López-Velázquez Gabriel, Hernández Roberto, López-Villaseñor Imelda, Reyes-Vivas Horacio, Segura-Valdez María de L, Jiménez-García Luis F
Department of Cell Biology, Faculty of Sciences, National Autonomous University of Mexico, México D.F. 04510, México.
Microsc Microanal. 2005 Aug;11(4):293-9. doi: 10.1017/S1431927605050233.
The nucleolus is the main site for synthesis and processing of ribosomal RNA in eukaryotes. In mammals, plants, and yeast the nucleolus has been extensively characterized by electron microscopy, but in the majority of the unicellular eukaryotes no such studies have been performed. Here we used ultrastructural cytochemical and immunocytochemical techniques as well as three-dimensional reconstruction to analyze the nucleolus of Trypanosoma cruzi, which is an early divergent eukaryote of medical importance. In T. cruzi epimastigotes the nucleolus is a spherical intranuclear ribonucleoprotein organelle localized in a relatively central position within the nucleus. Dense fibrillar and granular components but not fibrillar centers were observed. In addition, nuclear bodies resembling Cajal bodies were observed associated to the nucleolus in the surrounding nucleoplasm. Our results provide additional morphological data to better understand the synthesis and processing of the ribosomal RNA in kinetoplastids.
核仁是真核生物中核糖体RNA合成和加工的主要场所。在哺乳动物、植物和酵母中，核仁已通过电子显微镜进行了广泛的表征，但在大多数单细胞真核生物中尚未进行此类研究。在这里，我们使用超微结构细胞化学和免疫细胞化学技术以及三维重建来分析克氏锥虫的核仁，克氏锥虫是一种具有医学重要性的早期分化真核生物。在克氏锥虫前鞭毛体中，核仁是一种球形的核内核糖核蛋白细胞器，位于细胞核内相对中央的位置。观察到致密纤维组分和颗粒组分，但未观察到纤维中心。此外，在周围核质中观察到与核仁相关的类似卡哈尔体的核体。我们的结果提供了更多形态学数据，以更好地理解动基体中核糖体RNA的合成和加工。
