Sperm Cell Crawling in the Nematode Caenorhabditis Elegans

Abstract

Cell motility is important in biological processes, such as the immune response and cancer cell metastasis. Actin is implicated in most amoeboid cell movement, but Caenorhabditis elegans sperm cells lack actin, and their motility is driven by the Major Sperm Protein (MSP) cytoskeleton. MSP and actin form filament systems that are functionally similar, and the sperm cell therefore represents a simplified cellular model for studying the general properties of biopolymer-based movement.We use the sperm cell to test how membrane tension affects movement and cystokeleton dynamics. We relax or tense the cell membrane with biochemical treatments or osmotic shock and we observe that membrane tension reduction is correlated with a decrease in cell displacement speed, whereas an increase in membrane tension enhances motility. We show evidence for the idea that membrane tension optimizes motility by streamlining polymerization in the direction of movement, thus adding a layer of complexity to our current understanding of how membrane tension enters into the motility equation.We also use the sperm cell to study the effect of adhesion on retrograde flow and movement. We prepare substrates of varying compositions, and observe the interplay between cytoskeletal flows and the efficiency of displacement.In the long term, study of the simplified MSP system and comparison to actin based movement should lead to a better understanding of the fundamental principles cell motility.