Ophthalmic changes have occurred in a subset of astronauts on International Space Station missions. Visual deterioration is considered the greatest human health risk of spaceflight. Affected astronauts exhibit higher concentrations of 1-carbon metabolites (e.g., homocysteine) before flight. We hypothesized that genetic variations in 1-carbon metabolism genes contribute to susceptibility to ophthalmic changes in astronauts. We investigated 5 polymorphisms in the methionine synthase reductase (MTRR), methylenetetrahydrofolate reductase (MTHFR), serine hydroxymethyltransferase (SHMT), and cystathionine beta-synthase (CBS) genes and their association with ophthalmic changes after flight in 49 astronauts. The number of G alleles of MTRR 66 and C alleles of SHMT1 1420 both contributed to the odds of visual disturbances. Preflight dehydroepiandrosterone was positively associated with cotton wool spots, and serum testosterone response during flight was associated with refractive change. Block regression showed that B-vitamin status and genetics were significant predictors of many of the ophthalmic outcomes that we observed. In one example, genetics trended toward improving (P = 0.10) and B-vitamin status significantly improved (P < 0.001) the predictive model for refractive change after flight. We document an association between MTRR 66 and SHMT1 1420 polymorphisms and spaceflight-induced vision changes. This line of research could lead to therapeutic options for both space travelers and terrestrial patients.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26316272
Evolution of Russian Microgravity Countermeasures
INTRODUCTION: Countermeasures to prevent or partially offset the negative physiologic changes that are caused by the effects of microgravity play an important role in supporting the performance of crewmembers in flight and their safe return to Earth. Research conducted in Russia on the orbital stations Salyut and Mir, as well as simulation experiments on the ground, have demonstrated that changes that occur during extended spaceflight in various physiologic systems can be prevented or significantly decreased by using countermeasures. Hardware and techniques used on the ISS have been substantially improved to reflect the experience of previous extended missions on Russian orbital stations. Countermeasures used during early ISS missions consisted of the U.S. treadmill (TVIS), cycle ergometer (capital VE, Cyrilliccapital BE, Cyrillic-3), a set of resistance bands, a postural muscle loading suit (Penguin-3), electrical stimulator (Tonus-3), compression thigh cuffs (Braslet-capital EM, Cyrillic), a lower body negative pressure (LBNP) suit (Chibis), a lower body g-loading suit (Kentavr), and water/salt supplements. These countermeasures are described in this article.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26630193
Transient gene and microRNA expression profile changes of confluent human fibroblast cells in spaceflight
Microgravity, or an altered gravity environment different from the 1 g of the Earth, has been shown to influence global gene expression patterns and protein levels in cultured cells. However, most of the reported studies that have been conducted in space or by using simulated microgravity on the ground have focused on the growth or differentiation of these cells. It has not been specifically addressed whether nonproliferating cultured cells will sense the presence of microgravity in space. In an experiment conducted onboard the International Space Station, confluent human fibroblast cells were fixed after being cultured in space for 3 and 14 d, respectively, to investigate changes in gene and microRNA (miRNA) expression profiles in these cells. Results of the experiment showed that on d 3, both the flown and ground cells were still proliferating slowly, as measured by the percentage of Ki-67(+) cells. Gene and miRNA expression data indicated activation of NF-kappaB and other growth-related pathways that involve hepatocyte growth factor and VEGF as well as the down-regulation of the Let-7 miRNA family. On d 14, when the cells were mostly nonproliferating, the gene and miRNA expression profile of the flight sample was indistinguishable from that of the ground sample. Comparison of gene and miRNA expressions in the d 3 samples, with respect to d 14, revealed that most of the changes observed on d 3 were related to cell growth for both the flown and ground cells. Analysis of cytoskeletal changes via immunohistochemistry staining of the cells with antibodies for alpha-tubulin and fibronectin showed no difference between the flown and ground samples. Taken together, our study suggests that in true nondividing human fibroblast cells in culture, microgravity experienced in space has little effect on gene and miRNA expression profiles.-Zhang, Y., Lu, T., Wong, M., Wang, X., Stodieck, L., Karouia, F., Story, M., Wu, H. Transient gene and microRNA expression profile changes of confluent human fibroblast cells in spaceflight.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26917741
Coactivator-Dependent Oscillation of Chromatin Accessibility Dictates Circadian Gene Amplitude via REV-ERB Loading
A central mechanism for controlling circadian gene amplitude remains elusive. We present evidence for a "facilitated repression (FR)" model that functions as an amplitude rheostat for circadian gene oscillation. We demonstrate that ROR and/or BMAL1 promote global chromatin decondensation during the activation phase of the circadian cycle to actively facilitate REV-ERB loading for repression of circadian gene expression. Mechanistically, we found that SRC-2 dictates global circadian chromatin remodeling through spatial and temporal recruitment of PBAF members of the SWI/SNF complex to facilitate loading of REV-ERB in the hepatic genome. Mathematical modeling highlights how the FR model sustains proper circadian rhythm despite fluctuations of REV-ERB levels. Our study not only reveals a mechanism for active communication between the positive and negative limbs of the circadian transcriptional loop but also establishes the concept that clock transcription factor binding dynamics is perhaps a central tenet for fine-tuning circadian rhythm.
