Picard A, Dorée M
Exp Cell Res. 1983 May;145(2):315-23. doi: 10.1016/0014-4827(83)90010-1.
1-Methyladenine, which has been previously shown to be the hormone responsible for meiosis reinitiation in starfish oocytes, triggers parthenogenetic activation when applied to matured starfish oocytes after emission of the second polar body and formation of the pronucleus. In Marthasterias glacialis and Asterias rubens oocytes parthenogenetic activation includes elevation of a fertilization membrane, cleavage and the formation of normal bipinnaria larvae. Activation is likely to result from 1-methyladenine interaction with the category of stereospecific membrane receptors involved in meiosis reinitiation, since structural requirements of this compound are identical for both biological responses. Appearance of oocyte responsiveness to 1-MeAde after, but not before emission of the second polar body cannot be accounted for by their increased sensitivity to intracellular Ca2+ at that time, although it is shown that Ca2+ mediates hormone effect in inducing parthenogenetic activation. Pretreatment of immature oocytes with the free hormone in excess strongly inhibits the 1-methyladenine-induced parthenogenetic activation of the oocytes when they have completed maturation. It is suggested that reappearance of 1-MeAde sensitivity when oocytes form a pronucleus depends either upon recruitment or new receptor units or on the reactivation of pre-existing inactivated receptors at this stage of oocyte maturation.
1-甲基腺嘌呤先前已被证明是负责海星卵母细胞减数分裂重新启动的激素，当在第二极体排出和原核形成后应用于成熟的海星卵母细胞时，它会引发孤雌生殖激活。在冰川海星和红海星的卵母细胞中，孤雌生殖激活包括受精膜升高、卵裂以及正常双羽幼虫的形成。激活可能是由于1-甲基腺嘌呤与参与减数分裂重新启动的立体特异性膜受体类别相互作用所致，因为该化合物对这两种生物学反应的结构要求相同。卵母细胞在排出第二极体之后而非之前对1-甲基腺嘌呤产生反应性，这不能用此时它们对细胞内Ca2+的敏感性增加来解释，尽管已表明Ca2+在诱导孤雌生殖激活中介导激素效应。用过量的游离激素对未成熟卵母细胞进行预处理，当它们完成成熟时，会强烈抑制1-甲基腺嘌呤诱导的卵母细胞孤雌生殖激活。有人提出，卵母细胞形成原核时对1-甲基腺嘌呤敏感性的重新出现，要么取决于新受体单位的募集，要么取决于在此卵母细胞成熟阶段预先存在的失活受体的重新激活。
