【摘要】 斑马鱼中囊胚过渡（MBT）始于受精卵的第10次卵裂,此时亦伴有细胞周期延长,分裂同步性丧失,合子型基因开始转录活化,胚胎细胞开始具备运动迁移能力等现象。斑马鱼MBT的发生依赖于胚胎细胞的核质比,胚胎细胞周期中的G₁时相则只有在合子型基因组开始被转录活化后才能出现。细胞周期检验点的激活可能也是受转录调控的,但中期检验点对DNA复制抑制状态的响应不仅在MBT前后、甚至在MBT前的不同阶段也可能有具体作用途径的差异。活化的P38蛋白在胚胎中的不对称分布是维持卵裂阶段细胞分裂同步性的关键因素。尽管大规模的合子型基因的表达发生在MBT开始后,也有少数与胚层分化有关的合子型基因是在MBT前表达的,还有一些既有母型表达也有合子型表达的基固在MBT前后分别参与不同的信号途径来调控胚胎的发育与分化。更多还原

【Abstract】 The zebrafish midblastula transition （MBT） begins at cycle 10, in association with cell cyclelengthening, loss of cell synchrony, zygotic genome activation of transcription and appearance of cell motility. Thezebrafish MBT takes place dependently on the nucleocytoplasmic ratio of embryonic cell, whereas G₁ phase emergesonly at the onset of ZGA. The establishment of cell cycle checkpoint may also be controlled by transcriptionactivation, while metaphase checkpoint responds to the inhibitory elements of DNA replication in various mannersat pre-MBT and post-MBT stage, even distinct to individual stages pre-MBT. The asymmetric pattern of activatedP38 plays an indispensable role to maintain the synchrony of cell division at cleavage stage. Despite that the largescale of zygotic gene expression breaks out at the onset of MBT, a few of zygotic genes involving to the differen-tiation of germ layers are expressed pre-MBT, in addition that some genes expressed both maternally and zygoti-cally participate in distinct signal pathways pre-MBT and post-MBT to control the development and differentiationof embryos.更多还原