Hydra regeneration: a window on morphogenesis

Morphogenesis, the emergence of well-defined patterns of functional tissues during development, is carried out by the collective dynamics of multiple physical and biochemical processes at different levels of organization, from local molecular events to large-scale chemical, electrical and mechanical stress fields. Morphogenesis emerges by the interaction of these various processes, which must evolve simultaneously as coupled fields. We take advantage of a unique multicellular organism, Hydra, famous for its extraordinary regeneration capabilities, to advance our biophysical understanding of morphogenesis. I will discuss our recent experiments on Hydra regeneration, shedding light on the role of the actomyosin cytoskeleton and the forces it generates during morphogenesis. We apply mechanical constraints by studying regeneration from tissue segments anchored on wires, showing that the wires induce order in morphogenesis. Finally, we utilize external force fields, hydrodynamic flows, electric fields and magnetic forces on beads attached to the regenerating tissue, to induce spatio-temporal modes during the regeneration process. Perturbing the regeneration process and imposing external constraints enable us to expose alternative developmental trajectories.