Bone loss is one of the major health problems for astronauts during long-term spaceflight and for patients during prolonged bed rest or paralysis. Growing evidence suggests that osteocytes, the most abundant cells in the mineralized bone matrix, play a key role in sensing mechanical forces applied to the skeleton and in transducing them into subcellular biochemical signals to modulate bone homeostasis. However, the precise molecular mechanisms underlying both mechanosensation and mechanotransduction in osteocytes under the real microgravity (µG) condition are poorly understood. To unravel the mechanisms by which osteocyte, sense and responds to mechanical unloading, we exposed murine osteocytic cell line, Ocy454, seeded on a highly porous polystyrene 3D scaffold, to 2, 4, or 6 days of µG on board the International Space Station (ISS) and compared their gene expression with cells at 1G on Earth. Bioinformatics analysis of cells exposed to µG revealed several pathways differentially regulated upon exposure to microgravity.

Interaction of COP1 and UVR8 which regulate UV-B-induced photomorphogenesis and stress acclimation in Arabidopsis thaliana.

The root apex is an important section of the plant root involved in environmental sensing and cellular development. Analyzing the gene profile of root apex in diverse environments is important and challenging especially when the samples are limiting and precious such as in spaceflight. The feasibility of using tiny root sections for transcriptome analysis was examined in this study. To understand the gene expression profiles of the root apex Arabidopsis thaliana Col-0 roots were sectioned into Zone-I (0.5 mm root cap and meristematic zone) and Zone-II (1.5 mm transition elongation and growth terminating zone). Gene expression was analyzed using microarray and RNA seq. Both the techniques arrays and RNA-Seq identified 4180 common genes as differentially expressed (with > two-fold changes) between the zones. In addition 771 unique genes and 19 novel TARs were identified by RNA-Seq as differentially expressed which were not detected in the arrays. Single root tip zones can be used for full transcriptome analysis; further the root apex zones are functionally very distinct from each other. RNA-Seq provided novel information about the transcripts compared to the arrays. These data will help optimize transcriptome techniques for dealing with small rare samples.

The Heat Shock Factor A2 (HsfA2) as a part of the HSF network is essential to the plant s response to almost any environmental stress and to the cellular homeostatic control mechanisms. Plant cell cultures disabled in HsfA2 function were grown aboard the International Space Station (ISS) in order to ascertain whether or not they use the same terrestrially effective systems to adapt to the novel environment of spaceflight. Cultured lines of Arabidopsis thaliana derived from wild type (WT) cultivar Col-0 and from a knock-out line deficient in the gene encoding HSFA2 (HSFA2 KO) were launched to the ISS on SpaceX-2 as part of the Cellular Expression Logic (CEL) experiment of the BRIC17 spaceflight mission and were fixed in-flight after 10 days on orbit. Microarray gene expression data were analyzed using a two-part comparative approach. First differentially expressed genes were identified between the environments (spaceflight to ground) within cells of the same genotype which represented physiological adaptation to the spaceflight environment. Second gene expression profiles were identified between the genotypes (HSFA2 KO to WT) within the same environment defining genes uniquely required by the two genotypes in the ground and spaceflight adapted states. The physiological state of the cells as a result of disabling a gene has tremendous control over the mechanisms induced to adapt to the environment of spaceflight. The HsfA2 demonstrated a role in the physiological adaptation to the spaceflight environment since the cells disabled in the HsfA2 gene used substantially different genes to achieve the spaceflight adapted state than the WT cells. The endoplasmic reticulum (ER) stress and unfolded protein response (UPR) define the HSFA2 KO cells physiological state regardless of the environment and likely result from the deficiency in the chaperone-mediated protein folding machinery. HsfA2 seems to have a universal stress response role but also specific roles in the physiological adaptation to spaceflight through cell wall remodeling signal perception and transduction and starch biosynthesis. Implementation of knock-out cells identified a set of genes with a required expression level in order for a cell to achieve a spaceflight-adapted state. The HSFA2 KO cells helped to unravel the HsfA2-dependent genes of the adaption of wild type cells to the environment of spaceflight.

