National Institute for Basic Biology

Evolutionary Biology and Biodiversity

LABORATORY OF BIOLOGICAL DIVERSITYFUJITA Group
Assistant Professor:
Technical Assistant:

FUJITA, Hironori
EGAWA, Akane
TAKEKAWA, EikoIn nature, a variety of self-organized patterns, such as thegalaxy and the snowflake, are found on a wide range ofspatiotemporal scales. Particularly in living organisms, suchself-organization of spatiotemporal patterns is both remarkable and essential. Therefore, we aim to elucidate the mechanism of generation and control of self-organized patterns inliving systems with a particular focus on plants using boththeoretical and computational approaches (Figure 1).

formed under the condition of “spot inoculation”, in whichE. coli cells are inoculated in the center of soft-agar plates(Figure 2B). In order to further develop the research, wehave newly developed an assay system “uniform inoculation”, which causes a more dynamic self-organization inwhich colony spots initially emerge from the entire surfaceof agar medium, and they move and fuse with each otherrepeatedly (Figure 2C). Whereas experimental conditions
in biological experiments are usually greatly restricted, thesynthetic approach is a powerful research method that cancontrol and modify the experimental conditions in a more
flexible manner compared to the method used in standard
experiments. Therefore, we try to apply the synthetic
approach to E. coli to understand the principle of spatiotemporal self-organization of cell populations.

A

Desktop darkroom

Side angle LED
ring lights

Digitalcamera

E. coliSoft-agar medium

B Spot inoculation 

0 hr

24 hr

48 hr

72 hr

96 hr

E. coli (Soft-agar medium)

C Uniform inoculation

Hard-agar medium

Figure 1. (Left) Phyllotaxis pattern is self-organized by the feedback
regulation between auxin concentration and PIN1 polarization. (Middle)
Leaf venation pattern is self-organized by the feedback regulation
between auxin flux and PIN1 polarization. (Right) Shoot apical meristem(SAM) is self-organized by the interaction between WUS and CLV3.

0 hrI. S patiotemporal self-organization of cell
population

One well-known example of spatiotemporal self-organization in living systems is Dictyostelium discoideum, known
as cellular slime mold. D. discoideum usually exists as aunicellular organism, but when stimulated by starvation, cells
aggregate while forming a spiral pattern and develop a sluglike multicellular body. This remarkable self-organization isinduced by chemotaxis to the signal molecule cAMP.
On the other hand, it is reported that Escherichia coli,
which is a unicellular model organism, can self-organize
spotted colony patterns (Figure 2B). This pattern formation
is induced by the positive feedback between chemotaxis toaspartate (Asp) and Asp synthesis, and can be an excellent
experimental system in the study of self-organization ofcell populations. This stationary pattern of E. coli colony is80

2 hr

3 hr

4 hr

5 hr

Figure 2. (A) A device system for photographs and time-lapse videos ofspatiotemporal patterns of cell populations. (B) Spot inoculation; E. coli
cells are inoculated in the center of soft-agar plates. The cell population
spreads outward while forming a stable spot pattern. (C) Uniform inoculation; E. coli cells are evenly inoculated in soft-agar medium. The cell population shows a dynamic spatiotemporal self-organization in which colony
spots initially appear from the entire surface of soft-agar medium (2 hr),and they move to fuse with each other repeatedly (2–5 hr).

Publication List:〔Original paper〕

K., Fujita, H., Isa, M., Gotoh, S., Arasaki, A., Ishida, H.,• Kataoka,
and Kimura, R. (2021). The human EDAR 370V/A polymorphism

affects tooth root morphology potentially through the modification ofa reaction–diffusion system. Sci. Rep. 11, 5143. DOI: 10.1038/s41598021-84653-4