Topological defects induce layer formation in bacterial colonies
Speaker: Ricard Alert, Princeton Center for Theoretical Science Princeton University
Abstract: Under starvation, colonies of the soil bacterium Myxococcus xanthus develop macroscopic fruiting bodies, which initially grow by stacking up cell layers. But how are new cell layers formed? In each layer, elongated M. xanthus cells are densely packed and aligned, much like the elongated molecules of liquid crystals. Moreover, cells are motile, and hence the colony forms an active liquid crystal. We find that new layers form at topological defects of the nematic director field. We explain this finding by means of an active liquid crystal model, with which we predict cell flows around defects in agreement with experimental measurements. Thus, we conclude that cell motility and mechanical forces between cells are sufficient to induce layer formation at topological defects, thereby seeding fruiting bodies in M. xanthus colonies.
Room Reservation Information
Room Number: 106 McAllister
Time: 1:30pm - 2:30pm