atrial pressures (RAP) during 1991 flights had a variable early microgravity response: increases in n=3 and decrease in n=3 (supine) and increases in n=5, decreases in n=2 (upright). In 1992 flights, DH, upright and supine, changed -10 +/- 4.1 mmHg, -3.2 +/- 2.2 mmHg, respectively (p < .05) compared to the pull-up phase. In contrast, VE changed (from pull-up to microgravity) +13 +/- 1.5 mmHg and +4.25 +/- 2.9 mmHg (upright and supine, respectively, p < .05). EU increased with microgravity +6.9 +/- .9 mmHg (upright only). LAP responses were similar, but more variable. Finally, heart chamber areas paralleled pressure changes. Thus, right and left heart filling pressure changes with sudden entry into microgravity conditions were dependent on initial circulatory volume status and somewhat modified by position (supine vs upright).     

Effects of hypergravity on the development of cell number and asymmetry in fish brain nuclei.

Larval cichlid fish (Oreochromis mossambicus) siblings were subjected to 3 g hypergravity (hg) and total darkness for 21 days during development and subsequently processed for conventional histology. Further siblings reared at 1 g and alternating light/dark (12h:12h) conditions served as controls. Cell number counts of the visual Nucleus isthmi (Ni) versus the vestibular Nucleus magnocellularis (Nm) revealed that in experimental animals total cell number was decreased in the Ni, possibly due to retarded growth as a result of the lack of visual input whereas no effect was observed in the Nm. Calculating the percentual asymmetry in cell number (i.e., right vs. the left side of the brain), no effects of hg/darkness were seen in the Ni, whereas asymmetry was slightly increased in the Nm. Since the asymmetry of inner ear otoliths is decreased under hg, this finding may indicate efferent vestibular action of the CNS on the level of the Nm by means of a feedback mechanism.     

Effects of altered gravity on the swimming behaviour of fish.

Humans taking part in parabolic aircraft flights (PAFs) may suffer from space motion sickness-phenomena (SMS, a kinetosis). It has been argued that SMS during PAFs might not be based on microgravity alone but rather on changing accelerations from 0 g to 2 g. We test here the hypothesis that PAF-induced kinetosis is based on asymmetric statoliths (i.e., differently weighed statoliths on the right and the left side of the head), with asymmetric inputs to the brain being disclosed at microgravity. Since fish frequently reveal kinetotic behaviour during PAFs (especially so-called spinning movements and looping responses), we investigated (1) whether or not kinetotically swimming fish at microgravity would have a pronounced inner ear otolith asymmetry and (2) whether or not slow translational and continuously changing linear (vertical) acceleration on ground induced kinetosis. These latter accelerations were applied using a specially developed parabel-animal-container (PAC) to stimulate the cupular organs. The results suggest that the fish tested on ground can counter changing accelerations successfully without revealing kinetotic swimming patterns. Kinetosis could only be induced by PAFs. This finding suggests that it is indeed microgravity rather than changing accelerations, which induces kinetosis. Moreover, we demonstrate that fish swimming kinetotically during PAFs correlates with a higher otolith asymmetry in comparison to normally behaving animals in PAFs.     

Behavior of Japanese tree frogs under microgravity on MIR and in parabolic flight.

Japanese tree frogs (Hyla japonica) were flown to the space station MIR and spent eight days in orbit during December, 1990. Under microgravity, their postures and behaviors were observed and recorded. On the MIR, floating frogs stretched four legs out, bent their bodies backward and expanded their abdomens. Frogs on a surface often bent their neck backward and walked backwards. This behavior was observed on parabolic flights and resembles the retching behavior of sick frogs on land--a possible indicator of motion sickness. Observations on MIR were carried out twice to investigate the frog's adaptation to space. The frequency of failure in landing after a jump decreased in the second observation period. After the frogs returned to earth, readaptation processes were observed. The frogs behaved normally as early as 2.5 hours after landing.     

