@article{NegretePumirHsuetal.2016, author = {Negrete, Jose and Pumir, Alain and Hsu, Hsin-Fang and Westendorf, Christian and Tarantola, Marco and Beta, Carsten and Bodenschatz, Eberhard}, title = {Noisy Oscillations in the Actin Cytoskeleton of Chemotactic Amoeba}, series = {Physical review letters}, volume = {117}, journal = {Physical review letters}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.117.148102}, pages = {5}, year = {2016}, abstract = {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.}, language = {en} } @article{LeonhardtGerhardtHoeppneretal.2016, author = {Leonhardt, Helmar and Gerhardt, Matthias and Hoeppner, Nadine and Kr{\"u}ger, Kirsten and Tarantola, Marco and Beta, Carsten}, title = {Cell-substrate impedance fluctuations of single amoeboid cells encode cell-shape and adhesion dynamics}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {93}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, publisher = {American Physical Society}, address = {College Park}, issn = {2470-0045}, doi = {10.1103/PhysRevE.93.012414}, pages = {8}, year = {2016}, abstract = {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.}, language = {en} }