BIOPHYSICAL THEORY AND MODELING |
Locomotive Mechanism of Physarum Plasmodia based on
Spatiotemporal Analysis of Protoplasmic Streaming
Kenji Matsumoto 1, Seiji Takagi 1 and Toshiyuki Nakagaki 1*
1 Hokkaido University
* To whom correspondence should be addressed. E-mail: nakagaki{at}es.hokudai.ac.jp.
Submitted on June 7, 2007
Revised on July 13, 2007
Accepted on 6 November 2007
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Abstract |
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We investigate how an amoeba mechanically moves its own center of gravity using the model organism Physarum plasmodium. Time-dependent velocity fields of protoplasmic streaming over the whole plasmodia were measured with a particle image velocimetry program developed for this work. Combining these data with measurements of the simultaneous movements of the plasmodia revealed a simple physical mechanism of locomotion. The shuttle streaming of the protoplasm was not truly symmetric due to the peristalsis-like movements of the plasmodium. This asymmetry meant that the transport capacity of the stream was not equal in both directions, and a net forward displacement of the center of gravity resulted. The generality of this as a mechanism for amoeboid locomotion is discussed.
Key Words:
Physarum, amoeboid movement, cellular oscillation, particle image velocimetry, protoplasmic streaming, wave propagation
