Yuce O, Sadler K C
Department of Molecular Biology and Genetics, Bosphorus University, Bebek, 80815, Istanbul, Turkey.
Dev Biol. 2001 Sep 1;237(1):29-44. doi: 10.1006/dbio.2001.0361.
Fertilization of starfish eggs during meiosis results in rapid progression to embryogenesis as soon as meiosis II is completed. Unfertilized eggs complete meiosis and arrest in postmeiotic interphase for an, until now, indeterminate time. If they remain unfertilized, the mature postmeiotic eggs ultimately die. The aim of this study is to characterize the mechanism of death in postmeiotic unfertilized starfish eggs. We report that, in two species of starfish, in the absence of fertilization, postmeiotic interphase arrest persists for 16-20 h, after which time the cells synchronously and rapidly die. Dying eggs extrude membrane blebs, undergo cytoplasmic contraction and darkening, and fragment into vesicles in a manner reminiscent of apoptotic cells. The DNA of dying eggs is condensed, fragmented, and labeled by the TUNEL assay. Taken together, these data suggest that the default fate of postmeiotic starfish eggs, like their mammalian counterparts, is death by apoptosis. We further report that the onset and execution of apoptosis in this system is dependent on ongoing protein synthesis and is inhibited by a rise in intracellular Ca(2+), an essential component of the fertilization signaling pathway. We propose starfish eggs as a useful model to study developmentally regulated apoptosis.
在减数分裂过程中对海星卵进行受精，一旦减数分裂II完成，就会迅速进入胚胎发育阶段。未受精的卵完成减数分裂并在减数分裂后的间期停滞一段目前尚不确定的时间。如果它们一直未受精，成熟的减数分裂后卵最终会死亡。本研究的目的是阐明减数分裂后未受精海星卵的死亡机制。我们报告称，在两种海星中，在未受精的情况下，减数分裂后的间期停滞会持续16 - 20小时，之后细胞会同步且迅速地死亡。即将死亡的卵会挤出膜泡，经历细胞质收缩和变暗，并以类似于凋亡细胞的方式破碎成小泡。即将死亡的卵的DNA会发生浓缩、片段化，并通过TUNEL检测法进行标记。综合这些数据表明，减数分裂后海星卵的默认命运，就像它们的哺乳动物对应物一样，是通过凋亡死亡。我们进一步报告称，该系统中凋亡的起始和执行依赖于持续的蛋白质合成，并受到细胞内Ca(2+)升高的抑制，Ca(2+)是受精信号通路的一个重要组成部分。我们提出海星卵是研究发育调控凋亡的一个有用模型。
