PMC

(a) An image sequence showing a pair of synchronized slither swimming bull sperm, adopting a shared beating frequency and flagellar waveform and (b) their overlaid trajectories. Synchronized motion of (c) four bull sperm and (d) two human sperm in the slither swimming mode. The head of each individual sperm is colour coded along its swimming path. Scale bars, 20 μm. The image was inverted and contrast-adjusted for clarity.

(a) Bulk swimmer sperm propulsion. The net drag force, f, acting on each segment of flagellar helix has a propulsive, f_prop, and rotational component, f_rot. The result is propulsion with continuous rotation in opposite direction of the flagellar wave. (b) Slither swimmer propulsion. The net drag force, f, on each segment has a surface-aligned propulsive component, f_prop, and an oscillating perpendicular component, f_oci, which also lies in the 2D plane of the surface. With all forces acting within the same plane, slither swimmers achieve forward progression with no rotation.

Screenshot of the SLITHER input page.

(a) A slab view of the molecular surface representations of the human glucose transporter. The geometry of the access channel is depicted by HOLE. (b) Similar to (a), but the substrate conformations along the access channel are generated by SLITHER. (a) and (b) were created with DINO (http://www.dino3d.org/). (c) Pore radius profile along the access channel, generated by HOLE. (d) Free energy profile along the access channel, generated by SLITHER.