UC San Diego bioengineers fill holes in science of cellular self-or...( The chemical and biological aspects ...)

The chemical and biological aspects of cellular self-organization are well-studied; less well understood is how cell populations order themselves biomechanically how their behavior and communication are affected by high density and physical proximity. Bioengineers and physicists at the University of California San Diego, in a paper published in the current issue of the Proceedings of the National Academy of Sciences, have begun to address these fundamental questions.

The UC San Diego scientists focused their research on dense colonies of the rod-shaped bacteria Escherichia coli. By analyzing the spatial organization of the bacteria in a microfluidic chemostat a kind of mini-circuit board for liquids rather than electrons they found that growth and expansion of a dense colony of cells leads to a dynamic change from relative disorder to a remarkable re-orientation and alignment of the rod-like cells.

That finding, described in their paper "Biomechanical Ordering of Dense Cell Populations," allowed them to develop a model of collective cell dynamics, and to use this model to "elucidate the mechanism of cell ordering, and quantify the relationship between the dynamics of cell proliferation and the spatial structure of the population."

One of the authors, Lev S. Tsimring, at UC San Diego's Institute of Nonlinear Science, explained the bioengineers' use of bacteria to study the biomechanical ordering of cells.

"When environmental conditions are harsh, bacteria like to stick together. The most typical form of bacterial organization in nature is a biofilm: a dense quasi-two-dimensional colony of bacteria. Biofilms grow in and on living tissues, the surfaces of rocks and soils, and in aquatic environments," he said, "but they're also found in man-made systems and devices such as industrial piping and artificial implants. And bacteria are known to actively migrate toward surfaces and small cavities, where they form hig
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