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Updated: Aug 15, 2026

Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract
Published on: June 6, 2019
Cytoskeleton dynamics powers nematode sperm motility
Murray Stewart1, Thomas M Roberts
1MRC Laboratory of Molecular Biology, Hills Rd, Cambridge CB2 2QH, England.
Abstract:
Nematode sperm provide a simple and specialized system for studying the molecular mechanism of amoeboid cell motility. Locomotion is generated by the assembly dynamics of their cytoskeleton, which is based on the major sperm protein (MSP). Protrusive force is generated at the leading edge of the lamellipod by MSP filament formation and bundling, whereas the contractile force that drags the rearward cell body forward is generated by cytoskeleton disassembly. The dynamics of the system can be reconstituted in vitro using cell-free extracts of Ascaris sperm, in which vesicles derived from the leading edge of the cell can be either pushed or pulled. The addition of ATP to the cell-free extract initiates MSP filament polymerization and bundling immediately behind the vesicle, and the expansion of the resulting gel pushes the vesicle at rates comparable to those seen in living cells. In contrast, the addition of Yersinia tyrosine phosphatase generates depolymerization and gel contraction that pulls the vesicles. Overall, nematode sperm motility illustrates that cell locomotion can be generated by cytoskeletal dynamics alone without the use of myosin-like motor proteins.
Insights
Nematode sperm motility relies solely on cytoskeletal dynamics, specifically the major sperm protein (MSP). This research demonstrates how MSP assembly and disassembly drive cell movement without myosin motors.
Area of Science:
- Cell Biology
- Biophysics
- Molecular Motors
Background:
- Nematode sperm utilize amoeboid motility for locomotion.
- This movement is driven by the assembly dynamics of the major sperm protein (MSP) cytoskeleton.
- Understanding this system offers insights into fundamental cell motility mechanisms.
Purpose of the Study:
- To investigate the molecular mechanisms underlying nematode sperm locomotion.
- To demonstrate that cytoskeletal dynamics alone can generate cell motility.
- To explore the roles of MSP polymerization and depolymerization in force generation.
Main Methods:
- Utilized cell-free extracts of Ascaris sperm for in vitro reconstitution.
- Observed vesicle movement (pushing and pulling) in response to biochemical stimuli.
- Analyzed the effects of ATP and Yersinia tyrosine phosphatase on MSP dynamics.
Main Results:
- ATP addition induced MSP polymerization and bundling, generating protrusive force that pushed vesicles.
- Yersinia tyrosine phosphatase addition caused MSP depolymerization and gel contraction, generating contractile force that pulled vesicles.
- Nematode sperm motility was reconstituted in vitro, mimicking cellular movement.
Conclusions:
- Cell locomotion can be achieved through cytoskeletal dynamics alone, independent of myosin-like motor proteins.
- MSP dynamics are sufficient to generate both protrusive and contractile forces necessary for motility.
- Nematode sperm serve as a simplified model for studying fundamental principles of cell movement.
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