How nematode sperm crawl
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Updated: Oct 2, 2026
Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract
Published on: June 6, 2019
Dean Bottino1, Alexander Mogilner, Tom Roberts
1Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720-3112, USA.
Abstract:
Sperm of the nematode, Ascaris suum, crawl using lamellipodial protrusion, adhesion and retraction, a process analogous to the amoeboid motility of other eukaryotic cells. However, rather than employing an actin cytoskeleton to generate locomotion, nematode sperm use the major sperm protein (MSP). Moreover, nematode sperm lack detectable molecular motors or the battery of actin-binding proteins that characterize actin-based motility. The Ascaris system provides a simple 'stripped down' version of a crawling cell in which to examine the basic mechanism of cell locomotion independently of other cellular functions that involve the cytoskeleton. Here we present a mechanochemical analysis of crawling in Ascaris sperm. We construct a finite element model wherein (a) localized filament polymerization and bundling generate the force for lamellipodial extension and (b) energy stored in the gel formed from the filament bundles at the leading edge is subsequently used to produce the contraction that pulls the rear of the cell forward. The model reproduces the major features of crawling sperm and provides a framework in which amoeboid cell motility can be analyzed. Although the model refers primarily to the locomotion of nematode sperm, it has important implications for the mechanics of actin-based cell motility.
Insights
Nematode sperm crawl using a unique major sperm protein (MSP), not actin. A new model explains how MSP filament polymerization and stored energy drive this distinct cell locomotion.
Area of Science:
- Cell Biology
- Biophysics
- Biochemistry
Background:
- Nematode sperm exhibit amoeboid motility using major sperm protein (MSP) instead of actin.
- Unlike other eukaryotic cells, nematode sperm lack conventional molecular motors and actin-binding proteins.
- The Ascaris suum system offers a simplified model for studying cell crawling mechanisms.
Purpose of the Study:
- To perform a mechanochemical analysis of crawling in Ascaris suum sperm.
- To develop a model explaining the fundamental mechanism of MSP-based cell locomotion.
- To provide a framework for analyzing amoeboid cell motility.
Main Methods:
- Development of a finite element model for Ascaris sperm crawling.
- Modeling localized filament polymerization and bundling for lamellipodial extension.
- Incorporating stored energy in the leading edge gel for rearward contraction.
Main Results:
- The model successfully replicates key features of nematode sperm crawling.
- Demonstrates how filament polymerization generates force for extension.
- Shows how stored energy drives the contraction pulling the cell forward.
Conclusions:
- The mechanochemical model provides a robust explanation for MSP-driven amoeboid motility.
- This study offers insights into the fundamental mechanics of cell locomotion.
- The findings have implications for understanding actin-based cell motility in other systems.
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