PRESENCE OF 1-METHYLADENINE IN SEA URCHIN GONAD AND ITS RELATION TO OOCYTE MATURATION

A water extract of sea urchin ovary was found to induce maturation of starfish oocytes in vitro . The presence of the active substance was demonstrated in ovaries of the sea urchins, Pseudocentrotus depressus, Anthocidaris crassispina and Hemicentrotus pulcherrimus , and the sand dollars, Clypeaster japonicus and Peronella japonica . The active substance was also contained in the testes of these echinoids. That the content of this substance increases during the reproductive season was demonstrated with Anthocidaris gonads. The active substance present in ovary or testis of the sea urchins was successfully extracted with 85% ethanol and purified with gel-filtrations on Sephadex G-15 columns after washing with chloroform and ether. The purified active substances were the same and were identified as 1-1-methyladenine by thin layer chromatography. 1-Methyladenine was found to be effective in inducing oocyte maturation in Anthocidaris crassispina in vitro . Therefore, 1-methyladenine seems to play an important role in oocyte maturation in echinoids as well as in asteroids.     

Effect of 17β-Estradiol on Growth of Oocytes in Cultured Ovarian Fragments of the Starfish, Asterina Pectinifera

The development of growing oocytes of the starfish, Asterina pectinifera , was divided into five stages according to their histological features. Specimens collected monthly from Rishiri Island throughout a year were used. The effect of 17 β-estradiol on oocyte growth was investigated. When ovarian fragments taken from April females were cultured in artificial seawater containing Medium 199 and streptomycin sulfate for 3 days, oocytes within such fragments did not show any changes in diameter. However, when similar ovarian fragments were cultured in the presence of 10⁻⁵M 17 β-estradiol, the oocyte diameters increased significantly. It is concluded that 17 β-estradiol enhances the growth of starfish oocytes in cultured ovarian pieces.