Gautier J, Pal J K, Grossi de Sa M F, Beetschen J C, Scherrer K
Laboratoire de Biologie du Développement, U.A. CNRS no 675, Université P. Sabatier, Toulouse, France.
J Cell Sci. 1988 Aug;90 ( Pt 4):543-53. doi: 10.1242/jcs.90.4.543.
The prosomes, a novel type of small RNA-protein complex previously characterized in avian and mammalian cells, were isolated from axolotl (Ambystoma mexicanum) oocytes and identified by sedimentation analysis and protein composition. The prosomal nature of these particles was further ascertained by immunoblot analysis with anti-duck prosome monoclonal antibodies. By in vitro [35S]methionine labelling, de novo synthesis of prosomal proteins could be detected neither during oogenesis nor meiotic maturation. The results obtained by both indirect immunofluorescence and immunoblot analyses demonstrated a dramatic change in the localization of prosomal antigens during oocyte development. They were initially detected in the oocyte cytoplasm, during oocyte growth. At the end of vitellogenesis (stages V-VI), they entered the nucleus (germinal vesicle) and were accumulated there to the highest concentration. During oocyte maturation, after nuclear envelope breakdown, prosomal antigens were found to be localized again in the cytoplasm, until fertilization. No specific localization of prosomal antigens in mature oocytes, unfertilized and fertilized eggs was observed within the oocyte cytoplasm in relation to the cytoplasmic rearrangements leading to grey crescent formation.
核前体小体是先前在鸟类和哺乳动物细胞中发现的一种新型小RNA-蛋白质复合物，本研究从蝾螈（墨西哥钝口螈）卵母细胞中分离出核前体小体，并通过沉降分析和蛋白质组成鉴定了它们。用抗鸭核前体小体单克隆抗体进行免疫印迹分析，进一步确定了这些颗粒的核前体小体性质。通过体外[35S]甲硫氨酸标记，在卵子发生和减数分裂成熟过程中均未检测到核前体小体蛋白的从头合成。间接免疫荧光和免疫印迹分析结果均表明，在卵母细胞发育过程中，核前体小体抗原的定位发生了显著变化。在卵母细胞生长过程中，最初在卵母细胞细胞质中检测到它们。在卵黄发生末期（V-VI期），它们进入细胞核（生发泡）并在那里积累到最高浓度。在卵母细胞成熟过程中，核膜破裂后，核前体小体抗原再次定位于细胞质中，直至受精。在成熟卵母细胞、未受精卵和受精卵中，未观察到核前体小体抗原在卵母细胞细胞质内相对于导致灰色新月形成的细胞质重排有特异性定位。
