ACTIVATION OF RESPIRATION IN SEA URCHIN SPERMATOZOA BY EGG WATER

¹ Occanographic Institute, Florida State University, Tallahassee, Florida, and Marine Biological Laboratory, Woods Hole Mass.

1. Sea urchin gametes were used in measurements of the effect of egg materials upon sperm respiration.

2. Dense suspension of spermatozoa of Arbacia punctulata had a relatively low rate of oxygen uptake in buffered sea water. After the addition of egg water or materials diffusing from jellyless eggs (jellyless egg water), there was a marked increase in respiratory rates. A similar effect was seen after the addition of cysteine. but not after the addition of several other amino acids, Versene, or buffered sea water. It was concluded that Arbacia eggs contain an activator of sperm respiration.

3. Solutions lost their activating properties during interaction with spermatoza The respiratory activator diffused through dialyzing membrane, and was alcohol-soluble, heat-stable, and non-volatile. It differed from cysteine in its reaction with ninhydrin and iodoacetamide. It failed to activate respiration in starfish spermatozoa, unlike cysteine and Versene, which stimulated respiration in these cells. The activating agent in question remains unidentified, but it is evidently neither fertilizin nor cysteine.

4. Respiration of spermatozoa of Lytechinus variegatus was increased by diffusates from Lytechinus eggs. A species specificity exists in the respiratory activators of Lytechinus and Arbacia.

5. Suspensions of the red granules from the jelly-coat of Mellita quinquies perforata activated the respiration of spermatozoa of both Mellita and Arbacia. Diffusates from Arbacia eggs failed to affect Mellita sperm.

6. No structural changes were observed in Arbacia spermatozoa incubated with activating solutions. Unlike fertilizin, the activator in jellyless egg water failed to cause the release of sialic acid from sperm.