Influence Of Altered Gravity Research Articles

Bioprint FirstAid: A handheld bioprinter for first aid utilization on space exploration missions

Human exploratory missions to Moon or Mars are considered the next steps in human space exploration. Such activities result in the exposure of humans to the space environment for long time, especially under the constraints of orbital dynamics as with increasing distances from earth quick return possibilities are ruled out. Crews on these kinds of missions must be self-sustaining in medical treatments, as environmental conditions in space, such as the influence of altered gravity, radiation or isolation, raise health issues. Therefore, astronauts may use the here presented Handheld Bioprinter as part of the first-aid strategy for in situ wound treatment. The device consists of a handle capable of holding an exchangeable “Ink Printing Unit” containing two separate gel-like components (Bioink and Crosslinker), which are extruded during a printing process through a nozzle and form a skin-cell containing bioink band-aid. For ISS experiments cell simulants were used, as in-space experiments first demonstrated the general feasibility of handheld bioprinting under space conditions. On-ground human skin cells were mixed with the biogel, printed via the handheld bioprinter and cultivated, to demonstrate the overall feasibility of the “Bioprint FirstAid” technology. Concluding results were that a mobile, handheld tool like the bioprinter shows good applicability and offers a possibility of in situ wound treatment for in-space applications. The “Bioprint FirstAid” project was coordinated by the German Space Agency at the German Aerospace Center (DLR) in Bonn and funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK).

The Influence of Altered-Gravity on Bimanual Coordination: Retention and Transfer.

Many of the activities associated with spaceflight require individuals to coordinate actions between the limbs (e.g., controlling a rover, landing a spacecraft). However, research investigating the influence of gravity on bimanual coordination has been limited. The current experiment was designed to determine an individual’s ability to adapt to altered-gravity when performing a complex bimanual force coordination task, and to identify constraints that influence coordination dynamics in altered-gravity. A tilt table was used to simulate gravity on Earth [90° head-up tilt (HUT)] and microgravity [6° head-down tilt (HDT)]. Right limb dominant participants (N = 12) were required to produce 1:1 in-phase and 1:2 multi-frequency force patterns. Lissajous information was provided to guide performance. Participants performed 14, 20 s trials at 90° HUT (Earth). Following a 30-min rest period, participants performed, for each coordination pattern, two retention trials (Earth) followed by two transfer trials in simulated microgravity (6° HDT). Results indicated that participants were able to transfer their training performance during the Earth condition to the microgravity condition with no additional training. No differences between gravity conditions for measures associated with timing (interpeak interval ratio, phase angle slope ratio) were observed. However, despite the effective timing of the force pulses, there were differences in measures associated with force production (peak force, STD of peak force mean force). The results of this study suggest that Lissajous displays may help counteract manual control decrements observed during microgravity. Future work should continue to explore constraints that can facilitate or interfere with bimanual control performance in altered-gravity environments.

Eu:CROPIS \u2013 \u201cEuglena gracilis: Combined Regenerative Organic-food Production in Space\u201d - A Space Experiment Testing Biological Life Support Systems Under Lunar And Martian Gravity

Human space exploration needs stable life support systems for the supply of oxygen, water and food for each human explorer due to long term missions. The most promising approach for building stable life support systems is a combination of physico-chemical and biological systems. These hybrid systems combine the reliability of physico-chemical and the sustainability of biological life support systems. Also the disadvantages, which are the finite resources of physico-chemical and the imperfect reliability of biological systems, are mutually balanced. To improve the reliability of biological life support systems, a combination of different biological systems may stabilize the whole approach during long term operations. The satellite mission Eu:CROPIS (Euglena gracilis: Combined Regenerative Organic-food Production In Space) is a testbed for investigating the behavior of combined biological life support systems under the influence of altered gravity, here, Lunar and Martian gravity. The core systems are a biological trickle filter for processing urine into a fertilizer solution via nitrification and Euglena gracilis, a photosynthetic protist which is able to produce oxygen and biomass while protecting the whole system against high ammonia concentrations.

