From wildebeest herds to bacterial biofilms and every scale in between, how individuals self-assemble into large, spatially complex groups is a key problem in understanding collective behavior, multicellularity and development. The coordinated motion of individuals at the cellular level can drive the formation of higher-scale structure in tissues, organisms and populations. These phenomena arise statistically as cells modulate their direction and speed in response to both local and global cues. A full understanding of how collective behavior in cell populations arises has been difficult to achieve because the community currently lacks methods to physically probe sensory input, motor control, and group formation. Experiments examining the effect of specific mutations on single cell movement and group morphology have identified many important molecular players but lack the ability to probe the behavior of individuals within groups or physical aspects of motion production and coordination. While most current models of motile bacterial populations rely heavily on mechanical coupling between cells as a key driver of collective behavior, we have virtually no measurements of the effect of forces on cell movement or directionality in this context.
In this project the PI will study biophysical aspects of force production, motion control, and cell-cell coordination on the molecular to the multi-cellular level using the model social bacterium Myxococcus xanthus. The three aims of the work seek to determine the role of physical forces in coordinating cell speed and directionality and to elucidate the properties of single-cell motility that drive starvation-based aggregation. The experiments that will be performed will generate a huge leap forward in our understanding of how individual cells move and how they coordinate their activities to form large scale, motile structures. This project lies firmly within the goals of the Physics of Living Systems program at the NSF by using physical measurements and analyses to understand the dynamics of living cells across spatial scales. The PI has developed a cross-disciplinary Integrated Science course and will use the next several years to improve the course's curriculum by making it more accessible to a larger audience of US college students and, once complete, spearhead efforts to publish a textbook for broad dissemination. In addition, many of the techniques and analyses developed as part of this proposal will serve the larger microbiological community and will be made freely available.
This project is being jointly supported by the Physics of Living Systems program in the Division of Physics and the Cellular Dynamics and Function Program in the Division of Molecular and Cellular Biosciences.
