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DEMONSTRATION OF ON LINE CELL SHAPE CHANGES DUE TO GRAVITY   Jack J.W.A. van Loon^(1*), Meie C. van Laar⁽¹⁾, Jeroen P. Korterik⁽²), Frans B. Segerink⁽²⁾, Rene J. Wubbels⁽³⁾, Herman A. A. de Jong⁽³⁾, Niek F. Van Hulst^{(2)   1:} DESC-ACTA-VU, van der Boechorststraat7, Amsterdam. ^2: Applied Optics group, Fact. Appl. Physics, Univ. Twente, Enschede, NL. ^3:Vestibular Department ENT, AMC, UvA, Amsterdam, NL.

   Cell shape and integrity depend, at least partially, on the equilibrium of intracellular and extracellular mechanical forces applied to that cell. In contract to a complete organism under near weightlessness conditions where e.g. bones and muscles are highly unloaded, gravity is a nearly insignificant force at the scale of a single cell. Past space flight and ground based cell biological studies in hypogravity or hypergravity environments showed changes in e.g. cell behavior (signal transduction) cell shape (cytoskeleton) or proliferation. From these studies it is not always clear whether these result emerged from direct of indirect effects of (micro-) gravity.
In the current pilot study we measured changes of cell shape under various hypergravity conditions. Cell shape was measured both in cells fixed after rotation in a small diameter tissue culture centrifuge (MidiCAR) as well as on line using an atomic force microscope (AFM) mounted onto the large diameter centrifuge at the AMC in Amsterdam. We have shown that cells do change shape under hypergravity conditions and that it is feasible to investigate these changes on line using AFM.

(Supported by NWO-SRON grant MG-053/057)