Effects of spaceflight and PEG-IL-2 on rat physiological and immunological responses.

Sprague-Dawley rats were subjected to two 8-day spaceflights on the space shuttle. Rats housed in the National Aeronautics and Space Administration's animal enclosure were injected (iv or sc) with pegylated interleukin-2 (PEG-IL-2) or a placebo. We tested the hypothesis that PEG-IL-2 would ameliorate some of the effects of spaceflight. We measured body and organ weights; blood cell differentials; plasma corticosterone; colony-forming units (macrophage and granulocyte macrophage); lymphocyte mitogenic, superantigenic, and interferon-gamma responses; bone marrow cell and peritoneal macrophage cytokine secretion; and bone strength and mass. Few immunological parameters were affected by spaceflight. However, some spaceflight effects were observed in each flight. Specifically, peritoneal macrophage spontaneous secretion of tumor necrosis factor-alpha occurred in the first but not in the second flight. A significant monocytopenia and lymphocytopenia were detected in the second but not in the first flight. The second mission produced bone changes more consistent with past spaceflight investigations. PEG-IL-2 did not appear to be beneficial; however, this was mostly due to the lack of spaceflight effects. These studies reflect the difficulty in reproducing experimental models by using current space shuttle conditions.     

Spaceflight and development of immune responses

The NIH.R1 Space Shuttle experiment wasdesigned to study the effects of spaceflight on rodent development.Pregnant rats were flown on the Space Shuttle for 11 days, and pregnantcontrol rats were maintained in animal enclosure modules in aground-based chamber under conditions approximating those in flight.Additional controls were in standard housing. The effects of the flighton immunological parameters of dams, fetuses, and pups were determined. Blastogenesis of spleen cells in response to mitogen was inhibited inflown dams but was not inhibited in cells from their pups. Interferon- production by spleen cells showed a trend toward inhibition in flown dams but not in their pups. The response of bonemarrow cells to colony-stimulating factor showed a trend towardinhibition after spaceflight in dams, but the response of fetus and pupliver cells was not inhibited. Total serum IgG was not affected byspaceflight. None of the examined immune parameters that were alteredin rat dams after spaceflight was found to be altered in theiroffspring.

     

Penetration of Trichophyton terrestre in human hair

The systematic human hair degradation by Trichophyton terrestre was examined by electron and light microscopy. The cuticular and hair shaft regions were readily decomposed by the wild type or parent strain selected for phenotype studies after exposure to spaceflight parameters.     

Spaceflight Promotes Biofilm Formation by Pseudomonas aeruginosa

Understanding the effects of spaceflight on microbial communities is crucial for the success of long-term, manned space missions. Surface-associated bacterial communities, known as biofilms, were abundant on the Mir space station and continue to be a challenge on the International Space Station. The health and safety hazards linked to the development of biofilms are of particular concern due to the suppression of immune function observed during spaceflight. While planktonic cultures of microbes have indicated that spaceflight can lead to increases in growth and virulence, the effects of spaceflight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Space Shuttle Atlantis missions: STS-132 and STS-135, and the biofilms formed during spaceflight were characterized. Spaceflight was observed to increase the number of viable cells, biofilm biomass, and thickness relative to normal gravity controls. Moreover, the biofilms formed during spaceflight exhibited a column-and-canopy structure that has not been observed on Earth. The increase in the amount of biofilms and the formation of the novel architecture during spaceflight were observed to be independent of carbon source and phosphate concentrations in the media. However, flagella-driven motility was shown to be essential for the formation of this biofilm architecture during spaceflight. These findings represent the first evidence that spaceflight affects community-level behaviors of bacteria and highlight the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight.     

Spaceflight induces changes in splenocyte subpopulations: effectiveness of ground-based models

Spaceflight produces changes in the immune system. The mechanisms for the alterations in immune function after spaceflight remain unclear due in part to the difficulties associated with conducting spaceflight research. The purpose of the following studies, therefore, was to create a ground-based protocol that can reproduce the immunological changes found after spaceflight, i.e., changes in splenic lymphocyte populations. Rats were exposed to either flight aboard the Space Shuttle Endeavor (STS-77) or ground-based simulations of various components of the spaceflight experience. The ground-based mock spaceflight was comprised of exposure to launch and landing loads and unloading of the hindlimbs. In addition, each component of this ground-based mock spaceflight was tested separately. The results were that spaceflight reduced splenic CD4(+) T (helper/inducer) cells and CD11b(+) (neutrophils/macrophages) cells. The ground-based simulations of spaceflight did not reproduce the same pattern of splenocyte changes. In fact, exposure to landing loads alone increased splenic CD4(+) T (helper/inducer) cells. These findings support the conclusion that the ground models tested did not induce similar changes in the immune system as did spaceflight. It is possible, therefore, that stressors/factors unique to the spaceflight experience impact the immune system in ways that cannot be currently, fully modeled on the ground.     

