Bandyopadhyay Promode R, Hansen Joshua C
Autonomous & Defensive Systems Department, Naval Undersea Warfare Center, Newport, RI 02841, USA.
Sci Rep. 2013;3:1956. doi: 10.1038/srep01956.
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.
作为传感器和推进器，纤毛是具有高度组织化内部结构的进化保守细胞器。草履虫的纤毛在回摆过程中如何产生偏离推进平面的弯曲以打破对称性并减少阻力尚不清楚。我们通过建立一个节拍频率依赖于粘度的扭摆模型和一个姿势控制自我调节的橄榄小脑模型来解释这些纤毛变形。确定了纤毛扭转的相位依赖性，并提供了一个具有预测特征的硬度控制生物物理模型。在动力冲程期间，中央微管对之间的交叉桥连接使纤毛变硬；此冲程结束是一个关键阶段，在此期间ATP分子在纤毛拐点处软化交叉桥与微管的附着，此时扭转达到最大值。随后硬度急剧降低，这标志着ATP水解开始，从而使纤毛重新变硬。纤毛吸引盆可作为扰动传感的参考。
