Spaceflight Experiments Research Articles

Combined Environment Simulator for Low-Dose-Rate Radiation and Partial Gravity of Moon and Mars.

Deep space exploration by humans has become more realistic, with planned returns to the Moon, travel to Mars, and beyond. Space radiation with a low dose rate would be a constant risk for space travelers. The combined effects of space radiation and partial gravity such as on the Moon and Mars are unknown. The difficulty for such research is that there are no good simulating systems on the ground to investigate these combined effects. To address this knowledge gap, we developed the Simulator of the environments on the Moon and Mars with Neutron irradiation and Gravity change (SwiNG) for in vitro experiments using disposable closed cell culture chambers. The device simulates partial gravity using a centrifuge in a three-dimensional clinostat. Six samples are exposed at once to neutrons at a low dose rate (1 mGy/day) using Californium-252 in the center of the centrifuge. The system is compact including two SwiNG devices in the incubator, one with and one without radiation source, with a cooling function. This simulator is highly convenient for ground-based biological experiments because of limited access to spaceflight experiments. SwiNG can contribute significantly to research on the combined effects of space radiation and partial gravity.

The Importance of Earth Reference Controls in Spaceflight -Omics Research: Characterization of Nucleolin Mutants from the Seedling Growth Experiments.

SummaryUnderstanding plant adaptive responses to the space environment is a requisite for enabling space farming. Spaceflight produces deleterious effects on plant cells, particularly affecting ribosome biogenesis, a complex stress-sensitive process coordinated with cell division and differentiation, known to be activated by red light. Here, in a series of ground studies, we have used mutants from the two Arabidopsis nucleolin genes (NUC1 and NUC2, nucleolar regulators of ribosome biogenesis) to better understand their role in adaptive response mechanisms to stress on Earth. Thus, we show that nucleolin stress-related gene NUC2 can compensate for the environmental stress provided by darkness in nuc1 plants, whereas nuc2 plants are not able to provide a complete response to red light. These ground control findings, as part of the ESA/NASA Seedling Growth spaceflight experiments, will determine the basis for the identification of genetic backgrounds enabling an adaptive advantage for plants in future space experiments.

The FixBox: Hardware to Provide on-Orbit Fixation Capabilities to the EMCS on the ISS

Plant biology is an important area for the future of space exploration, but biological spaceflight experiments have been always constrained by the hardware capabilities. The European Modular Cultivation System (EMCS) unit was an incubator for small organisms, such as Arabidopsis thaliana, built by the European Space Agency (ESA) and was decommissioned in 2018. Here, we describe the FixBox system as add-on hardware to provide fixation capabilities to the plant growth cassettes, which, initially, were not designed to be used for that purpose. Tests were performed to ensure the successful use of this device in the EMCS facility. We also evaluate the required adaptations to the hardware, e.g., to guarantee that the reduced fluid motion in microgravity does not cause any bubbles that could impair the quality of fixation. Arabidopsis thaliana seedlings grown during spaceflight were fixed in the FixBox either in glutaraldehyde or formaldehyde. Electron microscopical images and confocal microscopy immunofluorescent localizations showed an excellent preservation of both cell ultrastructure and antigen conformation. Thus, it is possible to modify existing hardware to comply with the scientific requirements to augment the existing capabilities on board the ISS. In addition, it is also possible to reuse culture chambers from predesigned experimental containers into new modular subunits as FixBox. Similarly, we can design new hardware compatible with a novel cultivation chamber on board, such as is available in BIOLAB, to be used later with FixBox. Lessons learned for future space plant biology researchers include how to manage the number of hardware requirements and constraints on how to preserve the biological samples.

