Active Matter Workshop 2019

アクティブマター研究会2019日時：
2019年1月11日（金）、12日（土）於：明治大学 中野キャンパス

Active Matter Workshop 2019
VENUE:
Meiji University (Nakano Campus)
DATE:
11 - 12 January, 20191

Active Matter Workshop 2019

主催 | Organiser
共同利用・共同研究拠点

明治大学

先端数理科学インスティテュート（MIMS）現象数理学拠点
MEXT Joint Usage/Research Center Meiji University"Center for Mathematical Modeling and Applications" (CMMA)

世話人 | Organisation committee
江端宏之（九州大学） Hiroyuki Ebata (Kyushu Univ.)

北畑裕之（千葉大学） Hiroyuki Kitahata (Chiba Univ.)

末松 J. 信彦（明治大学） Nobuhiko J. Suematsu (Meiji Univ.)
多羅間充輔（京都大学） Mitsusuke Tarama (Kyoto Univ.)
山口智彦（明治大学） Tomohiko Yamaguchi (Meiji Univ.)

問い合わせ | Contact
email: active2019@googlegroups.com

2

Active Matter Workshop 2019

Program
2019/1/11 Fri.
10:00 - 10:20
10:20 - 10:30
10:30 - 11:10

11:10 - 11:50

11:50 - 13:10
13:10 - 14:55
14:55 - 15:20
15:20 - 16:00

16:00 - 16:40
19:00 -

Registration
Opening
FL Masahiro Takinoue (Tokyo Institute of Technology)“Phase-separated DNA microdroplets controlled by base sequence
information”
FL Yasuhiro Ikezoe (Nippon Institute of Technology)“Study of motion of the object caused by various energy conversion
processes in materials”
Lunch
ST1
Break
PL Ryoichi Yamamoto (Kyoto Univ.)“Active matter modeling: swimming microorganisms / crawling andproliferating cells on substrate”
FL Akihisa Shioi (Doshisha Univ.)“Design of chemical systems with semblance of life”
Banquet* Special lecture entitled "How do we describe the dynamic performance of materials - A
case study for cracking problems -" is given by Prof. Yasumasa Nishiura (Tohoku Univ.)from 17:10 to 18:50, after the first day of the workshop.

2019/1/12 Sat.
9:30 - 10:10

10:10 - 10:30
10:30 - 11:30
11:30 - 13:00
13:00 - 14:30
14:30 - 14:50
14:50 - 15:30

15:30 - 16:10

16:10 - 16:20

FL Ben Nanzai (Shizuoka Institute of Science and Technology)“Physicochemical approach for reaction in spontaneous running
droplet on glass substrate”
Break
ST3
Lunch
ST4
Break
FL Yoshiyuki Kageyama (Hokkaido Univ.)“Light-driven limit-cycle self-oscillation and autonomous swimming ofazobenzene-assembly under photostationary state”
FL Yusuke Hara (AIST)“Development of self-oscillating gel actuators for application to
microfluidic devices and soft robots”
Closing===========
Presentation time
PL: Plenary lectures [40 min each, including discussions]
FL: Focused lectures [40 min each, including discussions]
ST: Short talks [10 min presentation + 5 min discussions for each]3Active Matter Workshop 2019

基調講演
Plenary Lectures

1月11日（金）10:00 ‒ 11:00

Ryoichi Yamamoto(Kyoto Univ.)
Active matter modeling: swimming microorganisms /crawling and proliferating cells on substrate

4Active Matter Workshop 20195

Active Matter Workshop 2019

企画講演
Focused Lectures on"Active matter in chemistry”
１月１１日（金） １０：３０ ­ １１：１０
Masahiro Takinoue (Tokyo Institute of Technology)“Phase-separated DNA microdroplets
controlled by base sequence information”
１月１１日（金） １１：１０ ­ １１：５０
Yasuhiro Ikezoe (Nippon Institute of Technology)“Study of motion of the object caused byvarious energy conversion processes in materials”
１月１１日（土） １６：００ ­ １６：４０
Akihisa Shioi (Doshisha Univ.)“Design of chemical systems with semblance of life”
１月１２日（土） ９：３０ ­ １０：１０
Ben Nanzai (Shizuoka Institute of Science and Technology)“Physicochemical approach for reactionin spontaneous running droplet on glass substrate”
１月１２日（土） １４：５０ ­ １５：３０
Yoshiyuki Kageyama (Hokkaido Univ.)“Light-driven limit-cycle self-oscillation and autonomous swimmingof azobenzene-assembly under photostationary state”
１月１２日（土） １５：３０ ­ １６：１０
Yusuke Hara (AIST)“Development of self-oscillating gel actuators
for application to microﬂuidic devices and soft robots”
6Active Matter Workshop 2019

Light-driven limit-cycle self-oscillation and autonomous
swimming of azobenzene-assembly under photostationary state
Yoshiyuki KAGEYAMA

Condensed Matter Chemistry Laboratory,
Department of Chemistry Faculty of Science, Hokkaido Unmiversity
Due to the development in polymer science in light-responsive azobenzene polymer, especially AzoLCE(azobenzene liquid crystalline elastomer) in which the self-align properties of azobenzene motif play a keyrole for macroscopic motion, it became possible to make materials showing designed light-triggered
movements. Small assembled-machines equipped with such azobenzene polymer for a light-driven actuator
have been processed, and showed wonderful locomoting dynamics under light-control. However, perhaps theparticipants in the active matter symposium cannot be satisfied by such tiny and clever machines, because (a)we usually use more useful assembled-machines, such as vehicle, train, and airplane, (b) the requirement ofintermittent light is not so autonomous, and (c) the motion, which always follows the owner’s control, is not
active but passive.
Unfortunately, the author has not understand the meaning of “active”-matter until now. However, theauthor knows the active-matter require energy for their motion, and it can works against potential gradient with
consumption of the received energy. Here, the thermodynamics is a keyword. Unfortunately again, thethermodynamics of such open-system including information is quite difficult to understand for the author, andtherefore it is difficult to distinguish that a motion is active or not. However, materials, which can continuously
move directionally in plane potential surface against resistance with conversion of acquired energy, but without
under direction of external information, are active materials. It means that active materials should have abilityof self-sustained, self-directed, and self-regulated energy conversion to mechanical energy. We know suchmaterials and their motions have been reported, for instance, self-propelling Janus-particle, and self-walking
BZ-hydrogel. Especially when we aim to create such materials using multi-molecular system, it seems
synchronization of involving molecules is required, and the requirement may be satisfied by the combinationof nonlinear dynamics.
Following our study on a unique light-triggered cooperative dynamics of oleate-azobenzene mixed
lyotropic liquid crystals,[1,2] we successfully found self-oscillatory flips of crystalline assembly under steadyblue-light irradiation (Figure 1).[3] The self-continuous motion is the resultant of photoreaction velocity
regulation due to the photoreaction-induced forward and backward phase transitions (Figure 2). Since (a) thephotoreaction direction is considerable to be governed by the molecular alignment in the assembly, (b) there
are critical isomer-ratios for the subcritical transitions (the fact also means the reversible phase transition shows
hysteresis), and (c) the metaphases involving the dynamics are pseudo-stable, the periodic route is a limitcycle. The time-profile of the motion of an assembly shown in Figure 3 and its analyzed result shown in
Figure 4 indicate clearly that the assembly converts light energy for its periodic flipping motion. In other7

