Effect of l-phenylalanine on 1-methyladenine production and spontaneous oocyte maturation in starfish

Abstract

Production of 1-methyladenine (1-MA) in isolated ovarian fragment under the influence of the gonad-stimulating substance (GSS) was found to be inhibited by treatment with phenylalanine at concentrations higher than 10 mM in the starfish, Asterina pectinifera. The so-called ‘spontaneous’ maturation of the oocytes of Asterias amurensis isolated in sea water was also inhibited in the presence of phenylalanine. 1-MA was produced in the isolated follicle cells of this species in sea water in the absence of GSS. Such production of 1-MA was greatly reduced by lack of calcium ions, corresponding to the failure of spontaneous maturation in calcium-free sea water. Production of 1-MA in the isolated follicle cells of Asterias amurensis in sea water was suppressed by phenylalanine. The so-called ‘spontaneous’ oocyte maturation observed in the genus Asterias appears to be induced by 1-MA produced in the follicle cells in the absence of GSS. Therefore, it is concluded that oocyte maturation in starfish is invariably induced by 1-MA produced in the follicle cells. Failure of oocyte maturation in the presence of phenylalanine or in calcium deficiency does not seem to be due to the failure of release of pooled 1-MA from the follicle cells but to the inhibition of its synthesis in these cells.