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Endogenous Substrates for Energy Metabolism in Spermatozoa of the Sea Urchins Arbacia lixula and Paracentrotus lividus
Masatoshi Mita, Atsuko Oguchi, Sakae Kikuyama, Ikuo Yasumasu, Rosaria De Santis and Masaru Nakamura
Vol. 186, No. 3 (Jun., 1994), pp. 285-290
Published by: The University of Chicago Press
Stable URL: http://www.jstor.org/stable/1542274
Page Count: 6
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Energy metabolism was examined in the spermatozoa of the sea urchins Arbacia lixula and Paracentrotus lividus, which belong to the orders Arbacioida and Echinoida respectively. P. lividus spermatozoa contained various phospholipids and cholesterol, and their endogenous triglyceride (TG) content was quite low. After dilution of dry sperm in artificial seawater, the level of phosphatidylcholine (PC) decreased rapidly, but other phospholipids remained at constant levels. In contrast to those of P. lividus, the spermatozoa of A. lixula contained TG as well as phospholipids and cholesterol. Following incubation of A. lixula spermatozoa in artificial seawater, TG decreased, but there were no concomitant changes in the levels of phospholipids. Trace amounts of glycogen were present in both species. High lipase activity was demonstrated in A. lixula spermatozoa, but in P. lividus spermatozoa lipase activity was low and phospholipase A2 activity was high. It is thus concluded that A. lixula spermatozoa obtain energy for swimming through oxidation of endogenous TG, whereas P. lividus spermatozoa use PC as a substrate for energy metabolism. This suggests that the system of energy metabolism in spermatozoa is different in the orders Arbacioida and Echinoida.
Biological Bulletin © 1994 Marine Biological Laboratory