http://www.newscientist.com/news/news_224734.html What a downer We may have to abandon our dreams of colonising space
THE skeletons within living cells may not form properly in zero gravity, say researchers in France. This could dent human ambitions to live in space--at least without artificial gravity. 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. To prove gravity is responsible, the team sent up tubulin on a European Space Agency (ESA) rocket, which exposed its payload to 13 minutes of weightlessness. 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 shows gravity triggers the pattern," says Tabony.
"Physicists insisted this research wasn't worth doing, because gravity is too small, compared to electrostatic or thermal forces on molecules, to affect chemical reactions," says Didier Schmitt, head of life sciences at ESA's European Space Technology and Research Centre in Noordwijk, the Netherlands. "This proves they were wrong." [rest of article at link]