7/29/2023 0 Comments Mackup modelNear the end of the power stroke, the cilium abruptly wilts to a low-drag posture, initiating the return stroke with a shift to the lateral plane. The return stroke, on the other hand, is a continuously deforming, three-dimensional motion. High-speed stereomicroscopic measurements of cilia motion show that during the power stroke, the entire cilium-from the root to the distal point-remains virtually in a plane in a straight and taut posture 4. The assemblage of cilia also undergoes a coordinated motion, called metachronic motion-i.e., the assemblage beats with a constant phase difference between neighboring cilia 3. Cilia have a highly organized internal structure 2. For propulsion, each cilium beats at about 14.1 Hz in water while undergoing a complicated, three-dimensional, phase-dependent motion. Paramecia are 100 – 350 μm long, deformable and may contain up to 3000 flexible cilia, each being about 17 μm long and 0.25 μm in diameter 1. These animals propel themselves, albeit with limited maneuverability, by the synchronous motion of numerous tiny cilia populated around their flexible bodies. The paramecium is slipper-shaped ciliate protozoa widely found in oxygenated aquatic environments. The cilium attractor basin could be used as reference for perturbation sensing. A precipitous reduction in hardness ensues, signaling the start of ATP hydrolysis that re-hardens the cilium. 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. The phase dependence of cilia torsion is determined and a bio-physical model of hardness control with predictive features is offered. 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. How a paramecium's cilium produces off-propulsion-plane curvature during its return stroke for symmetry breaking and drag reduction is not known. Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a highly organized internal structure.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |