@misc{WestendorfBaeErlenkamperetal.2010,
  author    = {Westendorf, Christian and Bae, Albert J. and Erlenkamper, Christoph and Galland, Edouard and Franck, Carl and Bodenschatz, Eberhard and Beta, Carsten},
  title     = {Live cell flattening},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {835},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42831},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-428311},
  pages     = {17},
  year      = {2010},
  abstract  = {Eukaryotic cell flattening is valuable for improving microscopic observations, ranging from bright field (BF) to total internal reflection fluorescence (TIRF) microscopy. Fundamental processes, such as mitosis and in vivo actin polymerization, have been investigated using these techniques. Here, we review the well known agar overlayer protocol and the oil overlay method. In addition, we present more elaborate microfluidics-based techniques that provide us with a greater level of control. We demonstrate these techniques on the social amoebae Dictyostelium discoideum, comparing the advantages and disadvantages of each method.},
  language  = {en}
}
@article{WestendorfNegreteBaeetal.2013,
  author    = {Westendorf, Christian and Negrete, Jose and Bae, Albert J. and Sandmann, Rabea and Bodenschatz, Eberhard and Beta, Carsten},
  title     = {Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations},
  series = {Proceedings of the National Academy of Sciences of the United States of America},
  volume    = {110},
  journal   = {Proceedings of the National Academy of Sciences of the United States of America},
  number    = {10},
  publisher = {National Acad. of Sciences},
  address   = {Washington},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.1216629110},
  pages     = {3853 -- 3858},
  year      = {2013},
  abstract  = {The rapid reorganization of the actin cytoskeleton in response to external stimuli is an essential property of many motile eukaryotic cells. Here, we report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. When averaging the actin response of many cells to a short pulse of the chemoattractant cAMP, we observed a transient accumulation of cortical actin reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. To substantiate that an oscillatory mechanism governs the actin dynamics in these cells, we systematically exposed a large number of cells to periodic pulse trains of different frequencies. Our results indicate a resonance peak at a stimulation period of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the regulatory network of the actin system. To test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and actin-interacting protein 1, as well as knockout mutants that lack Coronin and actin-interacting protein 1. These actin-binding proteins enhance the disassembly of actin filaments and thus allow us to estimate the delay time in the regulatory feedback loop. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed in our periodic stimulation experiments.},
  language  = {en}
}
@article{SchaeferWestendorfBodenschatzetal.2011,
  author    = {Schaefer, Edith and Westendorf, Christian and Bodenschatz, Eberhard and Beta, Carsten and Geil, Burkhard and Janshoff, Andreas},
  title     = {Shape oscillations of dictyostelium discoideum cells on ultramicroelectrodes monitored by impedance analysis},
  series = {Small},
  volume    = {7},
  journal   = {Small},
  number    = {6},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1613-6810},
  doi       = {10.1002/smll.201001955},
  pages     = {723 -- 726},
  year      = {2011},
  language  = {en}
}
@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}
}