Title: Disorder and order of cell packing in developing fly wing

Speaker: Marko Popovic (Max Planck Institute, Dresden)

Abstract:

Tightly packed epithelial layers of cells are one of the main types of biological tissues. During tissue development, cellular packings commonly remains disordered, with a broad distribution of cell sizes. This pattern is also evident during the development of the wing of the fruit fly D. melanogaster. We analyze the dynamics of individual cells in developing fly wing over 13 hours of development and find that a simple model of cell cycle can explain the observed cell size distribution with no fitting parameters. Therefore, the polydispersity of cell sizes can be fully accounted for by the cell cycle. Strikingly, at a later stage of development, as cell proliferation halts, cellular packing transitions to an ordered hexagonal packing. We propose that this disorder-to-order transition is controlled by the reduction of cell size polydispersity, which we also observe in the experimental data. To explore this hypothesis further, we investigate this disorder-to-order transition in the vertex model of epithelial tissues, which allows us to interpret experimental observations. Finally, we explore mechanically and genetically perturbed fly wings and we find that the only case in which no transition to ordered state is observed corresponds to a perturbation where cell size polydispersity remained high. In summary, our work shows that natural progress of cell cycle maintains high cell size polydispersity, and corresponding disordered cell packing in developing fruit fly wing. However, upon sufficient decrease in cell size polydispersity cellular packing transitions to an ordered, hexagonally packed state.

This seminar will take place in room C4.174