Preliminary communication on the cytolytic action of ox-blood serum upon sea-urchin eggs,and its inhibition by proteins

Abstract

1. It has been shown by Loeb 1 that the eggs of sea urchins (Strongylocentrotus purpuratus and Strongylocentrotus franciscanus) may be fertilized by the blood-sera of mammalia, provided the eggs be previously sensitized by a brief immersion in a solution of SrCl₂ which is approximately isotonic with sea water.

2. I find that if ox-serum be rendered sufficiently potent by dilution (cf. below) the formation of a fertilization-membrane by the action of the serum is succeeded by cytolysis or may even be accompanied by marked agglutination of the eggs, thus confirming Loeb's view that the formation of a fertilization membrane is essentially a phenomenon of incipient cytolysis.

3. The cytolytic (and fertilizing) action of ox serum (rendered isotonic to sea water) upon sensitized sea-urchin eggs is enhanced by dilution with sea water, a maximum potency being attained at a dilution of about 1/16.

4. I find that the increase in the cytolytic activity of serum which accompanies dilution is attributable to the fact that the proteins in serum in some degree inhibit membrane-formation. The inhibitory effect of the proteins becomes negligible if these are sufficiently diluted. If a protein (e.g., gelatin or ovomucoid) be added to diluted serum its cytolytic activity is greatly diminished or even abolished.

5. The inhibiting action of proteins upon cytolysis is due to the fact that they penetrate the outer membranes of the cells either with difficulty or not at all, so that by their osmotic tension they prevent the taking up of water by the cells. This is well illustrated by the fact that the order of efficiency of different proteins (the mixed proteins of serum, gelatin, “insoluble” serum globulin, casein and ovomucoid) is the reverse order of their ability to pass through the pores of a porcelain filter.