March 9, 2009
3 pm in Howey Physics Room N110

 

Charles Wolgemuth
Department of Cell Biology
University of Connecticut Health Center

"A depolymerization winch drives nematode sperm motility"

 

Cell crawling motility is integral in many biological and biomedical processes, such as wound healing, cancer metastasis, and morphogenesis.  A complete understanding of the mechanisms by which cells crawl is still lacking, but it is known to entail at least three separate physical processes: (i) cytoskeletal extension at the front of the cell (also called protrusion); (ii) adhesion to the substrate at the cell front and release at the rear; and (iii) advance of the cell body (retraction of the rear). The motility of nematode sperm exhibits all three fundamental processes required for standard crawling motility.  These cells are considered to be a stripped-down motility apparatus, which makes them an ideal system for studying the biophysics of crawling motility.

In this talk I will present a mechanical model that describes the physics for how depolymerization of the cytoskeleton can drive motility.  This model accounts for both cytoskeletal displacements and the flow of fluid in the cell. The model accurately fits in vitro data using nematode sperm extracts where depolymerization induces contraction of polymer bundles. Application of this model to cell crawling produces testable predictions about how the size and shape of a cell affect crawling speed.  Experiments show good agreement with the model predictions.