GRAIN V2.0 (Influence of altered gravity on immune responses demonstrated with neutrophil migration performance) Migration and activation of immune cells in altered gravity

GRAIN V2.0 (Influence of altered gravity on immune responses demonstrated with neutrophil migration performance) Migration and activation of immune cells in altered gravity

The Effects of Clinorotation on the Host Plant, Medicago truncatula, and Its Microbial Symbionts

Understanding the outcome of the plant-microbe symbiosis in altered gravity is vital to developing life support systems for long-distance space travel and colonization of other planets. Thus, the aim of this research was to understand mutualistic relationships between plants and endophytic microbes under the influence of altered gravity. This project utilized the model tripartite relationship among Medicago truncatula ¬– Sinorhizobium meliloti – Rhizophagus irregularis. Plants were inoculated with rhizobial bacteria (S. meliloti), arbuscular mycorrhizal fungi (R. irregularis), or both microbes, and placed on a rotating clinostat. Vertical and horizontal static controls were also performed. Clinorotation significantly reduced M. truncatula dry mass and fresh mass compared to the static controls. The addition of rhizobia treatments under clinorotation also altered total root length and root-to-shoot fresh mass ratio. Nodule size decreased under rhizobia + clinorotation treatment, and nodule density was significantly decreased compared to the vertical treatment. However, inoculation with arbuscular mycorrhizal fungi was shown to increase biomass accumulation and nodule size. Thus, clinorotation significantly affected M. truncatula and its symbiotic relationships with S. meliloti and R. irregularis. In the long term, the results observed in this clinostat study on the changes of plant-microbe mutualism need to be investigated in spaceflight experiments. Thus, careful consideration of the symbiotic microbes of plants should be included in the design of bioregenerative life support systems needed for space travel.

Clinorotation impacts root apex respiration and the ultrostructure of mitochondria.

Mitochondrial respiration in plants provides energy for biosynthesis, and its balance with photosynthesis determines the rate of plant biomass accumulation. However, there are very limited data on the influence of altered gravity on the functional status of plant mitochondria. In the given paper, we presented the results of our investigations of root respiration, the mitochondrion ultrastructure, and AOX expression of pea 1-, 3- and 5-day old seedlings grown under slow horizontal clinorotation by using an inhibitor analysis, electron microscopy, and quantitative real-time RT-PCR. It was in the first time shown that enhancement of the respiration rate in root apices of pea etiolated seedlings at the 5th day of clinorotation does not connected with increasing of both alternative oxidize capacity and AOX expression. We assumed this phenomenon is provided by more intensive oxidation of respiratory substrates. At the structural level, mitochondria in cells of the distal elongation zone were the most sensitive to clinorotation that confirms the special physiological status of this zone. The performed investigation revealed an enough resistance of plant mitochondria to the influence of altered gravity that, on our opinion, is one of components providing plant adaptation to microgravity in space flight.

Role of cyclic GMP signaling in the melanocyte response to hypergravity

AbstractThe human skin acts as a first barrier of defense to protect the internal organs from various chemical and physical environmental stress factors like solar ultraviolet radiation (UV) and mechanical stimuli. Human melanocytes (located strategically in the basal layer of the skin epidermis) represent a crucial protective barrier against UV irradiation and oxidative stress by generating the radical‐scavenging pigment melanin. However, melanin is also known to act as a photosensitizer that generates active oxygen species upon UV irradiation, which may initiate pigmentary disorders like vitiligo due to loss of melanocytes as well as oncogenic melanocyte transformation. Melanocytes may further act as a protective immune barrier at the dermo‐epidermal junction and thus participate in immune surveillance. For melanocytes it is known that the second messenger cyclic guanosine‐3′,5′‐monophosphate (cGMP) plays a key role in UVB‐induced melanogenesis involving nitric oxide (NO) signaling. Moreover, cGMP is involved in NO‐induced perturbation of melanocyte‐extracellular matrix interactions that may lead to loss of melanocytes and support melanoma metastasis. In the frame of the current space exploration, investigations on the influence of altered gravity on melanocyte physiology are of special interest. As cGMP appears to play an important signaling role in melanocyte physiology, a brief overview is presented on the role of the guanylyl cyclase‐cGMP signaling, with a focus on the melanocyte response to hypergravity. An estimation of the gravity impact on melanocyte function may be of importance to asses the risk of astronauts to develop pigmentary disorders, particularly melanoma and other relevant skin cancers, during long‐term spaceflights.

