The nucleolus constitutes a prominent nuclear compartment, a membraneless organelle that was first documented in the 1830s. The fact that specific chromosomal regions were present in the nucleolus was recognized by Barbara McClintock in the 1930s, and these regions were termed nucleolar organizing regions, or NORs. The primary function of ribosomal DNA (rDNA) is to produce RNA components of ribosomes. Yet, ribosomal DNA also plays a pivotal role in nuclear organization by assembling the nucleolus. This review is focused on the rDNA and associated proteins in the context of genome organization. Recent advances in understanding chromatin organization suggest that chromosomes are organized into topological domains by a DNA loop extrusion process. We discuss the perspective that rDNA may also be organized in topological domains constrained by structural maintenance of chromosome protein complexes such as cohesin and condensin. Moreover, biophysical studies indicate that the nucleolar compartment may be formed by active processes as well as phase separation, a perspective that lends further insight into nucleolar organization. The application of the latest perspectives and technologies to this organelle help further elucidate its role in nuclear structure and function.

中文翻译：

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核糖体DNA和基因组组织中的核仁。

核仁构成一个突出的核区室，这是一种无膜细胞器，最早于1830年代被记录。在1930年代，芭芭拉·麦克林托克（Barbara McClintock）认识到核仁中存在特定的染色体区域，这些区域被称为核仁组织区或NOR。核糖体DNA（rDNA）的主要功能是产生核糖体的RNA成分。然而，核糖体DNA通过组装核仁在核组织中也起着关键作用。这项审查集中在基因组组织的背景下的rDNA和相关的蛋白质。在了解染色质组织方面的最新进展表明，染色体是通过DNA环挤出过程组织成拓扑域的。我们讨论的观点是，rDNA也可能在受染色体蛋白复合物（如粘着素和凝聚素）的结构维护约束的拓扑结构域中组织。此外，生物物理研究表明，可以通过活跃的过程以及相分离来形成核仁区室，这种观点有助于进一步了解核仁的组织。将最新的观点和技术应用于该细胞器有助于进一步阐明其在核结构和功能中的作用。