Quantitative analysis of Caenorhabditis elegans sperm motility and how it is affected by mutants spe11 and unc54.

The sperm of Caenorhabditis elegans translocate in a fashion similar to sperm of Ascaris suum even though their pseudopods are longer, more plastic in shape, and form multiple expansions zones around their perimeter. Mutants in spe-11 form primary spermatocytes with a defective perinuclear region, but the resulting spermatozoa can still crawl and fertilize eggs. However, the resultant zygotes die due to the absence of sperm-supplied spe-11. Computer-assisted analysis of translocating spe-11 sperm reveals a novel defect in the dynamic morphology of their pseudopods. A similar analysis of the C. elegans mutant unc-54, which lacks the most abundant isoform of myosin II, reveals no defect in sperm motility, as expected, since C. elegans sperm have substituted the protein MSP for actin in the process of pseudopod expansion. These results reveal an unexpected defect in the dynamic morphology of pseudopods of spe-11 sperm. This defect, however, does not significantly affect crawling velocity, and it demonstrates how computer-assisted motion analysis systems can reveal subtle behavioral phenotypes in C. elegans mutant spermatozoa.