Influence of altered gravity on intrachromosomal homologous recombination in mammalian cells

We isolated mouse Ltk- cells stably transfected with a DNA recombination substrate containing two defective herpes simplex virus thymidine kinase (tk) genes. Cells in which an intrachromosomal recombination event occured between the tk genes were recovered by selecting for tk+ clones. Cells were cultured either under standard 1g conditions or cultured for 4 days under conditions of hypergravity (4g or 10g) at the NASA Ames Research Center (ARC) (Palo Alto, CA) prior to fluctuation analysis. To do these experiments, cells were shipped back and forth between our lab in South Carolina and ARC. Two groups of 1g control cells were used. One group was shipped to ARC and grown at 1g in the same NASA facility housing the equipment used for the hypergravity cultures, while a second group of cells was maintained at 1g in our lab in South Carolina. Our results obtained with two cell lines indicate that growth of cells at 4g or 10g has no significant effect on recombination. The rate of recombination for cells maintained under all conditions was approximately 1 x 10 −6 (events per generation), with cells shipped back and forth displaying perhaps slightly elevated rates compared with cells that remained in South Carolina. Recombination events were classified as either gene conversions or popouts (crossovers). We observed no significant differences in the spectrum of events recovered from cells grown under all conditions. Preliminary experiments using a clinostat to simulate microgravity reveal no significant effect of microgravity on recombination rate. We will further investigate the influence of microgravity on the nature of chromosomal recombination events as well as the influence of altered gravity on double-strand break-induced recombination in mammalian cells. This work was supported by NASA grant NCC 2-1374.

Calcium signaling in plant cells in altered gravity

Changes in the intracellular Ca 2+ concentration in altered gravity (microgravity and clinostating) evidence that Ca 2+ signaling can play a fundamental role in biological effects of microgravity. Calcium as a second messenger is known to play a crucial role in stimulus - response coupling for many plant cellular signaling pathways. Its messenger functions are realized by transient changes in the cytosolic ion concentration induced by a variety of internal and external stimuli such as light, hormones, temperature, anoxia, salinity, and gravity. Although the first data on the changes in the calcium balance in plant cells under the influence of altered gravity have appeared in 80 th, a review highlighting the performed research and the possible significance of such Ca 2+ changes in the structural and metabolic rearrangements of plant cells in altered gravity is still lacking. In this paper, an attempt was made to summarize the available experimental results and to consider some hypotheses in this field of research. It is proposed to distinguish between cell gravisensing and cell graviperception; the former is related to cell structure and metabolism stability in the gravitational field and their changes in microgravity (cells not specialized to gravity perception), the latter is related to active use of a gravitational stimulus by cells presumebly specialized to gravity perception for realization of normal space orientation, growth, and vital activity (gravitropism, gravitaxis) in plants. The main experimental data concerning both redistribution of free Ca 2+ ions in plant cell organelles and the cell wall, and an increase in the intracellular Ca 2+ concentration under the influence of altered gravity are presented. Based on the gravitational decompensation hypothesis, the consequence of events occurring in gravisensing cells not specialized to gravity perception under altered gravity are considered in the following order: changes in the cytoplasmic membrane surface tension → alterations in the physicochemical properties of the membrane → changes in membrane permeability, ion transport, membrane-bound enzyme activity, etc. → metabolism rearrangements → physiological responses. An analysis of data available on biological effects of altered gravity at the cellular level allows one to conclude that microgravity environment appears to affect cytoskeleton, carbohydrate and lipid metabolism, cell wall biogenesis via changes in enzyme activity and protein expression, with involvement of regulatory Ca 2+ messenger system. Changes in Ca 2+ influx/efflux and possible pathways of Ca 2+ signaling in plant cell biochemical regulation in altered gravity are discussed.

Electrofusion of tobacco protoplasts in space

Electrofusion of evacuolated (N. Tabacum L. cvs. Gexin no1) and vacuolated (N. Rustic) tobacco mesophyll protoplasts was performed on the Chinese spacecraft (Shenzhou No. 4, from 30th Dec. 2002 to 6th Jan. 2003). The results showed that the frequency of bi-nucleated and multinucleated protoplasts was significantly increased under microgravity. Compared with the control samples incubated on the ground, the viability of protoplasts incubated in space was much higher. In addition, the influence of altered gravity on carbohydrates was also observed. These results confirmed the effect of microgravitation on electrofusion of plant cell protoplasts.

