ABSTRACT
Starfish oocyte maturation is induced by a hormone, 1-methyladenine (1-MeAde), produced in the ovarian follicle cells under the influence of a gonad-stimulating peptide hormone secreted from the supporting cells of the nervous system. The primary action of 1-MeAde in inducing oocyte maturation seems to be the binding with its receptor present on the surface of the oocyte. When treated with a dilute solution of Triton X-100, the denuded Asterina oocytes without their vitelline coat lost their capacity to respond to 1-MeAde. However, such “decapacitated” oocytes once again acquired the capacity to respond to 1-MeAde when incubated in the Triton X-100 extract. The active substance contained in the Triton X-100 extract seems to be a receptor of 1-MeAde or its fragment, or a cofactor of 1-MeAde action. In contrast to the case of starfishes, 1-MeAde failed to induce oocyte maturation in sea cucumbers. However, oocytes of the sea cucumber, Stichopus japonicus, underwent breakdown of their germinal vesicles and subsequent maturation processes when treated with dithiothreitol which also induces starfish oocyte maturation. Therefore, the reduction of disulfide bonds seems to play an important rôle in triggering maturation of echinoderm oocytes.