RNAseq Analysis of Rodent Spaceflight Experiments is Confounded by Sample Collection Techniques

To understand the physiological changes that occur in response to spaceflight, mice are transported to the International Space Station (ISS) and housed for variable periods of time before euthanasia on-orbit or return to Earth. Sample collection under such difficult conditions introduces confounding factors that need to be identified and addressed. We found large changes in the transcriptome of mouse tissues dissected and preserved on-orbit compared to tissues from mice euthanized on-orbit, preserved, and dissected after return to Earth. Changes due to preservation method eclipsed those between flight and ground samples making it difficult to identify spaceflight-specific changes. Follow-on experiments to interrogate the roles of euthanasia methods, tissue and carcass preservation protocols, and library preparation methods suggested that differences due to preservation protocols are exacerbated when coupled with polyA selection. This has important implications for the interpretation of existing datasets and the design of future experiments.

The Importance of Earth Reference Controls in Spaceflight – Omics Experiments: Dissecting Transcriptional Responses of Nucleolin Mutants to Red Light Stimulation

Understanding plant adaptive responses to the space environment is a requisite for enabling space farming. Spaceflight produces deleterious effects on plant cells, particularly affecting ribosome biogenesis, a complex stress-sensitive process coordinated with cell division and differentiation, known to be activated by red light. Here, we have used mutants from the two nucleolin genes in Arabidopsis (NUC1 and NUC2), encoding the main regulator of the ribosome biogenesis in the nucleolus, in order to better understand their role in adaptive response mechanisms to stress. Thus, we show that nucleolin stress-related gene NUC2 can compensate the environmental stress provided by darkness in nuc1 plants, while nuc2 plants are not able to provide a complete response to red light. These ground control findings, as part of the ESA/NASA Seedling Growth spaceflight experiments will determine the basis for the identification of a genetic background enabling an adaptive advantage for plants in future space experiments.

Fitness of Outer Membrane Vesicles From Komagataeibacter intermedius Is Altered Under the Impact of Simulated Mars-like Stressors Outside the International Space Station.

Outer membrane vesicles (OMVs), produced by nonpathogenic Gram-negative bacteria, have potentially useful biotechnological applications in extraterrestrial extreme environments. However, their biological effects under the impact of various stressors have to be elucidated for safety reasons. In the spaceflight experiment, model biofilm kombucha microbial community (KMC) samples, in which Komagataeibacter intermedius was a dominant community-member, were exposed under simulated Martian factors (i.e., pressure, atmosphere, and UV-illumination) outside the International Space Station (ISS) for 1.5 years. In this study, we have determined that OMVs from post-flight K. intermedius displayed changes in membrane composition, depending on the location of the samples and some other factors. Membrane lipids such as sterols, fatty acids (FAs), and phospholipids (PLs) were modulated under the Mars-like stressors, and saturated FAs, as well as both short-chain saturated and trans FAs, appeared in the membranes of OMVs shed by both post-UV-illuminated and “dark” bacteria. The relative content of zwitterionic and anionic PLs changed, producing a change in surface properties of outer membranes, thereby resulting in a loss of interaction capability with polynucleotides. The changed composition of membranes promoted a bigger OMV size, which correlated with changes of OMV fitness. Biochemical characterization of the membrane-associated enzymes revealed an increase in their activity (DNAse, dehydrogenase) compared to wild type. Other functional membrane-associated capabilities of OMVs (e.g., proton accumulation, interaction with linear DNA, or synaptosomes) were also altered after exposure to the spaceflight stressors. Despite alterations in membranes, vesicles did not acquire endotoxicity, cytotoxicity, and neurotoxicity. Altogether, our results show that OMVs, originating from rationally selected nonpathogenic Gram-negative bacteria, can be considered as candidates in the design of postbiotics or edible mucosal vaccines for in situ production in extreme environment. Furthermore, these OMVs could also be used as promising delivery vectors for applications in Astromedicine.

Test of Arabidopsis Space Transcriptome: A Discovery Environment to Explore Multiple Plant Biology Spaceflight Experiments.