Active Matter Workshop 2019

ショートトーク
Short talks8

Active Matter Workshop 2019

Short Talks 1
2019年1月11日（金）13:10 ‒ 14:55
1. Mitsusuke Tarama“Mechanochemical modeling of crawling cells”
2. Simon K. Schnyder“Control of cell colony growth by contact inhibition”
3. John Jairo Molina“Modeling the mechanosensitivity of fast-crawling cells”
4. Estelle Gauquelin“Emergence of large scale propagative signals during
epithelial cell migration”
5. Hiroyuki Ebata“Cell-type dependent durotaxis on micro-elasticallyheterogeneous gels”
6. Alexandre Baccouche“Seeing the shape of a molecular program”
7. Anthony Genot“Molecular programming with DNA”

9

Active Matter Workshop 2019

Mechanochemical modeling of crawling cells
Mitsusuke Tarama1, Kenji Mori2, Ryoichi Yamamoto2,3
1Fukui Institute for Fundamental Chemistry, Kyoto University
2Department of Chemical Engineering, Kyoto University
3Institute of Industrial Science, The University of Tokyo

Despite the diversity of cell types, biological cells, which are the basic unit of living creatures, sharecommon structures. They are composed of a number of proteins, lipids, and sugar, which form stablestructures such as cellular membranes. At the same time, a living cell is at a far-from-equilibrium state.
Complex chemical reactions take place inside a cell, the information of which is converted to mechanicalforces by molecular motors. Consequently, a cell exhibits various dynamics spontaneously.
Spontaneous motion is a key property of active matter, which generates force in itself by consuming
potential energy. Such force vanishes in total because of the law of action and reaction. To achieve a net
directional motion under the force-free condition, symmetry breaking plays a fundamental role.
Typical mechanism of cell crawling is thought of as a cycle of four processes: 1) protrusion of theleading edge, 2) adhesion of the leading edge to the substrate, 3) deadhesion of the trailing edge from thesubstrate, and 4) contraction of the trailing edge. In our previous study [1], we clarified the importance of theorder of these four basic processes by introducing a simple model crawling cell composed of two elements
connected by a viscoelastic spring. The spring contains a linear actuator that elongates and shrinks in time,
representing the protrusion and contraction. Since the force generated by the actuator acts on the twoelements symmetrically, the force-free condition is satisfied. In addition, the substrate friction characteristics
switches between the adhered stick state and the deadhered slip state, modelling the adhesion and deadhesion
processes. The phase shift between the stick-slip transitions in the substrate friction of the two elements
breaks the symmetry, which enables the cell to achieve a net migration.
In this presentation, we consider an extension of the model to two dimensions where the cell is modelled
by many of such subcellular elements connected by viscoelastic springs. In order to control the actuator
elongation and the stick-slip transition of the substrate friction of each subcellular element, we couple themechanical model with reaction-diffusion equations that represent intracellular chemical reactions. By
introducing mechanical and chemical dependence of the substrate friction, we show that the cell changes
migration behaviour including the direction.

References
1. M. Tarama and R. Yamamoto, J. Phys. Soc. Jpn. 87, 044803 (2018).

10

Active Matter Workshop 2019

Control of cell colony growth by contact inhibition
a

105

100

b
Tdiv
2 and R. Yamamoto
2
S. K. Schnyder1, J. TJ.mot ,Molina
128, 3
64, 3
32, 3
16, 3
0, 19
0, 10

104

80

0.3vss ∼

vss ∼

103

N1/2 − (N∗ )1/2

Number of cells N

1 Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto,
60 606-8103, Japan
2 Department of Chemical Engineering, Kyoto University, Kyoto 615-8510
102

40

Tmot , Tdiv

128, 320vB /v ssvB /v ss for t ≫ T ∗64, 3Contact inhibition is a cell property that limits
the migration and proliferation of cells in crowded
environ32, 3
101
16, 3
0
ments. However, its role in the emergence of the collective behaviors observed experimentallyis not clear.
0, 19
0, 10
Here we investigate the growth dynamics of10a0 cell colony, see panel a), composedof migrating and prolifer−20
0
10
20
0
250
500
ating cells on a substrate using a minimal model that Time
incorporates
the mechanismsTime
oft contact
inhibition of
t /T
− t∗
locomotion and proliferation. We find two distinct regimes. At early times, when contact inhibition is weak,
0.3
c
d 0.3
the colony grows exponentially in time, fully characterized by the proliferation rate, see panel b). At longtimes, the colony boundary moves at a constant
speed, determined only 0.2
by the migration speed of a single
0.2cell and independent of the proliferation rate, see panel c). Our model illuminates how simple local mechani0.1
0.1
cal interactions give rise to contact inhibition, and from this, howcell colony growth is self-organized and
T =3
T
=0
controlled on a local level.
0.0
0.0
div

mot

0

be

a

104

Area A/As

0.6

10

c

f

128, 3
64, 3
32, 3
16, 3
0, 19
0, 10

0.8

2

101

0.0
0.0

0

10

60
40

Tmot , Tdiv

128, 3
64, 3
32, 3
16, 3
0, 19
0, 10

20

0.2

0.4

−20

20

Time t /T

0.6

20

0.25vss ∼

0

0.2
100

15

100
80

0.4

t = 300

10

Time t /Tb Tmot , Tdiv

103

10 Rmax

50

Cell period T

1.0

Non-adhesive

100(A/As )1/2 − (A∗ )1/2

a

50

0.8

1.0

0

500

1000

Time t − t ∗Figure: a) Snapshot of a cell colony. New cells are marked in red, and cell velocities given as arrows. b) Size of thecolony versus time t. The exponential asymptote is marked by a black line. Both migrating cells and non-migrating
cells follow the same growth law at early times. c) Scaling plot exposing the collapse of the growth dynamics atlong times for the migrating cells.

