Frank Jülicher

Dynamic processes in cells and tissues

Previous and current research

The main focus of our research is the theoretical study of active processes in biological systems on the scale of the cell and in tissues. An important example is the force and motion generation in cells by motor enzymes or assemblies of such motors. Tissues are remodeled dynamically by division and apoptosis. Biophysics of cells plays an important role in the pattering of tissues by signaling molecules. In a broader context, the cytoskeleton and tissues represent active materials. Active materials are able to generate spontaneous motion, to reorganize in order to change their structure and their material properties. Self-organization phenomena arise from the interplay of a large number of elements. For example, a collection of molecular motors that generate motion may have different properties than just the sum of many individual motors. Active materials can exhibit behaviors that differ strikingly from ordinary passive systems such as the occurrence of oscillatory behaviors and the generation of patterns in space and time. In addition to the general properties of active materials in cells and tissues, we study specific examples of dynamic phenomena in specialized cellular structures. Cilia and flagella generate a beating motion of propagating bending waves of long elastic structures which allow sperm to swim in a viscous environment. Auditory hair cells are able to generate spontaneous oscillatory motion of their hair bundles. They play an important role for active sound amplification in hearing. During development, cells communicate with the help of signaling systems. Morphogens build graded concentration profiles which provide positional information. We study the interplay of signaling and growth in order to discuss how complex patterns form during development.

Future prospects and goals

Future lines of research include

• We develop theoretical approaches to study the dynamics of cell polarity in tissues.

• We study the growth of developing tissues and the implications of growth for morphogen signaling.

• We develop theoretical descriptions of the mitotic spindle to understand spindle geometry and dynamics.

• We develop theoretical descriptions of the cell cortex to account for active behaviors which are observed in particular during cell division.

• We study the dynamics of vertebrate segmentation by coupled genetic oscillatiors.

About

1994: PhD University of Köln 1994-1996: Postdoctoral work at Simon Fraser University, Vancouver, Canada 1996-1997: Postdoctoral work at ESPCI, Paris, and Institute Curie, Paris 1998-2002: CNRS researcher at Institute Curie, Paris since 2002: Director at the Max Planck Institute for the Physics of Complex Systems

Selected publications

O. Wartlick, P. Mumcu, A. Kicheva, T. Bittig, C. Seum, F. Jülicher and M. Gonzalez-Gaitan. (2011): Dynamics of Dpp Signaling and Proliferation Control, Science 331, 1154

J. Ranft, M. Basan, J. Elgeti, J.-F. Joanny, J. Prost and F. Jülicher (2010): Fluidization of Tissues by Cell Division and Apoptosis, Proc. Natl. Acad. Sci. USA 107, 20863

B. Aigouy, R. Farhadifar, D. B. Staple, A. Sagner, J.-C. Röper, F. Jülicher and S. Eaton (2010): Cell Flow Reorients the Axis of Planar Polarity in the Wing Epithelium of Drosophila, Cell 142, 773

B. M. Friedrich, I. H. Riedel-Kruse, J. Howard and F. Jülicher (2010): High-precision tracking of sperm swimming fine structure provides strong test of resistive force theory, Journal of Experimental Biology 213, 1226

L. Morelli, S. Ares, L. Herrgen, C. Schröter, F. Jülicher and A. Oates (2009): Delayed Coupling Theory of Vertebrate Segmentation, HFSP J. 3, 55

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