Heart, and peripheral arteries and veins during the 14 month MIR space flight

Ultrasound Doppler imaging and electrocardiography were used to study hemodynamic responses to spaceflight onboard the Mir space station. Cardiovascular adaptation was studied at rest and during the use of thigh cuffs or "Bracelets" for weightlessness countermeasures. Specific changes in hemodynamic parameters are presented and discussed, along with an evaluation of the effectiveness of the Bracelet countermeasures.     

Molecular aspects of stress-gene regulation during spaceflight

Spaceflight-associated stress has been the topic of investigation since the first terrestrial organisms were exposed to this unique environment. Organisms that evolved under the selection pressures of earth-normal environments can perceive spaceflight as a stress, either directly because gravity influences an intrinsic biological process, or indirectly because of secondary effects imparted by spaceflight upon environmental conditions. Different organisms and even different organs within an organism adapt to a spaceflight environment with a diversity of tactics. Plants are keenly sensitive to gravity for directed development, and are also sensitive to other stresses associated with closed-system spaceflight environments. Within the past decade, the tools of molecular biology have begun to provide a sophisticated evaluation of spaceflight-associated stress and the genetic responses that accompany metabolic adaptation to spaceflight.     

A mutational analysis of Caenorhabditis elegans in space

The International Caenorhabditis elegans Experiment First Flight (ICE-First) was a project using C. elegans as a model organism to study the biological effects of short duration spaceflight (11 days in the International Space Station). As a member of the ICE-First research team, our group focused on the mutational effects of spaceflight. Several approaches were taken to measure mutational changes that occurred during the spaceflight including measurement of the integrity of poly-G/poly-C tracts, determination of the mutation frequency in the unc-22 gene, analysis of lethal mutations captured by the genetic balancer eT1(III;V), and identification of alterations in telomere length. By comparing the efficiency, sensitivity, and convenience of these methods, we deduced that the eT1 balancer system is well-suited for capturing, maintaining and recovering mutational events that occur over several generations during spaceflight. In the course of this experiment, we have extended the usefulness of the eT1 balancer system by identifying the physical breakpoints of the eT1 translocation and have developed a PCR assay to follow the eT1 chromosomes. C. elegans animals were grown in a defined liquid media during the spaceflight. This is the first analysis of genetic changes in C. elegans grown in the defined media. Although no significant difference in mutation rate was detected between spaceflight and control samples, which is not surprising given the short duration of the spaceflight, we demonstrate here the utility of worms as an integrating biological dosimeter for spaceflight.     

Filamentous fungi exposed to spaceflight stresses including known levels of ultraviolet irradiations

Chaetomium globosum ascospores andTrichophyton terrestre conidia were exposed to spaceflight parameters of Apollo 16 then returned to Earch for studies in hyphal grwoth dynamics as one of the postflight investigations. Selected phenotypic strains of each species appeared to show changes in growth according to specific ultraviolet irradiations in space.     

Effect of Spaceflight on the Circadian Rhythm,Lifespan and Gene Expression of Drosophila melanogaster

Space travelers are reported to experience circadian rhythm disruption during spaceflight. However, how the space environment affects circadian rhythm is yet to be determined. The major focus of this study was to investigate the effect of spaceflight on the Drosophila circadian clock at both the behavioral and molecular level. We used China’s Shenzhou-9 spaceship to carry Drosophila. After 13 days of spaceflight, behavior tests showed that the flies maintained normal locomotor activity rhythm and sleep pattern. The expression level and rhythm of major clock genes were also unaffected. However, expression profiling showed differentially regulated output genes of the circadian clock system between space flown and control flies, suggesting that spaceflight affected the circadian output pathway. We also investigated other physiological effects of spaceflight such as lipid metabolism and lifespan, and searched genes significantly affected by spaceflight using microarray analysis. These results provide new information on the effects of spaceflight on circadian rhythm, lipid metabolism and lifespan. Furthermore, we showed that studying the effect of spaceflight on gene expression using samples collected at different Zeitgeber time could obtain different results, suggesting the importance of appropriate sampling procedures in studies on the effects of spaceflight.     

