Gene expression levels were determined in 3rd instar and adult Drosophila melanogaster reared during spaceflight, to elucidate the genetic and molecular mechanisms underpinning the effects of microgravity on the immune system. The goal was to validate the Drosophila model for understanding alterations of innate immune responses in humans due to spaceflight. Five containers of flies, with ten female and five male fruit flies in each container, were housed and bred on the space shuttle (average orbit altitude of 330.35 km) for 12 days and 18.5 hours, with a new generation reared in microgravity. RNA was extracted on the day of shuttle landing from whole body animals (3rd instar larvae and adults), hybridized to Drosophila 2.0 Affymetrix genome arrays, and the expression level of all genes was normalized against the gene expression level from the corresponding developmental stage animals raised on ground. Spaceflight altered the expression of larval genes involved in the maturation of plasmatocytes (macrophages) and their phagocytic response, as well as the level of constitutive expression of pattern recognition receptors and opsonins that specifically recognize bacteria, and of lysozymes, antimicrobial peptide pathway and immune stress genes, hallmarks of humoral immunity. Larval microarrays (FL 6 samples) are based on RNA extracted from 6 independent sets of 50 mid 3rd instar larvae reared in microgravity and collected on the day of landing after 12 days and 18.5 hours on the space shuttle and the same number of control larvae raised on ground (GL 6 samples). Adults microarrays (F1 3 samples) are based on RNA from 3 sets of 20 adult females each, that emerged during spaceflight and within 4 hours of landing and the same number of adult females from the corresponding ground control containers (G1 3 samples).

Space travel presents unlimited opportunities for exploration and discovery but requires a more complete understanding of the immunological consequences of long-term exposure to the conditions of spaceflight. To understand these consequences better and to contribute to design of effective countermeasures we used the Drosophila model to compare innate immune responses to bacteria and fungi in flies that were either raised on earth or in outer space aboard the NASA Space Shuttle Discovery (STS-121). Microarrays were used to characterize changes in gene expression that occur in response to infection by bacteria and fungus in drosophila that were either hatched and raised in outer space (microgravity) or on earth (normal gravity). Whole Oregon R strain drosophila melanogaster fruit flies either raised on earth or in space that were (1) uninfected (2) infected with bacteria (Escherichia coli) or (3) infected with fungus (Beauveria bassiana) were used for RNA extraction and hybridization on Affymetrix microarrays.

Here we present a whole-genome survey of the murine transcriptomic response to physiologically-relevant radiation doses 2 and 8 Gy. There are 18 distinct biological samples here. Mice were exposed to ionizing radiation (Cesium-138 source) and whole blood was collected by cardiac puncture 6 hours post treatment. Doses were 0 (7 samples) 2 (5 samples) and 8 (6 samples) gy.

BACKGROUND: Ionizing radiation (IR) can be extremely harmful for human cells since an improper DNA-damage response (DDR) to IR can contribute to carcinogenesis initiation. Perturbations in DDR pathway can originate from alteration in the functionality of the microRNA-mediated gene regulation being microRNAs (miRNAs) small noncoding RNA that act as post-transcriptional regulators of gene expression. In this study we gained insight into the role of miRNAs in the regulation of DDR to IR under microgravity a condition of weightlessness experienced by astronauts during space missions which could have a synergistic action on cells increasing the risk of radiation exposure. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed miRNA expression profile of human peripheral blood lymphocytes (PBL) incubated for 4 and 24 h in normal gravity (1 g) and in modeled microgravity (MMG) during the repair time after irradiation with 0.2 and 2Gy of gamma-rays. Our results show that MMG alters miRNA expression signature of irradiated PBL by decreasing the number of radio-responsive miRNAs. Moreover let-7i* miR-7 miR-7-1* miR-27a miR-144 miR-200a miR-598 miR-650 are deregulated by the combined action of radiation and MMG. Integrated analyses of miRNA and mRNA expression profiles carried out on PBL of the same donors identified significant miRNA-mRNA anti-correlations of DDR pathway. Gene Ontology analysis reports that the biological category of Response to DNA damage is enriched when PBL are incubated in 1 g but not in MMG. Moreover some anti-correlated genes of p53-pathway show a different expression level between 1 g and MMG. Functional validation assays using luciferase reporter constructs confirmed miRNA-mRNA interactions derived from target prediction analyses. CONCLUSIONS/SIGNIFICANCE: On the whole by integrating the transcriptome and microRNome we provide evidence that modeled microgravity can affects the DNA-damage response to IR in human PBL. Overall Design: Gene expression signature was defined in PBL irradiated with gamma-rays (2.0 Gy) and incubated in modeled microgravity (mmg) and in parallel ground conditions (1g) for 24h. Five independent experiments were performed for each donor to address which mRNAs were regulated on IR stress. The level of each transcript was represented as Log2.

