Pochukalina G N, Davis D S, Kostiuchek D F, Murti K G, Parfenov V N
Institute of Cytology, Russian Academy of Sciences, St. Petersburg.
Tsitologiia. 1998;40(4):239-47.
Three groups of oocytes in the human antral follicules were previously distinguished on the basis of nuclear structures arrangement and 3H-uridine incorporation in the oocyte nuclei revealed by ultrastructural and autoradiographic research (Parfenov et al., 1984, 1989). These groups can be regarded as consecutive states of oocyte development, i. e. active, intermediate and inactive ones. The latter is characterized by compactization of nuclear structures arranged within a limited nuclear volume. The present study concerns the distribution of splicing factors (snRNP and SC35) and p80 coilin in the nuclei of oocytes being at either of the three states. Along with transcription decreasing in oocyte nuclei, reduction of snRNP and SC35 amounts in the karyoplasm was detected. Simultaneously, accumulation of these splicing factors occurred in clusters of interchromatin granules (CIG). snRNP and SC35 are spatially segregated in CIG. snRNP are located within the fibrillar zones of CIG, while SC35 corresponds to the granular component of CIG. CIG are the only structures containing splicing factors in the nuclei of oocytes from the human antral follicules. These nuclei lack typical coiled bodies (CB). Considerable amounts of the marker protein of CB--p80 coilin are revealed in the nucleolus-like bodies (NLB) of human oocyte nuclei. Contrary to the data obtained on the oocytes from the antral follicules of other mammals (Kopecny et al., 1996a, 1996b) NLB in human oocytes do not contain snRNPs and SC35. The present study allows to make the following conclusions: a) splicing factors recruted to the sites of transcription in karyoplasm of oocytes are assembled in CIG when inactivation of transcription takes place; b) CIG in preovulated human oocytes play substantial role in the storage and preservation of splicing factors.
根据超微结构和放射自显影研究（帕尔菲诺夫等人，1984年、1989年）显示的卵母细胞核结构排列和3H-尿苷掺入情况，先前已区分出人类窦状卵泡中的三组卵母细胞。这些组可被视为卵母细胞发育的连续状态，即活跃、中间和不活跃状态。后者的特征是核结构在有限的核体积内紧密排列。本研究关注处于这三种状态之一的卵母细胞核中剪接因子（snRNP和SC35）和p80卷曲螺旋蛋白的分布。随着卵母细胞核中转录减少，检测到核质中snRNP和SC35数量减少。同时，这些剪接因子在染色质间颗粒（CIG）簇中积累。snRNP和SC35在CIG中在空间上是分离的。snRNP位于CIG的纤维状区域内，而SC35对应于CIG的颗粒成分。CIG是人类窦状卵泡卵母细胞核中唯一含有剪接因子的结构。这些细胞核缺乏典型的卷曲小体（CB）。在人类卵母细胞核的核仁样体（NLB）中发现了大量CB的标记蛋白——p80卷曲螺旋蛋白。与从其他哺乳动物窦状卵泡卵母细胞获得的数据相反（科佩茨尼等人，1996年a、1996年b），人类卵母细胞中的NLB不含有snRNP和SC35。本研究可以得出以下结论：a）当转录失活时，募集到卵母细胞核质中转录位点的剪接因子在CIG中组装；b）排卵前人类卵母细胞中的CIG在剪接因子的储存和保存中起重要作用。
