What a downer By Debora MacKenzie THE skeletons within living cells may not form properly in zero gravity, say researchers in France. Their work also proves that, contrary to received wisdom, gravity can influence chemical reactions.
Most cells have cytoskeletons of microtubules, which are fibres made of the protein tubulin.
James Tabony and his colleagues at the French Atomic Energy Commission lab in Grenoble found that when cold solutions of mammalian tubulin and the energy-releasing compound GTP are warmed to body temperature for six minutes, microtubules form in distinct bands. What is striking is that the bands form at right angles to gravity or, if spun, to the centrifugal force. Some tubulin experienced only microgravity while being warmed for the critical six minutes, but other samples were spun in a centrifuge. The spinning microtubules formed bands as usual, but those that experienced only microgravity pointed in all directions. This proves they were wrong.