Experimentation on the International Space Station has reached the stage where repeated and nuanced transcriptome studies are beginning to illuminate the structural and metabolic differences between plants grown in space compared to plants on the Earth. Genes that are important in setting up the spaceflight responses are being identified; their role in spaceflight physiological adaptation are increasingly understood and the fact that different genotypes adapt differently is recognized. However the basic question of whether these spaceflight responses are required for survival has yet to be posed and the fundamental notion that spaceflight responses may be non-adaptive has yet to be explored. Therefore the experiments presented here were designed to ask if portions of the plant spaceflight response can be genetically removed without causing loss of spaceflight survival and without causing increased stress responses. The CARA experiment compared the spaceflight transcriptome responses of two Arabidopsis ecotypes Col-0 and WS as well as that of a PhyD mutant of Col-0. When grown with the ambient light of the ISS phyD displayed a significantly reduced spaceflight transcriptome response compared to Col-0 suggesting that altering the activity of a single gene can actually improve spaceflight adaptation by reducing the transcriptome cost of physiological adaptation. The WS genotype showed an even simpler spaceflight transcriptome response in the ambient light of the ISS more broadly indicating that the plant genotype can be manipulated to reduce the transcriptome cost of plant physiological adaptation to spaceflight and suggesting that genetic manipulation might further reduce or perhaps eliminate the metabolic cost of spaceflight adaptation. When plants were germinated and then left in the dark on the ISS the WS genotype actually mounted a larger transcriptome response than Col-0 suggesting that the in-space light environment affects physiological adaptation which further implies that manipulating the local habitat can also substantially impact the metabolic cost of spaceflight adaptation.

The effect of microgravity on gene expression in C.elegans was comprehensively analysed by DNA microarray. This is the first DNA microarray analysis for C.elegans grown under microgravity. Hyper gravity and clinorotation experiments were performed as reference against the flight experiment.

Changes in gene expression profiles implicated in oxidative stress and in ECM remodeling in mouse skin were examined after space flight. The metabolic effects of space flight in skin tissues were also characterized.

Analysis of human peripheral blood 48 hours after irradiation ex vivo with graded doses of gamma rays. Results have been used in building and testing classifiers to predict exposure dose for use in radiological triage and also provide insight into immune cell responses. Results were compared with those from earlier times and from patients exposed in vivo. Peripheral blood from 5 healthy donors was exposed ex vivo to 0. 0.5 2 5 or 8 Gy gamma-rays and gene expression was analyzed up to 48 hours after exposure.

Transcriptional crosstalk between mammary gland liver and adipose tissue Experiment Overall Design: Pregnant and Lactating rats exposed to 3 gravity conditions

Six to eight week old female C57BL/6J mice were exposed to 2 Gy of whole body xce xb3 radiation and mammary glands were surgically removed 2-month after radiation. RNA was isolated and microarray hybridization performed for gene expression analysis. 5 samples were analyzed: 2 controls at 2 months 1 2 Gy at 2 months and 2 7 Gy at 2 months