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Research Containing: Microgravity

Suppression of Hydroxycinnamate Network Formation in Cell Walls of Rice Shoots Grown under Microgravity Conditions in Space

by on 22 August 2016in Biology & Biotechnology No comment

Network structures created by hydroxycinnamate cross-links within the cell wall architecture of gramineous plants make the cell wall resistant to the gravitational force of the earth. In this study, the effects of microgravity on the formation of cell wall-bound hydroxycinnamates were examined using etiolated rice shoots simultaneously grown under artificial 1 g and microgravity conditions in the Cell Biology Experiment Facility on the International Space Station. Measurement of the mechanical properties of cell walls showed that shoot cell walls became stiff during the growth period and that microgravity suppressed this stiffening. Amounts of cell wall polysaccharides, cell wall-bound phenolic acids, and lignin in rice shoots increased as the shoot grew. Microgravity did not influence changes in the amounts of cell wall polysaccharides or phenolic acid monomers such as ferulic acid (FA) and p-coumaric acid, but it suppressed increases in diferulic acid (DFA) isomers and lignin. Activities of the enzymes phenylalanine ammonia-lyase (PAL) and cell wall-bound peroxidase (CW-PRX) in shoots also increased as the shoot grew. PAL activity in microgravity-grown shoots was almost comparable to that in artificial 1 g-grown shoots, while CW-PRX activity increased less in microgravity-grown shoots than in artificial 1 g-grown shoots. Furthermore, the increases in expression levels of some class III peroxidase genes were reduced under microgravity conditions. These results suggest that a microgravity environment modifies the expression levels of certain class III peroxidase genes in rice shoots, that the resultant reduction of CW-PRX activity may be involved in suppressing DFA formation and lignin polymerization, and that this suppression may cause a decrease in cross-linkages within the cell wall architecture. The reduction in intra-network structures may contribute to keeping the cell wall loose under microgravity conditions.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26378793

Extracellular Lipase and Protease Production from a Model Drinking Water Bacterial Community Is Functionally Robust to Absence of Individual Members

by on 22 August 2016in Biology & Biotechnology No comment

Bacteria secrete enzymes into the extracellular space to hydrolyze macromolecules into constituents that can be imported for microbial nutrition. In bacterial communities, these enzymes and their resultant products can be modeled as community property. Our goal was to investigate the impact of individual community member absence on the resulting community production of exoenzymes (extracellular enzymes) involved in lipid and protein hydrolysis. Our model community contained nine bacteria isolated from the potable water system of the International Space Station. Bacteria were grown in static conditions individually, all together, or in all combinations of eight species and exoproduct production was measured by colorimetric or fluorometric reagents to assess short chain and long chain lipases, choline-specific phospholipases C, and proteases. The exoenzyme production of each species grown alone varied widely, however, the enzyme activity levels of the mixed communities were functionally robust to absence of any single species, with the exception of phospholipase C production in one community. For phospholipase C, absence of Chryseobacterium gleum led to increased choline-specific phospholipase C production, correlated with increased growth of Burkholderia cepacia and Sphingomonas sanguinis. Because each individual species produced different enzyme activity levels in isolation, we calculated an expected activity value for each bacterial mixture using input levels or known final composition. This analysis suggested that robustness of each exoenzyme activity is not solely mediated by community composition, but possibly influenced by bacterial communication, which is known to regulate such pathways in many bacteria. We conclude that in this simplified model of a drinking water bacterial community, community structure imposes constraints on production and/or secretion of exoenzymes to generate a level appropriate to exploit a given nutrient environment.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26599415

Assessing Sensorimotor Function Following ISS with Computerized Dynamic Posturography

by on 22 August 2016in Biology & Biotechnology No comment

INTRODUCTION: Postflight postural ataxia reflects both the control strategies adopted for movement in microgravity and the direct effects of deconditioning. Computerized dynamic posturography (CDP) has been used during the first decade of the International Space Station (ISS) expeditions to quantify the initial postflight decrements and recovery of postural stability. METHODS: The CDP data were obtained on 37 crewmembers as part of their pre- and postflight medical examinations. Sensory organization tests evaluated the ability to make effective use of (or suppress inappropriate) visual, vestibular, and somatosensory information for balance control. This report focuses on eyes closed conditions with either a fixed or sway-referenced base of support, with the head erect or during pitch-head tilts (+/- 20 degrees at 0.33 Hz). Equilibrium scores were derived from peak-to-peak anterior-posterior sway. Motor-control tests were also used to evaluate a crewmember’s ability to automatically recover from unexpected support-surface perturbations. RESULTS: The standard Romberg condition was the least sensitive. Dynamic head tilts led to increased incidence of falls and revealed significantly longer recovery than head-erect conditions. Improvements in postflight postural performance during the later expeditions may be attributable to higher preflight baselines and/or advanced exercise capabilities aboard the ISS. CONCLUSIONS: The diagnostic assessment of postural instability is more pronounced during unstable-support conditions requiring active head movements. In addition to supporting return-to-duty decisions by flight surgeons, the CDP provides a standardized sensorimotor measure that can be used to evaluate the effectiveness of countermeasures designed to either minimize deconditioning on orbit or promote reconditioning upon return to Earth.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630195