Acknowledgements
We acknowledge support by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant No.
26610131, 16H00765, and 17H01083.
References
1. S.K. Schnyder, Y. Tanaka, J.J. Molina, and R. Yamamoto, “Collective motion of cells crawling on a sub-strate: Roles of cell shape and contact inhibition”, Scientific Reports 7, 5163 (2017).
2. S.K. Schnyder, J.J. Molina, and R. Yamamoto, “Control of cell colony growth by contact inhibition”,
arXiv:1810.00546.

11

Active Matter Workshop 2019

Modeling the mechanosensitivity of fast-crawling cells
John J. Molina1, Ryoichi Yamamoto1,2
1
Dept. of Chemical Engineering, Kyoto University
2
Institute of Industrial Science, The University of Tokyo

The ability of cells to actively
respond to signals received fromtheir environment is crucial for all
biological systems and can be
exploited to design novel cellsorting assays, as well as biomaterials capable of controlling theproliferation and differentiation ofstem cells.
In this work, we focus on themechanosensitive response of fastcrawling cells (e.g., dictyostelium,
HL-60, keratocytes) over cyclicallystretched substrates. Experiments
have shown that the cells reorient
in a cell-specific manner[1]. While
much is known regarding the
response of slow-crawling cells, Fig. 1 Phase-diagram showing the steady-state orientation of cells over cyclicallyour understanding of how fast- stretched substrates for different adhesion response functions d and stretching
crawling cells reorient is still frequencies ω.
limited. From experiments weknow that they prefer a perpendicular orientation, but the mechanism behind this has yet to be fully
determined[1].
To address this problem, we have developed a computational model capable of relating the mechanosensitive
response of such fast-crawling cells to their sub-cellular dynamics when placed on a cyclically stretchedsubstrate[2]. We consider the dynamics of the cell membrane, the actin-cytoskeleton, and the focal
adhesions. Depending on which process is being probed by the stretching, and the type of coupling with thesubstrate, we observe considerably different realignment dynamics. In particular, we show that an
asymmetry in the stability of the adhesions during extension/compression can align the cells at specificorientations (Fig. 1), and can account for the realignment observed experimentally. Our results and proposed
simulation method can be used to interpret current experiments and to propose new ones, in order to gain abetter understanding of how cells react to mechanical cues from their environment.
Acknowledgements
We acknowledge fruitful discussion with N. Yoshinaga to determine the source of the instability, as well as
useful feedback and suggestions during the preparation of this manuscript from K. Sadakane, K. Yoshikawa,
M. Turner, T. Taniguchi, and S. Schnyder. This work was supported by the Japan Society for the Promotionof Science Wakate B (17K17825) and Kakenhi (17H01083) Grants, as well as the JSPS bilateral joint
research project.
References
1. C. Okimura, K. Ueda, Y. Sakumura, Y. Iwadate: “Fast-crawling cell types migrate to avoid the directionof periodic substratum stretching”. Cell Adh. Migr. 10, 331-341 (2016).
2. J.J. Molina and R. Yamamoto: “Modeling the mechanosensitivity of fast-crawling cells”
Soft Matter (in press)

12Active Matter Workshop 2019

Emergence of large scale propagative signals during epithelial cell
migration
Estelle Gauquelin1, Marc-Antoine Fardin1, René-Marc Mège1, Benoît Ladoux1,21Institut Jacques Monod (IJM), Université Paris Diderot- Paris 7, CNRS UMR 7592, Paris
2
Mechanobiology Institute, National University of Singapore, Singapore

Collective cell migration is a fundamental phenomenon in biology involved in processes such asmorphogenesis and tissue repair. During collective cell migration, various mechanisms play a role in theregulation of tissue expansion including cell proliferation. It can indeed disturb the dynamic organization ofcell monolayers. This project is thus focusing on the study of collective cell behaviors and their link with cellproliferation. We developed an in vitro assay using micro-fabrication techniques to compare the migrating
behavior of cell monolayers with and without cell proliferation (Figure 1.a), and to measure the local effectsof cell division on their environment in migrating and non-migrating tissues.
We first measured velocities within the monolayer on a global scale. In the case of migration without
proliferation, patterns of high velocities appear in the monolayer, propagating from the front of migration
toward the bulk (Figure 1.d) [1]. Those velocity waves can propagate on distances as long as few millimeters
within the tissue. When there is proliferation, the waves are unable to propagate on long distances and are
rapidly damped within the monolayer (Figure 1.c). Our study of local velocity fields surrounding division
events during migration shows that there is a competition between velocities induced by division events andthe global velocity of migration, suggesting that divisions create defects that prevent the propagation of thevelocity waves towards the back of the migrating monolayer. Moreover the wave ability to propagate isdependent of the level of confinement of the tissue and of the initial cell density within the monolayer, andrely on the contractility of the cell actin cytoskeleton.

Figure 1. (a) Schematic representation of the protocol. Cells are first cultured overnight on a segment of the
micropatterned lines restricted by a block of PDMS (left), and then the block is removed and the cells are free
to invaded the fibronectin substrate. (b) Snapshot of a monolayer 16 hours after the start of the experiment.
The white arrow indicates the location of the front at t = 0, that is when recording starts. (c) Spatiotemporal
diagrams of the velocity with divisions. (d) Spatiotemporal diagrams of the velocity without divisions.
References
1. S. Tlili, E. Gauquelin, B. Li, O. Cardoso, B. Ladoux, H. Delanoë-Ayari and F. Graner: “Collective cell
migration without proliferation: density determines cell velocity and wave velocity”, Royal Society OpenScience 5, 172421 (2018).