Sedimenting particles and swimming micro-organisms in a rotating fluid.

Experiments and calculations on the trajectories of micron-sized spheres, suspended in a fluid that fills a dosed container which rotates about an axis perpendicular to g, relate to the planning and interpretation of clinostat experiments. For low Reynolds number motion, the orbits are nearly circular, the radius being inversely proportional to the rotation rate. The swimming direction of micro-organisms can be affected by light, gravity, vorticity etc. The trajectories of algae swimming in steadily rotating environments have been observed and compared with theoretical predictions for ideal gyrotactic micro-organisms, thus providing some insights into the mechanisms of gravitaxis, gyrotaxis and the behaviour of the cells.     

Quantum dosimetry and online visualization of X-ray and charged particle radiation in commercial aircraft at operational flight altitudes with the pixel detector Timepix

We investigate the application of the hybrid semiconductor pixel detector Timepix for precise characterization, quantum sensitivity dosimetry and visualization of the charged particle radiation and X-ray field inside commercial aircraft at operational flight altitudes. The quantum counting capability and granularity of Timepix provides the composition and spectral-characteristics of the X-ray and charged-particle field with high sensitivity, wide dynamic range, high spatial resolution and particle type resolving power. For energetic charged particles the direction of trajectory and linear energy transfer can be measured. The detector is operated by the integrated readout interface FITPix for power, control and data acquisition together with the software package Pixelman for online visualization and real-time data processing. The compact and portable radiation camera can be deployed remotely being controlled simply by a laptop computer. The device performs continuous monitoring and accurate time-dependent measurements in wide dynamic range of particle fluxes, deposited energy, absorbed dose and equivalent dose rates. Results are presented for in-flight measurements at altitudes up to 12 km in various flights selected in the period 2006–2013.     

Influence of long-term altered gravity on the swimming performance of developing cichlid fish: including results from the 2nd German Spacelab Mission D-2.

This study presents qualitative and quantitative data concerning gravity-dependent changes in the swimming behaviour of developing cichlid fish larvae (Oreochromis mossambicus) after a 9 resp. 10 days exposure to increased acceleration (centrifuge experiments), to reduced gravity (fast-rotating clinostat), changed accelerations (parabolic aircraft flights) and to near weightlessness (2nd German Spacelab Mission D-2). Changes of gravity initially cause disturbances of the swimming performance of the fish larvae. With prolonged stay in orbit a step by step normalisation of the swimming behaviour took place in the fish. After return to 1g earth conditions no somersaulting or looping could be detected concerning the fish, but still slow and disorientated movements as compared to controls occurred. The fish larvae adapted to earth gravity within 3-5 days. Fish seem to be in a distinct early developmental stages extreme sensitive and adaptable to altered gravity; However, elder fish either do not react or show compensatory behaviour e.g. escape reactions.     

Influence of long-term hyper-gravity on the reactivity of succinic acid dehydrogenase and NADPH-diaphorase in the central nervous system of fish: a histochemical study.

In the course of a densitometric evaluation, the histochemically demonstrated reactivity of succinic acid dehydrogenase (SDH) and of NADPH-diaphorase (NADPHD) was determined in different brain nuclei of two teleost fish (cichlid fish Oreochromis mossambicus, swordtail fish Xiphophorus helleri), which had been kept under 3g hyper-gravity for 8 days. SDH was chosen since it is a rate limiting enzyme of the Krebs cycle and therefore it is regarded as a marker for metabolic and neuronal activity. NADPHD reactivity reflects the activity of nitric oxide synthase. Nitric oxide (NO) is a gaseous intercellular messenger that has been suggested to play a major role in several different in vivo models of neuronal plasticity including learning. Within particular vestibulum-connected brain centers, significant effects of hyper-gravity were obtained, e.g., in the magnocellular nucleus, a primary vestibular relay ganglion of the brain stem octavolateralis area, in the superior rectus subdivision of the oculomotoric nucleus and within cerebellar eurydendroid cells, which in teleosts possibly resemble the deep cerebellar nucleus of higher vertebrates. Non-vestibulum related nuclei did not respond to hyper-gravity in a significant way. The effect of hyper-gravity found was much less distinct in adult animals as compared to the circumstances seen in larval fish (Anken et al., Adv. Space Res. 17, 1996), possibly due to a development correlated loss of neuronal plasticity.     

