Author's School

Graduate School of Arts & Sciences

Author's Department/Program



English (en)

Date of Award

Spring 3-28-2013

Degree Type


Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Anders E Carlsson


Forces and stresses generated by the action of myosin minifilaments are analyzed via simulation of their motion in idealized computer-generated random, isotropic actin networks and actin bundles. The networks and bundles are generated as random collections of actin filaments in two dimensions with constrained orientations, crosslinked and attached to fixed walls: four walls for isotropic networks, two for bundles). Myosin minifilaments are placed on actin filament pairs and allowed to move and deform the network so that it exerts forces on the walls.

The stresses are overwhelmingly contractile in both cases, because minifilament equilibrium positions having contractile stress have lower energy than those for expansive stress. Mini-filaments rotate into these energetically stable contractile configurations. This process is aided by the bending of actin filaments, which accomodates mini-filament rotation. The presence of force chains leads to unexpectedly large stresses especially in the random networks. Stresses for bundles are greater than those for isotropic networks, and antiparallel filaments generate more tension than parallel filaments. The forces transmitted by the actin network to the walls of the simulation cell often exceed the tension in the minifilament itself.


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