THE PYRUVATE METABOLISM OF SEA URCHIN EGGS DURING THE PROCESS OF CELL DIVISION

The eggs of Arbacia and starfish contained about 70 and 25 micrograms of pyruvate per gm. of dry cells respectively. Arbacia eggs utilized added pyruvate, although the O₂ uptake did not increase. On fertilization the utilization of pyruvate increased sevenfold. This pyruvate seems to be metabolized, as in other cells, with diphosphothiamine as coenzyme. The diphosphothiamine content of fertilized and non-fertilized eggs was about 16 micrograms; that of sperm, 30 micrograms. Penetration of sperm into the egg and fertilization with cell division to the pluteus stage did not bring forth appearance of succino-dehydrogenase. The possible mechanism of fertilization and cell division is discussed.