[
1987]
Nematode sperm are crawling cells that exhibit a type of locomotion characteristic of an entire class of protozoa as well as numerous embryonic, differentiated, and transformed metazoan cells. Despite considerable variation in morphology and speed of locomotion expressed by these various types of crawling, or amoeboid, cells, there is general agreement that in all cases locomotion is propelled by cytoplasmic contraction involving myosin-induced sliding of actin filaments and regulated, in ways that are not fully understood, by a spectrum of actin-binding proteins. We began to study the motility of sperm of Caenorhabditis elegans hoping to exploit the mutability of this cell in order to analyze the molecular basis of amoeboid movement genetically. Much to our surprise, we discovered that sperm motility is not driven by an actin-based mechanism. Subsequent work, however, has shown that nematode sperm do share many fundamental properties with other amoeboid cells. As a consequence, sperm continue to serve as a profitable model for understanding how cells crawl and, at the same time, have allowed us to examine a new type of cellular motor.
[
1989]
Sperm motility usually refers to swimming motion propelled by a beating flagellum. In fact, the abundance and availability of flagellated sperm, particularly from sea urchins, have made these cells valuable models for studying all aspects of microtubule-based motility. There are, however, other types of sperm that lack flagella and must use alternative methods to reach oocytes. Among these are the amoeboid sperm of nematodes...