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
Determining Physical Properties of the Cell Cortex
A. Saha, M. Nishikawa, M. Behrndt, C.-P. Heisenberg, F. Jülicher and S. W. Grill
Biophys J. 110, 1421 (2016)
[PDF (2 MB)]
Persistence, Period and Precision of Autonomous Cellular Oscillators from
the Zebrafish 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

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)]
Decision Making in the Arrow of Time

Irreversibility is a hallmark of nonequilibrium processes. It implies that time reversal invariance of microscopic equations of motion is broken at meso and macro scales. Here we show that the degree of irreversibility of a physical process can be quantified by the time it takes an observer to decide whether a movie of the process runs forward or in reverse. We derive an exact relation between the average entropy production rate and the optimal decision time and we introduce a fluctuation theorem for the decision time distribution.

E. Roldán, I. Neri, M. Dörpinghaus, H. Meyr and F. Jülicher
Phys. Rev. Lett. 115, 250602 (2015)
[PDF (426 kB)]
Polarized Endosome Dynamics by Spindle Asymmetry During Asymmetric Cell Division

During asymmetric cell division, the molecular components of the dividing cell are distributed unequally to the two daughter cells. Here, we study the asymmetric distribution of signaling endosomes to the two daughter cells which plays an important role for cell fate determination. We show that the unequal distribution of endosomes results from an asymmetry of the microtubule distribution at the central spindle. Using a simple stochastic model, we reveal a physical mechanism by which a weak asymmetry of the density of antiparallel microtubules is amplified by kinesin mediated endosome motility to generate a strong asymmetry of endosome targeting to the daughter cells. Out model can quantitatively account for the stochastic endosome trajectories observed during division.

E. Derivery, C. Seum, A. Daeden, S. Loubéry, L. Holtzer, F. Jülicher and M. Gonzalez-Gaitan
Nature 528, 280 (2015)
[PDF (17,9 MB)]
A Local Difference in Hedgehog Signal Transduction Increases Mechanical Cell Bond Tension
and Biases Cell Intercalations along the Drosophila Anteroposterior Compartment Boundary

We study the properties of tissue boundaries in the context of cellular signaling. Using a quantification of boundary roughness in different signaling conditions, we show that differences in Hedgehog signal transduction between neighboring cells are key to control cell bond tension. An increased cell bond tension subsequently provides smooth and stable tissue interfaces.

K. Rudolf, D. Umetsu, M. Aliee, L. Sui, F. Jülicher and C. Dahmann
Development 142, 3845 (2015)
[PDF (5 MB)]
Continuum Theory of Gene Expression Waves during Vertebrate Segmentation

The segmentation of the vertebrate body plan during embryonic development is a rhythmic and sequential process governed by genetic oscillations of cells that give rise to collective wave patterns. We present a continuum theory of genetic waves and discuss wave phenomena that can be observed in these nonlinear wave patterns: a Doppler effekt and a dynamic wavelength effect.

D. J. Jörg, L. G. Morelli, D. Soroldoni, A. C. Oates and F. Jülicher
New J. Phys. 17, 093042 (2015)
[PDF (2 MB)]
Suppression of Ostwald Ripening in Active Emulsions

We study the dynamics of fluid droplets that turn over by chemical processes. Such active droplets exhibit unusual properties both in the simple case of first-order reactions and for autocatalytic droplets. Active droplets can have stable sizes and several droplets of equal size can stably coexist. This suppression of Ostwald ripening can be understood as a consequence of chemical reactions.

D. Zwicker, A. A. Hyman and F. Jülicher
Phys. Rev. E 92, 012317 (2015)
[PDF (918 kB)]
Interplay of Cell Dynamics and Epithelial Tension during Morphogenesis of the Drosophila Pupal Wing

We combine experiment and theory to study tissue dynamics and remodeling in the developing fly wing. We quantify the contributions of different celular processes to tissue deformations. Using this information we develop a theory of tissue mechanics which reveals key principles underlying tissue deformation. We find that during pupal development, the fly wing is shaped in an active process that is guided by mechanical boundary conditions. We can explain the role of the extracellular matrix protein dumpy in this process and reveal the mechanism by which dumpy mutants exhibit misformed wing shapes.