Recent advances in the routine access to space along with increasing opportunities to perform plant growth experiments on board the International Space Station have led to an ever-increasing body of transcriptomic, proteomic, and epigenomic data from plants experiencing spaceflight. These datasets hold great promise to help understand how plant biology reacts to this unique environment. However, analyses that mine across such expanses of data are often complex to implement, being impeded by the sheer number of potential comparisons that are possible. Complexities in how the output of these multiple parallel analyses can be presented to the researcher in an accessible and intuitive form provides further barriers to such research. Recent developments in computational systems biology have led to rapid advances in interactive data visualization environments designed to perform just such tasks. However, to date none of these tools have been tailored to the analysis of the broad-ranging plant biology spaceflight data. We have therefore developed the Test Of Arabidopsis Space Transcriptome (TOAST) database (https://astrobiology.botany.wisc.edu/astrobotany-toast) to address this gap in our capabilities. TOAST is a relational database that uses the Qlik database management software to link plant biology, spaceflight-related omics datasets, and their associated metadata. This environment helps visualize relationships across multiple levels of experiments in an easy to use gene-centric platform. TOAST draws on data from The US National Aeronautics and Space Administration’s (NASA’s) GeneLab and other data repositories and also connects results to a suite of web-based analytical tools to facilitate further investigation of responses to spaceflight and related stresses. The TOAST graphical user interface allows for quick comparisons between plant spaceflight experiments using real-time, gene-specific queries, or by using functional gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway, or other filtering systems to explore genetic networks of interest. Testing of the database shows that TOAST confirms patterns of gene expression already highlighted in the literature, such as revealing the modulation of oxidative stress-related responses across multiple plant spaceflight experiments. However, this data exploration environment can also drive new insights into patterns of spaceflight responsive gene expression. For example, TOAST analyses highlight changes to mitochondrial function as likely shared responses in many plant spaceflight experiments.

NASA GeneLab Platform Utilized for Biological Response to Space Radiation in Animal Models.

Background: Ionizing radiation from galactic cosmic rays (GCR) is one of the major risk factors that will impact the health of astronauts on extended missions outside the protective effects of the Earth’s magnetic field. The NASA GeneLab project has detailed information on radiation exposure using animal models with curated dosimetry information for spaceflight experiments. Methods: We analyzed multiple GeneLab omics datasets associated with both ground-based and spaceflight radiation studies that included in vivo and in vitro approaches. A range of ions from protons to iron particles with doses from 0.1 to 1.0 Gy for ground studies, as well as samples flown in low Earth orbit (LEO) with total doses of 1.0 mGy to 30 mGy, were utilized. Results: From this analysis, we were able to identify distinct biological signatures associating specific ions with specific biological responses due to radiation exposure in space. For example, we discovered changes in mitochondrial function, ribosomal assembly, and immune pathways as a function of dose. Conclusions: We provided a summary of how the GeneLab’s rich database of omics experiments with animal models can be used to generate novel hypotheses to better understand human health risks from GCR exposures.

Effects of microgravity on living organisms revealed from space flight experiments using the nematode C. elegans.

Effects of microgravity on living organisms revealed from space flight experiments using the nematode <i>C. elegans</i>.

Comparative Transcriptomics Identifies Altered Neuronal and Metabolic Function as Common Adaptations to Microgravity and Hypergravity in&amp;nbsp; &lt;i&gt;Caenorhabditis elegans&lt;/i&gt;

Human exploration of deep space is firmly within reach, but health decline during extended spaceflight remains a key challenge. To provide a novel mechanistic foundation for future targeted therapeutics, we employed the worm Caenorhabditis elegans to contrast hypergravity versus microgravity and identified reproducible molecular signatures. Using NASA’s GeneLab Repository, we performed comparative transcriptomic analysis of C. elegans responses to 5xg, 10xg and 15xg hypergravity, and to two spaceflight experiments (ICE-FIRST and CERISE). We found that: (i) progressive hypergravitational load concomitantly increases the extent of differential gene regulation; (ii) subtle changes in 1032 genes are reproducibly observed during spaceflight-induced microgravity, and; (iii) 189 genes display comparable unidirectional expression changes during both hypergravity and microgravity. Within genes concordantly regulated by altered gravity per se, we identify several candidate targets (network hubs and putative transcriptional regulators) with terrestrial roles in neuronal function and/or cellular metabolism, which are linked to regulation by daf-16/FOXO signalling. Whilst comprising a smaller subset (n = 46 genes), genes displaying inverted expression profiles during hyper- versus microgravity were involved in a metabolic reprogramming response, also under putative control of daf-16/FOXO. Thus, neuronally-mediated changes in FOXO-mediated metabolic reprogramming might represent a promising therapeutic avenue against negative health effects of altered gravity.