On the influence of altered gravity on the growth of fish inner ear otoliths

Inner ear stones (otoliths) of developing cichlid fish ( Oreochromis mossambicus) were marked with the calcium tracer alizarin-complexone (AC) at 1g-earth gravity before and after a long-term (20 days) stay of the animals at moderate hypergravity conditions (3g; centrifuge). AC deposition at the otoliths resulted in two fluorescence bands, which enclosed the area grown during exposure to altered gravity. This area was measured with regard to size and asymmetry (size difference between the left and the right stones). Both utricular and saccular otoliths (lapilli and sagittae, respectively) were significantly smaller after hyper-g exposure as compared to parallely raised 1g-control specimens. The asymmetry concerning the lapilli was pronouncedly decreased in comparison to the 1g-controls. These findings suggest, that the growth and the development of bilateral asymmetry of otoliths is guided by the environmental gravity vector. Some of the hyper-g animals revealed a kinetotic behaviour at the transfer from hyper-g to normal 1g-earth gravity conditions, which was qualitatively similar to the behaviour observed in previous experiments at the transfer from 1g to microgravity in the course of parabolic aircraft flights. The lapillar asymmetry of kinetotic samples was found to be significantly higher than that of normally behaving experimental specimens. This result supports an earlier theoretical concept, according to which human static space sickness might be based on asymmetric utricular otoliths.

Influence of altered gravity on the cytochemical localization of cytochrome oxidase activity in central and peripheral gravisensory systems in developing cichlid fish

Cichlid fish larvae were reared from hatching to active free swimming under different gravity conditions: natural environment, increased acceleration in a centrifuge, simulated weightlessness in a clinostat and near weightlessness during space flight. Cytochrome oxidase activity was analyzed semiquantitatively on the ultrastructural level as a marker of regional neuronal activity in a primary, vestibular brainstem nucleus and in gravity receptive epithelia in the inner ear. Our results show, that gravity seems to be positively correlated with cytochrome oxidase activity in the magnocellular nucleus of developing fish brain. In the inner ear the energy metabolism is decreased under microgravity concerning utricle but not saccule. Hypergravity has no effect on cytochrome oxidase activity in sensory inner ear epithelia.

Influence of altered gravity on brain cellular energy and plasma membrane metabolism of developing lower aquatic vertebrates

Biochemical analyses of the brain of cichlid fish larvae , exposed for 7 days to increased acceleration of 3g (hyper-g), revealed an increase in energy availability (succinate dehydrogenase activity, SDH), and in mitochondrial energy transformation (creatine kinase, Mi a-CK), but no changes in an energy consumptive process (high-affinity Ca 2+-ATPase). Brain glucose-6-phosphate dehydrogenase (G6PDH) of developing fish was previously found to be increased after hyper-g exposure. Three respectively 5 hours thereafter dramatic fluctuations in enzyme activity were registered. Analysing the cytosolic or plasma membrane-located brain creatine kinase (BB-CK) of clawed toad larvae after long-term hyper-g exposure a significant increase in enzyme activity was demonstrated, whereas the activity of a high affinity Ca 2+-ATPase remained unaffected.

Development and altered gravity dependent changes in glucose-6-phosphate dehydrogenase activity in the brain of the cichlid fish Oreochromis Mossambicus

Glucose-6-phosphate dehydrogenase activity was studied in the brain of the cichlid fish Oreochromis mossambicus during early ontogenetic development. In general a slight but continuous decrease in enzyme activity was found (9.5 ± 0.5 nmol substrate cleaved per mg protein and per min at developmental stage 13 {=1 day post hatch at 28°C} to a value of 7.9±0.6 in adult brain). In order to investigate the possible influence of altered gravity during early ontogenetic brain development, fish larvae were exposed to an increased acceleration of three times earth gravity (3 g ) or to functional weightlessness in a fast-rotating clinostat for 7 days. A significant increase of brain G6PDH activity of approx. 15% was found after exposure to hyper gravity, whereas a significant decrease of the enzyme activity, ∼ 10%, was detected following functional weightlessness in respect to the corresponding 1 g controls. Analyses concerning the regain of normal control enzyme activity of the larvae revealed dramatic fluctuations within the first 5 h after exposure to an increased acceleration of 3 g . Thereafter, between day 1 and day 3 after exposure, brain glucose-6-phosphate dehydrogenase decreased slowly. At day 3 after exposure no further differences of the hyper- g larvae compared to the controls were found. Only slight changes in total brain glucose-6-phosphate dehydrogenase activity occur during ontogenetic development of cichlid fish. This suggests that a more or less constant enzyme activity is important during brain development, but is reacting very sensitively to changes in the environmental factor gravity.