Pal J K, Gounon P, Grossi de Sa M F, Scherrer K
Institut Jacques Monod, Université Paris VII, France.
J Cell Sci. 1988 Aug;90 ( Pt 4):555-67. doi: 10.1242/jcs.90.4.555.
The prosomes, biochemically well characterized small RNA-protein complexes, found associated with mRNA in all eukaryotic cells tested, have been identified as maternal components in sea urchin and chick embryos. In this study, we investigated their presence and cytolocalization in the oocytes and embryos of Pleurodeles waltl by immunoblot analysis and immunofluorescence, using monoclonal antibodies prepared against duck prosome proteins. Of the four antibodies tested, three recognized the corresponding antigens in oocyte total protein extracts. Immunofluorescence analysis, using the three prosomal antibodies, demonstrated a drastic change in the localization of the prosome antigens, which changed from the cytoplasm to the nucleus during oogenesis. In the nucleus, in diplotene stages, prosomal antigens appeared to be associated with the lampbrush chromosomes and the nuclear matrix. During embryogenesis, the subcellular distribution of the prosome antigens was a function of development and differentiation: in the cleavage stages up to the mid-blastula they were localized in the cytoplasm and on the plasma membrane, while in the late blastula, gastrula and neurula they were in the nucleus. Interestingly, one of the prosome antigens, p31K, was found to be in a different location in certain cells in the animal pole of the mid-blastula and was absent in the neural tissue in the neurula. In still later stages, in the free-swimming larva, all three antigens were localized in the cytoplasm, specifically in certain cell types in the epidermal tissues. Furthermore, they were sectorially distributed in the cytoplasm. These data taken together indicate the possible presence of tissue-type-specific prosome antigens in Pleurodeles. Differentiation-dependent subcellular localization of the prosome antigens suggests a cell-compartment-related multiple function of prosomes.
核小体是生物化学特性得到充分表征的小RNA - 蛋白质复合物，在所有检测的真核细胞中均发现其与mRNA相关联，已被鉴定为海胆和鸡胚胎中的母体成分。在本研究中，我们使用针对鸭核小体蛋白制备的单克隆抗体，通过免疫印迹分析和免疫荧光法，研究了它们在疣螈卵母细胞和胚胎中的存在情况及细胞定位。在所测试的四种抗体中，三种在卵母细胞总蛋白提取物中识别出相应抗原。使用这三种核小体抗体进行的免疫荧光分析表明，核小体抗原的定位发生了剧烈变化，在卵子发生过程中从细胞质转移到了细胞核。在细胞核中，在双线期阶段，核小体抗原似乎与灯刷染色体和核基质相关联。在胚胎发生过程中，核小体抗原的亚细胞分布是发育和分化的函数：在囊胚中期之前的卵裂阶段，它们定位于细胞质和质膜上，而在囊胚后期、原肠胚和神经胚阶段，它们位于细胞核中。有趣的是，发现一种核小体抗原p31K在囊胚中期动物极的某些细胞中位于不同位置，而在神经胚的神经组织中不存在。在更后期阶段，在自由游动的幼虫中，所有三种抗原都定位于细胞质中，特别是在表皮组织的某些细胞类型中。此外，它们在细胞质中呈扇形分布。这些数据综合起来表明，疣螈中可能存在组织类型特异性的核小体抗原。核小体抗原的分化依赖性亚细胞定位表明核小体具有与细胞区室相关的多种功能。
