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Flexural rigidity of echinoderm sperm flagella
1Biological Laboratory, Faculty of Science, Tokyo Institute of Technology, Japan.
Cell Structure and Function
|December 1, 1994
Summary
Echinoderm sperm flagella stiffness varies with bending direction and ATP presence. Microtubule structure, specifically cross-bridge distribution, influences flagellar flexibility and movement.
Area of Science:
- Biophysics
- Cell Biology
- Reproductive Biology
Background:
- Sperm flagella are crucial for motility, but their mechanical properties are not fully understood.
- Understanding flagellar stiffness is key to deciphering the mechanics of sperm locomotion.
Purpose of the Study:
- To quantify the stiffness of echinoderm sperm flagella and their components.
- To investigate how factors like ATP, demembranation, and enzymatic digestion affect flagellar stiffness.
- To correlate structural components with mechanical properties.
Main Methods:
- Measured flagellar deformation under fluid flow to determine flexural rigidity.
- Utilized live sperm, demembranated flagella (axonemes), and isolated doublet microtubules.
- Applied inhibitors (EHNA, vanadate) and varying ATP concentrations.
Main Results:
- Flagellar stiffness differed significantly between bending perpendicular (5.8 x 10⁻²¹ Nm²) and parallel (4.2 x 10⁻²² Nm²) to the beating plane.
- Stiffness was maintained in demembranated flagella and decreased with specific inhibitors.
- Doublet microtubules showed lower stiffness in ATP-containing medium.
Conclusions:
- Flagellar stiffness is anisotropic, influenced by the arrangement of microtubule doublets and their associated cross-bridges.
- The mechanical properties of flagella are directly related to their structural organization and the presence of ATP-dependent cross-bridges.