Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 17: Posters: Physics of Cells

BP 17.39: Poster

Mittwoch, 28. März 2012, 17:30–19:30, Poster A

Critical behaviour and axis defining symmetry breaking in Hydra embryonic development — •Heike Dobicki¹, Andrea Gamba², Mario Nicodemi³, Albrecht Ott¹, Aravind Pasula¹, Mathias Sander¹, and Jordi Soriano⁴ — ¹Biol. Experimentalphysik, Univ. d. Saarlandes — ²Politecnico di Torino and CNISM — ³Dip.to di Science Fisiche, Universitá di Napoli "Federico II" — ⁴Dept. d'ECM, Facultat de Física, Univ. de Barcelona

Axis-determination plays a pivotal role in embryogenesis, development and tissue regeneration. Before axis locking, animal embryos usually go through a phase, which features a fluid-filled cavity, surrounded by a sphere of cells, called a blastula. Hydra vulgaris, a fresh-water cnidarian, has a radial symmetry with a head-to-foot axis. It can reproduce either sexually or asexually by budding. The hydra regeneration process starts with a spherical shape similar to a blastula in embryonic development. The cell sphere actively oscillates until it establishes the head-to-foot axis and subsequently develops into a complete animal. We have observed a self-similar distribution of the ks1-gene on the cell sphere at the symmetry breaking moment. We suggest that the main features of hydra axis establishment can be inferred from the limited communication ability of the cells. A numerical simulation based on a fluctuating cell state, which spreads between neighboring cells only, reproduces all of the observed experimental data well. Besides the critical state that occurs at the axis locking moment, this also includes a bistable distribution of the axis orientation by a weak temperature gradient.