Saint-Petersburg State University, Saint-Petersburg, 198504, Russia.
Chromosome Res. 2012 Dec;20(8):979-94. doi: 10.1007/s10577-012-9327-7.
Chromosome architecture and assorted nuclear compartments play an essential role in RNA transcription and processing. Growing vertebrate oocytes represent an advantageous model to study the principles of nuclear structure and function. In this article, the data on three-dimensional (3D) organisation of intact and non-deformed oocyte nuclei (germinal vesicles) in four species of birds (domestic chicken, Japanese quail, rock pigeon and chaffinch) obtained by confocal laser scanning microscopy are presented. The nucleus of the growing avian oocyte has an unusual structure of RNA processing machinery. Germinal vesicles from any of the avian species studied, with the exception of the rock pigeon, are characterized by absence of extrachromosomal RNA-enriched nuclear bodies including Cajal bodies, histone locus bodies and interchromatin granule clusters. The absence of Cajal bodies and histone locus bodies in chicken oocytes correlated with the inactivation of nucleolus organizer and clustered histone genes. Splicing factors such as SR-protein SC35 accumulated in chromosome-associated domains that were classified as complex loops (terminal giant and lumpy loops). Formation of such depot in avian oocyte nuclei is supposed to be nucleated by transcripts of non-coding tandem repeats. The results obtained strongly support a model of RNA-mediated nuclear domains formation.
染色体结构和各种核区在 RNA 转录和加工中起着重要作用。生长中的脊椎动物卵母细胞是研究核结构和功能原理的有利模型。本文介绍了通过共聚焦激光扫描显微镜获得的四种鸟类（家鸡、日本鹌鹑、岩鸽和金翅雀）完整和未变形卵母细胞核（生殖泡）的三维组织数据。生长中的禽类卵母细胞核具有不寻常的 RNA 处理机制结构。除了岩鸽之外，研究的任何一种禽类的生殖泡都缺乏额外的富含 RNA 的核体，包括 Cajal 体、组蛋白基因座体和染色质间颗粒簇。鸡卵母细胞中 Cajal 体和组蛋白基因座体的缺失与核仁组织者和聚集的组蛋白基因失活有关。剪接因子如 SR 蛋白 SC35 积累在染色体相关区域，这些区域被归类为复杂环（末端巨大和块状环）。这种禽类卵母细胞核中储存库的形成被认为是由非编码串联重复转录物引发的。所获得的结果强烈支持 RNA 介导的核区形成模型。
