An individual based model of rippling movement in a myxobacteria population

Migrating cells of Myxococcus xanthus (MX) in the early stages of starvation-induced development exhibit elaborate patterns of propagating waves. These so-called rippling patterns are formed by two sets of waves travelling in opposite directions. It has been experimentally shown that formation of these waves is mediated by cell–cell contact signalling (C-signalling). Here, we develop an individual-based model to study the formation of rippling patterns in MX populations. Following the work of Igoshin et al. (Proc. Natl. Acad. Sci. 98 (2001) 14913) we consider each moving cell to have an internal clock which controls its turning behaviour and sensitivity to C-signal. Specifically, we examine the effects of changing: C-signal strength, sensitivity/refractoriness, cell density, and noise upon the formation and structure of the rippling patterns. We also consider three modified models that have no explicit refractory period and examine their ability to produce rippling patterns.