R. Etournay, M. Popovic, M. Merkel, A. Nandi, C. Blasse, B. Aigouy, H. Brandl, G. Myers, G. Salbreux, F. Jülicher and S. Eaton
eLife 2015;10.7554/eLife.07090 (2015)
PDF (14 MB)]
Scaling and Regeneration of Self-Organized Patterns

Biological pattern formation such as for example the development and regeneration of an organism is often scalable with organism size. Here, we introduce a generalization of Turing patterns that is self-organized and self-scaling. A feedback loop regulates the reaction rates of a Turing system, thereby adjusting pattern length scales proportional to system size. Our model captures key features of body plan regeneration in flatworms as observed in experiments.

S. Werner, T. Stückemann, M. Beirán Amigo, J. C. Rink, F. Jülicher and B. M. Friedrich
Phys. Rev. Lett. 114, 138101 (2015)
PDF (295 kB)]
Active Torque Generation by the Actomyosin Cell Cortex Drives left-right
Symmetry Breaking

We show that chirally asymmetric flows occur in the cell cortex during cell division in C. elegans. These flows can be accounted for by a general hydrodynamic theory of gels in which active chiral processes take place. Our work suggests that active chiral flows generated in the actin cytoskeleton contribute to the left-right symmetry breaking of the C. elegans body plan.

S. R. Naganathan, S. Fürthauer, M. Nishikawa, F. Jülicher and S. W. Grill
eLife 2014;3:e04165 (2014)
PDF 2,8 MB)]

Synchronization in Networks of Mutually Delay-Coupled Phase-Locked Loops

We study the synchronization of coupled electronic oscillators based on phase-locked loops. We show that delays in signal transmission between such oscillators can facilitate synchronization. Despite the high transmission speeds in electronic circuits, such delays can be significant at the high frequencies used in modern electronics.

A. Pollakis, L. Wetzel, D. J. Jörg, W. Rave, G. Fettweis and F. Jülicher
New J. Phys. 16, 113009 (2014)
PDF (655 kB)]

The Balance of Prickle/Spiny-Legs Isoforms Controls the Amount of Coupling
between Core and Fat PCP Systems

We study the dynamics of planar cell polarity in the developing fly wing. We show that the observed time-dependence of cell polarity patterns in wild type and several mutant conditions can be understood from a general hydrodynamic theory. We find that cell polarity reorientation is guided by both tissue shear and by coupling to the Fat planar polarity system. The latter is regulated by the Prickle/Spiny-Legs Isoforms.

M. Merkel, A. Sagner, F. S. Gruber, R. Etournay, C. Blasse, E. Myers, S. Eaton and F. Jülicher
Current Biololgy 24, 2111 (2014)
PDF (18,1 MB)]

Stress Distributions and Cell Flows in a Growing Cell Aggregate

We present a hydrodynamic theory of the mechanics and dynamics of spherical cell aggragates. Our work suggests that cells exhibit a radial pattern of cell polarity that is relevant to the cell density and stress profiles obtained when the cell aggregate is subject to a jump in external pressure.

M. Delarue, J.-F. Joanny, F. Jülicher and J. Prost
Interface Focus 4, 20140033 (2014)
PDF (492 kB)]

Quantification of Surface Tension and Internal Pressure Generated by Single Mitotic Cells

Using an assay in which cells are compressed between two surfaces, we determine the active mechanical tension of the cell cortex of mitotic cells.

E. Fischer-Friedrich, A. A. Hyman, F. Jülicher, D. J. Müller and J. Helenius
Scientific Reports 4, 6213 (2014)
PDF (705 kB)]

An Active Oscillator Model Describes the Statistics of Spontaneous Otoacoustic Emissions

The ears of mammals have the ability to amplify weak stimuli by active processes. A signature of this cochlear amplifier are spontaneous emissions that can be detected in the ear canal. Here we present a model of the mammalian cochlea that contains dynamic oscillators as active elements.We show that this model can account for the statistics of spontaneous emissions observed in humans.

