Control Strategies for the Polarotactic Orientation of the Microorganism Euglena gracilis

A simple mathematical model for the signal received by the dichroic photoreceptor molecules in the motile alga, Euglena gracilis, when irradiated by polarized light, is described and used to test hypotheses for the control strategies employed by the microorganism during negative phototaxis. The model is used to analyse and explain the experimental results of Häder (1987. Arch. Microbiol.147, 179–183).