Vázquez-Nin G H, Echeverría O M, Martin T E, Lührmann R, Fakan S
Department of Biology, Faculty of Sciences, National Autonomous University of Mexico, D.F./Mexico.
Eur J Cell Biol. 1994 Dec;65(2):291-7.
Nucleoplasmic structural constituents observed in partially decondensed nuclei of the central nervous system of the rat were analyzed by postembedding immunoelectron microscopy using antibodies specifically recognizing heterogenous nuclear ribonucleoprotein (hnRNP) and small nuclear ribonucleoprotein (snRNP) complexes and DNA. Fibrogranular RNP structures (polyparticles) were found in close proximity to DNA containing fibrillar areas resulting from partial dispersion of compact chromatin. The polyparticle-type fibrils are labeled by antibodies recognizing hnRNP core proteins as well as snRNPs (Sm antigen or 70 kDa protein of U1snRNP) or the m3G-cap structure of snRNAs. These observations suggest that such polyparticle-type fibrils correspond to extended perichromatin fibrils. Partially decondensed perichromatin granules are rarely labeled by anti-snRNP or snRNA antibodies. When labeling occurs it is restricted to the periphery of the granules. However, anti-hnRNP antibodies frequently label these granules. Our results favor the idea, previously proposed for Balbiani ring granules, that perichromatin granules are formed by the folding of hnRNP containing perichromatin fibrils (polyparticles) in the process of splicing, and that mature perichromatin granules contain already spliced messenger RNA.
利用特异性识别异质性核核糖核蛋白（hnRNP）、小核核糖核蛋白（snRNP）复合物和DNA的抗体，通过包埋后免疫电子显微镜技术，对大鼠中枢神经系统部分解聚核中观察到的核质结构成分进行了分析。在靠近因紧密染色质部分分散而产生的含DNA纤维区域发现了纤维颗粒状核糖核蛋白结构（多颗粒）。多颗粒型纤维被识别hnRNP核心蛋白以及snRNP（Sm抗原或U1snRNP的70 kDa蛋白）的抗体或snRNA的m3G帽结构标记。这些观察结果表明，这种多颗粒型纤维对应于伸展的染色质周边纤维。部分解聚的染色质周边颗粒很少被抗snRNP或snRNA抗体标记。当出现标记时，它仅限于颗粒的周边。然而，抗hnRNP抗体经常标记这些颗粒。我们的结果支持之前针对巴尔比亚尼环颗粒提出的观点，即染色质周边颗粒是在剪接过程中由含hnRNP的染色质周边纤维（多颗粒）折叠形成的，并且成熟的染色质周边颗粒包含已经剪接的信使RNA。
