The next small step

Zebrafish Bone and General Physiology Are Differently Affected by Hormones or Changes in Gravity

Teleost fish such as zebrafish (Danio rerio) are increasingly used for physiological, genetic and developmental studies. Our understanding of the physiological consequences of altered gravity in an entire organism is still incomplete. We used altered gravity and drug treatment experiments to evaluate their effects specifically on bone formation and more generally on whole genome gene expression. By combining morphometric tools with an objective scoring system for the state of development for each element in the head skeleton and specific gene expression analysis, we confirmed and characterized in detail the decrease or increase of bone formation caused by a 5 day treatment (from 5dpf to 10 dpf) of, respectively parathyroid hormone (PTH) or vitamin D3 (VitD3). Microarray transcriptome analysis after 24 hours treatment reveals a general effect on physiology upon VitD3 treatment, while PTH causes more specifically developmental effects. Hypergravity (3g from 5dpf to 9 dpf) exposure results in a significantly larger head and a significant increase in bone formation for a subset of the cranial bones. Gene expression analysis after 24 hrs at 3g revealed differential expression of genes involved in the development and function of the skeletal, muscular, nervous, endocrine and cardiovascular systems. Finally, we propose a novel type of experimental approach, the "Reduced Gravity Paradigm", by keeping the developing larvae at 3g hypergravity for the first 5 days before returning them to 1g for one additional day. 5 days exposure to 3g during these early stages also caused increased bone formation, while gene expression analysis revealed a central network of regulatory genes (hes5, sox10, lgals3bp, egr1, edn1, fos, fosb, klf2, gadd45ba and socs3a) whose expression was consistently affected by the transition from hyper- to normal gravity.

Mitochondrial responses to extreme environments: insights from metabolomics

Humans are capable of survival in a remarkable range of environments, including the extremes of temperature and altitude as well as zero gravity. Investigation into physiological function in response to such environmental stresses may help further our understanding of human (patho-) physiology both at a systems level and in certain disease states, making it a highly relevant field of study. This review focuses on the application of metabolomics in assessing acclimatisation to these states, particularly the insights this approach can provide into mitochondrial function. It includes an overview of metabolomics and the associated analytical tools and also suggests future avenues of research.

Changes in immune cell signalling, apoptosis and stress response functions in mice returned from the BION-M1 mission in space

To explore the effect of the spaceflight environment on immunity in animals, C57/BL6 mice flown on a 30-day space high-orbit satellite mission (BION-M1) were analyzed. Cytokine response in mice was measured in tandem with the following parameters: the synthesis of inducible forms of the heat shock proteins HSP72 and HSP90α; activity of the NF-κB, IFR3, and SAPK/JNK signalling pathways; and TLR4 expression. In addition, apoptosis in the thymus was measured by caspase-3 and ph-p53/p53 ratio testing. In response to flight environment exposure, mice had a reduction in spleen and thymus masses and decreased splenic and thymic lymphocyte counts. Plasma concentration of IL-6 and IFN-γ but not TNF-α was decreased in C57BL6 mice. The NF-κB activity in splenic lymphocytes through the canonical pathway involving IκB degradation was significantly increased at 12h after landing. One week after landing, however, the activity of NF-κB was markedly decreased below even the control values. Non-canonical NF-κB activity increased during the whole observation period. The activities of SAPK/JNK and IRF-3 were invariable at 12h but significantly increased 7 days after landing. The expression of Hsp72 and Hsp90α was somewhat increased 12h (Hsp72) and 7 days (Hsp90α). TLR4 expression in splenic cells was significantly increased only at 12h, returning to normal 7 days after landing. To assess the apoptosis in thymus lymphocytes, caspase-3 and levels of p53 protein along with its phosphorylated form were measured in thymic lymphocytes. The results indicated that the high-orbit spaceflight environment caused an increase in the level of p53 but more notably in the activated, phosphorylated form of the p53 protein. The calculated ratio of the active to inactive forms of the protein (ph-53/p53) 12h after landing increased by more than twofold, indicating the apparent induction of apoptosis in thymus cells. Interestingly, 7 days after the landing, this ratio was not restored, but rather increased: the specified ratio was four times higher compared to the ground-based control. Measurements of caspase-3 in thymic cells indicated more expressive increase in apoptosis. Taken together, the results of the present study indicate that spaceflight induces an imbalance in the immunity of mice, showing variation in signalling, apoptosis and stress response that are not restored by 7 days after landing. These changes are distinguished from classic stress-related alterations usually caused by conventional stressors.

How and why does the proteome respond to microgravity?

For medical and biotechnological reasons, it is important to study mammalian cells, animals, bacteria and plants exposed to simulated and real microgravity. It is necessary to detect the cellular changes that cause the medical problems often observed in astronauts, cosmonauts or animals returning from prolonged space missions. In order for in vitro tissue engineering under microgravity conditions to succeed, the features of the cell that change need to be known. In this article, we summarize current knowledge about the effects of microgravity on the proteome in different cell types. Many studies suggest that the effects of microgravity on major cell functions depend on the responding cell type. Here, we discuss and speculate how and why the proteome responds to microgravity, focusing on proteomic discoveries and their future potential.

Microarray analysis of spaceflown murine thymus tissue reveals changes in gene expression regulating stress and glucocorticoid receptors

The detrimental effects of spaceflight and simulated microgravity on the immune system have been extensively documented. We report here microarray gene expression analysis, in concert with quantitative RT-PCR, in young adult C57BL/6NTac mice at 8 weeks of age after exposure to spaceflight aboard the space shuttle (STS-118) for a period of 13 days. Upon conclusion of the mission, thymus lobes were extracted from space flown mice (FLT) as well as age- and sex-matched ground control mice similarly housed in animal enclosure modules (AEM). mRNA was extracted and an automated array analysis for gene expression was performed. Examination of the microarray data revealed 970 individual probes that had a 1.5-fold or greater change. When these data were averaged (n = 4), we identified 12 genes that were significantly up- or down-regulated by at least 1.5-fold after spaceflight (P < or = 0.05). The genes that significantly differed from the AEM controls and that were also confirmed via QRT-PCR were as follows: Rbm3 (up-regulated) and Hsph110, Hsp90aa1, Cxcl10, Stip1, Fkbp4 (down-regulated). QRT-PCR confirmed the microarray results and demonstrated additional gene expression alteration in other T cell related genes, including: Ctla-4, IFN-alpha2a (up-regulated) and CD44 (down-regulated). Together, these data demonstrate that spaceflight induces significant changes in the thymic mRNA expression of genes that regulate stress, glucocorticoid receptor metabolism, and T cell signaling activity. These data explain, in part, the reported systemic compromise of the immune system after exposure to the microgravity of space.

Four men in a space station - To say nothing of the cow! The quest for finding respite and work in the ultimate frontier

Fed up with life on earth, four scientists attempt to make it to space to live in the International Space Station (ISS) and carry out experiments. The difficulties in getting selected by NASA, the rigourous training to fly and the risks of the journey to life and health are the rate limiting steps in their quest. They propose commercialization of space and also ferrying cows to space for food as well as generation of biogas. The anaerobic environment is particularly suitable for biogas generation and if successful they plan to get NASA to launch space vehicles to Mars using this natural fuel with the ISS as the staging area.