Theory of Living Matter Group

A central question in developmental biology concerns the relationship between gene activity and the arrangements of cells that we call tissues and organs. Classical biology envisions this as the result of deterministic programmes of gene expression acting homogeneously within cell populations. However, analysis of gene expression at the level of single cells engaged in these programmes reveals an unexpected degree of transcriptional heterogeneity which needs to be reconciled with the homogeneous and reproducible organization observable at the level of large groups of cells. The mechanisms that mediate, maintain and regulate these heterogeneities are at the center of my interests and the main subject of the research of my group. In this talk I shall discuss how we use mouse Embryonic Stem (ES) cells to understand the ways in which heterogeneous, and to a certain degree stochastic, patterns of gene expression are averaged within cell populations to produce dynamically stable patterns of cell fates in a reproducible manner. At the end I shall show some examples of symmetry breaking and self organization in ensembles of ES cells which raise significant challenges to both physicists and biologists. Throughout my discussion I shall emphasize how statistical physics provides an inspiration and a reference to address the relationship between genes and tissues.