Active nematic order and dynamic lane formation of microtubules driven by membrane-bound diffusing motors.

Dynamic lane formation and long-range active nematic alignment are reported using a geometry in which kinesin motors are directly coupled to a lipid bilayer, allowing for in-plane motor diffusion during microtubule gliding. We use fluorescence microscopy to image protein distributions in and below the dense two-dimensional microtubule layer, revealing evidence of diffusion-enabled kinesin restructuring within the fluid membrane substrate as microtubules collectively glide above. We find that the lipid membrane acts to promote filament-filament alignment within the gliding layer, enhancing the formation of a globally aligned active nematic state.

Membrane mediated motor kinetics in microtubule gliding assays.

Motor-based transport mechanisms are critical for a wide range of eukaryotic cell functions, including the transport of vesicle cargos over long distances. Our understanding of the factors that control and regulate motors when bound to a lipid substrate is however incomplete. We used microtubule gliding assays on a lipid bilayer substrate to investigate the role of membrane diffusion in kinesin-1 on/off binding kinetics and thereby transport velocity.

Acoustic scattering from a solid aluminum cylinder in contact with a sand sediment: measurements, modeling, and interpretation.

Understanding acoustic scattering from objects placed on the interface between two media requires incorporation of scattering off the interface. Here, this class of problems is studied in the particular context of a 61 cm long, 30.5 cm diameter solid aluminum cylinder placed on a flattened sand interface.

Time course and histology of urethrocutaneous fistula formation in a porcine model of urethral healing.

Objective: Urethrocutaneous fistula is a well-known complication of hypospadias surgery and is reported in 5-10% of repairs. Using a previously described juvenile pig model, we present a histological analysis of the healing of the ventral aspect of the urethral repair and describe the histological mechanism of fistula formation.

Materials And Methods: Twelve juvenile pigs underwent ventral, longitudinal urethral incision and closure over a 5-French feeding tube.