DISPERSAL OF THE GELATINOUS COAT MATERIAL OF MELLITA QUINQUIESPERFORATA EGGS BY HOMOLOGOUS SPERM AND SPERM EXTRACTS 1 JOHN W. BROOKBANK Department of Biology, University of Florida, Gainesville, Florida Live sperm or sperm extracts of a number of animal species have been found to possess the property of solubilizing or dispersing the secondary and tertiary envelopes normally surrounding the unfertilized eggs of these species, thus fa-cilitating the approach of the sperm to the egg surface. Groups in which this phenomenon has been demonstrated include amphibians (Hibbard, 1928; Wintre-bert. 1929 and 1933), mammals (see reviews by Duran-Reynals, 1942; Meyer, 1947; Meyer and Rapport, 1952), gastropods (Tyler, 1939 and 1948; von Medem, 1942), and bivalves (Berg, 1949). In addition, a number of \vorkers have de-scribed the solubilization of the gelatinous coat material (fertilizin) of echinoid eggs by live sperm or sperm extracts. Hartmann ct al. (1940) extracted the residue of methanol-precipitated seminal fluid of Arbacia pushdosa with sea water and reported that the resulting solution was capable of dispersing the gelatinous coat material of unfertilized Arbacia eggs. This extract was also capable of neutralizing the sperm agglutinating property of Arbacia fertilizin, and thus pos-sessed antifertilizin activity. Monroy and Ruffo (1947) described an acid extract of sea urchin sperm which was reported as acting to dissolve the fertilizin of unfertilized eggs. Others have described a decreased viscosity of fertilizin solu-tions in the presence of live sperm or sperm extracts (Lundblad and Monroy. 1950; Vasseur, 1951 ; Monroy and Tosi, 1952; Monroy et al., 1954). It has been emphasized (Tyler and O'Melveny, 1941 ; Krauss. 1950; Monroy and Tosi, 1952; Monroy et al., 1954) that apparent dispersal of the gelatinous coat of unfertilized eggs by sperm or sperm extracts, as well as the decrease in viscosity observed when live sperm or extracts are added to fertilizin solutions, can be accounted for by precipitation of fertilizin by antifertilizin present in the extracts or on the surface of the live sperm. Therefore, any investigation of supposed lytic or dispersing agents from sperm must include experiments which demonstrate that the activity of the agent is separable from the activity of antifertilizin. Ishida (1954) has presented evidence that a fertilizin-dissolving factor is released at fertilization from the sperm of Heiniccntrotus pulchcrrimus. Treatment of the sperm with fertilizin, which rendered the sperm non-fertilizing, did not prevent the solution of the fertilizin coat of the eggs by these sperm. This latter observation tends to eliminate antifertilizin as the agent responsible for removing the fertilizin from the eggs. However, though the sperm concentration employed in the experiments was not stated, sperm carbon dioxide might have been responsible for the solubilizing action 1 This investigation was supported in part by a research gfant (RG 4659 s ) from the Na-tional Institutes of Health of the Puhlic Health Service. 74
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