13

Active Matter Workshop 2019

Cell-type dependent durotaxis
on micro-elastically heterogeneous gels
Hiroyuki Ebata, Kousuke Moriyama, Thasaneeya Kuboki, and Satoru Kidoaki
Institute for Materials Chemistry and Engineering, Kyushu University

In general, the mechanical properties of living body are heterogeneous. For examples, macroscopic
elasticities of the organs vary from 102 to 109 Pa depending on the type of those, such as nerve, muscle, andbone. Even in the same organs, microscopic spatial distribution of the elasticity is also heterogeneous. It
should be noted that the cells in our body lives in such a heterogeneous environment of mechanical property,
and spontaneously migrate in microscopic spatial heterogeneity of the matrix elasticity. Therefore, tocharacterize, predict, and manipulate the cell migration in the living tissues, it is essential to reveal the
migratory behavior on elastically heterogeneous environment.
When the soft and stiff substrates are joined, cells exhibit directional migration from soft to stiff region,
which is called as durotaxis1. The elasticity gradient required to induce the durotaxis has positive dependence
on the elasticity of the soft region2. For fibroblast cells and mesenchymal stem cells (MSCs), soft domain
with the elasticity of 10 kPa requires 100 – 300 kPa for the hard domain to induce the durotaxis2, 3. On theother hand, many living tissue (~ 63 %) have the elasticity of more than 10 kPa on the average, while thelocal variation of elasticity is up to tens of kPa for most tissues. According to these observations, strong
durotaxis seems not to be induced in the most of living tissues, and occurs only in the limited condition.
Since the sizes of soft and hard domains in living tissue typically range from 10 to 1000 µm, cells should
sense microscopically heterogeneous filed of elasticity3, 4. However, while migration on broad elasticity
gradient or a single steep elasticity jump has been focused, the size effect of soft and stiff domain, i.e.,
microscopic heterogeneity, on the durotaxis has not been systemically investigated.
In this study, we aimed to get principle insight for the role of microscopic heterogeneous filed ofelasticity on the durotaxis in a model system of living tissues. By systematically changing the domain sizesof micro-elastically stripe patterned gels that mimic the fibrous tissues, we examined the durotaxis offibroblast cells and MSCs on heterogeneous substrates that have elasticity distribution of typical fibrousorgans (10 ~ 70 kPa). We found that the different type of cells have a preferable domain size to induce strong
durotaxis with the small elasticity gradient. Fibroblasts accumulated in wider hard stripes, while MSCs
localized in narrower hard stripes. To explain the domain-size dependent durotaxis, we provided the cell
migration model by incorporating the response of pseudopodia to the elasticity gradient into the shapefluctuation based cell migration model5. The model well reproduced the domain-size and cell-species
dependent durotaxis (Fig. 1). The model suggested that the dynamics of the pseudopodia on the elasticity
boundary is a key to determine preferable domain size for durotaxis.
Figure 1. (a, b) Examples of
the cell-shape dynamics of(a) a fibroblast and (b) a
MSC on patterned gels with
100 µm period. Gary areas
indicate hard domains. (c, d)cell-shape dynamics
calculated from the modelfor (c) a fibroblast and (d) a
MSC on patterned gels with
100 µm period.

References
1. C-M. Lo, H-B. Wang, M. Dembo, and Y-l. Wang, Biophys. J. 79, 144 (2000).
2. K. Moriyama and S. Kidoaki, Langmuir (2018).
3. T. Kawano and S. Kidoaki, Biomaterials 32, 2725- 33 (2011). Biomaterials 34, 7563-7564 (2013).
4. A. Ueki, and S. Kidoaki, Biomaterials 41, 45-52 (2015).
5. H. Ebata, et al. Sci. Rep. 8, 5153 (2018).

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Active Matter Workshop 2019

Seeing the shape of a molecular program
Alexandre Baccouche​1​, Yannick Rondelez​2​, Teruo Fujii​1​, Anthony Genot​1
1 LIMMS/CNRS-IIS, Institute of Industrial Science, The University of Tokyo, Japan
2 Laboratoire Gulliver, ESPCI, PSL Research University/CNRS, Paris, France

Unicellular organisms like bacterias are computing at the molecular level byprocessing sets of stimuli into an appropriate response through chemical reactions. For
instance in chemotaxis, where a bacteria computes and travels along a spatial gradient of
nutrients to find the best source of food. The emerging ​field of molecular programming aims
at programming molecules in a similar way a bacteria would do, in order to control complex
mechanisms and engineer new functions.
Our objective is to demonstrate innovative computational behaviors in micro-nanosystems. To this end, we assemble short DNA molecules and enzymes into reaction
networks using the PEN-DNA toolbox,​1,2 a set of 3 cascadables enzymatic reactions:activation, inhibition and degradation. The continuous anabolism and catabolism of the DNA
strands is ruled by the topology of the network, and drive the system out of equilibrium, thus
enabling dynamics such as oscillations​3​ and bistability.​4
In order to test molecular programs with high throughput, we developed a droplet
microfluidic platform, which allows us to screen the parameter space with high resolution
while reducing both reagent consumption and work-up time by 3 or 4 orders of magnitude.​5
Here, I will present the first high-throughput mapping of a nonlinear biochemicalsystem using droplet microfluidic. The large scale of the data sets (10​4 points) allowed us todiscover subtle dynamics in two PEN-DNA toolbox circuits : a bistable switch and a
predator-prey oscillator.​6 The maps grasped the bifurcation frontiers in parameter space, andconfirmed experimentally prior theoretical predictions on how competition for the processing
enzymes shapes the molecular program landscape.​7,8

1. Montagne, K., Plasson, R., Sakai, Y., Fujii, T. & Rondelez, Y., ​Mol. Syst. Biol. ​7​, 466–466 (2014).
2. Baccouche, A., Montagne, K., Padirac, A., Fujii, T. & Rondelez, Y., ​Methods ​67​, 234–249 (2014).
3. Fujii, T. & Rondelez, Y., ​ACS Nano ​7​, 27–34 (2013).
4. Padirac, A., Fujii, T. & Rondelez, Y, ​Proc. Natl. Acad. Sci. ​109​, E3212–E3220 (2012).
5. Baccouche, A. ​et al.​, ​Nat. Protoc. ​12​, 1912–1932 (2017).
6. Genot, A. J. ​et al.​, ​Nat. Chem. ​8​, 760–767 (2016).
7. Rondelez, Y., ​Phys. Rev. Lett. ​108​, (2012).
8. Genot, A. J., Fujii, T. & Rondelez, Y., ​Phys. Rev. Lett. ​109​, (2012).

15

Active Matter Workshop 2019

Generation, encapsulation and control of micrometric beads of
DNA hydrogels
Anthony Genot1,2
1

CNRS

2University of Tokyo

Hydrogels have recently attracted a lot of attention in fields like regenerative medecine or drug delivery
due to their biocompatibility, their 3D scaffold and their mechanical properties. Hydrogels made of DNA areespecially interesting because they can be programmed to respond to external stimuli, such as a change intemperature, pH or the presence of a target DNA strand. The encapsulation, culture and unloading of cells
would bring numerous benefits, not only for tissue engineering, but also for single-cell analysis.
Our DNA gels are based on a design reported by the Murata group at Tohoku University. In this design 4
DNA strands mutually bind to each other to form a X motif, from which protude sticky ends that allow the
X-motifs to reticulate into a large network. Starting from this design, we adapted to a microfluidic format demonstrating the generation of DNA beads of ~50 micrometers in diameters. We also encapsulated
antibodies in the beads, and demonstrated the control dissolution of the gel beads through the addition ofcomplementary strands.

