Locally and globally coupled oscillators in muscle.

At an intermediate activation level, striated muscle exhibits autonomous oscillations called SPOC, in which the basic contractile units, sarcomeres, oscillate in length, and various oscillatory patterns such as traveling waves and their disrupted forms appear in a myofibril. Here we show that these patterns are reproduced by mechanically connecting in series the unit model that explains characteristics of SPOC at the single-sarcomere level. We further reduce the connected model to phase equations, revealing that the combination of local and global couplings is crucial to the emergence of these patterns.

A theory on auto-oscillation and contraction in striated muscle.

It is widely accepted that muscle cells take either force-generating or relaxing state in an all-or-none fashion through the so-called excitation-contraction coupling. On the other hand, the membrane-less contractile apparatus takes the third state, i.e.

Actin oligomers at the initial stage of polymerization induced by increasing temperature at low ionic strength: Study with small-angle X-ray scattering.

Using small-angle X-ray scattering (SAXS), we have studied the initial stage (nucleation and oligomerization) of actin polymerization induced by raising temperature in a stepwise manner from 1°C to 30°C at low ionic strength (4.0 mg ml actin in G-buffer). The SAXS experiments were started from the mono-disperse G-actin state, which was confirmed by comparing the scattering pattern in - and real space with X-ray crystallographic data.

Noise-induced phase locking in coupled coherence-resonance oscillators.

We investigate the effects of additive noise on coupled excitable chemical oscillators, particularly focusing on how oscillatory coupled modes can be induced by noise. We find that phase locking in the weak coupling regime occurs through coherence resonance, although the resulting phase locking modes are apparently similar to those in coupled deterministic oscillators. Experimental observations are approximately reproduced in a numerical simulation with a forced Oregonator reaction-diffusion model.