title: The Trypanosoma cruzi nucleolus: a morphometrical analysis of cultured epimastigotes in the exponential and stationary phases.
abstract: Our group is interested in rRNA and ribosome biogenesis in the parasitic protozoan Trypanosoma cruzi. Epimastigotes represent an extracellular replicative stage of T. cruzi and can be cultured in axenic media. The growth curve of epimastigotes allows assessment of potential differences in the nucleoli of cells undergoing growth-rate transitions. To establish cellular parameters for studying ribosome biogenesis in T. cruzi, a morphometric analysis of the nucleoli of cultured cells in the exponential and stationary phases was conducted. Electron micrograph-based measurements of nuclear sections from independent cells demonstrated that the nucleolar area is over twofold higher in exponentially growing cells, as compared with epimastigotes in the stationary phase. The granular component of the nucleoli of actively growing cells was the main structural element. Cycloheximide moderately reduced the apparent size of the nucleoli without an apparent disruption of their architecture. Our results provide a firm basis for the establishment of an experimental model to study the organization of the nucleolus during the growth and development of T. cruzi.
authors.affiliation: Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D.F., Mexico.
authors.forename: Tomás
authors.initials: T
authors.lastname: Nepomuceno-Mejía
authors.forename: Reyna
authors.initials: R
authors.lastname: Lara-Martínez
authors.forename: Ana María
authors.initials: AM
authors.lastname: Cevallos
authors.forename: Imelda
authors.initials: I
authors.lastname: López-Villaseñor
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Jiménez-García
authors.forename: Roberto
authors.initials: R
authors.lastname: Hernández
mesh_terms: D002466:Cell Nucleolus / Q000187:drug effects / Q000648:ultrastructure; D003513:Cycloheximide / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014349:Trypanosoma cruzi / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure
chemical_list: D011500:Protein Synthesis Inhibitors; D003513:Cycloheximide