Jelly coat and induction of the acrosome reaction in echinoid sperm

In a previous study we established that sperm from four species of echinoids differ in their specificity for induction of the acrosome reaction by heterotypic jelly coat and we presented evidence that there were only small compositional differences in the active component of the jelly coat, a polysaccharide composed of fucose sulfate units. In the current report we present additional studies related to the species specificity of jelly coat with respect to Ca²⁺ uptake (or exchange), which occurs concomitantly with the acrosome reaction, and activation of phospholipase activity, which appears to occur subsequent to the acrosome reaction. The specificity of jelly coat in inducing these processes is the same as that previously observed in induction of the acrosome reaction. Binding of jelly coat to sperm has been demonstrated, and has been shown to be species specific. This finding raises the possibility that a receptor for jelly coat exists on the surface of the sperm. Finally, based on chemical and physical-chemical studies, evidence is presented that establishes that, despite compositional similarities, the fucose sulfate polysaccharides from the four species of eggs differ in structure.