Stem Cell Culture Under Simulated Microgravity.

Challenging environment of space causes several pivotal alterations in living systems, especially due to microgravity. The possibility of simulating microgravity by ground-based systems provides research opportunities that may lead to the understanding of in vitro biological effects of microgravity by eliminating the challenges inherent to spaceflight experiments. Stem cells are one of the most prominent cell types, due to their self-renewal and differentiation capabilities. Research on stem cells under simulated microgravity has generated many important findings, enlightening the impact of microgravity on molecular and cellular processes of stem cells with varying potencies. Simulation techniques including clinostat, random positioning machine, rotating wall vessel and magnetic levitation-based systems have improved our knowledge on the effects of microgravity on morphology, migration, proliferation and differentiation of stem cells. Clarification of the mechanisms underlying such changes offers exciting potential for various applications such as identification of putative therapeutic targets to modulate stem cell function and stem cell based regenerative medicine.

Comparison of Microgravity Analogs to Spaceflight in Studies of Plant Growth and Development.

Life on Earth has evolved under the influence of gravity. This force has played an important role in shaping development and morphology from the molecular level to the whole organism. Although aquatic life experiences reduced gravity effects, land plants have evolved under a 1-g environment. Understanding gravitational effects requires changing the magnitude of this force. One method of eliminating gravity'’s influence is to enter into a free-fall orbit around the planet, thereby achieving a balance between centripetal force of gravity and the centrifugal force of the moving object. This balance is often mistakenly referred to as microgravity, but is best described as weightlessness. In addition to actually compensating gravity, instruments such as clinostats, random-positioning machines (RPM), and magnetic levitation devices have been used to eliminate effects of constant gravity on plant growth and development. However, these platforms do not reduce gravity but constantly change its direction. Despite these fundamental differences, there are few studies that have investigated the comparability between these platforms and weightlessness. Here, we provide a review of the strengths and weaknesses of these analogs for the study of plant growth and development compared to spaceflight experiments. We also consider reduced or partial gravity effects via spaceflight and analog methods. While these analogs are useful, the fidelity of the results relative to spaceflight depends on biological parameters and environmental conditions that cannot be simulated in ground-based studies.

EcAMSat spaceflight measurements of the role of σs in antibiotic resistance of stationary phase Escherichia coli in microgravity

We report the results of the EcAMSat (Escherichia coli Antimicrobial Satellite) autonomous space flight experiment, investigating the role of σs in the development of antibiotic resistance in uropathogenic E. coli (UPEC) in microgravity (µ-g). The presence of σs, encoded by the rpoS gene, has been shown to increase antibiotic resistance in Earth gravity, but it was unknown if this effect occurs in µ-g. Two strains, wildtype (WT) UPEC and its isogenic ΔrpoS mutant, were grown to stationary phase aboard EcAMSat, an 11-kg small satellite, and in a parallel ground-based control experiment; cell growth rates for the two strains were found to be unaltered by µ-g. After starvation for over 24 h, stationary-phase cells were incubated with three doses of gentamicin (Gm), a common treatment for urinary tract infections (which have been reported in astronauts). Cellular metabolic activity was measured optically using the redox-based indicator alamarBlue (aB): both strains exhibited slower metabolism in µ-g, consistent with results from previous smallsat missions. The results also showed that µ-g did not enhance UPEC resistance to Gm; in fact, both strains were more susceptible to Gm in µ-g. It was also found, via a second ground-control experiment, that multi-week storage in the payload hardware stressed the cells, potentially obscuring small differential effects of the antibiotic between WT and mutant and/or between µ-g and ground. Overall, results showed that the ∆rpoS mutant was 34–37% less metabolically active than the WT for four different sets of conditions: ground without Gm, ground with Gm; µ-g without Gm, µ-g with Gm. We conclude therefore that the rpoS gene and its downstream products are important therapeutic targets for treating bacterial infections in space, much as they are on the ground.

