title: Electron microscopy analysis of the nucleolus of Trypanosoma cruzi.
abstract: 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.
authors.affiliation: Department of Cell Biology, Faculty of Sciences, National Autonomous University of Mexico, México D.F. 04510, México.
authors.forename: Gabriel
authors.initials: G
authors.lastname: López-Velázquez
authors.forename: Roberto
authors.initials: R
authors.lastname: Hernández
authors.forename: Imelda
authors.initials: I
authors.lastname: López-Villaseñor
authors.forename: Horacio
authors.initials: H
authors.lastname: Reyes-Vivas
authors.forename: María de L
authors.initials: Mde L
authors.lastname: Segura-Valdez
authors.forename: Luis F
authors.initials: LF
authors.lastname: Jiménez-García
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear / Q000032:analysis; D002466:Cell Nucleolus / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D009687:Nuclear Proteins / Q000032:analysis; D014349:Trypanosoma cruzi / Q000648:ultrastructure*
chemical_list: D034961:Antigens, Nuclear; D009687:Nuclear Proteins; C051963:nucleolar organizer region associated proteins