Department Biological Physics
Frank Jülicher

for the Physics of Complex Systems
Nöthnitzer Straße 38
01187 Dresden

Tel. +49 351 871-1202
Fax. +49 351 871-1299
Curriculum Vitae
List of Publications
Research Interests

Theory of Biological Systems and Processes

The main focus of our research are theoretical approaches to understand dynamic processes in cells and tissues. Work on active cellular processes includes the study of cellular oscillations, cellular signaling and the cytoskeletal dynamics during cell division and cell motility. We furthermore study the biophysical basis of hearing. Finally, we investigate the biophysical properties and dynamics of tissues and epithelia. Based on the properties of individual cells and of cellular signaling systems, we are interested in the dynamics of developmental processes, for example wing development in the fruit fly.

Research topics include:

Active cellular processes
Cellular oscillations
Swimming of microorganisms
Cell locomotion

Physics of the cytoskeleton and of motor proteins
Active gels and fluids
Collective behaviors of motor proteins
Self-organization phenomena in the cytoskeleton

Physics of Cell Division

Tissues and developmental processes
Cellular packings in epithelia
Cellular rearrangements during growth and development
Morphogen signaling and morphogen gradient formation

Biophysics of hearing
Active mechanics of hair cells
Cochlear waves
Signal amplification by nonlinear oscillators

Research Highlights
Droplet Ripening in Concentration Gradients
C. Weber, C. F. Lee and F. Jülicher
New J. Phys. 19, 053021 (2017)
PDF (676 kB)]
Controlling Contractile Instabilities in the Actomyosin Cortex
M. Nishikawa, S. R. Naganathan, F. Jülicher and S. W. Grill
eLife 2017;10.7554/eLife.19595 (2017)
PDF (9,5 MB)]
Triangles Bridge the Scales: Quantifying Cellular Contributions to Tissue Deformation
M. Merkel, R. Etournay, M. Popovic, G. Salbreux ,S. Eaton and F. Jülicher
Phys. Rev. E. 95, 032401 (2017)
PDF (4 MB)]
Active Dynamics of Tissue Shear Flow
M. Popovic, A. Nandi, M. Merkel, R. Etournay, S. Eaton, F. Jülicher and G. Salbreux
New J. Phys. 19, 033006 (2017)
PDF (1,6 MB)]
Statistics of Infima and Stopping Times of Entropy Production and Applications to Active Molecular Processes

We derive general properties of entropy production fluctuations in nonequilibrium mesoscopic systems. In particular, we show that the minimal values of produced entropy are stochastic variables with a statistic that obeys general bounds. The average infimum of entropy production is bounded from below by - k_B. Our results can be applied to active molecular processes such as the stepping motion of molecular motors.

I. Neri, É. Roldán and F. Jülicher
Phys. Rev X, 7, 011019 (2017)
PDF (1,4 MB)]
Growth and Division of Active Droplets Provides a Model for Protocells

We show that liquid droplets that are driven away from thermodynamic equilibrium by chemical reactions can undergo cycles of growth and division reminiscent of living cells. We propose such active droplets as simple models for prebiotic protocells. Our work shows that protocells could have been able to propagate and divide without having established membranes.

D. Zwicker, R. Seyboldt, C. A. Weber, A. A. Hyman and F. Jülicher
Nature Physics 13, 408 (2017)
PDF (981 kB)]
Curvature regulation of the ciliary beat through axonemal twist

Cilia are hair like appendages of many cells that can generate motion and that can propel the swimming of microorganisms and sperm. We study the interplay between force generating processes and the three dimensional geometry of curved cilia. We show that torques generated by molecular motors in the cilium provide conditions in which local curvature can influence motor activity. Such curvature control provides a key mechanism for the generation of wave-like beats in short cilia.

P. Sartori, V. F. Geyer, J. Howard and F. Jülicher
Phys. Rev. E. 94, 042426 (2016)
PDF (754 kB)]
Sequential pattern formation governed by signaling gradients

The segmented body plan of vertebrate animals forms during the development of the embryo in a sequential process by which segment after segment is added. We presents a dynamic model for the interplay of dynamic oscillators and spatially graded signaling profiles that can account for the segmentation process as a self-organized pattern forming system in an active medium.

D. J. Jörg, A. C. Oates and F. Jülicher
Phys. Biol. 13 (2016)
PDF (1,3 MB)]
Polar Positioning of Phase-Separated Liquid Compartments in Cells Regulated by an mRNA Competition Mechanicsm

The cell cytoplams is a complex mixture of many molecules including proteins and RNA. Phase separation provides a physical mechanism to spatially organize the cytoplasm via the fromation of liquid-like droplets. Here we show that phase separation of certain RNA-protein droplets is regulated by RNA binding competition.

