Electron Tomography of Metaphase Nucleolar Organizer Regions: Evidence for a Twisted-Loop Organization

click for CBE Life Science Education Page

QUICK SEARCH:

[advanced]

	Author:		Keyword(s):
Year:		Vol:		Page:

This Article

	Full Text
	Full Text (PDF)
	Alert me when this article is cited
	Alert me if a correction is posted

Services

	Similar articles in this journal
	Similar articles in PubMed
	Alert me to new issues of the journal
	Download to citation manager


Citing Articles

	Citing Articles via HighWire
	Citing Articles via Google Scholar

Google Scholar

	Articles by Heliot, L.
	Articles by Ploton, D.
	Search for Related Content

PubMed

	PubMed Citation
	Articles by Heliot, L.
	Articles by Ploton, D.

Vol. 8, Issue 11, 2199-2216, November 1997

Electron Tomography of Metaphase Nucleolar Organizer Regions: Evidence for a Twisted-Loop Organization

Laurent Heliot,^* Hervé Kaplan,^* Laurent Lucas,^* Christophe Klein,^* Adrien Beorchia,^* Martine Doco-Fenzy,^* Monique Menager,^* Marc Thiry, Marie-Françoise O'Donohue,^* and Dominique Ploton^*

^*Unité 314 Institut National de la Santé et de la Recherche Médicale, Laboratoire Pol Bouin, and Institut Féderatif de Recherche 53, Centre Hospitalier Regional Maison Blanche, 51092 Reims Cedex, France; and Laboratoire de Biologie Cellulaire, Institut Pitteurs, Liege, Belgique

Metaphase nucleolar organizer regions (NORs), one of four types of chromosome bands, are located on human acrocentric chromosomes.They contain r-chromatin, i.e., ribosomal genes complexed withproteins such as upstream binding factor and RNA polymerase I,which are argyrophilic NOR proteins. Immunocytochemical and cytochemicallabelings of these proteins were used to reveal r-chromatin insitu and to investigate its spatial organization within NORs byconfocal microscopy and by electron tomography. For each labeling,confocal microscopy revealed small and large double-spotted NORsand crescent-shaped NORs. Their internal three-dimensional (3D)organization was studied by using electron tomography on specificallysilver-stained NORs. The 3D reconstructions allow us to concludethat the argyrophilic NOR proteins are grouped as a fiber of 60-80nm in diameter that constitutes either one part of a turn or twoor three turns of a helix within small and large double-spottedNORs, respectively. Within crescent-shaped NORs, virtual slicesreveal that the fiber constitutes several longitudinally twistedloops, grouped as two helical 250- to 300-nm coils, each centeredon a nonargyrophilic axis of condensed chromatin. We propose amodel of the 3D organization of r-chromatin within elongated NORs,in which loops are twisted and bent to constitute one basic chromatidcoil.

This article has been cited by other articles:

E. Sanij, G. Poortinga, K. Sharkey, S. Hung, T. P. Holloway, J. Quin, E. Robb, L. H. Wong, W. G. Thomas, V. Stefanovsky, et al.
UBF levels determine the number of active ribosomal RNA genes in mammals
J. Cell Biol., December 29, 2008; 183(7): 1259 - 1274.
[Abstract] [Full Text] [PDF]

B. McStay
Nucleolar dominance: a model for rRNA gene silencing.
Genes & Dev., May 15, 2006; 20(10): 1207 - 1214.
[Full Text] [PDF]

M. Derenzini, G. Pasquinelli, M.-F. O'Donohue, D. Ploton, and M. Thiry
Structural and Functional Organization of Ribosomal Genes within the Mammalian Cell Nucleolus
J. Histochem. Cytochem., February 1, 2006; 54(2): 131 - 145.
[Abstract] [Full Text] [PDF]

C. Mais, J. E. Wright, J.-L. Prieto, S. L. Raggett, and B. McStay
UBF-binding site arrays form pseudo-NORs and sequester the RNA polymerase I transcription machinery
Genes & Dev., January 1, 2005; 19(1): 50 - 64.
[Abstract] [Full Text] [PDF]

T. Cheutin, M.-F. O'Donohue, A. Beorchia, C. Klein, H. Kaplan, and D. Ploton
Three-dimensional Organization of pKi-67: A Comparative Fluorescence and Electron Tomography Study Using Fluoronanogold
J. Histochem. Cytochem., November 1, 2003; 51(11): 1411 - 1423.
[Abstract] [Full Text] [PDF]

T. Cheutin, M.-F. O'Donohue, A. Beorchia, M. Vandelaer, H. Kaplan, B. Defever, D. Ploton, and M. Thiry
Three-dimensional organization of active rRNA genes within the nucleolus
J. Cell Sci., August 15, 2002; 115(16): 3297 - 3307.
[Abstract] [Full Text] [PDF]

