Developmental decisions in Physarum polycephalum: Single cell trajectories of gene expression, Petri nets, and the Waddington quasipotential landscape

Prof. Dr. Wolfgang Marwan

Regulationsbiologie, Otto von Guericke Universit├Ąt, Magdeburg

 

The developmental switch to sporulation in the unicellular eukaryote Physarum polycephalum is a phytochrome-mediated far-red light-induced cell fate decision. It synchronously encompasses the entire multinucleate plasmodial cell and is associated with extensive reprogramming of the transcriptome. By repeatedly taking samples of single cells after delivery of a light stimulus pulse, we quantitatively analyse differential gene expression to obtain a time series dataset for each cell. Computational analyses of the gene expression data reveal individually different single cell trajectories eventually leading to sporulation. Characterization of the trajectories as walks through states of gene expression allows to reconstruct Petri nets that model and predict the behavior of single cells. Structural analyses of these Petri nets reveals the global behaviour of the regulatory network, the differential regulation of individual genes, and it gives access to the quasipotential landscape that determines the developmental decision.