This review surveys motile biological systems that possess liquid‑crystalline architectures—notably myofibrils and the mitotic spindle—and proposes an integrative framework that bridges liquid‑crystal physics with molecular‑motor physiology.
Smectic‑A order in striated muscle.
Using the sarcomere as a paradigmatic “smectic A” lattice, Ishiwata and colleagues describe the discovery of Spontaneous Oscillatory Contraction (SPOC), which arises under specific Ca²⁺ and ADP/Pi conditions, and its theoretical treatment via a set of three coupled differential equations.
Active‑nematic behavior of the mitotic spindle.
The authors then discuss microrheological analyses of the spindle, whose microtubules exhibit nematic alignment, and examine how external forces modulate chromosome‑segregation timing—revealing unusual elastic and viscous responses characteristic of an active liquid crystal.
Self‑organized actomyosin rings in artificial cells.
Experiments in cell‑sized emulsions and giant liposomes show that spherical confinement, combined with filament bending elasticity, can spontaneously generate contractile rings.
From these multi‑scale studies, the review extracts a universal design principle: “balance and antagonism of forces” at each hierarchical level give rise to emergent functions. Potential applications to regenerative medicine and bio‑soft‑material design are also outlined.
Article information & citation
Shin'ichi Ishiwata, Makito Miyazaki, Katsuhiko Sato, Koutaro Nakagome, Seine A. Shintani, Fuyu Kobirumaki‑Shimozawa, et al. Dynamic properties of bio‑motile systems with a liquid‑crystalline structure. Molecular Crystals and Liquid Crystals 647, 127‑150 (2017).