Membrane flow during nematode spermiogenesis.

Abstract

Two distinct types of surface membrane rearrangement occur during the differentiation of Caenorhabditis elegans spermatids into amoeboid spermatozoa. The 1st, detected by the behavior of latex beads attached to the surface, is a nondirected, intermittent movement of discrete portions of the membrane. This movement starts when spermatids are stimulated to differentiate and stops when a pseudopod is formed. The 2nd type of movement is a directed, continual flow of membrane components from the tip of the pseudopod to its base. Both membrane glycoproteins and fluorescent phospholipids inserted in the membrane flow backward at the same rate, .apprx. 4 .mu.m/min, although their lateral diffusion coefficients in the membrane differ by at least a factor of 5. Pseudopodial membrane movement may be due to bulk flow of membrane components away from the tip of the pseudopod.