Sperm Motility   Unlike most sperm cells, which swim with a flagellum, nematode sperm crawl with a pseudopod. This sperm cell's "body" (lower right) is stuck down on a glass slide, so it can't move forward, but the pseudopod is trying to crawl anyway. Membrane continuously flows from the tip of the pseudopod rearward to the base where it joins with the cell body; as the membrane flows rearward, it would normally push the cell forward, in the direction of the pseudopod. Within the pseudopod you can see a branched cytoskeletal network. Unlike almost all other cytoskeletons found in nature, this one does not contain the proteins actin or tubulin. Instead, it is a polymer of the Major Sperm Protein (MSP). MSP filaments assemble at the leading edge of the pseudopod and disassemble at the base. This "treadmilling" of the cytoskeleton is thought to generate the force that makes the pseudopod membrane flow. References on Nematode Sperm Motility Stewart, M, et al. Amoeboid motility without actin: insights into the molecular mechanism of locomotion using the major sperm protein (MSP) of nematodes. Biol Bull. 1998 Jun; 194(3): 342-343. Bullock, TL, et al. Structural basis for amoeboid motility in nematode sperm. Nat Struct Biol. 1998 Mar 5(3): 184-189. Roberts, TM, et al. Nematode sperm locomotion. Curr Opin Cell Biol. 1995 Feb; 7(1): 13-17. Review. Theriot, JA. Worm sperm and advances in cell locomotion. Cell. 1996 Jan 12; 84(1): 1-4. Review. Thomas Roberts Laboratory Florida State University. The Roberts lab studies the biochemical basis of sperm motility in the parasitic nematode, Ascaris.

http://www.mcb.arizona.edu/wardlab/treadingvid.html All Contents Copyright © 2000. All rights reserved. Last Modified: February 27, 1998 Paul Muhlrad pmuhlrad@u.arizona.edu