16

Active Matter Workshop 2019

Short Talks 3
2019年1月12日（土）10:30 ‒ 11:30
1. Hiroyuki Kitahata“Spontaneous motion of a camphor particle depending on
its shape”
2. Makoto Yoneya“Azo liquid-crystals as a molecular active matter:
Molecular dynamics simulation study”
3. Yoshino Hasegawa“Traveling wave of graphite particles induced by photoirradiation”
4. Nicolas Lobato-Dauzier“MEGABOTS: DNA nano-robots swarms for multiscale
dynamic construction”

17Active Matter Workshop 2019

Spontaneous motion of a camphor particle depending on its shape
Hiroyuki Kitahata, Yuki Koyano
Department of Physics, Chiba University

In nonequilibrium systems, a particle or a droplet can spontaneously move by dissipating free energy.
Such particles or droplets are called self-propelled particles. The fundamental theory on the relation between
the motion and the shape of the self-propelled particles was proposed by Ohta and Ohkuma [1,2]. Based on
the model, the characteristics of some experimental systems have been discussed [3]. A camphor particle onwater is a good example of a self-propelled particle [4,5]. When a camphor particle is put on water, camphor
molecules are released to the water surface from the particle. The camphor molecules reduce the surface
tension of water. The imbalance of the surface tension around the camphor particle drives the camphor
particle. If the position of the camphor particle changes, it rearranges the camphor molecule concentration at
the water surface. By this procedure, the rest state of a camphor particle can be destabilized and it may startspontaneous motion. Since the camphor concentration profile at the water surface is affected by the shape ofthe camphor particle, the shape of the particle can affect the motion of the camphor particle.
In our previous study, we investigated the motion of the elliptic camphor particle [6,7]. Based on atheoretical model composed of a reaction-diffusion equation for the camphor surface concentration and a
Newtonian equation for the camphor particle motion [8], we predicted that an elliptic camphor particle
moves in its minor-axis direction. This prediction was confirmed with the numerical calculation and actual
experiments [6,7].
In the present study, we extended our previous study for the case with other shapes. Especially, we
consider the camphor particle with the third-mode deformation. We theoretically discuss the coupling
between translational and rotational motion of the camphor particle by considering the force and torque [9].
In the presentation, we will show the results of the analysis together with the results of the preliminary
experiments.
References
1. T. Ohta and T. Ohkuma: “Deformable self-propelled particles”, Phys. Rev. Lett. 102, 154101 (2009).
2. T. Ohta: “Dynamics of deformable active particles”, J. Phys. Soc. Jpn. 86, 072001 (2017).
3. H. Ebata and M. Sano: “Swimming droplets driven by a surface wave”, Sci. Rep. 5, 8546 (2015).
4. S. Nakata, Y. Iguchi, S. Ose, M. Kuboyama, T. Ishii, and K. Yoshikawa: “Self-rotation of a camphor
scraping on water: new insight into the old problem”, Langmuir 13, 4454 (1997).
5. S. Nakata, M. Nagayama, H. Kitahata, N. J. Suematsu, and T. Hasegawa: “Physicochemical design andanalysis of self-propelled objects that are characteristically sensitive to environments”, Phys. Chem.
Chem. Phys. 17, 10326 (2015).
6. H. Kitahata, K. Iida, and M. Nagayama: “Spontaneous motion of an elliptic camphor particle”, Phys. Rev.
E 87, 010901 (2013).
7. K. Iida, H. Kitahata, and M. Nagayama: “Theoretical study on the translation and rotation of an elliptic
camphor particle”, Physica D 272, 39 (2014).
8. M. Nagayama, S. Nakata, Y. Doi, and Y. Hayashima: “A theoretical and experimental study on theunidirectional motion of a camphor disk”, Physica D 194, 151 (2004).
9. H. Kitahata, Y. Koyano, K. Iida, and M. Nagayama: “Mathematical model and analyses on spontaneous
motion of camphor particle”, in “Self-organized motion: Physicochemical design based on nonlinear
dynamics” (eds.) S. Nakata, V. Pimienta, I. Lagzi, H. Kitahata, and N. J. Suematsu (Royal Soc. Chem.,2018).

18

Active Matter Workshop 2019

Azo liquid-crystals as a molecular active matter:
Molecular dynamics simulation study
Makoto Yoneya and Yasuo Norikane

National Institute of Advanced Industrial Science and Technology (AIST)
Azo-dyes are known to show mass-transportation upon irradiation of (UV and/or visible) light 1-3).
Photoisomerization of azobenzene chromophore is considered to be the origin of this mass-transportation as
schematically shown in Fig. 1 3). Although, the picture shown in Fig. 1 is totally uncertain, this figure
inspired us that the azo-dyes could be a candidate of light-driven molecular active matter.
Last year, we reported results of molecular dynamics (MD) simulations of azo-dye 4-(dimethylamino)
azobenzene (DMAAB) shown in Fig. 1 under periodic irradiation of UV and visible (VIZ) lights thatenforced periodic photoisomerization between trans- and cis-form (Fig. 1). Our simulation results showedenhanced diffusion of DMAAB molecules under the irradiation.
In this study, we have done the corresponding MD simulations with an azo liquid crystal (LC) molecule
4-pentyl-4’-metoxy azobenzene (PMAB) 4) shown in Fig. 2. If the picture shown in Fig. 1 is somehow
correct, we can expect enhanced anisotropy of diffusion along molecular long-axis. Our simulation results
showed enhancement of molecular diffusion of azo LC but reduction of diffusion anisotropy upon
irradiation.
References
1. Uchida E. et al.: “Light-induced crawling of crystals on a glass surface”, Nat. Commun. 6, 7310 (2015).
2. Nakano H. and Tanino T.: “Surface relief grating formation on a single crystal of 4-(dimethylamino)
azobenzene”, Appl. Phys. Lett. 87, 061910 (2005).
3. Fiorini C. et al.: “Molecular migration mechanism for laser induced surface relief grating formation”,
Synth. Met. 115 121 (2000).
4. Steistrasser and Pohl: “Niedrigschmelzende p-alkyl-p’-alkoxy- und p-alkyl-p’-acyloxy-azobenzole”, Z.
Naturforsch B, 25b, 577 (1971)

Fig.１: Photoinduced caterpillar-like DMAAB molecule motion
upon light irradiation (after Ref. 3)

19

Fig. 2: Azo liquid-crystal molecule PMAB
(Cry. 39℃ Nem. 65℃ Iso.) 4)

Active Matter Workshop 2019

Traveling wave of graphite particles induced by photo-irradiation
Yoshino Hasegawa, Tomoko Tanaka, Satoshi Takatori,
Koichiro Sadakane, Takahiro Kenmotsu, Kenichi Yoshikawa
Faculty of Life and Medical Sciences, Doshisha Univ.