The calcium endocrine system of adolescent rhesus monkeys and controls before and after spaceflight

The calcium endocrine system of nonhuman primates can be influenced by chairing for safety and the weightless environment of spaceflight. The serum of two rhesus monkeys flown on the Bion 11 mission was assayed pre- and postflight for vitamin D metabolites, parathyroid hormone, calcitonin, parameters of calcium homeostasis, cortisol, and indexes of renal function. Results were compared with the same measures from five monkeys before and after chairing for a flight simulation study. Concentrations of 1,25-dihydroxyvitamin D were 72% lower after the flight than before, and more than after chairing on the ground (57%, P < 0.05). Decreases in parathyroid hormone did not reach significance. Calcitonin showed modest decreases postflight (P < 0.02). Overall, effects of spaceflight on the calcium endocrine system were similar to the effects of chairing on the ground, but were more pronounced. Reduced intestinal calcium absorption, losses in body weight, increases in cortisol, and higher postflight blood urea nitrogen were the changes in flight monkeys that distinguished them from the flight simulation study animals.     

Analysis of influences of spaceflight on chemical constituents in licorice by HPLC–ESI-MS/MS

Focusing on the variations of chemical constituents in licorice root, influences of exposure to physical factors of spaceflight on licorice (Glycyrrhiza uralensis Fisch.) seeds were investigated. Licorice seeds obtained from two different producing areas were flown on a recoverable satellite for 18 days. After returning to earth, the seeds carried by the satellite and the parallel ground control were cultivated to maturity under the same condition. Chromatographic fingerprint of 1 year licorice root analyzed by high performance liquid chromatography with diode-array detection not only displayed the contents of glycyrrhizic acid and liquiritin increasing in the spaceflight samples but showed the variation of the kinds of chemical constituents. The main components in the root extract were identified by high performance liquid chromatography coupled with electrospray ionization multi-tandem mass spectrometry. The changes in the kind of secondary metabolites of licorice root after spaceflight were firstly reported. A total of 26 components which included 9 flavonoids, 16 triterpene saponins and 1 coumarin were identified according to their mass spectra determined in both negative and positive ion modes. The research provided the scientific data for spaceflight breeding of medicinal plant and indicated that the technology of spaceflight may be a new effective method for the breeding and cultivation of licorice.     

Transgene expression patterns indicate that spaceflight affects stress signal perception and transduction in arabidopsis

The use of plants as integral components of life support systems remains a cornerstone of strategies for long-term human habitation of space and extraterrestrial colonization. Spaceflight experiments over the past few decades have refined the hardware required to grow plants in low-earth orbit and have illuminated fundamental issues regarding spaceflight effects on plant growth and development. Potential incipient hypoxia, resulting from the lack of convection-driven gas movement, has emerged as a possible major impact of microgravity. We developed transgenic Arabidopsis containing the alcohol dehydrogenase (Adh) gene promoter linked to the beta-glucuronidase (GUS) reporter gene to address specifically the possibility that spaceflight induces the plant hypoxia response and to assess whether any spaceflight response was similar to control terrestrial hypoxia-induced gene expression patterns. The staining patterns resulting from a 5-d mission on the orbiter Columbia during mission STS-93 indicate that the Adh/GUS reporter gene was activated in roots during the flight. However, the patterns of expression were not identical to terrestrial control inductions. Moreover, although terrestrial hypoxia induces Adh/GUS expression in the shoot apex, no apex staining was observed in the spaceflight plants. This indicates that either the normal hypoxia response signaling is impaired in spaceflight or that spaceflight inappropriately induces Adh/GUS activity for reasons other than hypoxia.     

Modification of reproductive development in Arabidopsis thaliana under spaceflight conditions

Reproductive development in Arabidopsis thaliana (L.) Heynh. cv. Columbia plants was investigated under spaceflight conditions on shuttle mission STS-51. Plants launched just prior to initiation of the reproductive phase developed flowers and siliques during the 10-d flight. Approximately 500 flowers were produced in total by the 12 plants in both the ground control and spaceflight material, and there was no significant difference in the number of flowers in each size class. The flower buds and siliques of the spaceflight plants were not morphologically different from the ground controls. Pollen viability tests immediately post-flight using fluorescein diacetate indicated that about 35% of the pollen was viable in the spaceflight material. Light-microscopy observations on this material showed that the female gametophytes also had developed normally to maturity. However, siliques from the spaceflight plants contained empty, shrunken ovules, and no evidence of pollen transfer to stigmatic papillae was found by light microscopy immediately post-flight or by scanning electron microscopy on fixed material. Short stamen length and indehiscent anthers were observed in the spaceflight material, and a film-like substance inside the anther that connected to the tapetum appeared to restrict the release of pollen from the anthers. These observations indicate that given appropriate growing conditions, early reproductive development in A. thaliana can occur normally under spaceflight conditions. On STS-51, reproductive development aborted due to obstacles in pollination or fertilization.     

