Ascaris sperm

Fig. 3. Leading edge dynamics can be reconstituted in vitro using cell-free extracts of Ascaris sperm in which vesicles derived from the plasma membrane induce the assembly of MSP filament meshworks called fibers that push the vesicles forward as they elongate. The two images were taken 10 sec apart. Bar, 2.5 /im. Reproduced from The Journal of Cell Biology, 1999, vol. 146, pp. 1087-1095 by copyright permission of the Rockefeller University Press.

Evidence for a specific retraction force in Ascaris sperm was obtained by exploiting the sensitivity of the MSP cytoskeleton to changes in intracellular pH to uncouple protrusion of the leading edge from retraction of the cell body (Italiano et al., 1999). Lowering intracellular pH in sperm below... 

Miao et al. (2003) have been able to reconstitute the essential features of retraction in vitro by adding Yersinia phosphatase (YOP) to the MSP-based motility apparatus assembled from cell-free extracts from Ascaris sperm... 

Buttery, S. M., Ekman, G. C., Seavy, M., Italiano, J. E., Stewart, M., and Roberts, T. M. (2003). Dissection of the Ascaris sperm motility machinery identifies novel proteins involved in MSP-based amoeboid locomotion. Mol. Biol. Cell 14, 5082-5088. 

Le Claire, L. L., Ill, Roberts, T. M., and Stewart, M. (2003). A 48 kDa integral membrane phosphoprotein orchestrates the cytoskeletal dynamics that generate amoeboid cell motility in Ascaris sperm./. Cell Sci. 116,2655-2663. 

Roberts, T.M., E.D. Salmon, and M. Stewart, Hydrostatic pressure shows that lamelhpodial motihty in Ascaris sperm requires membrane-associated major sperm protein Hlament nucleation and elongation. 

Bacteria also contain filamentous proteins that resemble F-actin and which may be utilized for cell-shape determination 301c Actin-based motility is used by some bacteria and other pathogens during invasion of host cells (Box 19-C). It is employed by sperm cells of Ascaris and of C. elegans, which crawl by an ameboid movement that utilizes treadmilling of filaments formed from a motile sperm protein, which does not... 

Italiano, J. E.,Jr., Roberts, T. M., Stewart, M., and Fontana, C. A. (1996). Reconstitution in vitro of the motile apparatus from the amoeboid sperm of Ascaris shows that filament assembly and bundling move membranes. Cell 84, 105-114. 

Sepsenwol, S., Ris, H., and Roberts, T. M. (1989). A unique cytoskeleton associated with crawling in the amoeboid sperm of the nematode. Ascaris suum. J. Cell Biol. 108, 55-66. 

Figure 7 Wireframe representations of the X-ray crystal structures of the active sites of the oxy forms of sperm whale and Hb from the nematode, Ascaris suumd Proximal His ligands are at bottom (with...

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