title: Breakup and then makeup: a predictive model of how cilia self-regulate hardness for posture control.
abstract: Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a highly organized internal structure. How a paramecium's cilium produces off-propulsion-plane curvature during its return stroke for symmetry breaking and drag reduction is not known. We explain these cilium deformations by developing a torsional pendulum model of beat frequency dependence on viscosity and an olivo-cerebellar model of self-regulation of posture control. The phase dependence of cilia torsion is determined, and a bio-physical model of hardness control with predictive features is offered. Crossbridge links between the central microtubule pair harden the cilium during the power stroke; this stroke's end is a critical phase during which ATP molecules soften the crossbridge-microtubule attachment at the cilium inflection point where torsion is at its maximum. A precipitous reduction in hardness ensues, signaling the start of ATP hydrolysis that re-hardens the cilium. The cilium attractor basin could be used as reference for perturbation sensing.
authors.affiliation: Autonomous & Defensive Systems Department, Naval Undersea Warfare Center, Newport, RI 02841, USA. promode.bandyopadhya@navy.mil
authors.forename: Promode R
authors.initials: PR
authors.lastname: Bandyopadhyay
authors.forename: Joshua C
authors.initials: JC
authors.lastname: Hansen
mesh_terms: D000465:Algorithms; D002923:Cilia / Q000502:physiology*; D008954:Models, Biological