TY  - JOUR
A1  - Hsu, H. F.
A1  - Krekhov, Andrey
A1  - Tarantola, Marco
A1  - Beta, Carsten
A1  - Bodenschatz, Eberhardt
T1  - Interplay between myosin II and actin dynamics in chemotactic amoeba
JF  - New journal of physics : the open-access journal for physics
N2  - The actin cytoskeleton and its response to external chemical stimuli is fundamental to the mechano-biology of eukaryotic cells and their functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin II. Based on a phase space embedding we have identified from experiments three phases in the cytoskeletal dynamics of starved Dictyostelium discoideum in response to a precisely controlled chemotactic stimulation. In the first two phases the dynamics of actin and myosin II in the cortex is uncoupled, while in the third phase the time scale for the recovery of cortical actin is determined by the myosin II dynamics. We report a theoretical model that captures the experimental observations quantitatively. The model predicts an increase in the optimal response time of actin with decreasing myosin II-actin coupling strength highlighting the role of myosin II in the robust control of cell contraction.
KW  - actin
KW  - myosin II
KW  - chemotaxis
KW  - oscillations
KW  - coupling
KW  - delay differential equation
KW  - contraction
Y1  - 2019
U6  - https://doi.org/10.1088/1367-2630/ab5822
SN  - 1367-2630
VL  - 21
IS  - 11
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Negrete, Jose
A1  - Pumir, Alain
A1  - Hsu, Hsin-Fang
A1  - Westendorf, Christian
A1  - Tarantola, Marco
A1  - Beta, Carsten
A1  - Bodenschatz, Eberhard
T1  - Noisy Oscillations in the Actin Cytoskeleton of Chemotactic Amoeba
JF  - Physical review letters
N2  - Biological systems with their complex biochemical networks are known to be intrinsically noisy. Here we investigate the dynamics of actin polymerization of amoeboid cells, which are close to the onset of oscillations. We show that the large phenotypic variability in the polymerization dynamics can be accurately captured by a generic nonlinear oscillator model in the presence of noise. We determine the relative role of the noise with a single dimensionless, experimentally accessible parameter, thus providing a quantitative description of the variability in a population of cells. Our approach, which rests on a generic description of a system close to a Hopf bifurcation and includes the effect of noise, can characterize the dynamics of a large class of noisy systems close to an oscillatory instability.
Y1  - 2016
U6  - https://doi.org/10.1103/PhysRevLett.117.148102
SN  - 0031-9007
SN  - 1079-7114
VL  - 117
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Leonhardt, Helmar
A1  - Gerhardt, Matthias
A1  - Hoeppner, Nadine
A1  - Krüger, Kirsten
A1  - Tarantola, Marco
A1  - Beta, Carsten
T1  - Cell-substrate impedance fluctuations of single amoeboid cells encode cell-shape and adhesion dynamics
JF  - Physical review : E, Statistical, nonlinear and soft matter physics
N2  - We show systematic electrical impedance measurements of single motile cells on microelectrodes. Wild-type cells and mutant strains were studied that differ in their cell-substrate adhesion strength. We recorded the projected cell area by time-lapse microscopy and observed irregular oscillations of the cell shape. These oscillations were correlated with long-term variations in the impedance signal. Superposed to these long-term trends, we observed fluctuations in the impedance signal. Their magnitude clearly correlated with the adhesion strength, suggesting that strongly adherent cells display more dynamic cell-substrate interactions.
Y1  - 2016
U6  - https://doi.org/10.1103/PhysRevE.93.012414
SN  - 2470-0045
SN  - 2470-0053
VL  - 93
PB  - American Physical Society
CY  - College Park
ER  -