The temporal and spatial patterns appear almost everywhere in the nature, especially under nonequilibrium open system; BZ reaction, the stripe on the skin of a zebra and so on. These complicated selforganized patterns emerged by some simple physics stimulate our curiosity. Besides this social and scientificinterest, we previously reported the collective motion of micro particles and centimeter-sized droplets inopen and multiparticle nonequilibrium systems by photo-irradiation[1-3]. In these former works, themovements of targets in gas and in liquid switch forward and backward via photo-thermal effect.
In this presentation, we newly reported how micro particles behave in alcohol solution by steady photoirradiation(λ=532 nm)(Fig. 1). Here, an experimental setup is described briefly, where the CW laser is
induced horizontally to ethanol solution that graphite particles scattered in. We discovered that thecompressional pattern of micro particles is emerged in gas-liquid interface of alcohol solution by laser. In
Fig. 2, we found that long wavelength of compressional wave already exists and flows forward, then rightafter photo-irradiation, the wavelength of compressional wave became shorter. The shape and the velocity of
the wave are significantly different between the cases the upper side of the container is open and close withthe lid; it shows how important high volatility of ethanol is. For example, where the gas-liquid interface isthe open state, translational compressional waves is emerged constantly. The wavelength is about 1 to 3 mm.
Whereas, where the gas-liquid interface is the closed state, the compressional waves become remarkably
instable. The wavelength is about 12 mm and 4mm. Also, the velocity in open state is 2.5 mm/sec, and it is 5
to 40% faster than that in the closed state. This result suggested that the volatility of ethanol in the gas-liquidinterface is largely involved in the formation of compressional waves. Also, by changing relevant
parameters, we find a similar tendency of graphite particle’s compressional wave by solving adventive
diffusion equation numerically. In our presentation, we discuss the mechanism of this self-organizing
phenomenon of graphite particles by photo-induced effects, such as Marangoni instability and radiometricforce.

Fig. 1 The experimental setup and the compressional
waves of graphite particles by photo-irradiation.

Fig. 2 The spatio-temporal plot of the gas-liquidinterface of solution.

References
1. S. Watanabe, et al., "Negative photophoresis of smoke particles observed under microgravity”, Chem.
Phys. Lett., 511, 447-451 (2011).
2. M. Ichikawa, K. Yoshikawa, et al., "Controlling negative and positive photothermal migration ofcentimeter-sized droplets", Phys. Rev. E, 88, 12403/1-8 (2013).
3. S. Rybalko, N. Magome, and K. Yoshikawa, "Forward and backward laser-guided motion of an oil
droplet", Phys. Rev. E, 70, 046301/1-4(2004).

20

Active Matter Workshop 2019

MEGABOTS:
DNA nano-robots swarms for multiscale dynamic construction
N. Lobato-Dauzier1, G. Gines2, Y. Rondelez2, T. Fujii1, A.J. Genot1
LIMMS, CNRS-Institute of Industrial Science, UMI 2820, The University of Tokyo, Tokyo, Japan
2
UMR Gulliver 7083 CNRS, ESPCI ParisTech, PSL Research University, Paris, France
1

The environment, healthcare or energy need radically new techniques to orchestrate matter at a multi-scalelevel, from meters (human scale) to nanometers (molecular scale). For instance, tissue engineering to create
in-vitro organs requires to arrange in space and time a network of blood microvasculature. In photovoltaics,
periodically organizing single nanocrystals (quantum dots) could dramatically improve the performance of
solar panels. DNA nanosystems, because of their nanometric size, their inherent compatibility withbiological systems and their programmability could offer a new dimension to tackle such challenges.
Imagining swarms of DNA nano-robots becoming the architects, engineers and workers in our future
constructions can seem pure science-fiction as the possibilities it opens are beyond our understanding.
However, recent breakthrough in DNA nanotechnology [1], show we are not that far from our goal:
designing and programing swarms of millions of DNA nano-robots (Figure 1) to self-assemble fromnanometers to centimeters in a massively parallel and reprogrammable way.
In this talk I will present how the PEN-DNA Toolbox allows to create microscopic agents that can computeand communicate [1]. I will then introduce how such a framework can allow to shape matter dynamically byshowing experimental results of conditional aggregation of micro sized robots. Finally, I will show the work
done using DNA coated gold nanoparticles and how using the Transmission Electron Microscope liquid celland the high-throughput droplet platform [2] will allow a better understanding of the thermodynamics
involved.

Figure 1- Smart swarms of millions of DNA nano-robots that self-assemble could enable ultra-sensitive sensor to monitor air
pollution, help the growth of artificial organs or enhance quantic properties of solar panels to improve their efficiency.

References
1. G. Gines, et al.: “Microscopic agents programmed by DNA circuits”. Nature nanotechnology 12.4 351.
(2017)
2. A. J. Genot et al.: “High-resolution mapping of bifurcations in nonlinear biochemical circuits”. Nature
Chemistry 8, 760–767 (2016)21

Active Matter Workshop 2019

Short Talks 4
2019年1月12日（土）13:00 ‒ 14:30
1. Kei Kikuchi“Characteristics of the collective motion of barnacle
larvae”
2. Shiho Sato
“Self-running droplets: Mode bifurcation andsynchronization”
3. Saori Suda
“Coupling between the internal convention and the selfpropelled motion in a water-in-oil droplet system"
4. Masahide Okada“Self-split of oil droplets on surfactant aqueous solution”
5. Masahiro Makuta“Anomalous diﬀusion of a microparticle encapsulated in acell-sized active gel droplet composed of actomyosin”
6. Ryota Takenaka“experiment of development of reconstruction system toﬁnd out the mechanism of cytokinesis”
22Active Matter Workshop 2019

Characteristics of collective motion of barnacle larvae
Kei Kikuchi1, Yukitaka Ishimoto1, Keiju Okano1, Stephanie Nix1
1
Akita Prefectural University

1. Background
Barnacles are a type of crustacean with two distinct
larval stages, the nauplius and cypris stages.
Cyprids are on a mission to find a good surface tosettle and cement themselves on. Many features ofcyprid motion have been revealed, including thatthey are attracted to adult pheromones. However,
the mechanism of group formation on an adult-freesurface, analysis of cypris swimming modes, andmechanical details have not been clarified.
In order to elucidate the barnacle cypris
navigation system, we tracked barnacle larvae
swimming and analyzed characteristics of theircollective motion.