Medication use by U.S. crewmembers on the International Space Station

by on 22 August 2016in Biology & Biotechnology No comment

The environment on the International Space Station (ISS) includes a variety of potential physiologic stressors, including low gravity, elevated exposure to radiation, confined living and working quarters, a heavy workload, and high public visibility. This retrospective study examined medication use during long-duration spaceflights (>30 d). Medication records from 24 crewmembers on 20 missions longer than 30 d over a 10 yr period were examined for trends in usage rates, efficacy, and indication, as well as adverse event quality, frequency, and severity. Results were compared with those from crewmembers on shorter space shuttle missions (>16 d) and other reports of medication use by healthy adults. The most frequently used medications on the ISS were for sleep problems, pain, congestion, or allergy. Medication use during spaceflight missions was similar to that noted on the Space Shuttle and in adult ambulatory medicine, except that usage of sleep aids was about 10 times higher during spaceflight missions. There were also 2 apparent treatment failures in cases of skin rash, raising questions about the efficacy or suitability of the treatments used. Many spaceflight-related medication uses (at least 10%) were linked to extravehicular activities, exercise protocols, or equipment and operationally driven schedule changes. It seems likely that alterations in spaceflight mission operations (schedule-shifting and lighting) or hardware (extravehicular activity suits and exercise equipment) could reduce the need for a sizable fraction of medication uses.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26187345

Expression of p53-Regulated Proteins in Human Cultured Lymphoblastoid TSCE5 and WTK1 Cell Lines during Spaceflight

by on 22 August 2016in Biology & Biotechnology No comment

The aim of this study was to determine the biological effects of space radiations, microgravity, and the interaction of them on the expression of p53-regulated proteins. Space experiments were performed with two human cultured lymphoblastoid cell lines: one line (TSCE5) bears a wild-type p53 gene status, and another line (WTK1) bears a mutated p53 gene status. Under 1 gravity or microgravity conditions, the cells were grown in the cell biology experimental facility (CBEF) of the International Space Station for 8 days without experiencing the stress during launching and landing because the cells were frozen during these periods. Ground control samples were simultaneously cultured for 8 days in the CBEF on the ground for 8 days. After spaceflight, protein expression was analyzed using a PanoramaTM Ab MicroArray protein chips. It was found that p53-dependent up-regulated proteins in response to space radiations and space environment were MeCP2 (methyl CpG binding protein 2), and Notch1 (Notch homolog 1), respectively. On the other hand, p53-dependent down-regulated proteins were TGF-β, TWEAKR (tumor necrosis fac- tor-like weak inducer of apoptosis receptor), phosho-Pyk2 (Proline-rich tyrosine kinase 2), and 14-3-3θ/τ which were affected by microgravity, and DR4 (death receptor 4), PRMT1 (protein arginine methyltrans- ferase 1) and ROCK-2 (Rho-associated, coiled-coil containing protein kinase 2) in response to space radi- ations. ROCK-2 was also suppressed in response to the space environment. The data provides the p53- dependent regulated proteins by exposure to space radiations and/or microgravity during spaceflight. Our expression data revealed proteins that might help to advance the basic space radiation biology.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/22374402

Estimation of Plasma Parameters in Dusty Plasmas for Microgravity Experiments

by on 22 August 2016in Physical Sciences No comment

Dust particles of micro-meter size are levitated around a sheath in discharges. Gravity pushes the dust particles from a bulk of plasma to the sheath on the ground. Microgravity conditions brought by sounding rockets, parabolic flights of aircract and the International Space Station allow the dust particles to suspend in the bulk of plasma. Many researches have required phenomena of the dust particles under microgravity to be understood with connected to plasma parameters. Here several examples estimating the plasma parameters of microgravity experiments were shown, and described as manners to elucidate the phenomena in dusty plasmas with the plasma parameters. A rough estimation of ion density was obtained in observing wave propagation, and spatial distribution of the dust particles changed by a discharge control was understood in measuring electron density.

