METHYLATION PROCESS IN 1-METHYLADENINE PRODUCTION BY STARFISH OVARIAN FOLLICLE CELLS

摘要

In starfish the fully grown oocytes in the ripe ovary remain arrested at the prophase of the first maturation division. Resumption of meiosis in these immature oocytes is induced by 1-methyladenine (l-MeA)(Kanatani, 1969,1973; Kanatani et al, 1969), which is produced by follicle cells after stimulation with a gonad-stimulating substance (GSS) secreted from nervous tissue (Kanatani et al, 1969; Hirai & Kanatani, 1972; Hirai et al, 1973). Previous In vitro studies have shown that the 1-MeA produced under the influenced of GSS is newly synthesized, rather than being pre-stored within follicle cells (Shirai, 1972fMita 1991a) or a breakdown product of some 1-MeA-containing substance, such as ribonucleic acid (Shirai, 1972). It has also been shown that the 1-MeA synthesized via process of methylation from methionine (Met)(Shirai et al, 1972; Shirai, 1973; Tarr, 1985; Mita, 1991b). Since S-adenosylmethionine (SAM) is known to be a direct methyl donor in biological methylation, this study focussed on SAM in 1-MeA biosynthesis in follicle cells of the starfish Asterina pectinifera.