MSP Dynamics Drives Nematode Sperm Locomotion

Abstract

Most eukaryotic cells can crawl over surfaces. In general, this motility requires three sequential actions: polymerization at the leading edge, adhesion to the substrate, and retraction at the rear. Recent in vitro experiments with extracts from spermatozoa from the nematode Ascaris suum suggest that retraction forces are generated by depolymerization of the major sperm protein cytoskeleton. Combining polymer entropy with a simple kinetic model for disassembly we propose a model for disassembly-induced retraction that fits the in vitro experimental data. This model explains the mechanism by which disassembly of the cytoskeleton generates the force necessary to pull the cell body forward and suggests further experiments that can test the validity of the models.

The Function of Snodprot in the Cerato-Platanin Family fromDactylellina cionopagain Nematophagous Fungi

“…The locomotion of nematodes involves neurons, neurotransmitters, G protein-coupled receptors, mechanically gated ion channels, the cytoskeleton, and muscle tissues. [56][57][58][59][60] Colostrums, non-fat milk, and MFP2 were presented to increase the migration of C. elegans. 61,62) MFP2 increased the rate of locomotion by enhancing the effective rate of major sperm protein (MSP) filament polymerization.…”

The geometry and motion of nematode sperm cells

“…However, complications quickly arise when examining these processes more closely. In most eukaryotic cells the main players in cellular movement are actin and myosin [15]. In addition to providing the basis of cell motility, these structures also function in the process of phagocytosis, movement of vesicles and organelles, surface rearrangement, and cytokinesis.…”

“…Protrusion: The process of protrusion in Ascaris suum is accomplished at the leading edge of the lamellipod by polymerization reactions which produce enough force to push the front of the cell forward [15]. Polymerization refers to the process in which additional MSP units are added on to subfilaments through a nucleation-elongation reaction [4].…”

“…One protein has been identified, called Yersinia Enterocolytica Tyrosine Phosphatse (YOP), and this protein disassembles the bundles at the back of the cell into their individual polymerizing units [7]. In vitro experiments have led to the proposal of cytoskeletal depolymerization as a force-producing mechanism which pulls the cell body forward [17,7,15].…”

Cytoskeleton and Cell Motility

“…In the proposed microscopic models, mechanisms underlying the traction-force generation by solely cytoskeletal disassembly can be qualitatively understood as follows [175,181]: because of pH gradient, MSP filaments tend to bundle at the front, and split apart and disassemble at the rear [179]. A bundle with N filaments being much stiffer than N isolated individuals (with an effective persistence length of N 2 L p as each individual has a persistence length L p ), it pushes the cell membrane at the leading edge where filaments are bundled, while splitting filaments exert contractile forces at the rear.…”