MONDAY, March 17, 2003

3:00 PM

CAB 657

Dr. Eirikur Palsson

Department of Biological Sciences
Simon Fraser University

A 3-D model to study interplay of cell adhesion and chemotaxis in multicellular systems.


A biologically realistic three dimensional mathematical model that facilitates the simulation and visualization of cell movement in multicellular systems, has been developed. In this talk I will introduce the model, show examples of its applications, compare the results with experimental data and present results that highlight the interplay of chemotaxis and adhesion in cell sorting and movements. The building blocks of the model are individual deformable ellipsoidal cells; each cell having certain given properties, not neccesarily the same for all cells. Since the model is based on known processes, the parameters can be estimated or measured exprimentally. The organism that I focus on here is the cellular slime mold Dictyostelium discoideum; A videly used model system for studying a variety of basic processes in development, including cell-cell signaling, signal transduction, pattern formation and cell motility. Here I will show that this model can reproduce the observations of the chemotactic behavior of single cells, streaming during aggregation, and the collective motion of an aggregate of cells driven by a small group of pacemakers. The model predicts that the motion of two-dimensional slugs results from the same behavior that are exhibited by individual cells; it is not necessary to invoke different mechanisms or behaviors. I will also demonstrate how differences in adhesion between pre-stalk and pre-spore cells, affect the sorting and separation of those cell types, that occurs during the slug stage, and I will suggest and explain why chemotaxis alone might not be sufficient to achieve complete sorting.