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http://www.ncbi.nlm.nih.gov/pubmed/26611104
A spheroid toxicity assay using magnetic 3D bioprinting and real-time mobile device-based imaging
An ongoing challenge in biomedical research is the search for simple, yet robust assays using 3D cell cultures for toxicity screening. This study addresses that challenge with a novel spheroid assay, wherein spheroids, formed by magnetic 3D bioprinting, contract immediately as cells rearrange and compact the spheroid in relation to viability and cytoskeletal organization. Thus, spheroid size can be used as a simple metric for toxicity. The goal of this study was to validate spheroid contraction as a cytotoxic endpoint using 3T3 fibroblasts in response to 5 toxic compounds (all-trans retinoic acid, dexamethasone, doxorubicin, 5′-fluorouracil, forskolin), sodium dodecyl sulfate (+control), and penicillin-G (-control). Real-time imaging was performed with a mobile device to increase throughput and efficiency. All compounds but penicillin-G significantly slowed contraction in a dose-dependent manner (Z’ = 0.88). Cells in 3D were more resistant to toxicity than cells in 2D, whose toxicity was measured by the MTT assay. Fluorescent staining and gene expression profiling of spheroids confirmed these findings. The results of this study validate spheroid contraction within this assay as an easy, biologically relevant endpoint for high-throughput compound screening in representative 3D environments.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26365200
Comprehensive Study of the Influence of Altered Gravity on the Oxidative Burst of Mussel (Mytilus edulis) Hemocytes
Microgravity induces alterations in the function- ing of immune cell; however, the underlying mechanisms have not yet been identified. In this study, hemocytes (blood cells) of the blue mussel Mytilus edulis were investigated under altered gravity conditions. The study was conducted on the ground in preparation for the BIOLAB TripleLux- B experiment, which will be performed on the International Space Station (ISS). On-line kinetic measurements of reac- tive oxygen species (ROS) production during the oxidative burst and thus cellular activity of isolated hemocytes were performed in a photomultiplier (PMT)-clinostat (simulated microgravity) and in the 1g operation mode of the clino- stat in hypergravity on the Short-Arm Human Centrifuge (SAHC) as well as during parabolic flights. In addition to studies with isolated hemocytes, the effect of altered gravity conditions on whole animals was investigated. For this pur- pose, whole mussels were exposed to hypergravity (1.8 g) on a multi-sample incubator centrifuge (MuSIC) or to simu- lated microgravity in a submersed clinostat. After exposure for 48 h, hemocytes were taken from the mussels and ROS production was measured under 1 g conditions. The results from the parabolic flights and clinostat studies indicate that mussel hemocytes respond to altered gravity in a fast and reversible manner. Hemocytes (after cryo-conservation)exposed to simulated microgravity (μ g), as well as fresh hemocytes from clinorotated animals, showed a decrease in ROS production. Measurements during a permanent exposure of hemocytes to hypergravity (SAHC) show a decrease in ROS production. Hemocytes of mussels mea- sured after the centrifugation of whole mussels did not show an influence to the ROS response at all. Hypergravity dur- ing parabolic flights led to a decrease but also to an increase in ROS production in isolated hemocytes, whereas the cen- trifugation of whole mussels did not influence the ROS response at all. This study is a good example how ground- based facility experiments can be used to prepare for an upcoming ISS experiment, in this case the TRIPLE LUX B experiment.
Related URLs:
http://link.springer.com/article/10.1007/s12217-015-9438-9
ELITE S2 – AN INSTRUMENT FOR MOTION ANALYSIS ON BOARD THE INTERNATIONAL SPACE STATION
This paper describes the activities for utilization and control of ELITE S2 on board the International Space Station (ISS). ELITE S2 is a payload of the Italian Space Agency (ASI) for quantitative human movement analysis in weightlessness. Within the frame of a bilateral agreement with NASA, ASI has funded a number of facilities, enabling different scientific experiments on board the ISS. ELITE S2 has been developed by the ASI contractor Kayser Italia, delivered to the Kennedy Space Center in 2006 for pre-flight processing, launched in 2007 by the Space Shuttle Endeavour (STS-118), integrated in the U.S. lab and used during the Increments 16 and 17 through 2008. The ELITE S2 flight segment comprises equipment mounted into an Express Rack and a number of stowed items to be deployed for experiment performance (video cameras and accessories). The ground segment consists in a User Support Operations Center (based at Kayser Italia) enabling real-time payload control and a number of User Home Bases (located at the ASI and PIs premises), for the scientific assessment of the experiment performance. Two scientific protocols on reaching and cognitive processing have been successfully performed in five sessions involving two ISS crewmembers: IMAGINE 2 and MOVE.