S. Saha, C. A. Weber, M. Nousch, O. Adame-Arana, C. Hoege, M. Y. Hein, E. Osborne-Nishimura,
J. Mahamid, M. Jahnel, L. Jawerth, A. Pozniakovski, C. R. Eckmann, F. Jülicher, and A. A. Hyman
Cell 166, 1572 (2016)
PDF (6 MB)]
The Selector Gene apterous and Notch Are Required to Locally Increase Mechanical Cell Bond Tension at the Drosophila Dorsoventral Compartment Boundary

Compartment boundaries separate different compartments in tissues. A local increase of mechanical tension at cell bonds governs the shape and roughness of such compartment boundaries. We show that specific signals are involved in the upregulation of tension. A physical model of tissue mechanics reveals the role of cell bond tension in shaping clones of mutant cells.

M. Michel, M. Aliee, K. Rudolf, L. Bialas, F. Jülicher and C. Dahmann
PLoS ONE 11, e0161668 (2016)
PDF (13,2 MB)]
Rheology of the Active Cell Cortex in Mitosis

The cell cortex is a thin film of an active gel below the cell membrane that generates an active tension. We study the material properties of this active film during cell division. We find that stress relaxation is governed by a range of relaxation processes that provide the cortex with dynamic response functions in response to tension changes and liquid like rheology at long times.

E. Fischer-Friedrich, Y. Toyoda, C. J. Cattin, D. J. Müller, A. A. Hyman and F. Jülicher
Biophys J. 111, 589 (2016)
PDF (2 MB)]
TissueMiner: a Multiscale Analysis Toolkit to Quantify how Cellular Processes Create Tissue dynamics

We provide a computational tool to study the collective dynamics of cells in tissues. Starting from microscopy data, large scale tissue deformations can be decomposen in contributions from cellular processes such as cell shape changes and cell rearrangments.

R. Etournay, M. Merkel, M. Popovic, H. Brandl, N. Dye, B. Aigouy, G. Salbreux,
S. Eaton and F. Jülicher
eLife 2016;10.7554/eLife.14334 (2016)
PDF (12,5 MB)]
Dynamic Curvature Regulation Accounts for the Symmetric and Asymmetric Beats of Chlamydomonas Flagella

The periodic bending motion of cilia and flagella arises from mechanical feedback: dynein motors generate sliding forces that bend the flagellum, and bending leads to deformations and stresses, which feed back and regulate the motors. Different possible feedback mechanisms have been proposed: regulation by the sliding forces, regulation by the curvature of the flagellum, and regulation by the normal forces that deform the cross-section of the flagellum. Here, we combined theoretical and experimental approaches to show that the curvature control mechanism accords best with the bending waveforms of Chlamydomonas flagella.

P. Sartori, V. F. Geyer, A. Scholich, F. Jülicher and J. Howard
eLife 2016;10.7554/eLife.13258 (2016)
PDF (5,9 MB)]
Determining Physical Properties of the Cell Cortex

Using a continuum description of active visco-elastic gels, we study the response of a contractile layer of an actomyosin gel to mechanical perturbations. This work is motivated by laser ablation experiments in cell biophysics. Our work shows that from the observation of the flow response to a linear later cut, key biophysical parameters of the contractile layer can be inferred.

A. Saha, M. Nishikawa, M. Behrndt, C.-P. Heisenberg, F. Jülicher and S. W. Grill
Biophys J. 110, 1421 (2016)
[PDF (2 MB)]
Activity Induces Traveling Waves, Vortices and Spatiotemporal Chaos in a Model Actomyosin Layer

Using a numerical approach, we investigate the spatiotemporal dynamics of an active polar gel in two dimensions. We find that when increasing the magnitude of active stresses, the system first undergoes a flow instability to stationary flow patterns. Subsequently, traveling wave solutions appear. Finally, for further increased active stress the system undergoes a transition to spatiotemporal chaos.

R. Ramaswamy and F. Jülicher
Scientific Reports 6, 20838 (2016)
[PDF (1,5 MB)]
Persistence, Period and Precision of Autonomous Cellular Oscillators from
the Zebrafish Segmentation Clock

We study the dynamics of gene expression of cells from the zebrafish segmentation clock in vitro. We show that single cells can behave as autonomous noisy cellular oscillations. The observed variability of cell behaviors can be captured by a generic oscillator model with correlated noise. We find that single cells have longer periods and lower precision than the tissue, highlighting the role of collective processes in the segmentation clock.

A. B. Webb, I. M. Lengyel, D. J. Jörg, G. Valentin, F. Jülicher, L. G Morelli and A. C. Oates
eLife 2016;10.7554/eLife.08438 (2016)
[PDF (2,6 MB)]
Interface Contractility between Differently Fated Cells Drives Cell Elimination
and Cyst Formation

We use a novel generalized vertex model to analyze epithelial morphogenesis in three dimensions. We show that increased actomyosin contractility at the interface between normal and aberrantly specified cells drives the formation of cysts while single cells are eliminated from the tissue.

C. Bielmeier, S. Alt, V. Weichselberger, M. La Fortezza, H. Harz, F. Jülicher,
G. Salbreux, A. Classen
Current Biology 26, 1 (2016)
[PDF (31,5 MB)]
Highlights 2015
Highlights 2014
Highlights 2013
Highlights 2012
Highlights 2011
Highlights 2010
Highlights 2009
Highlights 2008
Highlights 2007
Last updated: June 22, 2017