Shah S B, Terry C D, Wells D A, DiMario P J
Department of Biochemistry, Louisiana State University, Baton Rouge, LA 70803-1806, USA.
Chromosoma. 1996 Aug;105(2):111-21. doi: 10.1007/BF02509521.
Immunoelectron microscopy with anti-nucleolin defined substructures within the multiple nucleoli of biosynthetically active stage II-III oocytes and within the nucleoli of relatively quiescent stage VI oocytes of Xenopus laevis. Dense fibrillar components (DFCs) of nucleoli from stage II-III oocytes consisted of nucleolonemas that radiated from a continuous DFC sheath surrounding fibrillar centers (FCs). Discernible granular regions (GRs) were absent in these same nucleoli. Conversely, stage VI oocyte nucleoli displayed compacted DFCs and prominent GRs. Immunofluorescence microscopy then tracked fibrillarin, nucleolin, and condensed DNA through oogenesis and into progesterone-induced meiotic maturation and nuclear breakdown. In stage II-III oocyte nucleoli, fibrillarin was enriched near the FC-DFC boundaries, while nucleolin was distributed throughout these same DFCs. Both proteins were enriched within the compacted DFCs of stage VI oocyte nucleoli. Staining with (DAPI) 4',6-diamidino-2-phenylindole showed condensed DNA within nucleolar FCs of both stage II-III and stage VI oocyte. Upon nuclear breakdown, we found fibrillarin and nucleolin in small particles and in the surrounding cytoplasm. Although we saw no trace of fibrillarin or nucleolin in nuclear remnants prepared just minutes later, DAPI-stained particles remained within these preparations, thus suggesting that FCs were at least slow to disassemble.
用抗核仁素的免疫电子显微镜技术确定了非洲爪蟾生物合成活跃的II-III期卵母细胞多个核仁内以及相对静止的VI期卵母细胞核仁内的亚结构。II-III期卵母细胞核仁的致密纤维成分（DFC）由从围绕纤维中心（FC）的连续DFC鞘放射状发出的核仁丝组成。在这些相同的核仁中没有可辨别的颗粒区域（GR）。相反，VI期卵母细胞核仁显示出致密的DFC和明显的GR。然后，免疫荧光显微镜追踪了纤维蛋白原、核仁素和浓缩DNA在卵子发生过程中以及孕酮诱导的减数分裂成熟和核破裂过程中的变化。在II-III期卵母细胞核仁中，纤维蛋白原在FC-DFC边界附近富集，而核仁素分布在这些相同的DFC中。这两种蛋白质都在VI期卵母细胞核仁的致密DFC中富集。用4',6-二脒基-2-苯基吲哚（DAPI）染色显示，II-III期和VI期卵母细胞核仁FC内都有浓缩的DNA。在核破裂时，我们在小颗粒和周围的细胞质中发现了纤维蛋白原和核仁素。尽管在几分钟后制备的核残余物中没有发现纤维蛋白原或核仁素的踪迹，但DAPI染色的颗粒仍留在这些制剂中，因此表明FC至少解体缓慢。
