title: Identification of nucleoli in the early branching protist Giardia duodenalis.
abstract: Giardia duodenalis has been described as 'anucleolated'. In this work we analysed the subcellular distribution of several nucleolar markers in Giardia nuclei using silver and immunostaining techniques for electron and confocal laser microscopy as well as expression of epitope-tagged proteins in transgenic trophozoites. We identified anteronuclear fibrogranular structures corresponding to nucleolar organising regions with recruited ribonucleoprotein complexes, rRNA and epitope-tagged fibrillarin and rRNA-pseudouridine synthase (CBF5). Recombinant fibrillarin and CBF5 were targeted to this subcompartment. This study demonstrates the presence of nucleoli in G. duodenalis and provides a model to analyse minimal requirements for nucleolar assembly and maintenance in eukaryotic cells.
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias-Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Jiménez-García
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Zavala
authors.forename: Bibiana
authors.initials: B
authors.lastname: Chávez-Munguía
authors.forename: María del Pilar
authors.initials: Mdel P
authors.lastname: Ramos-Godínez
authors.forename: Gabriel
authors.initials: G
authors.lastname: López-Velázquez
authors.forename: María de Lourdes
authors.initials: Mde L
authors.lastname: Segura-Valdez
authors.forename: Cecilia
authors.initials: C
authors.lastname: Montañez
authors.forename: Adrian B
authors.initials: AB
authors.lastname: Hehl
authors.forename: Raúl
authors.initials: R
authors.lastname: Argüello-García
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Ortega-Pierres
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism / Q000648:ultrastructure*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D019143:Evolution, Molecular; D005872:Giardia / Q000378:metabolism / Q000648:ultrastructure*; D006801:Humans; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D009697:Nucleolus Organizer Region / Q000378:metabolism / Q000648:ultrastructure*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D015800:Protozoan Proteins; D012335:RNA, Ribosomal; C047458:fibrillarin