Defect-mediated morphogenesis. Do cellular tissues know geometry?
Livio Nicola Carenza
Abstract: It has been a long-standing mystery how complex biological structures emerge during embryonic development from such seemingly uncoordinated building blocks as cells and tissues without guidance. Recent experiments have suggested that misalignment in the collective structure of tissues –the so called topological defects– could play a fundamental guiding role in morphogenesis, that is the process of complex shape formation in the early-stage of life.
In this seminar, I will discuss the origin of this phenomenon explaining how active defects interact with geometry and how this plays a crucial role in morphogenetic processes. I will start by introducing the well-recognized active gel theory (1) to model an active deformable surface and study structure formation in cell monolayers. By means of analytical and numerical analysis, I will show how the cooperative interaction of active defects and geometry drives the buckling instability of the active membrane. This eventually results in the formation of long protrusions with a tentacle shape or even the nucleation of a vesicle (2).
This work clarifies the interaction of active defects and geometry and provides new insight into the physics beyond processes such as the metastatic cascade in cancer development or embryogenesis
(1) K. Kruse, J. F. Joanny et al. Phys. Rev. Lett. 92, 078101 (2004); R. A. Simha and S. Ramaswamy Phys. Rev. Lett. 89, 058101 (2002).