Microtubule self-organization is gravity-dependent

Although weightlessness is known to affect living cells, the manner by whic h this occurs is unknown. Some reaction-diffusion processes have been theor etically predicted as being gravity-dependent. Microtubules. a major consti tuent of the cellular cytoskeleton, self-organize in vitro by way of reacti on-diffusion processes. To investigate how self-organization depends on gra vity, microtubules were assembled under low gravity conditions produced dur ing space flight. Contrary to the samples formed on an in-flight 1 x g cent rifuge. the samples prepared in microgravity showed almost no self-organiza tion and were locally disordered.