# Spontaneous center formation in Dictyostelium discoideum

## TL;DR

This paper investigates how spontaneous formation of activity centers and target waves of cAMP in Dictyostelium discoideum can be explained by adding cell inhomogeneity to a reaction-diffusion model, revealing the role of cell density and wave dynamics.

## Contribution

It introduces a mechanism for spontaneous center formation in D.d. by incorporating cell inhomogeneity into a reaction-diffusion model, advancing understanding of natural pattern emergence.

## Key findings

- Stable activity centers emerge in high-density areas.
- cAMP wave velocity increases with cell density.
- Cells react to waves and form aggregation streams.

## Abstract

Dictyostelium discoideum (D.d.) is a widely studied amoeba due to its capabilities of development, survival, and self-organization. During aggregation it produces and relays a chemical signal (cAMP) which shows spirals and target centers. Nevertheless, the natural emergence of these structures is still not well understood. We present a mechanism for creation of centers and target waves of cAMP in D.d. by adding cell inhomogeneity to a well known reaction-diffusion model of cAMP waves and we characterize its properties. We show how stable activity centers appear spontaneously in areas of higher cell density with the oscillation frequency of these centers depending on their density. The cAMP waves have the characteristic dispersion relation of trigger waves and a velocity which increases with cell density. Chemotactically competent cells react to these waves and create aggregation streams even with very simple movement rules. Finally we argue in favor of the existence of bounded phosphodiesterase to maintain the wave properties once small cell clusters appear.