ON THE INFLUENCE OF PYOCYANINE ON THE RESPIRATION OF THE SEA URCHIN EGG

¹ From the Laboratories of the Rockefeller Institute for Medical Research, New York, and the Marine Biological Laboratory, Woods Hole, Mass.

Addition of pyocyanine to a suspension of sea urchin eggs causes an increase of the respiration of the eggs. The percentage increase is higher in the unfertilized than in the fertilized eggs. The absolute values of the oxygen consumption in presence of pyocyanine are higher after than before fertilization. The respiration of the unfertilized eggs is enhanced in the presence of pyocyanine by the addition of HCN. In the fertilized eggs, on the contrary, the respiration enhanced by pyocyanine is always decreased by HCN. Pyocyanine is auto-oxidized in the sea urchin egg the iron-containing enzyme is not involved in the oxidations induced by pyocyanine. The rate of oxidation induced by pyocyanine is somewhat higher than that of the respiration induced by methylene blue both in intact eggs and in eggs broken up by freezing and thawing. The block of division of the sea urchin egg caused by HCN or by anærobic conditions is not removed by addition of pyocyanine. In the fertilized eggs the respiration in the presence of pyocyanine and HCN can be higher than in the control; in spite of this the division stops at the same stage as when the respiration is decreased 75 per cent by the addition of HCN alone. The general conclusion is drawn that neither the iron-containing enzyme nor the dehydrase-substrate system act as limiting factors for the oxidation rate in the unfertilized or newly fertilized egg.