QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online March 21, 2007
doi: 10.1242/10.1242/jcs.000026

This Article Figures Only Full Text Full Text (PDF) Supplementary Material Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend 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 Tessadori, F. Articles by Gaudin, V. Search for Related Content PubMed PubMed Citation Articles by Tessadori, F. Articles by Gaudin, V. Social Bookmarking                         What's this?

Large-scale dissociation and sequential reassembly of pericentric heterochromatin in dedifferentiated Arabidopsis cells

¹ Nuclear Organization Group, Swammerdam Institute for Life Sciences, University of Amsterdam, BioCentrum Amsterdam, Kruislaan 318, 1098SM Amsterdam, The Netherlands
² Laboratoire de Biologie Cellulaire, IJPB, INRA, Route de St Cyr, 78026 Versailles Cedex, France

^* Authors for correspondence (e-mail: fransz{at}science.uva.nl; Valerie.Gaudin{at}versailles.inra.fr)

Accepted 5 February 2007

Chromocenters in Arabidopsis thaliana are discrete nuclear domains of mainly pericentric heterochromatin. They are characterized by the presence of repetitive sequences, methylated DNA and dimethylated histone H3K9. Here we show that dedifferentiation of specialized mesophyll cells into undifferentiated protoplasts is accompanied by the disruption of chromocenter structures. The dramatic reduction of heterochromatin involves the decondensation of all major repeat regions, also including the centromeric 180 bp tandem repeats. Only the 45S rDNA repeat remained in a partly compact state in most cells. Remarkably, the epigenetic indicators for heterochromatin, DNA methylation and H3K9 dimethylation, did not change upon decondensation. Furthermore, the decondensation of pericentric heterochromatin did not result in transcriptional reactivation of silent genomic elements. The decondensation process was reversible upon prolonged culturing. Strikingly, recondensation of heterochromatin into chromocenters is a stepwise process. Compaction of the tandemly arranged 45S rDNA regions occurs first, followed by the centromeric 180 bp and the 5S rDNA repeats and finally the dispersed repeats, including transposons. The sequence of reassembly seems to be correlated to the size of the repeat domains. Our results indicate that different types of pericentromeric repeats form different types of heterochromatin, which subsequently merge to form a chromocenter.

Key words: Arabidopsis thaliana, Protoplast, Heterochromatin, Chromocenter

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. de Nooijer, J. Wellink, B. Mulder, and T. Bisseling Non-specific interactions are sufficient to explain the position of heterochromatic chromocenters and nucleoli in interphase nuclei Nucleic Acids Res., June 1, 2009; 37(11): 3558 - 3568. [Abstract] [Full Text] [PDF]

				R. Papait, C. Pistore, U. Grazini, F. Babbio, S. Cogliati, D. Pecoraro, L. Brino, A.-L. Morand, A.-M. Dechampesme, F. Spada, et al. The PHD Domain of Np95 (mUHRF1) Is Involved in Large-Scale Reorganization of Pericentromeric Heterochromatin Mol. Biol. Cell, August 1, 2008; 19(8): 3554 - 3563. [Abstract] [Full Text] [PDF]

				T. A. Dittmer, N. J. Stacey, K. Sugimoto-Shirasu, and E. J. Richards LITTLE NUCLEI Genes Affecting Nuclear Morphology in Arabidopsis thaliana PLANT CELL, September 1, 2007; 19(9): 2793 - 2803. [Abstract] [Full Text] [PDF]