β-glucosidase PYK 10 gene expression in Arabidopsis thaliana (L.) Heynh. seedlings under clinorotation and X-radiation

Aim. Among plants used in spaceflight experiments, species of family Brassicaceae are considered as the most resistant to radiation exposure. It is supposed that ER-bodies, which are derivative of granular endoplasmic reticulum and selectively accumulate an enzyme β-glucosidase, may be responsible for this resistance. We firstly investigated expression of β-glucosidase PYK10 gene in A. thaliana seedlings under slow horizontal clinorotation and Х-radiation of doses 0.5 Gy, 1 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy, 10 Gy, and 12 Gy. Methods. Seedlings were grown on agar nutrient medium. PYK 10 expression was determined using a method of real-time PCR. Results. Significant enhancement of PYK 10 expression and increasing a number of ER-bodies in A. thaliana seedlings under the influence of clinorotation and X-radiation in comparison with control was established. An increase in the number of ER-bodies was due to PYK 10 high expression and β-glucosidase synthesis without a rise of enzyme activity under clinorotation, while β-glucosidase activity increased under X-radiation. Plant responses to X-radiation became adaptive during 10 days after radiation, in which β-glucosidase plays a crucial role. Conclusions. Increased PYK 10 expression in A. thaliana seedlings under clinorotation and X-radiation is a part of the internal program of plant protection against the action of environmental factors. ER-bodies containing β-glucosidase may be one of the main components of the plant protection system from the influence of clinorotation and X-radiation.&#x0D; Keywords: Arabidopsis thaliana (L.) Heynh., ER-bodies, β-glucosidase, gene expression, clinorotation, Х-radiation.

Reptiles in Space Missions: Results and Perspectives.

Reptiles are a rare model object for space research. However, some reptile species demonstrate effective adaptation to spaceflight conditions. The main scope of this review is a comparative analysis of reptile experimental exposure in weightlessness, demonstrating the advantages and shortcomings of this model. The description of the known reptile experiments using turtles and geckos in the space and parabolic flight experiments is provided. Behavior, skeletal bones (morphology, histology, and X-ray microtomography), internal organs, and the nervous system (morphology, histology, and immunohistochemistry) are studied in the spaceflight experiments to date, while molecular and physiological results are restricted. Therefore, the results are discussed in the scope of molecular data collected from mammalian (mainly rodents) specimens and cell cultures in the parabolic and orbital flights and simulated microgravity. The published data are compared with the results of the gecko model studies after the 12–44.5-day spaceflights with special reference to the unique peculiarities of the gecko model for the orbital experiments. The complex study of thick-toed geckos after three spaceflights, in which all geckos survived and demonstrated effective adaptation to spaceflight conditions, was performed. However, future investigations are needed to study molecular mechanisms of gecko adaptation in space.

Fungi and Mycotoxins in Space-A Review.

Fungi are not only present on Earth but colonize spacecraft and space stations as well. This review provides an extensive overview of the large and diverse group of fungal species that have been found in space, as well as those corresponding detection methods used and the existing and potential future prevention and control strategies. Many of the identified fungal species in space, such as Aspergillus flavus and Alternaria sp., are mycotoxigenic; thus, they are potential mycotoxin producers. This indicates that, although the fungal load in space stations tends to be non-alarming, the effects should not be underestimated, since the effect of the space environment on mycotoxin production should be sufficiently studied as well. However, research focused on mycotoxin production under conditions found on space stations is essentially nonexistent, since these kinds of spaceflight experiments are rare. Consequently, it is recommended that detection and monitoring systems for fungi and mycotoxins in space are at some point prioritized such that investigations into the impact of the space environment on mycotoxin production is addressed.