F. Fruth, F. Jüicher, B. Lindner
Biophys J. 107, 817 (2014)
PDF (1,6 MB)]

Local Increases in Mechanical Tension Shape Compartment Boundaries by
Biasing Cell Intercalations

We discuss the dynamics of tissues in the developing fly. Within a tissue compartment, cells can mix while cells of different tissue compartments do not mix. We show that local mechanical tension at a compartment boundary biases cell junction remodeling, thereby preventin cell mixing across compartment boundaries.

D. Umetsu, B. Aigouy, M. Aliee, S. Sui, S. Eaton, F. Jülicher and C. Dahmann
Current Biology 24, 1798 (2014)
PDF (3,9 MB)]

Active Phase and Amplitude Fluctuations of Flagellar Beating

Flagella are hair-like extensions of many cells that generate periodic movements and can propel microorganisms in a fluid. Here, we analyze the motion of a beating flagellum and quantify amplitude and phase fluctuations. We discuss these active fluctuations in the context of stochastic many-motor systems.

R. Ma, G. S. Klindt, I. H. Riedel-Kruse, F. Jülicher and B. Friedrich
Phys. Rev. Lett. 113, 048101 (2014)
PDF (1,3 MB)]

Multimotor Transport in a System of Active and inactive Kinesin-1 Motors

We study the collective effects of large groups of motor molecules of which a fraction is inactive. We show that interesting dynamic instabilities and bimodal velocity distributions can occur as a function of the fraction of inactive motors.

L. Scharrel, R. Ma, R. Schneider, F. Jülicher and S. Diez
Biophys. J. 107, 365 (2014)
PDF (1 MB)]

A Doppler Effect in Embryonic Pattern Formation

The segmented body plan of vertebrate animals is formed by a sequential process during development called somitogenesis. The subsequent formation of somites is organized by collective genetic oscillations in the unpatterned tissue. These cellular oscillations give rise to nonlinear wave patterns of gene activity. Here we analyze the dynamics of these waves and show that a Doppler effects contributes to the timing of segmentation.

D. Soroldoni, D. J. Jörg, L. G. Morelli, D. L. Richmond, J. Schindelin, F. Jülicher and
A. C. Oates
Science 345, 222 (2014)
PDF (623 kB)] Supplementary Material

Centrosomes are Autocatalytic Droplets of Pericentriolar Material Organized by Centrioles

Centrosomes are located at the poles of mitotic spindles during cell division. They assemble around centrioles and can occur in different sizes. We propose that centrosome properties can be understood as a liquid like phase that assembles by an autiocatalytic reaction. The centrioles are active nucleators of centrosome assembly by starting the autocatalyic process by their catalytic activity. Our theory can quantitatively account for the observed assembly dynamics of centrosomes in normal and perturbed conditions.

D. Zwicker, M. Decker, S. Jaensch, A. A. Hyman and F. Jülicher
Proc. Natl. Acad. Sci. USA 111, E2636 (2014)
PDF (1,2 MB)]

Active Elastic Thin Shell Theory for Cellular Deformations

Cell shape is governed by the mechanics of the action cytoskeletion together with cell- cell adhesion. The actin cytoskeleton forms athin layer near the cell membraje called cell cortex. The cell cortex is an active material in which contractile stresses are generated by motor molecules. At short times the cortex is an elastic solid which at longer times exhibits viscous material properties. We develop a theory of active and elastic thin shells in order to calculate shapes of cells at short times after forced detachment of cell-cell adhesion.

H. Berthoumieux, J.-L. Maître, C.-P. Heisenberg, E. K. Paluch, F. Jülicher and G. Salbreux
New J. Phys. 16 065005 (2014)
PDF (950 kB)]

Motor Regulation Results in Distal Forces that Bend Partially Disintegrated Chlamydomonas Axonemes
into Circular Arcs

We investigate the mechanics of microtubule doublets interacting with dynein motors that can lead to circular configurations of filaments. We show that these shapes can be understood as the consquence of a dependence of the motor detachmenht rate by forces acting normal to filaments. This mechanism of motor regulation could have an important role in beating cilia such as those of swimming algea.

