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  Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations

Westendorf, C., Negrete Jr., J., Bae, A. J., Sandmann, R., Bodenschatz, E., & Beta, C. (2013). Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations. PNAS, 110(10), 3853-3858. doi:10.1073/pnas.1216629110.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0029-1013-1 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0029-1014-0
Genre: Journal Article

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 Creators:
Westendorf, Christian1, Author              
Negrete Jr., Jose1, Author              
Bae, Albert J.1, Author              
Sandmann, Rabea1, Author              
Bodenschatz, Eberhard1, Author              
Beta, Carsten1, Author              
Affiliations:
1Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Max Planck Society, ou_2063287              

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Free keywords: Dictyostelium discoideum, microfluidics, caged cAMP, delay-differential equation
 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.

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Language(s): eng - English
 Dates: 2013-03-05
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: eDoc: 649923
DOI: 10.1073/pnas.1216629110
 Degree: -

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Title: PNAS
Source Genre: Journal
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Publ. Info: -
Pages: - Volume / Issue: 110 (10) Sequence Number: - Start / End Page: 3853 - 3858 Identifier: -