Spaceflight-induced alternative splicing during seedling development in Arabidopsis thaliana

Plants grown in spaceflight experience novel environmental signals, including those associated with microgravity and ionizing radiation. Spaceflight triggers a response involving transcriptional re-programming and altered cell morphology, though many aspects of this response remain uncharacterized. We analyzed the spaceflight-induced transcriptome with a focus on genes that undergo alternative splicing to examine differential splicing associated with spaceflight—an unstudied characteristic of the molecular response to spaceflight exposure. RNA sequence data obtained during the APEX03 spaceflight experiment that was collected from two Arabidopsis thaliana ecotypes at two seedling stages grown onboard the International Space Station, or as ground controls at Kennedy Space Center, were re-examined to detect alternative splicing differences induced by spaceflight. Presence/absence variation analysis was used to identify putative expression-level differences in alternatively spliced isoforms between spaceflight and ground controls and was followed by analysis of significant differential alternative splicing. This study provides the first evidence of a role for alternative splicing in the molecular processes of physiological adaptation to the spaceflight environment.

Human cartilage-bone-synovium microphysiological system to study ptoa pathogenesis and treatment on earth and in space

Purpose: Acute joint injuries from sports, exercise or accident-related trauma often progress to post-traumatic Osteoarthritis (PTOA), comprising ∼12% of all OA cases. Such joint injuries can cause mechanical damage to cartilage combined with an inflammatory response associated with the synovial lining of the joint capsule. Together, these events lead to cartilage and subchondral bone pathologies including cell death, tissue degradation, neoangiogenesis, osteophyte and cyst formation and synovial fibrosis. Astronauts on International Space Station-National Laboratory (ISS-NL) sustain a higher rate of exercise-related injuries, including those compromising joints, during their training and mission period. Acknowledging the urgent need to identify disease-modifying therapeutics to ameliorate degenerative evolution of OA/PTOA, we carried out this study to (1) simulate aspects of acute joint injury biology on earth and in space using a human Cartilage-Bone-Synovium coculture model (CBS-MPS), (2) to investigate the potential of dexamethasone (Dex) in reducing cell death and ECM degradation, and (3) to utilize a Multi-Use Variable-g Platform (MVP) to study PTOA-related pathogenesis and management on the ISS. Methods: Osteochondral plugs (3.5mm diameter and 5mm thick, including 1.5-2mm thick cartilage) harvested from condyles and trochlear grooves of cadaveric human distal femurs (n=8 knees, Collins grade 1/2, 64-82 yr) were co-cultured with 4-5mm diameter synovium explants harvested from synovial joint capsule of the same knees. All procedures were approved by the Rush University Medical Center Institutional Review Board and the Committee on the use of Humans as Experimental Subjects at MIT. PTOA-like mechanical trauma was simulated by subjecting the cartilage surface of the osteochondral plugs to a single injurious unconfined compression of 60% strain rate to a peak stress of 5MPa using an incubator-housed loading apparatus. The study design included the following groups: (1) Mechanical injury (INJ) - injured osteochondral plugs were cultured in presence of pro-inflammatory cytokines (including TNF-α, IL-6 and IL-8) that were released by synovial explants and quantified by multiplex-readout in situ, (2) Treatment group (INJ + DEX): 100nM Dex was added to the cocultures of injured osteochondral plugs and synovial tissues immediately after injury. A preliminary science validation test was performed to identify a suitable mechanism to adapt CBS cocultures to the custom experiment module and the MVP facility. Engineering validation testing was then carried out to build logistical protocols for the spaceflight including transport of cultures and simulation of tasks preceding launch operations. Results: The levels of pro-inflammatory cytokines such as IL-6, IL-8 and TNF-α were upregulated in CBS cocultures. The combination of mechanical injury and increased release of inflammatory cytokines from synovial tissues caused extensive cell death and biochemical changes in both bone and cartilage. In the INJ group, cartilage tissue showed widespread cell death [Fig1 a], and subchondral bone showed increased cell death as well, indicated by numerous empty lacunae in the matrix. Biochemical analysis showed aggravated release of matrix component (including GAGs) into the medium, associated with cartilage degradation [Fig 1c]. Addition of Dex significantly reduced the injury-induced cell death [Fig 1b] and GAG loss by week 2 [Fig 1c]. For spaceflight preparation, tissue cards [Fig 1d] were optimized for long-term holding and maintenance of CBS co-cultures, which were placed into custom culture chambers [Fig 1e]. Multiple tests using this instrumentation were used to guide the design and operation of automated MVP facility [Fig 1f]. Investigation of disease biology and acute injury management is currently being tested in preparation for eventual spaceflight experiments in microgravity aboard ISS-NL. Conclusions: By providing a platform to study cartilage, bone and synovium together, our CBS MPS can potentially enable a more physiologically relevant understanding of tissue interactions that may lead to PTOA pathogenesis. This system can also be used to test the efficacy of therapeutics. In Space, this MPS will be used to explore the role of therapeutic agents to ameliorate cartilage degradation in microgravity to support astronaut health during long space missions.