Whole seedlings of wild type (4d) and atm mutants (4d) have been analyzed after a gamma ray irradiation of 0.75h 1.5h 3h & 5h (time course). Roots of wt (4d) atm (3d) and atr (4d) mutants have been analyzed after a 1h irradiation. Ataxia Telangiectasia Mutated (ATM) encodes a large protein with a phosphatidylinositol 3-kinase (PI3K)-like domain at the C terminus (reviewed by Rotman and Shiloh 1998). PI3K-related proteins make up a large family of Ser-Thr protein kinases numerous members of which are involved in the regulation of cell cycle progression responses to DNA damage and the maintenance of genomic stability (Hoekstra 1997). AtATM plays an essential role in meiosis and in the somatic response to DNA damage in plants similar to the function of ATM in mammals and other eukaryotes. Ataxia telangiectasia-mutated and Rad3-related (ATR) plays a central role in cell-cycle regulation transmitting DNA damage signals to downstream effectors of cell-cycle progression.

We investigated differentially regulated genes in human myelomonocytic U937 cells in 20s and 5min microgravity and in hypergravity and compared expression profiles to identify potential gravity-regulated genes and adaptation processes. Overall design: Human myelomonocytic U937 cells were exposed to altered gravity during a parabolic flight.

Gene expression changes induced by acute skeletal muscle unloading which leads to physiological changes including muscle atrophy fibre-type switching and loss of ability to transition between lipid and glucose as energy source (metabolic inflexibility) was investigated by hind-limb suspension (HLS) treatment of Male ICR mice (28 x9632 g body wt; Harlan Indianapolis IN). Agilent Whole Mouse Genome Oligo Microarrays were utilised to examine the effects of HLS on mRNA expression profiles of the soleus muscle and the gastrocnemius muscle in the hindlimbs of freely ambulating control and 24h HLS treated mice.

Four days old rice calli were selected to grow 324h under spaceflight controls 1g-flight controls and 1g-ground controls. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. Rice calli were selected at different treatment for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain the diff-genes that caused by the microgravity.

We investigated differentially regulated genes in human myelomonocytic U937 cells in 20s and 5min microgravity and in hypergravity and compared expression profiles to identify potential gravity-regulated genes and adaptation processes. Overall design: Human myelomonocytic U937 cells were exposed to altered gravity during a sounding rocket mission.

Plants exhibit a robust transcriptional response to gamma radiation which includes the induction of transcripts required for homologous recombination and the suppression of transcripts that promote cell cycle progression. Various DNA damaging agents induce different spectra of DNA damage as well as collateral damage to other cellular components and therefore are not expected to provoke identical responses by the cell. Here we study the effects of two different types of ionizing radiation (IR) treatment HZE (1 GeV Fe26+ high mass high charge and high energy relativistic particles) and gamma photons on the transcriptome of Arabidopsis thaliana seedlings. Both types of IR induce small clusters of radicals that can result in the formation of double strand breaks (DSBs) but HZE also produces linear arrays of extremely clustered damage. We performed these experiments across a range of time points (1.5-24 h after irradiation) in both wild-type plants and in mutants defective in the DSB-sensing protein kinase ATM. The two types of IR exhibit a shared double strand break-repair-related damage response although they differ slightly in the timing degree and ATM-dependence of the response. The ATM-dependent DNA metabolism-related transcripts of the DSB response were also induced by other DNA damaging agents but were not induced by conventional stresses. Both Gamma and HZE irradiation induced at 24 h post-irradiation ATM-dependent transcripts associated with a variety of conventional stresses; these were overrepresented for pathogen response rather than DNA metabolism. In contrast only HZE-irradiated plants at 1.5 h after irradiation exhibited an additional and very extensive transcriptional response shared with plants experiencing extended night. This response was not apparent in gamma-irradiated plants.