2023-11-09 カリフォルニア大学サンディエゴ校(UCSD)
◆このモデルは、精子の運動と形状変化、流体力学の相互作用を捉えており、特に精子の運動が増加すると、第二の異なる泳ぎモードが現れると示唆しています。この発見は受精において重要な役割を果たす可能性があり、将来的な生殖医学や避妊技術の向上に寄与する可能性があります。
<関連情報>
- https://today.ucsd.edu/story/model-suggests-that-mammalian-sperm-cells-have-two-modes-of-swimming
- https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.113102
精子の運動の化学機械モデルは2つの遊泳モードを明らかにする Chemomechanical model of sperm locomotion reveals two modes of swimming
Chenji Li, Brato Chakrabarti, Pedro Castilla, Achal Mahajan, and David Saintillan
Physical Review Fluids Published 15 November 2023
DOI:https://doi.org/10.1103/PhysRevFluids.8.113102
ABSTRACT
The propulsion of mammalian spermatozoa relies on the spontaneous periodic oscillation of their flagella. These oscillations are driven internally by the coordinated action of ATP-powered dynein motors that exert sliding forces between microtubule doublets, resulting in bending waves that propagate along the flagellum and enable locomotion. We present an integrated chemomechanical model of a freely swimming spermatozoon that uses a sliding-control model of the axoneme capturing the two-way feedback between motor kinetics and elastic deformations while accounting for detailed fluid mechanics around the moving cell. We develop a robust computational framework that solves a boundary integral equation for the passive sperm head alongside the slender-body equation for the deforming flagellum described as a geometrically nonlinear internally actuated Euler-Bernoulli beam, and captures full hydrodynamic interactions. Nonlinear simulations are shown to produce spontaneous oscillations with realistic beating patterns and trajectories, which we analyze as a function of sperm number and motor activity. Our results indicate that the swimming velocity does not vary monotonically with dynein activity, but instead displays two maxima corresponding to distinct modes of swimming, each characterized by qualitatively different wave forms and trajectories. Our model also provides an estimate for the efficiency of swimming, which peaks at low sperm number.
