International workshop: Complex motile matter from single agents to collective behaviors
Date/Time:

July 21st (Fri.) and 22nd (Sat.)

Venue:Nakano campus, Meiji University

Organizers:

Carsten Beta (Univ. Potsdam, Kanazawa Univ.) Satoshi Nakata (Hiroshima Univ.),
Nobuhiko J. Suematsu (Meiji Univ.), Masaki Itatani (Budapest Univ. Technol. Econ.)
Hiroyuki Kitahata (Chiba Univ.)

July 21st (Fri.)
12:50 - 13:00

Opening[Chair: Hiroyuki Kitahata (Chiba University)]
13:00 - 13:45

Kei Fujiwara (Keio University)"Behaviors and characteristics of intracellular Reaction-diffusion wave revealed by areconstitution system in artificial cells"

13:45 - 14:30

Natsuhiko Yoshinaga (Tohoku University)"Reaction-diffusion models for Min oscillations: wave instability in a confined space"

14:30 - 14:45

break[Chair: TBA]
14:45 - 15:30

Satoshi Sawai (The University of Tokyo)"Cell-cell contact mediated regulation of cell polarity and collective movement"

15:30 - 16:15

Masatoshi Ichikawa (Kyoto University)"Self-propelled droplets: from model system to living cell"

16:15 - 16:30

break[Chair: Carsten Beta (University of Potsdam, Kanazawa University)]
16:30 - 17:05Muneyuki Matsuo (The University of Tokyo)"Supramolecular recursion due to complex motility"

17:05 - 17:40

Masaki Itatani (Budapest University of Technology and Economics)"Design of transient pH oscillations utilizing a combination of two antagonistic enzymatic
reactions and implementing it to synthetic cells"

17:40 - 17:50

Announcement

18:30 -Party

July 22nd (Sat.)[Chair: Nobuhiko J. Suematsu (Meiji University)]
10:00 - 10:45

Akihiro Isomura (Kyoto University)"Illuminating oscillatory gene expression in cell-cell communications"

10:45 - 11:30

Shuji Ishihara (The University of Tokyo)"Onset of pattern propagation on curved surfaces"

11:30 - 13:00

Lunch[Chair: Satoshi Nakata (Hiroshima University)]
13:00 - 13:45

Carsten Beta (University of Potsdam, Kanazawa University)"Hybrid active matter – how motile cells actuate passive micro-cargo"

13:45 - 14:30

Akira Kakugo (Kyoto University)"Implementation of transport tasks by Active Matter"

14:30 - 14:40

Closing

This workshop is supported by MEXT Joint Usage/Research Center Meiji University "Center for Mathematical
Modeling and Applications" (CMMA).

Behaviors and characteristics of intracellular Reaction-diffusion wave revealed bya reconstitution system in artificial cells
Kei Fujiwara
Keio University, Japan
Coupling of chemical reaction and molecular diffusion emerges nonlinear wave such as propagation
wave and stationary periodic patterns. These reaction-diffusion waves are known as the underlying
mechanism of animal skins and their behavior has been analyzed by model systems such BZ waves.
Recently, biological studies found that these reaction-diffusion waves are associated with molecularplacements in living cells. However, the wavelength of these waves is comparable to the size of thespace size, and their behaviors should be extensively distinct from those in the bulk. To elucidate thispoint, we focused on a reaction-diffusion waves for cell division plane determination (Min wave) andanalyzed their physics by reconstituting them in artificial cells. In this presentation, we will discuss
the characteristics of Min waves, including the relationship between spatial size and structure, methodsof controlling their periodicity, its conversion to Turing patterns, and the principles governing theselection mechanism to select traveling and standing waves.
References[1] S. Takada, et al., Sci. Adv, 2022, 8, eabm8460.
[2] S. Takada, et al., ACS Nano, 2022, 16, 10, 16853–16861.

Reaction-diffusion models for Min oscillations: wave instability in a confined space
Natsuhiko Yoshinaga
WPI Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, JapanThe emergence of patterns in biological cells has attracted much attention to understanding the genericmechanism of biological functions associated with these patterns. The Min system may be the best
example of such pattern formation due to its robust realisation both for in vivo and in vitro systems[1].
The Min system exhibits a standing wave of higher concentrations of Min proteins on a cell membrane.
FtsZ proteins accumulate at the wave node and, as a result, the cell is divided into two daughter cells.
Therefore, the wave plays a role in finding the centre of the cell. Motivated by these experiments,
several reaction-diffusion models have been proposed. Nevertheless, the mechanism underlying thewave generation remains controversial.
In this presentation, I shall summarise the models for the Min system and discuss the potential
mechanism of wave generation. Particular focus is on the effect of confinement; the proteins aredistributed on the closed membrane and its inside. I shall discuss how the confinement results in wave
instability by suppressing uniform oscillation on the membrane[1]. I shall also discuss how the cellchooses standing and travelling waves[2].
[1] S. Kohyama, Shunshi, N. Yoshinaga, M. Yanagisawa, K. Fujiwara, and N. Doi, eLife, 8, e44591(2019).
[2] S. Takada, N. Yoshinaga, N. Doi, and K. Fujiwara, Science Advances, 8, eabm8460 (2022).

