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Control of interaction strength in a network of the true slime mold by a microfabricated structure
1Biochemical Systems Laboratory, RIKEN (The Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako-shi, Saitama, Japan. takamatu@cel.riken.go.jp
Abstract:
The plasmodium of the true slime mold, Physarum polycephalum, which shows various nonlinear oscillatory phenomena, for example, in its thickness, protoplasmic streaming and concentration of intracellular chemicals, can be regarded as a collective of nonlinear oscillators. The plasmodial oscillators are interconnected by microscale tubes whose dimensions can be closely related to the strength of interaction between the oscillators. Investigation of the collective behavior of the oscillators under the conditions in which the interaction strength can be systematically controlled gives significant information on the characteristics of the system. In this study, we proposed a living model system of a coupled oscillator system in the Physarum plasmodium. We patterned the geometry and dimensions of the microscale tube structure in the plasmodium by a microfabricated structure (microstructure). As the first step, we constructed a two-oscillator system for the plasmodium that has two wells (oscillator part) and a channel (coupling part). We investigated the oscillation behavior by monitoring the thickness oscillation of the plasmodium in the microstructure with various channel widths. It was found that the oscillation behavior of two oscillators dynamically changed depending on the channel width. Based on the results of measurements of the tube dimensions and the velocity of the protoplasmic streaming in the tube, we discuss how the channel width relates to the interaction strength of the coupled oscillator system.
Insights
Physarum polycephalum slime mold exhibits nonlinear oscillations. Researchers created a model system to study how microscale tube dimensions influence the interaction strength between these biological oscillators.
Area of Science:
- Nonlinear dynamics
- Systems biology
- Biophysics
Background:
- The Physarum polycephalum slime mold displays complex nonlinear oscillatory behaviors.
- These oscillations are linked to interconnected microscale tubes, suggesting a collective oscillator system.
- Understanding interaction strength is key to characterizing the system's collective behavior.
Purpose of the Study:
- To develop a living model system of coupled oscillators using Physarum polycephalum.
- To investigate how systematically controlled interaction strengths affect oscillator behavior.
- To establish a relationship between microchannel dimensions and oscillator coupling.
Main Methods:
- Fabrication of microstructures to pattern Physarum polycephalum.
- Construction of a two-oscillator system with variable channel widths.
- Monitoring thickness oscillations and measuring protoplasmic streaming velocity.
Main Results:
- Oscillation dynamics of the two-oscillator system varied with channel width.
- Channel dimensions were shown to influence the interaction strength between oscillators.
- Protoplasmic streaming velocity correlated with channel dimensions.
Conclusions:
- The Physarum plasmodium serves as a viable model for studying coupled nonlinear oscillators.
- Microfabricated structures allow for controlled manipulation of interaction strengths in biological systems.
- Channel width is a critical factor determining the coupling and emergent behavior of slime mold oscillators.