N. Hutchings | Searcharxiv

arXiv2005

Geometry of Axoneme-like Filament Bundles

We develop a formalism that describes the bending and twisting of axoneme-like filament bundles. We obtain general formulas to determine the relative sliding between any arbitrary filaments in a bundle subjected to unconstrained deformations. Particular examples for bending, twisting, helical and toroidal shapes, and combinations of these are discussed. Resulting equations for sliding and transversal shifting, expressed in terms of the curvature and torsion of the bundle, are applied to flagellar bend data. We prove that simultaneous combination of twisting and bending can produce a drastically drop in the sliding, by decreasing bending rigidity.

q-bio.CB↗

arXiv2003

Dynamics of Immobilized Flagella

Although the auger-like 'swimming' motility of the African trypanosome was described upon its discovery over one hundred years ago, the precise biomechanical and biophysical properties of trypanosome flagellar motion has not been elucidated. In this study, we describe five different modes of flagellar beat/wave patterns in African trypanosomes by microscopically examining the flagellar movements of chemically tethered cells. The dynamic nature of the different beat/wave patterns suggests that flagellar motion in Trypanosoma brucei is a complex mixture of oscillating waves, rigid bends, helical twists and non-linear waves. Interestingly, we have observed soliton-like depression waves along the flagellar membrane, suggesting a nonlinear mechanism for the dynamics of this system. The physical model is inspired by the 2-dimensional elastic dynamics of a beam, and by taking into account uniform distribution of molecular motors torque and nonlinear terms in the curvature.

physics.bio-ph↗