V. Mukundan, P. Sartori, V. F. Geyer, F. Jülicher and J. Howard
Biophys J., 106, 2434 (2014)
PDF (1 MB)]

Pulsatory Patterns in Active Fluids

The regulation of active stresses by diffusing regulatory molecules provides a simple example for mechano-chemical pattern formation. In such systems, flows are generated by gradients of active stresses which lead to the transport of regulators. The regulators themselves organize the profiles of active stress. We show that two diffusing regulators, one which upregulates and one which downregulates stress can lead to oscillating spatial patterns and waves.

K. V. Kumar, J. S. Bois, F. Jülicher and S. W. Grill
Phys. Rev. Lett. 112, 208101 (2014)
PDF (721 kB]

Transduction Channels' Gating can Control Friction on Vibrating Hair-Cell Bundles in the Ear

Hair bundles are the sensory organelles of auditory hair cells. We study the mechanical response of hair bundles to mechanical stimuli of different velocity. We show that the hair bundle exhibits a friction that is due to dissipation associated with the opening and closing of mechanosensitive ion channels. This channel friction can be larger than the friction due to motion in the viscous environment of the hair bundle.

V. Bormuth, J. Barral, J.-F. Joanny, F. Jülicher and P. Martin
Proc. Natl. Acad. Sci. USA, 111, 7185 (2014)
PDF (1,1 MB)]

Synchronization Dynamics in the Presence of Coupling Delays and Phase Shifts

We study the synchronization of dynamic oscillators in spatially extended systems. Oscillatiors are coupled to their neighbors with a time delay. We show that for sufficiently large time delay long wavelength modes can relax faster than certain short wavelength modes.

D. J. Jörg, L. G. Morelli, S. Ares and F. Jülicher
Phys. Rev. Lett. 112, 174101 (2014)
PDF (328 kB)]

Growth Control by a Moving Morphogen Gradient during Drosophila Eye Development

We study the spatial profile of cell division in the developing eye of the fly. We show that the observed pattern of tissue growth can be understood as the result of a growth control mechanism mediated by a moving morphogen profile. Our work shows that the very different proliferation patterns in the wing an the eye can be understood by a common simple principle. Cell growth and division is stimulated by the relative rate of increase of a morphogen induced signal.

O. Wartlick, F. Jülicher and M. Gonzales-Gaitan
Development 141 1884 (2014)
PDF (4,8 MB)]

Wnt-regulated Dynamics of Positional Information in Zebrafish Somitogenesis

All vertebrate animals generate the segmented body plan and the precursors of vertebra by a dynamic oscillatory process that involves genetic wave patterns. We study the influence of Wnt signaling on the dynamics of the wavefront. We show that the segment size can be varied by varying the speed of the wave front while leaving the clock period unchanged.

L. Bajard, L. G. Morelli, S. Ares, J. Pécréaux, F. Jülicher and A. C. Oates
Development 141 1381 (2014)
PDF (5,7 MB)]

Mechanically Driven Interface Propagation in Biological Tissues

We discuss the competition of two tissues with different homeostatic pressure in a continuum theory. We show that a tissue with larger homeostatic pressure invades the second tissue by a propagating interface and calculate the propagation velocity. This is a generalization of the Fisher-Kolmogorov wave taking in to account stress distributions and mechanics. Interestingly, we find both pulled and pushed fronts as a function of parameter values.

J. Ranft, M. Aliee, J. Prost, F. Jülicher and J.-F. Joanny
New J. Phys. 16 035002 (2014)
PDF (406 kb)]

General Theory for the Mechanics of Confined Microtubule Asters

We discuss the positioning of microtubule asters in confined geometries mediated by pushing and pulling forces on the boundary. Pulling forces can lead to robust centering and off-center positioning due to asymmetric districutions of force generators. This work applies to the positioning of mitotic spindles in the cell during symmetric and asymmetric cell divisions.

R. Ma, L. Laan, M. Dogterom, N. Pavin and F. Jülicher
New J. Phys. 16 013018 (2014)
PDF (885 kb)]

Highlights 2013
Highlights 2012
Highlights 2011
Highlights 2010
Highlights 2009
Highlights 2008
Highlights 2007
Last updated: April 21, 2016