  Actin is a filamentary protein which has many remarkable properties making it
an ideal system for the study of the dynamics and mechanics of semi-flexible
polymer solutions and gels; actin has a persistence length of over 10 microns
and can polymerize to lengths of several tens of microns, this permits the use
of video microscopy and other optical methods in the study polymer dynamics.
Many associated proteins exist which can be used to regulate length or
crosslink filaments. We discuss the dynamics and rheology of these solutions.
