Revealing the unseen: the organizer region of the nucleolus

2001 ◽  
Vol 114 (17) ◽  
pp. 3199-3205 ◽  
Author(s):  
Marco Biggiogera ◽  
Manuela Malatesta ◽  
Sousan Abolhassani-Dadras ◽  
François Amalric ◽  
Lawrence I. Rothblum ◽  
...  
Keyword(s):  
Inner Core ◽  
Organizer Region ◽  
Exact Distribution ◽  
Dense Fibrillar Component ◽  
Fibrillar Center ◽  
Energy Filtering ◽  
Dna And Rna ◽  
Highly Sensitive ◽  
Fibrillar Component ◽  
First Time

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.

scholarly journals Localization of DNA in the fibrillar components of the nucleolus: a cytochemical and morphometric study.

1993 ◽  
Vol 41 (6) ◽  
pp. 829-836 ◽  
Author(s):  
M Derenzini ◽  
F Farabegoli ◽  
D Trerè
Keyword(s):  
Morphometric Analysis ◽  
Mean Value ◽  
Morphometric Study ◽  
Dense Fibrillar Component ◽  
Thin Sections ◽  
Fibrillar Center ◽  
The Mean ◽  
Fibrillar Component ◽  
Resting Lymphocytes ◽  
The Relationship

We studied the distribution of DNA in human circulating lymphocyte nucleoli using three different cytochemical methods for selective visualization of DNA in thin sections: the Feulgen-like osmium-ammine reaction, the NAMA-Ur procedure, and the osmium-ammine staining in glycine buffer, pH 1.5. All three methods indicated the presence of uniformly distributed, highly decondensed DNA filaments forming a large solitary agglomerate in the central part of the nucleolar area, corresponding to the solitary large fibrillar center (FC) as revealed by uranium and lead staining. We also studied the relationship between DNA agglomerates and nucleolar fibrillar components in resting and phytohemagglutinin (PHA)-stimulated lymphocytes by morphometric analysis of the areas occupied by these structures. In resting lymphocytes the mean area of the DNA agglomerates was 0.479 micron 2 +/- 0.161 SD, whereas that of FCs was 0.380 micron 2 +/- 0.149 SD, with a ratio of 1.26. In PHA-stimulated lymphocytes the mean area of the DNA agglomerates was 0.116 micron 2 +/- 0.056 SD, whereas that of the FCs was 0.075 micron 2 +/- 0.032 SD, with a ratio of 1.55. In PHA-stimulated lymphocytes we also measured the area occupied by the FCs plus the closely associated dense fibrillar component (DFC). The mean value of these two fibrillar components was 0.206 micron 2 +/- 0.081 SD. These data demonstrate that decondensed DNA filaments are uniformly distributed in the FCs and that in transcriptionally active nucleoli they are also present in the proximal portion of the DFC surrounding the FCs.

scholarly journals SUMO-1 Modification Alters ADAR1 Editing Activity

2005 ◽  
Vol 16 (11) ◽  
pp. 5115-5126 ◽  
Author(s):  
Joana M.P. Desterro ◽  
Liam P. Keegan ◽  
Ellis Jaffray ◽  
Ron T. Hay ◽  
Mary A. O'Connell ◽  
...  
Keyword(s):  
Rna Editing ◽  
Nucleolar Localization ◽  
Dense Fibrillar Component ◽  
Wild Type ◽  
Fibrillar Center ◽  
Editing Activity ◽  
Fibrillar Component ◽  
Editing Enzyme

We identify ADAR1, an RNA-editing enzyme with transient nucleolar localization, as a novel substrate for sumoylation. We show that ADAR1 colocalizes with SUMO-1 in a subnucleolar region that is distinct from the fibrillar center, the dense fibrillar component, and the granular component. Our results further show that human ADAR1 is modified by SUMO-1 on lysine residue 418. An arginine substitution of K418 abolishes SUMO-1 conjugation and although it does not interfere with ADAR1 proper localization, it stimulates the ability of the enzyme to edit RNA both in vivo and in vitro. Moreover, modification of wild-type recombinant ADAR1 by SUMO-1 reduces the editing activity of the enzyme in vitro. Taken together these data suggest a novel role for sumoylation in regulating RNA-editing activity.

lncRNA SLERT controls phase separation of FC/DFCs to facilitate Pol I transcription

Science ◽  
2021 ◽  
Vol 373 (6554) ◽  
pp. 547-555
Author(s):  
Man Wu ◽  
Guang Xu ◽  
Chong Han ◽  
Peng-Fei Luan ◽  
Yu-Hang Xing ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Noncoding Rna ◽  
Rna Polymerase I ◽  
Dense Fibrillar Component ◽  
Biophysical Properties ◽  
Fibrillar Center ◽  
Dead Box ◽  
Pol I ◽  
Fibrillar Component ◽  
Polymerase I

