title: Revealing the unseen: the organizer region of the nucleolus.
abstract: We carried out a high-resolution ultrastructural analysis of the nucleolus in mouse P815 cells by combining specific DNA and RNA staining, anti-fibrillarin immunolabeling, contrast enhancement by energy filtering TEM and phosphorus mapping by ESI to visualize nucleic acids. We demonstrated that specifically contrasted DNA, fibrillarin and phosphorus overlap within the nucleolar dense fibrillar component. Moreover, we describe a 'DNA cloud' consisting of an inner core of DNA fibers (fibrillar center) and a periphery made of extremely thin fibrils overlapping the anti-fibrillarin immunolabeling (dense fibrillar component). This highly sensitive approach has allowed us to demonstrate, for the first time, the exact distribution of DNA within the decondensed interphase counterpart of the NOR, which includes both the fibrillar center and the dense fibrillar component.
authors.affiliation: Centre of Electron Microscopy, University of Lausanne, 1005 Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Biggiogera
authors.forename: M
authors.initials: M
authors.lastname: Malatesta
authors.forename: S
authors.initials: S
authors.lastname: Abolhassani-Dadras
authors.forename: F
authors.initials: F
authors.lastname: Amalric
authors.forename: L I
authors.initials: LI
authors.lastname: Rothblum
authors.forename: S
authors.initials: S
authors.lastname: Fakan
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004275:DNA, Ribosomal / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D008854:Microscopy, Electron; D008954:Models, Biological; D009697:Nucleolus Organizer Region / Q000502:physiology* / Q000648:ultrastructure*; D011485:Protein Binding; D014158:Transcription, Genetic
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004275:DNA, Ribosomal; C047458:fibrillarin; D004247:DNA