Spatial patterns from oscillating microtubules.

Microtubules are fibers of the cytoskeleton involved in the generation of cell shape and motility. They can be highly dynamic and are capable of temporal oscillations in their state of assembly. Solutions of tubulin (the subunit protein of microtubules) and guanosine triphosphate (GTP, the cofactor required for microtubule assembly and oscillations) can generate various dissipative structures. They include traveling waves of microtubule assembly and disassembly as well as polygonal networks. The results imply that cytoskeletal proteins can form dynamic spatial structures by themselves, even in the absence of cellular organizing centers. Thus the microtubule system could serve as a simple model for studying pattern formation by biomolecules in vitro.