RNA polymerase I (Pol I) transcription takes place at the border of the fibrillar center (FC) and the dense fibrillar component (DFC) in the nucleolus. Here, we report that individual spherical FC/DFC units are coated by the DEAD-box RNA helicase DDX21 in human cells. The long noncoding RNA (lncRNA) SLERT binds to DDX21 RecA domains to promote DDX21 to adopt a closed conformation at a substoichiometric ratio through a molecular chaperone–like mechanism resulting in the formation of hypomultimerized and loose DDX21 clusters that coat DFCs, which is required for proper FC/DFC liquidity and Pol I processivity. Our results suggest that SLERT is an RNA regulator that controls the biophysical properties of FC/DFCs and thus ribosomal RNA production.

scholarly journals Building an efficient factory

2002 ◽  
Vol 157 (5) ◽  
pp. 739-741 ◽  
Author(s):  
Sui Huang
Keyword(s):  
Rrna Synthesis ◽  
Dense Fibrillar Component ◽  
Rdna Transcription ◽  
Granular Component ◽  
Fibrillar Center ◽  
Pol I ◽  
Fibrillar Component ◽  
Polymerase I

The subnucleolar structure that is involved in rDNA transcription has been controversial. A report by Koberna et al. (2002)(this issue, page 743) adds significant weight toward the idea that dense fibrillar components (DFCs)**Abbreviations used in this paper: DFC, dense fibrillar component; FC, fibrillar center; GC, granular component; Pol I, polymerase I. and fibrillar center (FC)/DFC borders are the sites of pre-rRNA synthesis.

scholarly journals Ultrastructural distribution of DNA and RNA within the nucleolus of human Sertoli cells as seen by molecular immunocytochemistry

1993 ◽  
Vol 105 (1) ◽  
pp. 33-39 ◽  
Author(s):  
M. Thiry
Keyword(s):  
Sertoli Cells ◽  
Ultrastructural Level ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Dense Fibrillar Component ◽  
Granular Component ◽  
Dna And Rna ◽  
Nucleotidyl Transferase ◽  
Immunocytochemical Techniques ◽  
Fibrillar Component

The precise distribution of DNA and RNA within the human Sertoli cell nucleolus has been investigated, at the ultrastructural level, by cytochemical and molecular immunocytochemical techniques. In Sertoli cells, the nucleolar components show a typical spatial distribution. The fibrillar centres are not surrounded by a layer of dense fibrillar component, but come in contact only with strands of dense fibrillar component. These fibrillar parts of strands are the extensions of granular strands connected to a large granular mass. These strands delimit numerous nucleolar interstices in which chromatin fibres are clearly obvious. Using the in situ terminal deoxynucleotidyl transferase/immunogold procedure for detecting DNA, we find evident label exclusively over the chromatin fibres enclosed in the nucleolar interstices and over the fibrillar centres, and no significant label over the dense fibrillar component and granular component of the nucleolus. Furthermore, using the polyadenylate nucleotidyl transferase/immunogold procedure for detecting RNA, we show that label is deposited not only over the granular component and dense fibrillar component, as expected, but also quite obviously over the fibrillar centres. No label is seen over the interstices containing chromatin.

A study on nucleolar DNA: isolation of DNA from fibrillar components and ultrastructural localization of different DNA probes

1993 ◽  
Vol 104 (4) ◽  
pp. 1199-1205 ◽  
Author(s):  
P. Hozak ◽  
C. Schofer ◽  
J. Sylvester ◽  
F. Wachtler
Keyword(s):  
Ribosomal Rna ◽  
Sertoli Cells ◽  
Ultrastructural Localization ◽  
Ribosomal Rna Genes ◽  
Border Region ◽  
Dense Fibrillar Component ◽  
Mitotic Chromosomes ◽  
Electron Microscopic ◽  
Fibrillar Component ◽  
Rna Genes

The nature and localization of DNA contained in the fibrillar centres and the dense fibrillar component (the fibrillar complex) in the nucleoli, was studied in human LEP cells, Sertoli cells, spermatogonia A and in mitotic chromosomes of stimulated lymphocytes. A novel procedure for isolating the intact fibrillar complex from LEP cells was used; the complex contains DNA that hybridizes to secondary constrictions of mitotic chromosomes and to 28 S rDNA sequences, on Southern blots. Electron microscopic DNA-DNA in situ hybridization was performed, with (a) a probe prepared from DNA extracted from the fibrillar complex of LEP cells, (b) a probe for human total genomic DNA, and (c) a probe for the transcribed part of human rDNA. On the basis of the results obtained we conclude that the ribosomal RNA genes in human Sertoli cells and spermatogonia A are predominantly associated with the dense fibrillar component, including the border region between fibrillar centres and the dense fibrillar component. The ribosomal RNA genes are the main, if not exclusive, DNA type present in the fibrillar complex in the studied cell types.

