Research Groups

Research Area: Biophysics

Self-Organization of Multicellular Systems


Previous and current research:

Cell sheet deformations during animal development are driven by an intricate interplay of cell shape changes, cell division, ....
Models of these processes have therefore often been cell-based, but, by their very nature, such models obfuscate the tissue-level mechanical properties arising from properties at the cellular level. To elucidate this mechanical basis of morphogenesis, my research has focused on the continuum mechanics of simple morphogenetic events.
My research interests are at the interface of biophysics, soft matter physics, and mathematical biology. Two areas of interest for my past and current research on the mechanics of developmental biology are
(1) Inversion in Volvox: the embryos of the green alga Volvox are spherical sheets of cells that turn themselves inside out at the end of their development. This inversion, arising from cell shape changes alone yet sharing features of development in higher organisms, is a simple model organism for the mechanics of cell sheet folding.
In close collaboration with experimentalists, I have derived a theory for Volvox inversion in which the cell shape changes appear as variations of the intrinsic stretches and curvatures of an elastic shell, explained the mechanical basis for the arrest of inversion in mutants and chemically treated embryos. This work culminated in a detailed, quantitative comparison of experiment and theory.
(2) Continuum mechanics of cell sheets: Cell sheets and tissues undergo large out-of-equilibrium deformations during development. While there is now a framework of active gels to describe such out-of-equilibrium continuum materials, the nonlinear constitutive laws for large deformations of continuum biological materials are still poorly understood. I have contributed to this question by showing how the continuum limit of a class of well-studied discrete models of cell sheets differs from nonlinear elasticity by additional, nonlocal and nonelastic terms. Moreover, extending the classical elastic thin shell theories, I have shown how the large bending deformations that are common in development lead to a material anisotropy of purely geometric origin.

Future projects and goals:

At the MPI-PKS and the CSBD, my group will collaborate with experimental groups at the MPI-CBG to answer fundamental questions of developmental biology, while also contributing to more theoretical problems of biological mechanics. Questions for future research include:
(1) How is robust development possible in spite of large amounts of biological variability and mechanical constraints?
(2) What are the continuum theories that describe biological tissues and the processes of cell migration and cell intercalation that they undergo during development?

Methodological and technical expertise:

Theoretical Biophysics, Continuum Mechanics, Theory of Soft Matter, Mathematical Biology, Numerical modeling and data analysis