It seems that the skeletons within living cells may not form properly in zero gravity. This means that it may be impossible to live in space over the long-term without creating a form of artificial gravity.
Most cells have skeletons made up of microtubules made from fibres of the protein tubulin.
New Scientist magazine reports that Dr James Tabony and his colleagues from the French Atomic Energy Commission mixed up cold solutions of mammalian tubulin with an energy-releasing compound. Chemotherapy drugs may produce a similar effect When the mixture was warmed to body temperature for six minutes, microtubules began to form in distinct bands at right angles to gravity. They found that when microtubules formed, they pointed in all directions. Dr Lewis's team tested the impact of weightlessness on human white blood cells that were flown on board the space shuttle. After a day in orbit, the microtubules grew in random directions.