Deciphering Coarsening Dynamics and Cluster Migration using Experiments and Models

University Of California-San Diego, La Jolla CA

Investigators

Abstract

During the process known as coarsening, smaller objects merge together into larger and larger ones. This process occurs on many different length scales and plays an important role in living systems: nuclear proteins coarsen into condensed droplets, bacteria coalesce into multicellular aggregates, and animals aggregate into large groups. The dynamics of these biological systems are typically driven by long-range communication between the elements. It is currently not clear, however, how this communication and the motion of the elements are coupled and result in coarsening. This award will focus on the coarsening dynamics of clusters of Dictyostelium discoideum cells, an amoeboid system. These cells form small and isolated clusters that subsequently move together and coarsen into larger and larger ones. The communication in this system is provided by a secreted chemoattractant, a chemical that directs the motion of the cells and clusters. This award will quantify the dynamics of coarsening by measuring the number and size of clusters and the secretion of the chemoattractant as a function of time. In addition, the study will use traction force microscopy, a technique that uses beads on deformable substrates, to quantify the forces exerted by the clusters when they migrate and coalesce. Together, these measurements will provide a better understanding of the mechanisms that are responsible for the collective migration exhibited by clusters during coarsening. The experimental results will also be used to develop comprehensive mathematical models, which will generate predictions that can be experimentally verified, resulting in a two-way dialogue between experiments and modeling. In addition, this award will include the training of high school, undergraduate, and graduate students who will be directly involved in the proposed research. Finally, as part of this project, yearly “Dicty Days" will be organized at two local high schools. During these two-day events students will be able to perform simple hands-on experiments to help stimulate their interest in biological physics. These students will be integrated into the lab and taught how to design, carry out, and interpret experiments and simulations, with the goal of attracting diverse students to a career in the biophysical sciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.