Zatsepina O V, Schöfer C, Weipoltshammer K, Mosgoeller W, Almeder M, Stefanova V N, Jordan E G, Wachtler F
A.N. Belozersky Institute of Physical and Chemical Biology, Moscow State University, Russia.
Cytogenet Cell Genet. 1996;73(4):274-8. doi: 10.1159/000134354.
Indirect immunolabeling with anti-UBF antibodies, in situ hybridization with an rDNA probe, and confocal scanning laser microscopy were used to study nucleolar organizer regions (NORs) during the cell cycle in pig embryonic kidney (PK) cells. The chromosomal distribution of the polymerase I transcription factor UBF and rDNA was compared with the number of silver-stained NORs (Ag-NORs) present and nucleolar size. It was shown, both at interphase and mitosis, that the majority of UBF and rDNA signals were located at the same foci and that the amounts of UBF and rDNA at any given site were in a striking positive correlation. At mitosis, only the NORs were labeled; at interphase, the signals for both UBF and rDNA were arranged in necklace-like structures around the nucleoli. No chromosomal NORs without Ag-proteins or UBF were present, indicating that all NORs in PK cells are active at interphase. It was concluded that (1) UBF and rDNA co-localize throughout the cell cycle in PK cells; (2) their association with mitotic NORs is determined by the number of rDNA repeats, rather than by any differential ability of NORs to recruit the transcription factor; and (3) the amount of UBF can be correlated with the size and activity of the nucleoli at interphase.
运用抗UBF抗体进行间接免疫标记、用rDNA探针进行原位杂交以及共聚焦扫描激光显微镜技术，研究猪胚胎肾（PK）细胞在细胞周期中的核仁组织区（NORs）。将聚合酶I转录因子UBF和rDNA的染色体分布与银染NORs（Ag-NORs）的数量以及核仁大小进行比较。结果显示，在间期和有丝分裂期，大多数UBF和rDNA信号位于相同的位点，并且在任何给定位点，UBF和rDNA的量呈现出显著的正相关。在有丝分裂期，只有NORs被标记；在间期，UBF和rDNA的信号围绕核仁呈项链状结构排列。不存在没有Ag蛋白或UBF的染色体NORs，这表明PK细胞中的所有NORs在间期都是活跃的。得出的结论是：（1）在PK细胞的整个细胞周期中，UBF和rDNA共定位；（2）它们与有丝分裂NORs的关联由rDNA重复序列的数量决定，而非由NORs招募转录因子的任何差异能力决定；（3）UBF的量可以与间期核仁的大小和活性相关联。