Cell-cell contact mediated regulation of cell polarity and collective movement.
Satoshi Sawai
Univ of Tokyo, JapanThe social amoeba Dictyostelium is well-known for chemotaxis-mediate aggregation, however it has
noticed that these cells switch to another mode of movement mediated by cell-cell contact. I will goover our recent findings and discuss their relevance to the collective dynamics and pattern formation.

Self-propelled droplets: from model system to living cell
Masatoshi Ichikawa
Graduate School of Science, Kyoto University, Japan
A swimming microdroplet is one of simplest systems of self-propulsion modeling microorganisms
and living cells. Various mode of motions, straight, curvilinear, spiral, reciprocal, figure-8s and zigzag
motions have been demonstrated by controlling an anisotropic nature of the internal liquid [1].
Interestingly, even for droplets composed with isotropic liquids, diversification of motion occurred.
In this study, we measured the motion and internal flow of a swimming micro-droplet of water, andquantitatively identified the mechanism of a straight-to-curvilinear motion transition [2,3].
References[1] M. Suga, S. Suda, M. Ichikawa, Y. Kimura, Phys. Rev. E 97, 062703 (2018).
[2] S. Suda, T. Suda, T. Ohmura, M. Ichikawa, Phys. Rev. Lett. 127, 088005 (2021).
[3] S. Suda, T. Suda, T. Ohmura, M. Ichikawa, Phys. Rev. E 106, 034610 (2022).

Supramolecular recursion due to complex motility
Muneyuki Matsuo
Graduate School of Arts and Sciences, The University of Tokyo, Japan
There is no room to differ that part of the organism's characteristic feature lies in the supramolecularrecursion due to the complex motility. Such recursion could appear at any scale, i.e., molecules,reactions, supramolecules, and supramolecular populations. It is well known that the recursion itself
is realized by coupling a system with periodic perturbations or an oscillatory reaction. Selfoscillating systems have also been constructed by introducing structural anisotropy, in which anoscillation emerges from non-oscillatory perturbations. Here, however, we report complex recursive
systems in which the system itself spontaneously forms structural anisotropy based on non-recursive
perturbations, and then recurses using the spontaneous symmetry breaking as the mechanism ofoscillation. In these systems, autocatalytic processes are incorporated, which dynamically couple theapparent rates of chemical reactions and the physical properties of supramolecules far fromequilibrium, and the structural anisotropy required for recursion emerges autonomously. Suchsystems may provide an insight into the process by which life spontaneously acquired recursivity inthe ancient terrestrial environment, which was likely to have been random and homogeneous.

Design of Transient pH Oscillations Utilizing a Combination of Two Antagonistic
Enzymatic Reactions and Implementing it to Synthetic Cells○Masaki Itatani,1 Gábor Holló,2 Paola Albanese,3 Nadia Valletti,3 Sándor Kurunczi,4Róbert Horváth,4 Federico Rossi,3 István Lagzi1[1] Department of Physics, Institute of Physics, Budapest University of Technology and Economics, Budapest, Hungary.
[2] Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
[3] Department of Earth, Environmental and Physical Sciences, Univeristy of Siena, Siena, Italy.
[4] Nanobiosensorics Group, Institute of Technical Physics and Materials Science, Centre for Energy Research,Budapest, Hungary.

Implementing internal chemical oscillations to synthetic cells and inducing dynamic behaviors suchas self-propelled motion and self-replication of vesicles by the internal oscillators are still challenging
although internal reaction-induced self-organization is originally adopted by living cells. pH
oscillations are one of the eligible candidates for internal oscillators because they can combine withmany bio-related molecular self-assembly. However, an autonomous pH oscillator having a mild pH
range has not been reported, that can straightforwardly apply to synthetic cells. In this study, we show
a novel concept to design pH oscillations satisfying the above biological requirements utilizing a
combination of two antagonistic enzymatic reactions which produce basic and acidic compounds,
namely urea–urease and ester–esterase reactions. The basic properties of the designed pH oscillations
have been investigated in a batch system and pH oscillated transiently ranging from ~6.8 to ~8.5,
which could be controlled depending on the concentration ratio between two enzymes and substrates.
Furthermore, we have tried to construct a skeleton model to explain the mechanism of the obtainedoscillation. At the end of the presentation, we would like to show some possible applications of thedesigned oscillators to liposomes, to extend our developed system to synthetic cell studies.

