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A "virtual cell" that biologists can use to test theories about how cells move has been created by University of California, Davis, mathematician Alex Mogilner and colleagues at UC Berkeley, Florida State University and the Medical Research Council laboratories in Mill Hill, England.

As a starting point, Mogilner took the motion of sperm cells from the hog roundworm, Ascaris. Biologists interested in cell motion study Ascaris sperm because they have a simple crawling motion driven by a single protein. Depending on the local pH, the protein either straightens itself out or curls up. By creating a pH gradient from the front to the back of the cell, the cell can pull itself along.

But while biology can supply some general answers, working out exactly how the cell moves requires complex mathematics, Mogilner said. To build the model, he wrote equations to describe the different processes inside the cell. Solving the equations produces an animation that shows how the virtual cell behaves under different conditions. For example, by changing the pH gradient in the virtual cell, the researchers could reproduce the responses of a real cell.

Mogilner is part of a large collaboration, funded by a National Institutes of Health "glue grant," to study cell motion. The studies have potential implications for understanding cancer, heart disease and wound healing, among other things.

The paper was published in the February issue of the Journal of Cell Science. Details were also presented at the recent annual meeting of the American Association for the Advancement of Science.

Note: Quicktime movies of the "virtual cell" model and of real Ascaris sperm cells in motion are available. Contact Andy Fell for details.