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Microtubules Disruption and Repair in Cultured Glial Cells under Microgravity.   M.A. Masini1, F. Strollo2, F. Ricci3, M. Pastorino1 and B.M. Uva1 1Dept. of Biology, University of Genoa, 2INRCA and University La Sapienza, Rome, 3ENEA-C.R. Casaccia, Rome, Italy.

   The cytoskeleton is a network of fibres sensitive to altered environmental factors including gravitational vector changes. Microtubules, one  of the major components of the cytoskeleton are responsible of intracellular transport of mitochondria and other organelles and of cell division. Microtubules therefore have a pivotal role in cellular integrity and function. Lymphocytes flown in Space (Lewis et al., 1998) showed severe alterations in the cytoskeleton and earth-bound simulation of low gravity using a 3D Random Positioning Machine showed disassemblation of the microtubules in cultured astrocytes after only 15 minutes. After 1 hour about 70% of the cell population underwent apoptosis (Uva et al., 2002). Glia is  fundamental component of the nervous system, glial cells interact with the neurons in a complex way that is essential for the nervous system to work properly. Glial membranes are in fact actively involved in exchange of nutrients, neurotransmitters, second messengers, ions and growth factors all of which are fundamental processes of brain function. Impairment at central nervous system level were experienced by astronauts during spaceflights. Aim of our study was to investigate if bivalent ions, like Mg2+ and Ca2+, added to the culture medium are able to protect the cellular cytoskeleton preventing the depolymerization of microtubules. For the purpose we submitted glial cells (C6 line) to  clinorotation for 15 min, 30 min, 1 h, 24 h cultured in medium with or without bivalent ions.