Fig. 2: Example trajectories in x-y plane.
The MSD (mean squared displacement) of
two characteristic patterns are shown in Figure 3.
Circular points show MSD of active cyprids
travelling for relatively further distance. Trianglar
points show MSD of static cyprids who seem
relatively disfavour travelling. The ‘active’ MSD
increases steadily up to 4 s, thenit becomes nearly
constant from 4 to 8 sec. This may be wellaccounted by a fact that cyprids mostly do notswim straight. They swim a certain distance, thenchange their angles of motion. On the other hand,the ‘static’ MSD increases monotonically. It may
be because some of such larvae which rarely swim
would move while falling/sedimenting.
From the speed autocorrelation, we found thatthey swim with a period of about 0.024 sec.

2. Method
Figure 1 shows an overview of the experimentdevices used in this study. Barnacle cypris larvaeof genus Rhizocephala were placed in a chamberconsisting of acrylic and rubber. A laser sheet(KANOMAX, CW532-5W) was shone from above
the chamber, and barnacle larvae swimming wasrecorded for 10 sec at a frame rate of 250 fps witha high-speed camera (Photron,SA5). The captured
video was analyzed partially by using ImageJ.

Fig. 1: Experimental setup.
3. Results and Discussion
Figure 2 extracted some trajectories of barnacle
cyprids. We confirmed three swimming patterns:(a) swimming, (b) sinking, and (c) swimming andsinking. These swimming patterns were also
observed in [1, 2]. In addition, the overall averageswimming speed was 17 mm/s.

Fig. 3: Mean squared displacement of barnacle
cyprids.
References
1. S. Maleschlijski, Journal of the Royal SocietyInterface, 12, 1-9 (2015)
2. A. I. Larsson, PLoS ONE 11, 1-17 (2016)23

Active Matter Workshop 2019

Self-running droplets: Mode bifurcation and synchronization
Shiho Sato, Hiroki Sakuta, Koichiro Sadakane, Kenichi Yoshikawa
Faculty of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan
We report characteristic behavior of self-running droplets driven by chemical nonequilibricity underisothermal condition. We discuss the mechanism of mode switching on the motion and synchronous motion interms of nonlinear dynamics under interfacial instability.
1. Mode Bifurcation of motion by drop position
It will be shown that unique behavior of selfpropelled droplets of nitrobenzene floating on an
aqueous solution. Fig.1(a) exemplify the traces ofoil droplets, representing difference on the modesof self-motion. It was found that, even under thesame experimental conditions, different modes
are generated depending on the initial positioningof the droplet, either on the center of near the wall;
reciprocating back-and-go motion and revolution
motion. Self-propelled modes of the droplet aresummarized as a phase diagram in Fig. 1(b).

2. Synchronous motion
When droplets are dropped onto the water surface, they move synchronously. A Pasteur pipette is inserted in
the center of a glass container with a diameter of 14 cm and a width of 1 cm. The aqueous phase is acetic acidaqueous solution (0.3M, 10mL). Nitrobenzene droplets are dropped on the left and right sides of the containerand start moving immediately. In a little, the two droplets show a swinging motion. This is a synchronous
phenomenon that occurs due to the interaction of droplets at the center. Mathematical model is also createdfrom the experiment result and the essence of synchronous motion is reproduced.

References
1. Y. Sumino and K.Yoshikawa: " Self-Running Droplet: Emergence of Regular Motion from Nonequilibrium Noise ",Phys. Rev. Lett., 94, 068301/1-4 (2005).
2. Y. Chen, K. Sadakane, et al: "Spontaneous Oscillations and Synchronization of Active Droplets on a Water Surface
via Marangoni Convection", Langmuir, 33, 12362-12368 (2017)
3. Y. Chen, Y. Nagamine and K. Yoshikawa: "Self-Propelled Motion of a Droplet Induced by Marangoni-Driven",
Physical Review E, 80, 16303-7 (2009)
4. H. Sakuta, N. Magome, et al: "Negative/Positive Chemotaxis of a Droplet: Dynamic Response to a Stimulant Gas",
Appl. Phys. Lett. 108, 203703(2016).
5. Y. Sumino, et al: “Emergence of vortices of microtubules”, Nature, 483, 448-452 (2012)24

Active Matter Workshop 2019

Coupling between the internal convention and the self-propelled
motion in a water-in-oil droplet system
Saori Suda1, Takuya Ohmura1, Tomoharu Suda2 and Masatoshi Ichikawa1
1
Grad. Sch. of Sci. Kyoto Univ.
2
Grad. Sch. of Human & Environ. Studies Kyoto Univ.

A self-propelling swimming droplet is one of simple systems of active matters, with potential
applications such as micro and nano machinery. In this study, we investigate the Marangoni effect driven
droplet of water introduced into the oil including surfactant [1].
By controlling the size of droplets, we found a transition behavior of the mode of motion. The smaller
droplets move straight ahead, whereas larger ones wander in a curved fashion. We measured the internalconvection via Particle Imaging Velocimetry (PIV), and then decomposed it into spherical harmonics
components [2]. Through comparison between the components and the motion of the droplet, we discuss thepossible mechanism of the transition of motion.

Fig.１：Characteristic motions of water-in-oil droplet as a function of droplet size.

The lines are the trails of the center-of-mass of the droplets.
References
1. Z. Izri, M. N. van der Linden, S. Michelin, and O. Dauchot, Phys. Rev. Lett. 113, 248302 (2014).
2. M. Schmitt and H. Stark, Phys. of Fluids 28, 012106 (2016).

