Cofilin stimulates actin filament disassembly and accelerates actin filament turnover. Cofilin is also involved in stimulus-induced actin filament assembly during lamellipodium formation. However, it is not clear whether this occurs by replenishing the actin monomer pool, through filament disassembly, or by creating free barbed ends, through its severing activity. Using photoactivatable Dronpa-...

In three-dimensional reaction-diffusion systems, excitation waves may form and rotate around a one-dimensional phase singularity called the filament. If the filament forms a closed curve, it will shrink over time and eventually collapse. However, filaments may pin to non-reactive objects present in the medium, reducing their rate of collapse or even allowing them to persist indefinitely. We use...

The non-Cu critical current density of Nb3Sn strands has been pushed towards 3000 A/mm2 (12 T, 4.2 K) by increasing the Sn content and reducing the interfilamentary Cu. We compare the susceptibility to A15 filament breakage (under 0.5% bend strain) of the new high-Jc internal Sn conductor geometries with both high-Jc Powder-in-Tube (PIT) and low hysteresis loss distributed filament ITER designs...

Ordered arrays of thin filaments (65 A diameter) along with other apparently random arrangements of thin and thick filaments (100-200 A diameter) are observed in contracted guinea pig taenia coli rapidly fixed in glutaraldehyde. The thin-filament arrays vary from a few to more than 100 filaments in each array. The arrays are scattered among isolated thin and thick filaments. Some arrays are reg...

Cardiac sarcomeres produce greater active force in response to stretch, forming the basis of the Frank-Starling mechanism of the heart. The purpose of this study was to provide the systematic understanding of length-dependent activation by investigating experimentally and mathematically how the thin filament "on-off" switching mechanism is involved in its regulation. Porcine left ventricular mu...

Sarcomeric filament proteins display extraordinary properties in terms of protein length and mechanical elasticity, requiring specific anchoring and assembly mechanisms. To establish the molecular basis of terminal filament assembly, we have selected the sarcomeric M-band protein myomesin as a prototypic filament model. The crystal structure of the myomesin C-terminus, comprising a tandem array...

The dynamics of a flexible filament sedimenting in a viscous fluid are explored analytically and numerically. Compared with the well-studied case of sedimenting rigid rods, the introduction of filament compliance is shown to cause a significant alteration in the long-time sedimentation orientation and filament geometry. A model is developed by balancing viscous, elastic and gravitational forces...

The Hasimoto planar vortex filament is one of the rare exact solutions to the classical local induction approximation (LIA). This solution persists in the absence of friction or other disturbances, and it maintains its form over time. As such, the dynamics of such a filament have not been extended to more complicated physical situations. We consider the planar vortex filament under the quantum ...

Recent X-ray diffraction studies on actively contracting fibres from skeletal muscle showed that the number of myosin motors available to interact with actin-containing thin filaments is controlled by the stress in the myosin-containing thick filaments. Those results suggested that thick filament mechano-sensing might constitute a novel regulatory mechanism in striated muscles that acts indepen...

The earliest gene duplications in the evolution of the intermediate filament proteins created the ancestors of acidic keratins, basic keratins, nonepithelial intermediate filament proteins, and lamins. Biochemistry and function of cytoplasmic intermediate filaments differ greatly from those of lamins. Cytoplasmic intermediate filament proteins have a different cellular location than lamins, for...