000202435 001__ 202435
000202435 005__ 20180317092645.0
000202435 0247_ $$2doi$$a10.1371/journal.pone.0103954
000202435 022__ $$a1932-6203
000202435 02470 $$2ISI$$a000341357200050
000202435 037__ $$aARTICLE
000202435 245__ $$aInhibition of DNA Methylation Alters Chromatin Organization, Nuclear Positioning and Activity of 45S rDNA Loci in Cycling Cells of Q. robur
000202435 269__ $$a2014
000202435 260__ $$aSan Francisco$$bPublic Library of Science$$c2014
000202435 300__ $$a15
000202435 336__ $$aJournal Articles
000202435 520__ $$aAround 2200 copies of genes encoding ribosomal RNA (rRNA) in pedunculate oak, Quercus robur, are organized into two rDNA loci, the major (NOR-1) and the minor (NOR-2) locus. We present the first cytogenetic evidence indicating that the NOR-1 represents the active nucleolar organizer responsible for rRNA synthesis, while the NOR-2 probably stays transcriptionally silent and does not participate in the formation of the nucleolus in Q. robur, which is a situation resembling the well-known phenomenon of nucleolar dominance. rDNA chromatin topology analyses in cycling root tip cells by light and electron microscopy revealed the minor locus to be highly condensed and located away from the nucleolus, while the major locus was consistently associated with the nucleolus and often exhibited different levels of condensation. In addition, silver precipitation was confined exclusively to the NOR-1 locus. Also, NOR-2 was highly methylated at cytosines and rDNA chromatin was marked with histone modifications characteristic for repressive state. After treatment of the root cells with the methylation inhibitor 5-aza-2'-deoxycytidine, we observed an increase in the total level of rRNA transcripts and a decrease in DNA methylation level at the NOR-2 locus. Also, NOR-2 sites relocalized with respect to the nuclear periphery/nucleolus, however, the relocation did not affect the contribution of this locus to nucleolar formation, nor did it affect rDNA chromatin decondensation, strongly suggesting that NOR-2 has lost the function of rRNA synthesis and nucleolar organization.
000202435 700__ $$aBockor, Vedrana Vicic$$uUniv Zagreb, Fac Sci, Dept Mol Biol, Zagreb 41000, Croatia
000202435 700__ $$aBarisic, Darko$$uFriedrich Miescher Inst Biomed Res, Basel, Switzerland
000202435 700__ $$aHorvat, Tomislav$$uUniv Zagreb, Fac Sci, Dept Mol Biol, Zagreb 41000, Croatia
000202435 700__ $$0244380$$aMaglica, Zeljka$$g196146
000202435 700__ $$aVojta, Aleksandar$$uUniv Zagreb, Fac Sci, Dept Mol Biol, Zagreb 41000, Croatia
000202435 700__ $$aZoldos, Vlatka$$uUniv Zagreb, Fac Sci, Dept Mol Biol, Zagreb 41000, Croatia
000202435 773__ $$j9$$k8$$qe103954$$tPlos One
000202435 8564_ $$s4154830$$uhttps://infoscience.epfl.ch/record/202435/files/journal.pone.0103954.pdf$$yPublisher's version$$zPublisher's version
000202435 909CO $$ooai:infoscience.tind.io:202435$$particle$$pSV
000202435 909C0 $$0252451$$pGHI$$xU11270
000202435 917Z8 $$x182396
000202435 937__ $$aEPFL-ARTICLE-202435
000202435 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000202435 980__ $$aARTICLE