Related URLs:
http://www.jasma.info/journal/wp-content/uploads/sites/2/2015/10/2015_p320409.pdf

Rapid Access:Dream Chaser® Space Traffic Management and Operations to Enable Near-Immediate Payload Access for Responsive Mission and Payload Support

by on 22 August 2016in Technology Development & Demonstration No comment

As research institutions all over the world are placing a higher value on space-based science, the need for rapid access to vehicles returning from space carrying experiments grows more important. One of the challenges of enhanced science utilization is rapid access to space vehicles post-flight, which is significantly enabled by effective space traffic management and integration of space operations into a mature commercial aviation system to achieve radically improved orbit to researcher timelines. Sierra Nevada Corporation’s (SNC) Space Systems’ Dream Chaser® reusable spacecraft is designed for multiple applications including cargo and/or crew resupply to the International Space Station and independent long duration science missions. The Dream Chaser is an optionally-piloted, reusable lifting-body spacecraft that lands horizontally on a runway, similar to the Space Shuttle. Unlike the Space Shuttle, the Dream Chaser design supports the unique capability of being able to land at many domestic and international commercial and public-use airports, and offers access to cargo and/or crew almost immediately thereafter. Though this capability presents a unique opportunity for researchers in the field of microgravity science, there are challenges when considering the current landscape of regulation, public risk, and autonomous flight. The potential opportunities associated with landing the Dream Chaser at public-use airports to enable globally convenient and rapid access to crew, cargo, and time critical microgravity experiments post-flight are identified and addressed in this paper.

Related URLs:
http://arc.aiaa.org/doi/abs/10.2514/6.2015-4582

Impact of space flight on bacterial virulence and antibiotic susceptibility

by on 22 August 2016in Biology & Biotechnology No comment

Manned space flight induces a reduction in immune competence among crew and is likely to cause deleterious changes to the composition of the gastrointestinal, nasal, and respiratory bacterial flora, leading to an increased risk of infection. The space flight environment may also affect the susceptibility of microorganisms within the spacecraft to antibiotics, key components of flown medical kits, and may modify the virulence characteristics of bacteria and other microorganisms that contaminate the fabric of the International Space Station and other flight platforms. This review will consider the impact of true and simulated microgravity and other characteristics of the space flight environment on bacterial cell behavior in relation to the potential for serious infections that may appear during missions to astronomical objects beyond low Earth orbit.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26251622

Three-dimensional structure of phosphoribosyl pyrophosphate synthetase from E. coli at 2.71 Å resolution

by on 22 August 2016in Biology & Biotechnology No comment

Phosphoribosyl pyrophosphate synthetase from Escherichia coli was cloned, purified, and crystal- lized. Single crystals of the enzyme were grown under microgravity. The X-ray diffraction data set was col- lected at the Spring-8 synchrotron facility and used to determine the three-dimensional structure of the enzyme by the molecular-replacement method at 2.71 Å resolution. The active and regulatory sites in the molecule of E. coli phosphoribosyl pyrophosphate synthetase were revealed by comparison with the homol- ogous protein from Bacillus subtilis, the structure of which was determined in a complex with functional ligands. The conformations of polypeptide-chain fragments surrounding and composing the active and reg- ulatory sites were shown to be identical in both proteins.

Related URLs:
http://link.springer.com/article/10.1134%2FS1063774516010247

Three-dimensional structure of carboxypeptidase T from Thermoactinomyces vulgaris in complex with N-BOC-L-leucine

by on 22 August 2016in Biology & Biotechnology No comment

The 3D structure of recombinant bacterial carboxypeptidase T (CPT) in complex with N-BOC-L-leucine was determined at 1.38 A resolution. Crystals for the X-ray study were grown in microgravity using the counter-diffusion technique. N-BOC-L-leucine and SO4(2-) ion bound in the enzyme active site were localized in the electron density map. Location of the leucine side chain in CPT-N-BOC-L-leucine complex allowed identification of the S1 subsite of the enzyme, and its structure was determined. Superposition of the structures of CPT-N-BOC-L-leucine complex and complexes of pancreatic carboxypeptidases A and B with substrate and inhibitors was carried out, and similarity of the S1 subsites in these three carboxypeptidases was revealed. It was found that SO4(2-) ion occupies the same position in the S1′ subsite as the C-terminal carboxy group of the substrate.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/23586718