Radiation situation determining the possibility of a manned flight to Mars and back.

Possible manned flights toward Mars are discussed from the viewpoint of radiation hazard. A standard situation is considered for the fast two times crossing of the Earth radiation belts. The flight to Mars is shown to be practically impossible without a special system of radiation shelters, because of the effect of penetrating galactic and solar radiations which are responsible for almost maximum permissible doses. But even in case there were radiation shelters on board the spacecraft their flights are undesirable in the periods of maximum and minimum solar activity. It would obviously be worthwhile to schedule Martian flights for intervals in between minima and maxima of 11-year cycles of solar activity when primary cosmic rays levels are considerable reduced and flare activity is not yet sufficiently high. It should be mentioned that it would not be easy to select such allowed intervals. Further studies of that aspect are discussed.     

The C23A: first step to a monitoring system of CELSS in flight.

Studies for every level of CELSS: Waste processing, food production, photosynthesis system, and so on ..., imply an automatic system to control, command and quantify gases, water and chemical compounds. Used for many years in plant physiology studies, the C23A system monitors the analysis and quantifies gases (O2, CO2. N2, ...), physical parameters (temperature, humidity, ...) and chemical compounds (NH4+, N03-, ...) on numerous experiments. In the new version, the architecture of the computing system is near of the space requirements. We have chosen a structure with three independent levels: acquisition, monitoring and supervision. Moreover, we use multiplexed analysers: IRGA, mass spectrometer and cheminal analyser. The multiplexing increases the accuracy of the measurements and could facilitate the spatialization. Thus the whole structure anticipates the entire separation between automation in space and control-command on ground.     

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.     

Changes in the central nervous system during long-duration space flight: implications for neuro-imaging.

The purpose of this paper is to review the potential functional and morphological effects of long duration space flight on the human central nervous system (CNS) and how current neuroimaging techniques may be utilized to study these effects. It must be determined if there will be any detrimental changes to the CNS from long term exposure to the space environment if human beings are to plan interplanetary missions or establish permanent space habitats. Research to date has focused primarily on the short term changes in the CNS as the result of space flight. The space environment has many factors such as weightlessness, electromagnetic fields, and radiation, that may impact upon the function and structure of the CNS. CNS changes known to occur during and after long term space flight include neurovestibular disturbances, cephalic fluid shifts, alterations in sensory perception, changes in proprioception, psychological disturbances, and cognitive changes. Animal studies have shown altered plasticity of the neural cytoarchitecture, decreased neuronal metabolism in the hypothalamus, and changes in neurotransmitter concentrations. Recent progress in the ability to study brain morphology, cerebral metabolism, and neurochemistry in vivo in the human brain would provide ample opportunity to investigate many of the changes that occur in the CNS as a result of space flight. These methods include positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI).     

Accumulation of tumor suppressor p53 in rat muscle after a space flight.

Tumor suppressor p53 functions as a cell cycle checkpoint under stressful conditions. Early studies have shown that genotoxic stress activates p53 pathway. Recently, many kinds of non-genotoxic stress such as heat shock, cold shock, and low pH also have been found to activate p53 pathway. The effects on living organism remains to be explored. Here, we show that an 18-day space flight induced a 3.6 fold accumulation of p53 in rat skeletal muscle. This results suggests that the p53 pathway plays a role in safeguarding genomic stability against the stressful space environments and supports our previous observation of p53 accumulation in rat skin after a space flight.     

