Effect of magnetically simulated zero-gravity and enhanced gravity on the walk of the common fruitfly†

School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
Journal of The Royal Society Interface (Impact Factor: 3.92). 01/2012; 9(72):1438-49. DOI: 10.1098/rsif.2011.0715
Source: PubMed

ABSTRACT Understanding the effects of gravity on biological organisms is vital to the success of future space missions. Previous studies in Earth orbit have shown that the common fruitfly (Drosophila melanogaster) walks more quickly and more frequently in microgravity, compared with its motion on Earth. However, flight preparation procedures and forces endured on launch made it difficult to implement on the Earth's surface a control that exposed flies to the same sequence of major physical and environmental changes. To address the uncertainties concerning these behavioural anomalies, we have studied the walking paths of D. melanogaster in a pseudo-weightless environment (0g*) in our Earth-based laboratory. We used a strong magnetic field, produced by a superconducting solenoid, to induce a diamagnetic force on the flies that balanced the force of gravity. Simultaneously, two other groups of flies were exposed to a pseudo-hypergravity environment (2g*) and a normal gravity environment (1g*) within the spatially varying field. The flies had a larger mean speed in 0g* than in 1g*, and smaller in 2g*. The mean square distance travelled by the flies grew more rapidly with time in 0g* than in 1g*, and slower in 2g*. We observed no other clear effects of the magnetic field, up to 16.5 T, on the walks of the flies. We compare the effect of diamagnetically simulated weightlessness with that of weightlessness in an orbiting spacecraft, and identify the cause of the anomalous behaviour as the altered effective gravity.

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Available from: F. Javier Medina, Sep 29, 2015
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    • "The technique of stable diamagnetic levitation has been described in detail elsewhere, e.g. [5,34,36]. Seedlings and imbibed seeds of Arabidopsis levitated in the same position in the magnet as the water droplet, since the magnetic mass susceptibility of most of the plant tissues is similar to that of water [37]. Under these conditions, the gravitationally-induced stresses on such tissues are expected to be much reduced by diamagnetic levitation [35]. "
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    ABSTRACT: Cell growth and cell proliferation are intimately linked in the presence of Earth's gravity, but are decoupled under the microgravity conditions present in orbiting spacecraft. New technologies to simulate microgravity conditions for long-duration experiments, with stable environmental conditions, in Earth-based laboratories are required to further our understanding of the effect of extraterrestrial conditions on the growth, development and health of living matter. We studied the response of transgenic seedlings of Arabidopsis thaliana, containing either the CycB1-GUS proliferation marker or the DR5-GUS auxin-mediated growth marker, to diamagnetic levitation in the bore of a superconducting solenoid magnet. As a control, a second set of seedlings were exposed to a strong magnetic field, but not to levitation forces. A third set was exposed to a strong field and simulated hypergravity (2 g). Cell proliferation and cell growth cytological parameters were measured for each set of seedlings. Nucleolin immunodetection was used as a marker of cell growth. Collectively, the data indicate that these two fundamental cellular processes are decoupled in root meristems, as in microgravity: cell proliferation was enhanced whereas cell growth markers were depleted. These results also demonstrated delocalisation of auxin signalling in the root tip despite the fact that levitation of the seedling as a whole does not prevent the sedimentation of statoliths in the root cells. In our model system, we found that diamagnetic levitation led to changes that are very similar to those caused by real- [e.g. on board the International Space Station (ISS)] or mechanically-simulated microgravity [e.g. using a Random Positioning Machine (RPM)]. These changes decoupled meristematic cell proliferation from ribosome biogenesis, and altered auxin polar transport.
    BMC Plant Biology 09/2013; 13(1):124. DOI:10.1186/1471-2229-13-124 · 3.81 Impact Factor
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    • "A different kind of reduced gravity simulator, free of the rotational, mechanical and inertial forces generated by spinning simulators and with the advantage of acting at the molecular level, is based on diamagnetic levitation [9-13]. Diamagnetic material, such as water, is repelled from a magnetic field. "
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    ABSTRACT: Previous experiments have shown that the reduced gravity aboard the International Space Station (ISS) causes important alterations in Drosophila gene expression. These changes were shown to be intimately linked to environmental space-flight related constraints. Here, we use an array of different techniques for ground-based simulation of microgravity effects to assess the effect of suboptimal environmental conditions on the gene expression of Drosophila in reduced gravity. A global and integrative analysis, using "gene expression dynamics inspector" (GEDI) self-organizing maps, reveals different degrees in the responses of the transcriptome when using different environmental conditions or microgravity/hypergravity simulation devices. Although the genes that are affected are different in each simulation technique, we find that the same gene ontology groups, including at least one large multigene family related with behavior, stress response or organogenesis, are over represented in each case. These results suggest that the transcriptome as a whole can be finely tuned to gravity force. In optimum environmental conditions, the alteration of gravity has only mild effects on gene expression but when environmental conditions are far from optimal, the gene expression must be tuned greatly and effects become more robust, probably linked to the lack of experience of organisms exposed to evolutionary novel environments such as a gravitational free one.
    BMC Evolutionary Biology 06/2013; 13(1):133. DOI:10.1186/1471-2148-13-133 · 3.37 Impact Factor
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    • "(Color images available online at strength of at least 16 T, so this technology was made available to the space biologist community only some years ago (Valles et al., 2005; Guevorkian and Valles 2006; Beuls et al., 2009; Hammer et al., 2009; Dijkstra et al., 2011; Herranz et al., 2012; Hill et al., 2012; Manzano et al., 2012). "
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    ABSTRACT: Abstract Earth-based microgravity simulation techniques are required due to space research constraints. Using diamagnetic levitation, we exposed Arabidopsis thaliana in vitro callus cultures to environments with different levels of effective gravity and magnetic field strengths (B) simultaneously. The environments included simulated 0g* at B=10.1 T, an internal 1g* control (B=16.5 T), and hypergravity (2g* at B=10.1 T). Furthermore, samples were also exposed to altered gravity environments that were created with mechanical devices, such as the Random Positioning Machine (simulated μg) and the Large Diameter Centrifuge (2g). We have determined the proteomic signature of cell cultures exposed to these altered-gravity environments by means of the difference gel electrophoresis (DiGE) technique, and we have compared the results with microarray-based transcriptomes from the same samples. The magnetic field itself produced a low number of proteomic alterations, but the combination of gravitational alteration and magnetic field exposure produced synergistic effects on the proteome of plants (the number of significant changes is 3-7 times greater). Tandem mass spectrometry identification of 19 overlapping spots in the different conditions corroborates a major role of abiotic stress and secondary metabolism proteins in the molecular adaptation of plants to unusual environments, including microgravity. Key Words: DiGE-Microgravity simulation-Magnetic levitation-Proteome/transcriptome comparison-Callus cell cultures. Astrobiology 13, xxx-xxx.
    Astrobiology 03/2013; 13(3). DOI:10.1089/ast.2012.0883 · 2.59 Impact Factor
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