УЛЬТРАСТРУКТУРА ЕР-ТІЛЕЦЬ У СТАТОЦИТАХ І КЛІТИНАХ ДИСТАЛЬНОЇ ЗОНИ РОЗТЯГУ КОРЕНЕВИХ АПЕКСІВ ARABIDOPSIS THALIANA (L.) HEYNH. ПІД ДІЄЮ Х-ОПРОМІНЕННЯ

Among plants used in spaceflight experiments, species of family Brassicaceaeare considered as the most resistant to radiation exposure. It is supposed that ER-bodies, which are derivative of granular endoplasmic reticulum and selectively accumulate an enzyme β-glucosidase, may be responsible for this resistance. The aim of the study was to investigate the ultrastructure and topography of ER-bodies in statocytes and cells of the distal elongation zone in root apices of A. thaliana seedlings in the control and under X-radiation. Methods. Seedlings grown on agar nutrient medium were treated with X-rays of doses 0.5 Gy, 1 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy, 10 Gy, and 12 Gy on the unit RUM-17 (dose rate 0.43 cGr/s). The root apices were fixed with a mixture of epoxide resins. Ultra-thin longitudinal sections were investigated with a transmission electron microscope JEM-1230 EX. Results. It was shown the similarity in the root apex cell ultrastructure in control and under X-radiation. At the same time there were some differences in the ultrustructure of statocytes and cells of the distal elongation zone under X-radiation. An increase in the number of profiles of granular endoplasmic reticulum and the total area of ER-bodies per cell in two hours and ten days after X-radiation more than twice in comparison to control was established. It was revealed the variability of ER-bodies in shape and size depending on the dose of X-rays. The nature of such alterations in the cell may indicate certain changes in metabolism, carried out within the range of cell physiological responses. Conclusions. For the first time, the influence of X-radiation on dynamics of the formation of ER-bodies, which are derivative of granular endoplasmic reticulum, in statocytes and cells of the distal elongation zone in root apices of A. thaliana seedlings has been studied. The increased area of ER-bodies, which contain β-glucosidase (PYK 10), is considered as an adaptive cell response to ionizing radiation.

Preparation of a Spaceflight Experiment to Study Tropisms in Arabidopsis Seedlings on the International Space Station.

Utilization of orbiting spacecraft allows for studying biological processes in conditions of microgravity. Centrifuges on board these platforms also allow for the creation of partial gravity vectors (to simulate the Moon or Mars levels of gravity) as well as onboard 1-g controls for the space experiments. Thus, the mechanisms of gravity and light perception in plants can be analyzed in a unique environment which can give insights into fundamental processes in biology. Here, we describe the methods for preparation of a plant biology experiment with seedlings of Arabidopsis thaliana utilizing the European Modular Cultivation System (EMCS) on the International Space Station (ISS). The procedures outlined in this paper have been successfully used in several of our recent spaceflight experiments, which have given unique insights into the basic mechanisms of tropisms.