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Spaceflight-related suboptimal conditions can accentuate the altered gravity response of Drosophila transcriptome

Authors

  • RAUL HERRANZ,

    1. Departamento de Bioquímica & Instituto de Investigaciones Biomédicas ‘Alberto Sols’ (UAM-CSIC), C/Arzobispo Morcillo, 4 Madrid, 28029 Spain
    2. Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, E-28040, Madrid, Spain
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  • ALBERTO BENGURÍA,

    1. Centro Nacional de Biotecnología (UAM-CSIC), Madrid, Spain
    2. Genomics Unit. Centro Nacional de Investigaciones Cardiovasculares, C/Melchor Fernández Almagro, 3. Madrid, Spain
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  • DAVID A. LAVÁN,

    1. Departamento de Bioquímica & Instituto de Investigaciones Biomédicas ‘Alberto Sols’ (UAM-CSIC), C/Arzobispo Morcillo, 4 Madrid, 28029 Spain
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  • IRENE LÓPEZ-VIDRIERO,

    1. Centro Nacional de Biotecnología (UAM-CSIC), Madrid, Spain
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  • GILBERT GASSET,

    1. GSBMS, Université Paul Sabatier, Toulouse, France
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  • F. JAVIER MEDINA,

    1. Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, E-28040, Madrid, Spain
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  • JACK J. W. A. Van LOON,

    1. Dutch Experiment Support Center, DESC at OCB-ACTA, VU-University and Univ. of Amsterdam, Amsterdam, the Netherlands
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  • ROBERTO MARCO

    1. Departamento de Bioquímica & Instituto de Investigaciones Biomédicas ‘Alberto Sols’ (UAM-CSIC), C/Arzobispo Morcillo, 4 Madrid, 28029 Spain
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    • Our colleague and friend Professor Roberto Marco passed away June 27th, 2008. This paper, his last contribution to Space Biology, is affectionately dedicated to his memory.


Raul Herranz, Fax: +34 91 536 04 32; E-mail: rherranz@cib.csic.es; raul.herranz@uam.es.

Abstract

Genome-wide transcriptional profiling shows that reducing gravity levels during Drosophila metamorphosis in the International Space Station (ISS) causes important alterations in gene expression: a large set of differentially expressed genes (DEGs) are observed compared to 1g controls. However, the preparation procedures for spaceflight and the nonideal environmental conditions on board the ISS subject the organisms to additional environmental stresses that demonstrably affect gene expression. Simulated microgravity experiments performed on the ground, under ideal conditions for the flies, using the random position machine (RPM), show much more subtle effects on gene expression. However, when the ground experiments are repeated under conditions designed to reproduce the additional environmental stresses imposed by spaceflight procedures, 79% of the DEGs detected in the ISS are reproduced by the RPM experiment. Gene ontology analysis of them shows they are genes that affect respiratory activity, developmental processes and stress-related changes. Here, we analyse the effects of microgravity on gene expression in relation to the environmental stresses imposed by spaceflight. Analysis using ‘gene expression dynamics inspector’ (GEDI) self-organizing maps reveals a subtle response of the transcriptome to microgravity. Remarkably, hypergravity simulation induces similar response of the transcriptome, but in the opposite direction, i.e. the genes promoted under microgravity are usually suppressed under hypergravity. These results suggest that the transcriptome is finely tuned to normal gravity and that microgravity, together with environmental constraints associated with space experiments, can have profound effects on gene expression.

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