Dissipative structures and morphogenetic pattern in unicellular algae

Abstract

Patterns of cell wall growth and ornamentation in unicellular algae, mainly in desmids, are compared with patterns generated by Tyson’s Brusselator, a two-morphogen reaction-diffusion model. The model generates hexagonal arrays of points in two dimensions, according well with the observed patterns of surface ornamentation on desmid zygospores. Computed patterns in one dimension and of branching on a circular disc account both qualitatively and quantitatively for morphogenetic patterns that develop following cell division in several desmid genera. Cell wall ingrowths appear to be under similar pattern control to wall outgrowths during morphogenesis, which suggests the involvement of a reaction-diffusion mechanism in establishing and correctly positioning the cell division septum. The application of the model to morphogenesis in Acetabularia and diatoms is also discussed.