Effects of a Closed Space Environment on Gene Expression in Hair Follicles of Astronauts in the International Space Station

Adaptation to the space environment can sometimes pose physiological problems to International Space Station (ISS) astronauts after their return to earth. Therefore, it is important to develop healthcare technologies for astronauts. In this study, we examined the feasibility of using hair follicles, a readily obtained sample, to assess gene expression changes in response to spaceflight adaptation. In order to investigate the gene expression changes in human hair follicles during spaceflight, hair follicles of 10 astronauts were analyzed by microarray and real time qPCR analyses. We found that spaceflight alters human hair follicle gene expression. The degree of changes in gene expression was found to vary among individuals. In some astronauts, genes related to hair growth such as FGF18, ANGPTL7 and COMP were upregulated during flight, suggesting that spaceflight inhibits cell proliferation in hair follicles.     

Reserve nutrient substance accumulation in Brassica rapa L. seeds in microgravity conditions (STS-87)

The results of study of Brassica embryo differentiation and reserve nutrient substance accumulation in the seeds were represented. Near resemblance of the spaceflight and around control embryo development was revealed. Different character of the reserve substance accumulation was noted, despite of the morphologic similarity in seeds produced in spaceflight and on the ground. It allows to consider spaceflight embryos morphologically more younger compared to the ground control.     

The effects of 10 days of spaceflight on the shuttle Endeavour on predominantly fast-twitch muscles in the rat

The primary purpose of this investigation was to determine the effects of microgravity on muscle fibers of the predominantly fast-twitch muscles in the rat. Cross sectional area and myosin heavy chain (MHC) composition were assessed in order to establish the acute effects of microgravity associated with spaceflight. The extensor digitorum longus (EDL) and gastrocnemius muscles were removed from 12 male Fisher 344 rats which had undergone 10 days of spaceflight aboard the space shuttle Endeavor and from 12 age- and weight-matched control animals. Both groups of animals received similar amounts of food and water and were synchronized for photoperiods, environmental temperature, and humidity. Significant (P < 0.05) reductions in muscle fiber size were observed in the gastrocnemius (fiber types I, IIA, IIDB, and IIB) and EDL (fiber type IIB) muscles after spaceflight. Significant MHC isoform transformations also resulted during this brief period of microgravity exposure with a significant decrease in MHC IId isoform in the EDL muscle. A significant decrease was also observed in the MHC IId isoform in the superficial (white) component of the gastrocnemius muscle after spaceflight, although no alterations in MHC profile were demonstrated in the deep (red) component of this muscle. These findings highlight the rapid plasticity of skeletal muscle during short-term spaceflight. If such pronounced adaptations to spaceflight also occur in humans, then astronauts are likely to suffer severe decrements in skeletal muscle performance with long-term space flight and upon return to earth after both short- and long-term missions. Thus, countermeasures aimed at slowing or even preventing muscle fiber atrophy are warranted.     

The Effect of Spaceflight on Growth of Ulocladium chartarum Colonies on the International Space Station

The objectives of this 14 days experiment were to investigate the effect of spaceflight on the growth of Ulocladium chartarum, to study the viability of the aerial and submerged mycelium and to put in evidence changes at the cellular level. U. chartarum was chosen for the spaceflight experiment because it is well known to be involved in biodeterioration of organic and inorganic substrates covered with organic deposits and expected to be a possible contaminant in Spaceships. Colonies grown on the International Space Station (ISS) and on Earth were analysed post-flight. This study clearly indicates that U. chartarum is able to grow under spaceflight conditions developing, as a response, a complex colony morphotype never mentioned previously. We observed that spaceflight reduced the rate of growth of aerial mycelium, but stimulated the growth of submerged mycelium and of new microcolonies. In Spaceships and Space Stations U. chartarum and other fungal species could find a favourable environment to grow invasively unnoticed in the depth of surfaces containing very small amount of substrate, posing a risk factor for biodegradation of structural components, as well as a direct threat for crew health. The colony growth cycle of U. chartarum provides a useful eukaryotic system for the study of fungal growth under spaceflight conditions.     

The effects of spaceflight on mammary metabolism in pregnant rats.

The effects of spaceflight on mammary metabolism of 10 pregnant rats was measured on Day 20 of pregnancy and after parturition. Rats were flown on the space shuttle from Day 11 through Day 20 of pregnancy. After their return to earth, glucose oxidation to carbon dioxide increased 43% (P < 0.05), and incorporation into fatty acids increased 300% (P < 0.005) compared to controls. It is unclear whether the enhanced glucose use is due to spaceflight or a response to landing. Casein mRNA and gross histology were not altered at Day 20 of pregnancy. Six rats gave birth (on Day 22 to 23 of pregnancy) and mammary metabolic activity was measured immediately postpartum. The earlier effects of spaceflight were no longer apparent. There was also no difference in expression of beta-casein mRNA. It is clear from these studies that spaceflight does not impair the normal development of the mammary gland, its ability to use glucose, nor the ability to express mRNA for a major milk protein.