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Swimming by Spinning: Spinning-Top Type Rotations Regularize Sperm Swimming Into Persistently Progressive Paths in 3D
Xiaomeng Ren1, Hermes Bloomfield-Gadêlha1
1School of Engineering Mathematics and Technology & Bristol Robotics Laboratory, University of Bristol, Bristol, BS8 1UB, UK.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|December 19, 2024
Summary
Sperm use head rotation to swim forward even with asymmetrical flagellar beats. This body orientation, not just the swimming path, reveals flagellar symmetry and aids navigation.
Area of Science:
- Biophysics
- Fluid Mechanics
- Reproductive Biology
Background:
- Sperm motility is crucial for reproduction, relying on flagellar beating for movement.
- Understanding how sperm navigate using asymmetrical flagellar beats is vital but challenging.
- Current methods struggle to detect flagellar symmetry in free-swimming sperm.
Purpose of the Study:
- To investigate the fluid mechanics of sperm swimming with asymmetrical flagellar beats.
- To determine how sperm achieve progressive swimming despite broken flagellar symmetry.
- To identify reliable indicators of flagellar symmetry state in motile spermatozoa.
Main Methods:
- Numerical simulations of sperm hydrodynamics.
- Analysis of flagellar beat dynamics and resulting fluid flow.
- Investigation of sperm head orientation and swimming path.
Main Results:
- Sperm rotation effectively regularizes motion, enabling progressive swimming with asymmetrical flagellar beats.
- 3D sperm head orientation, not the swimming path, is a key indicator of flagellar symmetry.
- Sperm head precession during swimming mimics spinning-top dynamics, driven by helical flagellar action.
Conclusions:
- Sperm utilize a rotational mechanism for stable forward propulsion and navigation, even with flagellar asymmetry.
- Body orientation analysis offers a robust method for assessing flagellar symmetry in microorganisms and artificial swimmers.
- This study elucidates a fundamental principle of biological propulsion and navigation.
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