Intramolecular photoinitiator induced atom transfer radical polymerization for electrochemical DNA detection

The Analyst ◽  
2020 ◽  
Vol 145 (3) ◽  
pp. 858-864
Author(s):  
Ligang Ma ◽  
Qianrui Liu ◽  
Lihe Jian ◽  
Shan Ye ◽  
Xiaoke Zheng ◽  
...  
Keyword(s):  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Electrochemical Biosensor ◽  
Dna Detection ◽  
Atom Transfer ◽  
Highly Sensitive ◽  
Electrochemical Dna Detection ◽  
First Time

A novel electrochemical biosensor was reported for the first time to achieve highly sensitive DNA detection based on photoinduced atom transfer radical polymerization (photoATRP).

scholarly journals Analysis of free and protein-bound nitrotyrosine in human plasma by a gas chromatography/mass spectrometry method that avoids nitration artifacts

2000 ◽  
Vol 345 (3) ◽  
pp. 453-458 ◽  
Author(s):  
Matthew T. FROST ◽  
Barry HALLIWELL ◽  
Kevin P. MOORE
Keyword(s):  
Reactive Nitrogen Species ◽  
Plasma Proteins ◽  
Biological Fluids ◽  
Plasma Concentrations ◽  
Normal Subjects ◽  
Gas Chromatography Mass Spectrometry ◽  
Highly Sensitive ◽  
Acidic Conditions ◽  
First Time

Measurement of nitrotyrosine in biological fluids and tissues is increasingly being used to monitor the production of reactive nitrogen species in vivo. The detection of nitrotyrosine in vivo has been reported with the use of a variety of methods including immunoassay, HPLC and GLC/MS. The validity of HPLC and immunoassays have been questioned with regard to their selectivity and sensitivity limits. In principle, the measurement of nitrotyrosine by GLC/MS permits a highly specific, highly sensitive and fully quantitative assay. The nitration of tyrosine under acidic conditions in the presence of nitrite is well documented. Derivatization for the full quantification of nitrotyrosine by using GLC/MS can lead to the artifactual nitration of tyrosine if performed under acidic conditions in the presence of nitrite. We describe a novel alkaline method for the hydrolysis and derivatization of nitrotyrosine and tyrosine, and demonstrate its applicability to the measurement of plasma concentrations of both free and protein-bound nitrotyrosine and tyrosine. A detection limit of 1 pg for nitrotyrosine and 100 pg for tyrosine has been achieved. Our method allows, for the first time, the analysis of free and protein-bound nitrotyrosine and tyrosine in biological samples. The plasma concentrations (means±S.E.M.) of free tyrosine and nitrotyrosine in eight normal subjects were 12±0.6 μg/ml and 14±0.7 ng/ml respectively. Plasma proteins contained tyrosine and nitrotyrosine at 60.7±1.7 μg/mg and 2.7±0.4 ng/mg respectively.

scholarly journals The growth of interest for astronomical X-ray polarimetry

2018 ◽  
Author(s):  
Frédéric Marin
Keyword(s):  
Quantitative Assessment ◽  
Supernova Remnant ◽  
Scientific Literature ◽  
High Energy ◽  
X Ray ◽  
Highly Sensitive ◽  
In The Beginning ◽  
First Time

Astronomical X-ray polarimetry was first explored in the end of the 60's by pioneering rocket instruments. The craze arising from the first discoveries on stellar and supernova remnant X-ray polarization led to the addition of X-ray polarimeters on-board of early satellites. Unfortunately, the inadequacy of the diffraction and scattering technologies required to measure polarization with respect to the constraints driven by X-ray mirrors and detectors, coupled to long integration times, slowed down the field for almost 40 years. Thanks to the development of new, highly sensitive, compact X-ray polarimeters in the beginning of the 2000's, the possibility to observe astronomical X-ray polarization is rising again and scientists are now ready to explore the high energy sky thanks to modern X-ray polarimeters. In the forthcoming years, several X-ray missions (both rockets, balloons and satellites) will open a new observational windows. A wind of renewal blows over the area of X-ray polarimetry and this paper presents for the first time a quantitative assessment, all based on scientific literature, of the growth of interest for astronomical X-ray polarimetry.

Sign in / Sign up

Export Citation Format

Share Document