Illuminating oscillatory gene expression in cell-cell communications
Akihiro Isomura
Institute for Life and Medical Sciences, Kyoto University, Japan
Dynamic cell-to-cell communication is prevalent and plays pivotal roles in embryonic development
and tissue formation of multicellular organisms. One of the most striking example is somitogenesis;
in developing embryos of vertebrates, regular sizes of metameric structures called somites are formed
in a synchronized and periodic manner [1]. Top-down approaches based on genetic or pharmacologicalperturbations have revealed dynamic signaling molecules involved in somitogenesis, such as periodic
activity of Delta-Notch signaling. However, it has been challenging to identify minimally suﬃcientcondition for synchronized generation of somites. Here, we introduce a bottom-up approach thatcombines optogenetics, synthetic biology and live-cell imaging to dissect functional capabilities ofsignaling molecules in collective behaviors of coupled genetic oscillators [2-5].
References[1] A. Hubaud, O. Pourquie, Nat. Rev. Mol. Cell Biol. 15, 709 (2014).
[2] A. Isomura, F. Ogushi, H. Kori, R. Kageyama, Genes & Dev. 31, 524 (2017).
[3] M. Matsumiya, T. Tomita, K. Yoshioka-Kobayashi, A. Isomura, R. Kageyama, Development 145,dev156836 (2018).
[4] K. Yoshioka-Kobayashi, M. Matsumiya, Y. Niino, A. Isomura, H. Kori, A. Miyawaki, R.
Kageyama, Nature 580, 119 (2020).
[5] A. Isomura, R. Kageyama, unpublished.

Onset of pattern propagation on curved surfaces
Shuji Ishihara
Graduate School of Arts and Sciences, The University of Tokyo, Japan
Pattern formation often occurs on curved surfaces, and the influence of surface geometry on pattern
dynamics has attracted much attentions in recent years. For Turing pattern, previous studies havereported that the stability conditions and positions of the pattern change depending on the surface
geometry, while it has been considered that the pattern remains static regardless of the surface
geometry. We find that a static Turing pattern on a flat surface can become a moving pattern on acurved surface [2]. This propagation is not allowed in 1D systems where there is no intrinsic curvature,but can occur on curved 2D surfaces. By investigating patterns on axisymmetric surface, some genericconditions on the symmetry of the surface and pattern for pattern propagation were identified. Our
results provide new mechanism of pattern propagation and insights into the general role of surface
geometry.
References[1] A. L. Krause et al., Modern perspectives on near-equilibrium analysis of Turing systems, Phil.
Trans. R. Soc. A. 379, 20200268 (2021).
[2] R. Nsishide and S. Ishihara, Pattern Propagation Driven by Surface Curvature, Phys. Rev. Lett.
128, 22410 (2022).

Hybrid active matter – how motile cells actuate passive micro-cargo
Carsten Beta
Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany
WPI Nano Life Science Institute, Kanazawa University, Kanazawa, Japan
Biohybrid micro-transport ¬– the movement of micron-sized cargo particles by motile cells – is oneof the most prominent applications in the emerging field of biohybrid systems. Here, we demonstratethat motile amoeboid cells can act as efficient and versatile transport agents [1]. Their transport
properties result from the mechanical interactions with the passive cargo particle and reveal an
optimal cargo size that enhances the locomotion of the load-carrying cells, even exceeding theirmotility in the absence of cargo. The experimental findings are rationalized in terms of an active
particle model that describes the observed cell-cargo dynamics and enables us to derive the longtime diffusive transport of amoeboid microcarriers [2]. We have estimated the peak transport forces
under different environmental conditions [3] and also extended our studies to more complex
situations, where cargo particles are collectively actuated many cells at the same time, aiming at an
overall understanding of this novel type of composite active matter.
[1]

Nagel, Frey, Gerhardt, Beta (2019), Advanced Science 6 (3), 1801242.

[2]

Lepro, Großmann, Panah, Nagel, Klumpp, Lipowsky, Beta (2022), Physical Review

Applied 18 (3), 034014.
[3]

Panah, Großmann, Lepro, Beta (2023), arXiv e-prints, arXiv: 2305.15298.

Implementation of transport tasks by Active Matter
Akira Kakugo
Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Japan
Email: kakugo.akira.8n@kyoto-u.ac.jp
Cooperation is a strategy that has been adopted by groups of organisms to execute complex tasks more
efficiently than single entities. Cooperation increases the robustness and flexibility of the working
groups and permits sharing of the workload among individuals. Here, we demonstrate moleculartransportation through the cooperative action of a large number of artificial molecular machines,
photoresponsive DNA-conjugated microtubules driven by kinesin motor proteins. Mechanicalcommunication via conjugated photoresponsive DNA enables these microtubules to organize into
groups upon photoirradiation. The groups of transporters load and transport cargo, and cargo unloadingis achieved by dissociating the groups into single microtubules. The group formation permits theloading and transport of cargoes with larger sizes and in larger numbers over long distances comparedwith single transporters. We also demonstrate that cargo can be collected at user-determined locations
defined by ultraviolet light exposure.
References1. C.W. Reynolds et al. Computer Graphics, 21, 25 (1987)
2. Jakia Jannat Keya et al. Nature Communications, Vol. 9 (453) (2018)
3. Daisuke Inoue et al. Nature Communications, Vol. 7:12557 (2016)
4. Kento Matsuda et al. Nano Letters, Vol 19 (6), pp. 3933-3938 (2019)
5. Daisuke Inoue et al. ACS Nano, Vol. 13 (11), pp. 12452-12460, (2019)
6. Mousumi Akter et al. Sci. Robot., Vol. 7 (65), eabm0677 (2021).