Szöllösi M S, Szöllösi D
Unité de Biologie de la Fécondation, Station de Physiologie animale, INRA, Jouy-en-Josas, France.
J Cell Sci. 1988 Oct;91 ( Pt 2):257-67. doi: 10.1242/jcs.91.2.257.
In the mouse zygote and in two-cell stage embryos the inner leaflet of the nuclear envelope of pronuclei and that of blastomere and polar body II nuclei evaginate, forming multiple blebs within the perinuclear space, which contains a granular material. Blebbing exists only in oocytes activated by sperm in vivo or in vitro, or parthenogenetically by treatment with ethanol or puromycin. The germinal vesicle and an interphase nucleus formed after treatment of the oocyte at metaphase I by puromycin do not form blebs. Formation of blebs is specifically located in the cell cycle. The burst of the blebbing activity occurs during the first half of the cell cycle in one-cell embryos and in the earliest interphase period in the second cell cycle. Blebbing ceases from the beginning of the third cell cycle. The occurrence in the cytoplasm of 'double-layered' vesicles containing granular material resembling bleb contents and the disappearance of blebs from the nuclear envelope by the end of the cell cycle provide evidence that blebs represent a step in the transport of some material from the nucleus to the cytoplasm. Ethanolic phosphotungstic acid does not stain blebs, suggesting the absence of basic protein in their contents. Blebbing can be induced in somatic (thymocyte) and embryonic (blastomere of 8-cell stage embryo) nuclei following cell hybridization with activated oocytes. Their response to the oocyte cytoplasm by initiating blebbing depends on: (1) the position of the host cell in its cell cycle at the moment of hybridization, and (2) the time spent by the foreign nuclei in the host cytoplasm following cell fusion. If donor nuclei are introduced close to the time of activation, they start to produce blebs at the time corresponding to the initiation of blebbing by the female pronucleus in the first cell cycle. If foreign nuclei are introduced a few hours after activation they must be incubated in the host cytoplasm for some time before initiation of bleb formation, provided that the host pronucleus has initiated blebbing by that time. The existence of blebbing in nuclei formed only after oocyte activation, and the timing and the general occurrence of this event during the earliest cleavage stages of almost every mammalian embryo, suggest that this special nucleocytoplasmic transport plays a specific role at the beginning of development.
在小鼠受精卵和二细胞期胚胎中，原核、卵裂球和第二极体细胞核的核被膜内小叶会外翻，在核周空间形成多个泡，核周空间含有颗粒物质。泡的形成仅存在于体内或体外被精子激活的卵母细胞中，或通过乙醇或嘌呤霉素处理孤雌激活的卵母细胞中。用嘌呤霉素处理处于第一次减数分裂中期的卵母细胞后形成的生发泡和间期核不会形成泡。泡的形成在细胞周期中有特定定位。泡形成活动的爆发发生在单细胞胚胎细胞周期的前半段以及第二个细胞周期最早的间期。从第三个细胞周期开始泡的形成停止。在细胞质中出现含有类似泡内容物的颗粒物质的“双层”囊泡，以及在细胞周期结束时泡从核被膜消失，这表明泡代表了某些物质从细胞核向细胞质运输的一个步骤。乙醇磷钨酸不会对泡进行染色，这表明泡内容物中不存在碱性蛋白质。与激活的卵母细胞进行细胞杂交后，在体细胞（胸腺细胞）和胚胎（8细胞期胚胎的卵裂球）细胞核中可诱导形成泡。它们通过启动泡的形成对卵母细胞细胞质的反应取决于：（1）杂交时宿主细胞在其细胞周期中的位置，以及（2）细胞融合后外来细胞核在宿主细胞质中停留的时间。如果在激活时间附近引入供体细胞核，它们会在与第一个细胞周期中雌原核开始形成泡相对应的时间开始产生泡。如果在激活后几小时引入外来细胞核，只要宿主原核此时已经开始形成泡，它们必须在宿主细胞质中孵育一段时间后才开始形成泡。仅在卵母细胞激活后形成的细胞核中存在泡的形成，以及这一事件在几乎每个哺乳动物胚胎最早的卵裂阶段的时间和普遍发生情况，表明这种特殊的核质运输在发育开始时起特定作用。