Blood and clonogenic hemopoietic cells of newts after the space flight.

Ribbed newts were used for studying the effect of space flight on board of the biosatellite (Cosmos-2229) on blood and clonogenic hemopoietic cells. In blood of newts of the flight group, the relative proportion of neutrophils increased, whereas that of lymphocytes and eosinophils decreased. Space flight did not result in loss of the ability of newt blood cells to incorporate H3-thymidine. Analysis of clonogenic hemopoietic cells was performed using the method of hemopoietic colony formation on cellulose acetate membranes implanted into the peritoneal cavity of irradiated newts. To analyze reconstitution of hemopoiesis after irradiation donor hemopoietic cells from flight or control newts were transplanted into irradiated newts whose hemopoietic organs were investigated. The newt can be considered an adequate model for studying hemopoiesis under the conditions of the space flight.     

Approaches in the determination of plant nutrient uptake and distribution in space flight conditions.

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the radionuclides calcium-45 and iron-59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.     

The Rhesus monkey as a model for testing the immunological effects of space flight.

The Rhesus monkey has been proposed as a model for the effects of space flight on immunity. In order to determine the feasibility of the use of the Rhesus monkey as a model, we studied the use of Rhesus monkey cells for immunological procedures that have been shown to be affected by space flight in both rodents and humans. We have shown that both lymph node cells and peripheral blood leukocytes can be stained with monoclonal antibodies to detect the following surface markers: CD4, CD-8, Ia and surface immunoglobulin. Also, the level of Ia antigen expression was increased by treatment of the cells with human interferon-gamma. In addition, cells were induced to produce interferons and interleukins. Isolated neutrophils also demonstrated increased oxidative burst. These data indicate that the Rhesus monkey will be a useful model for space flight studies of immunity.     

Investigation on rice embryos and seeds after the LDEF flight: electronic spin resonance identification.

Rice caryopsis of Cigalon variety with short grain of the LDEF mission can develop and grow as well as those of the laboratory control. Rice caryopsis of Delta variety with long grain did not develop while a small number of excised embryos can develop and grow as well as the control group. A preliminary study of the Electron Spin Resonance (ESR) spectra of Rice embryos and seeds recorded several month after the flight on flight samples and on control ones has been carried out. All these samples had the same storage time. During storage the radical concentration which usually decreases, now depends on irradiation doses and on whether or not they were delivered in presence of oxygen. The signal variations are smaller than those usually observed in the different parts of the starch. An estimation of a "gamma-equivalent-dose" can be reached.     

Effects of space flight exposure on cell growth,tumorigenicity and gene expression in cancer cells

It is well recognized that harsh outer space environment, consisting of microgravity and radiation, poses significant health risks for human cells. To investigate potential effects of the space environment exposure on cancer cells we examined the biological changes in Caski cells carried by the “Shen Zhou IV” spaceship. After exposure for 7 days in spaceflight, 1440 survival subclonal cell lines were established and 4 cell lines were screened. 44F10 and 17E3 were selected because of their increased cell proliferation and tumorigenesis, while 48A9 and 31F2 had slower cytological events. Experiments with cell proliferation assay, flow cytometry, soft agar assay, tumorigenesis assay and DNA microarray analysis have shown that selected cell lines presented multiple biological changes in cell morphology, cell growth, tumorigenicity and gene expression. These results suggest that space environment exposure can make significant biological impact on cancer cells and provide an entry point to find the immunological target of tumorigenesis.     

State of erythrocyte membrane in man and monkeys after space flight.

The lipid and phospholipid composition of the erythrocyte membrane was investigated in man after long space flight and monkey after short space. The result obtained confirm structural changes in EM under the influence of SF factors and show that an increase of Ch and ChE fractions and in the Ch&ChE/PL ratio combined with a decrease of PL fractions. It was noticed that the magnitude of these changes is depend on duration of space flight.