A. C. O'Sullivan, G. J. Sullivan, and B. McStay
UBF Binding In Vivo Is Not Restricted to Regulatory Sequences within the Vertebrate Ribosomal DNA Repeat
Mol. Cell. Biol., January 15, 2002; 22(2): 657 - 658.
[Abstract] [Full Text] [PDF]

B. F. McEwen and M. Marko
The Emergence of Electron Tomography as an Important Tool for Investigating Cellular Ultrastructure
J. Histochem. Cytochem., May 1, 2001; 49(5): 553 - 564.
[Abstract] [Full Text]

L. Héliot, F. Mongelard, C. Klein, M.-F. O'Donohue, J.-M. Chassery, M. Robert-Nicoud, and Y. Usson
Nonrandom Distribution of Metaphase AgNOR Staining Patterns on Human Acrocentric Chromosomes
J. Histochem. Cytochem., January 1, 2000; 48(1): 13 - 20.
[Abstract] [Full Text]

C. Klein, T. Cheutin, M.-F. O'Donohue, L. Rothblum, H. Kaplan, A. Beorchia, L. Lucas, L. Héliot, and D. Ploton
The Three-dimensional Study of Chromosomes and Upstream Binding Factor-immunolabeled Nucleolar Organizer Regions Demonstrates Their Nonrandom Spatial Arrangement during Mitosis
Mol. Biol. Cell, November 1, 1998; 9(11): 3147 - 3159.
[Abstract] [Full Text]

M. Dundr and M. O.J. Olson
Partially Processed pre-rRNA Is Preserved in Association with Processing Components in Nucleolus-derived Foci during Mitosis
Mol. Biol. Cell, September 1, 1998; 9(9): 2407 - 2422.
[Abstract] [Full Text]

				B. McStay Nucleolar dominance: a model for rRNA gene silencing. Genes & Dev., May 15, 2006; 20(10): 1207 - 1214. [Full Text] [PDF]

				M. Derenzini, G. Pasquinelli, M.-F. O'Donohue, D. Ploton, and M. Thiry Structural and Functional Organization of Ribosomal Genes within the Mammalian Cell Nucleolus J. Histochem. Cytochem., February 1, 2006; 54(2): 131 - 145. [Abstract] [Full Text] [PDF]

				C. Mais, J. E. Wright, J.-L. Prieto, S. L. Raggett, and B. McStay UBF-binding site arrays form pseudo-NORs and sequester the RNA polymerase I transcription machinery Genes & Dev., January 1, 2005; 19(1): 50 - 64. [Abstract] [Full Text] [PDF]

				T. Cheutin, M.-F. O'Donohue, A. Beorchia, C. Klein, H. Kaplan, and D. Ploton Three-dimensional Organization of pKi-67: A Comparative Fluorescence and Electron Tomography Study Using Fluoronanogold J. Histochem. Cytochem., November 1, 2003; 51(11): 1411 - 1423. [Abstract] [Full Text] [PDF]

				A. C. O'Sullivan, G. J. Sullivan, and B. McStay UBF Binding In Vivo Is Not Restricted to Regulatory Sequences within the Vertebrate Ribosomal DNA Repeat Mol. Cell. Biol., January 15, 2002; 22(2): 657 - 658. [Abstract] [Full Text] [PDF]

				B. F. McEwen and M. Marko The Emergence of Electron Tomography as an Important Tool for Investigating Cellular Ultrastructure J. Histochem. Cytochem., May 1, 2001; 49(5): 553 - 564. [Abstract] [Full Text]

				L. Héliot, F. Mongelard, C. Klein, M.-F. O'Donohue, J.-M. Chassery, M. Robert-Nicoud, and Y. Usson Nonrandom Distribution of Metaphase AgNOR Staining Patterns on Human Acrocentric Chromosomes J. Histochem. Cytochem., January 1, 2000; 48(1): 13 - 20. [Abstract] [Full Text]

				C. Klein, T. Cheutin, M.-F. O'Donohue, L. Rothblum, H. Kaplan, A. Beorchia, L. Lucas, L. Héliot, and D. Ploton The Three-dimensional Study of Chromosomes and Upstream Binding Factor-immunolabeled Nucleolar Organizer Regions Demonstrates Their Nonrandom Spatial Arrangement during Mitosis Mol. Biol. Cell, November 1, 1998; 9(11): 3147 - 3159. [Abstract] [Full Text]

				M. Dundr and M. O.J. Olson Partially Processed pre-rRNA Is Preserved in Association with Processing Components in Nucleolus-derived Foci during Mitosis Mol. Biol. Cell, September 1, 1998; 9(9): 2407 - 2422. [Abstract] [Full Text]