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TAKAGI Seiji 准教授

TAKAGI, Seiji Associate Professor

Profile

My research focuses primarily on single-celled organisms like slime molds and the human heart, aiming to elucidate how groups of substances and cells create and function in an orderly manner, generating structure and movement.

Job introductions

What kind of movement makes us feel alive? Perhaps it's the kind of sensual movement that can be described with onomatopoeia like "thump-thump" or "undulating."

In anime and science fiction movies, unknown and mysterious creatures are often depicted as pulsating or throbbing.
In real living organisms, such movements are produced by the coordinated movements of a large number of substances and cells, which enable a variety of functional movements such as pumping, crawling, and swimming.

It is believed that such movements play a significant role in information processing in certain organisms. By clarifying the principles by which dynamic order is generated in living organisms and the functions that result from it, we hope to apply these principles to the design of new machines that are closer to those of living organisms, as well as to the treatment of diseases.

Order, movement, function, and information function of single-celled organisms

True slime molds are extremely unique single-celled organisms, with a single cell growing to a size of over 1 meter.
Since it is a single-celled organism, it naturally does not have an information center like a brain, and therefore operates and processes information on principles completely different from the centralized systems that we tend to design.
Slime molds exhibit a variety of behaviors depending on their environment, but if you create the right environment for them, they can demonstrate astonishing abilities.
For example, it has been shown to exhibit hesitant and troubled behavior in conflicting situations, and to demonstrate spatial information processing capabilities that allow it to create an ideal logistics network required for actual transportation networks when food is scattered. Considering that the term "single-celled organism" is generally used to mean a simple and one-sided way of thinking, the fact that it can perform such advanced and diverse information processing is astonishing.
By observing and analyzing the processes by which giant cells create order as a single cell under various conditions, and move around while deforming, we can discover their unique capabilities and elucidate the principles behind them.

Orderly movement of the heart and arrhythmia

The heart is a quintessential example of life-like movement and a symbolic organ of being alive. Billions of cardiomyocytes contract in sequence, like waves in a stadium, creating the pumping action of the heart. However, if this transmission is disrupted, the heart can repeatedly rotate around the same spot. This is a dangerous condition that can cause sudden cardiac death.
However, it is possible to change how the brain reacts to external stimuli and restore it to a normal state. The most common method is to use an AED (External Defibrillator), which is designed based on experience to deliver an electric shock of approximately 3 volts.

However, this method uses too high a voltage, damaging even healthy cells. Therefore, by theoretically investigating this mechanism, we are researching and developing a gentler method that restores cells to a normal state using the lowest possible voltage.

Recent Books

• Kei-Ichi Ueda, Seiji Takagi, and Toshiyuki Nakagaki, “Tactic direction determined by the interaction between oscillatory chemical waves and rheological deformation in an amoeba” Phys.Rev.E vol. 86 (2012) 011927
• Marcel Horning, Seiji Takagi, and Kenichi Yoshikawa “Controlling activation site density by low-energy far-field stimulation in cardiac tissue” Phys. Rev. E, vol. 85 (2012) 061906.
• Kei-Ichi Ueda, Seiji Takagi, Yasumasa Nishiura, and Toshiyuki Nakagaki, “Mathematical model for contemplative amoeboid locomotion,” Phys. Rev. E, vol. 83 (2011) 021916.
• Marcel Horning, Seiji Takagi, and Kenichi Yoshikawa “Wave emission on interacting heterogeneities in cardiac tissue” Phys. Rev. E, vol. 82 (2010) 021926.
• Takashi Yamamoto, Mitsuru Sugawara, Takashi Kikukawa, Seiji Miyauchi, Masahiro Yamaguchi, Atsushi Tero, Seiji Takagi and Toshiyuki Nakagak, “Kinetic study of antiviral ribavirin uptake mediated by hCNT3 and hENT1 in Xenopus laevis oocytes,” Biophys. Chem., vol. 147 (2010), pp. 59-65.
• Atsushi Tero, Seiji Takagi, Tetsu Saigusa, Kentaro Ito, Dan P. Bebber, Mark D. Fricker, Kenji Yumiki, Ryo Kobayashi, Toshiyuki Nakagaki, “Rules for Biologically Inspired Adaptive Network Design,” Science, vol. 327, no. 5964 (2010), pp. 439–442.
• Seiji Takagi, Testuo Ueda “Annihilation and creation of rotating waves by a local light pulse in a protoplasmic droplet of the Physarum plasmodium” Physica D, vol. 239 (2010) pp.873?878.
• Kenji Matsumoto, Seiji Takagi, and Toshiyuki Nakagaki “Locomotive Mechanism of Physarum Plasmodia Based on Spatiotemporal Analysis of Protoplasmic Streaming” Biophys. J., vol. 94 (2008) pp.2492-2504.
• Seiji Takagi and Tetsuo Ueda “Emergence and transition of dynamic patterns of thickness oscillation of the plasmodium of the true slime mold Physarum polycephalum” Physica D, vol. 237(2008) pp.420?427.
• MD Fricker, M. Tlalka, D. Bebber, S. Takagi, SC Watkinson, PR Darrah “Fourier-based spatial mapping of oscillatory phenomena in fungi” Fungal Genetics and Biology. vol. 44 (2007) pp. 1077-1084.
• S. Takagi, Y. Nishiura, T. Nakagaki, T. Ueda, K.-I.Ueda “Indecisive behavior of amoeba crossing an environmental barrier” Proceedings of the international symposium on Topological Aspects of Critical Systems and Networks pp. 86-93, (2007).
• S. Takagi, A. Pumir, D. Pazo, I. Efimov, V. Nikolski, V. Krinsky “A physical approach to remove anatomical reentries: a bidomain study” J. Theor. Biol, Vol 230 (2004) pp.489-497.
• S. Takagi, A. Pumir, D. Pazo, I. Efimov, V. Nikolski, and V. Krinsky “Unpinning and Removal of a Rotating Wave in Cardiac Muscle” Phys. Rev. Lett. Vol. 93 (2004) 058101.
• Seiji Takagi, Alain Pumir, Lorenz Kramer and Valentin Krinsky “Mechanism of standing wave patterns in cardiac muscle” Physical Review Letters Vol. 90 (2003) 124101.
• Seiji Takagi, Christian Frelin, Valentin Krinsky and Alain Pumir “The use of Faraday instability to produce defined topological organization in cultures of mammalian cells” International Journal of Bifurcation and Chaos, 12 (2002) , pp.2009-2019.
• S. Takagi, K. Tsumoto and K. Yoshikawa “Intra-molecular phase segregation in a single polyelectrolyte chain” J. Chem. Phys., 114 (2001), pp.6942-6949.

Review

• Marcel Horning, Seiji Takagi, "Nonlinear Treatment of Myocardial Irregularities," Mathematical Sciences No. 581.June 2011 November, 2011
• Seiji Takagi, Toshiyuki Nakagaki, "Self-organizing railway networks created by slime molds," Modern Chemistry No. 477.June 2010 December, 2010