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Active Matter Workshop 2019

Self-split of oil droplets on surfactant aqueous solution
1

Masahide Okada1, Hiroyuki Kitahata2
Graduate School of Science and Engineering, Chiba university
2
Graduate School of Science, Chiba university

Split of oil droplets which deform themselves on the surface of an aqueous phase has been reported[1-3].
In these studies, the droplet composed of tetradecane containing anionic surfactant (palmitic acid, PA) was puton the cationic surfactant (stearyltrimrthylammonium chloride, STAC) solution. At the boundary between theoil and aqueous phases, the aggregates are formed from PA and STAC. Then, the aggregates are stacked at theboundary and expand the droplets. Some time after, the aggregates are removed from the boundary and thedroplets shrink. As the result of the deformation (expansion and shrink, named “blebbing”), droplets
sometimes split by themselves[2].
In previous studies, blebbing of the droplets was often focused. For example, a simple equation to describe
the mechanism of blebbing was proposed[1-2]. However, self-splitting has been less concerned.
In the present study, we focused on the split of droplets like Fig. 1. Figure 2 shows the size-dependencyof split frequency (STAC:1 mM/ PA:20 mM). We fitted the experimental results to a sigmoid function f (A0).
From these results, we found that the larger droplets split themselves more frequently than the smaller droplets.
In this presentation, we will discuss the process of the droplet split based on the split frequency (Fig. 2), thedroplet are before and after split and so on.
0s

30 s

60 s

90 s

120 s

150 s

180 s

210 s

Split frequency f[Hz]Figure 1: Snapshot of the splitting droplets (STAC:1 mM/ PA:20 mM). Scale bar shows 10 mm.

0.3
0.3
0.2
0.2
0.1
0.1
00

00

50
50

100
100

150
150

200
200

250
250

300
300

Area of the droplet before split A0

350
350

400
400

450
450

[mm2]

Figure 2: Size-dependency of split frequency f (STAC:1 mM/ PA:20 mM). Experimental results are fit by a𝛼sigmoidal function 𝑓(𝐴0 ) =(𝐴0 −𝛽) , the result of which is shown with a red curve. By the fitting, we⁄𝛾)

1+exp⁡(−

obtained D = 0.1816 Hz, E = 99.5962 mm and J = 9.1735 mm2.
References
1. Y. Sumino et al.: “Blebbing dynamics in an oil-water-surfactant system through the generation anddestruction of a gel-like structure”, Phys. Rev. E, 76, 055201 (2007).
2. Y. Sumino et al.: “Dynamical blebbing at a droplet interface driven by instability in elastic stress: a novel
self-motile system”, Soft Matter, 7, 3204 (2011).
3. Y. Sumino et al.: “Formation of a multiscale aggregate structure through spontaneous blebbing of aninterface”, Langmuir, 28, 3378 (2012).
2

26

Active Matter Workshop 2019

Anomalous diffusion of a microparticle encapsulated in a cellsized active gel droplet composed of actomyosin
Masahiro MAKUTA1, Yukinori NISHIGAMI2 and Masatoshi ICHIKAWA1
1

Dept. of Phys., Kyoto Univ.
2
RIES, Hokkaido Univ.

Living cells actively regulate the generation of force during various biological processes. Cytoskeletons
and its associated proteins mainly perform such force generations. Actin filament, which is one of thecytoskeletons plays a major role in force generation of living cells. For example, muscle actin generates
contraction force in cooperation with the motor protein myosin. Actomyosin, which is a composite material ofactin and myosin also works in deformation and maintenance of the cell shapes. We have performed in vitro
experiments by using artificial cells to clarify the primitive mechanism of the deformation induced byactomyosin extracted from A. proteus [1,2]. These works figured out the dynamic interface deformation andanalyzed their statistical features. However, it has not yet examined internal dynamics inside the artificial cells
correlated with the interfacial deformations. We here studied active fluctuation induced by actomyosin throughthe motion of probe beads encapsulated in the droplet of actomyosin purified from rabbit skeletal muscle [3].
The basic behaviors of the interface were consistent with the results of previous studies, i.e., induction,
nonperiodic oscillation, and winkling phases were emerged in order. Through the experiments, fluctuation of
microbeads accompanied with motion transition of the interface exhibited correlations as shown in Figs. 1. (a)and (b). In induction phase (0 - 300 s), microbeads fluctuated around the initial position, and the motion became
larger in the nonperiodic oscillation phase (400 – 500 s). In the early winkling phase (600 – 700 s), themicrobead was fallen into the interface where the actomyosin cortex formed. In the former phases, anisotropic
fluctuation was observed, e.g., diffusion coefficient in the tangential direction was different from radial
direction. The result suggests anisotropic formation of actomyosin bundles and their force network due to thesmall spherical boundary condition.

Fig. 1. (a)Trajectory of microsphere in actomyosin
droplet.
(b)Displacement of microsphere from initial position.

References
1. H. Ito, Y. Nishigami, S. Sonobe, M. Ichikawa, Phys. Rev. E 92, 062711 (2015).
2. Y. Nishigami, H. Ito, S. Sonobe, M. Ichikawa, Sci. Rep. 6, 18964 (2016).
3. H. Ito, M. Makuta, Y. Nishigami, M. Ichikawa, J. Phys. Soc. Jpn 86 (2017).

27

Active Matter Workshop 2019

Experiment of development of reconstruction system
to find out the mechanism of cytokinesis
Ryota Takenaka1, Yukinori Nishigami 2, Masatoshi Ichikawa1
1
Kyoto University
2
Hokkaido University

The cytokinesis occurs in the final process of the cell division. In this process, multiple proteins are
localized on the cleavage furrow. For specifying proteins essential for the cytokinesis, we put actin, HMM(Heavy Meromyosin), and proteins related to the cytokinesis in water-in-oil droplets as a simple boundary
condition and observed them. The results showed that some of them formed constrictions or showed actin
rings in several conditions.
Acknowledgements
We would like to thank Makito Miyazaki and Tetsuya Takeda for providing reagents advice on experimental
design.
References
1. Miyazaki, M., Chiba, M., Eguchi, H., Ohki, T., & Ishiwata, S.: “Cell-sized spherical confinement induces
the spontaneous formation of contractile actomyosin rings in vitro”, Nature Cell Biology 17, 480–489(2015).
2. Takeda, T., Robinson, I. M., Savoian, M. M., Griffiths, J. R., Whetton, A. D., McMahon, H. T., &Glover, D. M.: “Drosophila F-BAR protein Syndapin contributes to coupling the plasma membrane andcontractile ring in cytokinesis”, Open Biology 3, 130081–130081 (2013).
3. Kessels, M. M., & Qualmann, B.: “Syndapin oligomers interconnect the machineries for endocytic
vesicle formation and actin polymerization”, Journal of Biological Chemistry 281, 13285–13299 (2006)

28