Space, the final frontier: A critical review of recent experiments performed in microgravity
Space biology provides an opportunity to study plant physiology and development in a unique microgravity environment. Recent space studies with plants have provided interesting insights into plant biology, including discovering that plants can grow seed-to-seed in microgravity, as well as identifying novel responses to light. However, spaceflight experiments are not without their challenges, including limited space, limited access, and stressors such as lack of convection and cosmic radiation. Therefore, it is important to design experiments in a way to maximize the scientific return from research conducted on orbiting platforms such as the International Space Station. Here, we provide a critical review of recent spaceflight experiments and suggest ways in which future experiments can be designed to improve the value and applicability of the results generated. These potential improvements include: utilizing in-flight controls to delineate microgravity versus other spaceflight effects, increasing scientific return via next-generation sequencing technologies, and utilizing multiple genotypes to ensure results are not unique to one genetic background. Space experiments have given us new insights into plant biology. However, to move forward, special care should be given to maximize science return in understanding both microgravity itself as well as the combinatorial effects of living in space.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/26795156
The SCD – Stem Cell Differentiation ESA Project: Preparatory Work for the Spaceflight Mission
Due to spaceflight, astronauts experience serious, weightlessness-induced bone loss because of an unbalanced process of bone remodeling that involves bone marrow mes- enchymal stem cells (BMSCs), as well as osteoblasts, osteo- cytes, and osteoclasts. The effects of microgravity on osteo- cells have been extensively studied, but it is only recently that consideration has been given to the role of BMSCs. Pre- vious researches indicated that human BMSCs cultured in simulated microgravity (sim-μg) alter their proliferation and differentiation. The spaceflight opportunities for biomedical experiments are rare and suffer from a number of opera- tive constraints that could bias the validity of the experiment itself, but remain a unique opportunity to confirm and explain the effects due to microgravity, that are only par- tially activated/detectable in simulated conditions. For this reason, we carefully prepared the SCD – STEM CELLS DIFFERENTIATION experiment, selected by the European Space Agency (ESA) and now on the International Space Station (ISS). Here we present the preparatory studies per- formed on ground to adapt the project to the spaceflight constraints in terms of culture conditions, fixation and stor- age of human BMSCs in space aiming at satisfying the biological requirements mandatory to retrieve suitable sam- ples for post-flight analyses. We expect to understand better the molecular mechanisms governing human BMSC growth and differentiation hoping to outline new countermeasures against astronaut bone loss.
Related URLs:
http://link.springer.com/article/10.1007/s12217-015-9466-5
Attachment of LcrV from Yersinia pestis at dual binding sites to human TLR-2 and human IFN-gamma receptor.
The virulence antigen (V-antigen, LcrV) of Yersinia pestis, the causative agent of bubonic plague, is an established protective antigen known to regulate, target, and mediate type III translocation of cytotoxic yersiniae outer proteins termed Yops; LcrV also prompts TLR2-dependent upregulation of anti-inflammatory IL-10. In this study, we determined the parameters of specific interaction of LcrV with TLR2 expressed on human transfected HEK293 cells (TLR2+/CD14-), VTEC2.HS cells (TLR2+/CD14-), primary monocytes (TLR2+/CD14+), and THP-1 cells (TLR2+/CD14+). The IRRL314-317 motif of the extracellular domain of human and mouse TLR2 accounted for high-affinity binding of LcrV. The CD14 co-receptor did not influence this interaction. LcrV did not bind to human U937 (TLR2-/CD14-) and alveolar macrophages (TLR2-/CD14+) in the absence of receptor-bound human IFN-gamma or a synthetic C-terminal fragment (hIFN-gamma132-143). The latter, but not mouse IFN-gamma (or synthetic control peptides), shared a GRRA138-141 site necessary for high-affinity specific binding. LcrV of Y. pestis shares the N-terminal LEEL32-35 binding site of Yersinia enterocolitica and also has an exposed internal DEEI203-206 binding site. Comparison of binding constants and consideration of steric restrictions indicate that binding is not cooperative and only the internal site binds LcrV to target cells. Both the LEEL32-35 and DEEI203-206 binding sites are removed by five amino acids from DKN residues associated with biological activity of bound LcrV. LcrV of Y. pestis promoted both TLR2/CD14-dependent and TLR2/CD14-independent amplification of IL-10 and concomitant downregulation of TNF-alpha in human target cells. The ability of LcrV to utilize human IFN-gamma (a major inflammatory effector of innate immunity) to minimize inflammation is insidious and may account in part for the severe symptoms of plague in man.
Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/17441749