References of "Thiry, Marc"
     in
Bookmark and Share    
Peer Reviewed
See detailLocation of DNA within the nucleolus of rat oocytes during the early stages of follicular growth.
Thiry, Marc ULg; Goessens, Guy ULg

in International Journal of Developmental Biology (1992), 36(1), 139-42

We have investigated the DNA distribution within the rat oocyte nucleolus during the early stages of follicular growth by means of the in situ terminal deoxynucleotidyl transferase method. In the ... [more ▼]

We have investigated the DNA distribution within the rat oocyte nucleolus during the early stages of follicular growth by means of the in situ terminal deoxynucleotidyl transferase method. In the fibrillogranular nucleolus, label is visualized on small clumps of peri- and intranucleolar chromatin. Such labeled clumps are frequently observed inside the interstices surrounding the fibrillar centers. Label is also consistently found in the fibrillar centers whereas the dense fibrillar component and the granular component are devoid of gold particles. These results contradict earlier data but conform with other recent immunocytochemical observations, obtained in nucleoli of a variety of somatic cell types, concerning the correlation between structure and function in the nucleolus. [less ▲]

Detailed reference viewed: 25 (0 ULg)
Peer Reviewed
See detailWhere, within the nucleolus, are the rRNA genes located?
Thiry, Marc ULg; Goessens, Guy ULg

in Experimental Cell Research (1992), 200(1), 1-4

Detailed reference viewed: 7 (1 ULg)
Peer Reviewed
See detailNew data concerning the functional organization of the mammalian cell nucleolus: detection of RNA and rRNA by in situ molecular immunocytochemistry.
Thiry, Marc ULg

in Nucleic Acids Research (1992), 20(23), 6195-200

We have investigated the fine spatial distribution of RNA and rRNA within the Ehrlich tumor cell nucleolus by in situ hybridization with a biotin-labeled probe and by two new strategies, the polyadenylate ... [more ▼]

We have investigated the fine spatial distribution of RNA and rRNA within the Ehrlich tumor cell nucleolus by in situ hybridization with a biotin-labeled probe and by two new strategies, the polyadenylate nucleotidyl transferase-immunogold technique and immuno-labeling with anti-RNA antibodies. Besides the presence, as expected, of RNA and rRNA in the granular component and the dense fibrillar component, we show, for the first time, significant label over all the fibrillar centers of the nucleoli. When RNA and DNA were detected simultaneously on the same sections, only the fibrillar centers were positive for both. These results throw light on the controversial subject of the precise location of transcribing rRNA genes within the nucleolus. The fibrillar centers, and not the dense fibrillar component, should thus be the site of rRNA synthesis. [less ▲]

Detailed reference viewed: 4 (0 ULg)
Peer Reviewed
See detailUltrastructural detection of DNA within the nucleolus by sensitive molecular immunocytochemistry.
Thiry, Marc ULg

in Experimental Cell Research (1992), 200(1), 135-44

This paper describes a new technique for locating DNA on semithin or ultrathin sections of aldehyde-fixed and plastic-embedded cells or tissues. Sections were incubated in a medium containing ... [more ▼]

This paper describes a new technique for locating DNA on semithin or ultrathin sections of aldehyde-fixed and plastic-embedded cells or tissues. Sections were incubated in a medium containing bromodeoxyuridine (BUdR) triphosphate and terminal deoxynucleotidyltransferase. The labeled nucleotides bound at the surface of the sections were subsequently detected with an anti-BUdR antibody and immunoglobulin-gold complex. On semithin sections, labeled nucleotide detection was achieved by an amplification step with silver enhancement. This technique was applied to a wide variety of biological materials allowing a sensitive detection of DNA-containing structures, even where these are present in very low amounts. Examples of high resolution and sensitive detection include the DNA present in mitochondria, chloroplasts, mycoplasmas, and DNA viruses. Special attention focused on the location of DNA inside the nucleolus. In Ehrlich tumor cell nucleoli, DNA was detected in the fibrillar centers and not in the dense fibrillar component. Identical results were found in the nucleoli of other cell types. These results contradict earlier data but conform with other recent immunocytochemical observations concerning the correlation between structure and function in the nucleolus. This method provides a useful tool for investigations requiring highly precise correlations between a molecular function and a given ultrastructural morphology. [less ▲]

Detailed reference viewed: 14 (1 ULg)
Peer Reviewed
See detailLocation of rRNA gene transcription sites within Ehrlich tumor cell nucleoli.
Thiry, Marc ULg

in Bulletin de l'Association des Anatomistes (1991), 75(229), 33-7

The nucleolus is the morphological visualization of ribosome biogenesis. The spatial distribution of nucleolar DNA has been investigated in Ehrlich tumor cells by various immunogold labelling techniques ... [more ▼]

The nucleolus is the morphological visualization of ribosome biogenesis. The spatial distribution of nucleolar DNA has been investigated in Ehrlich tumor cells by various immunogold labelling techniques. The DNase 1-sensitive regions within the nucleolus have been identified by in situ nick-translation at the ultrastructural level. The precise nucleolar location of rDNA and rRNA has been further specified by in situ hybridization and electron microscopy. Our results indicate that the fibrillar centers are the sole nucleolar structures where DNase 1-hypersensitive sequences, rDNA and rRNA are located together. These findings strongly suggest that rRNA gene transcription takes place within the confines of the fibrillar center, probably close to the boundary regions to the surrounding dense fibrillar component. [less ▲]

Detailed reference viewed: 12 (1 ULg)
See detailDigital 3D visualization of silver-stained NORs studied by medium-voltage TEM and STEM
Ploton, Dominique; Beorchia, A; Heliot, Laurent et al

Conference (1991)

Detailed reference viewed: 5 (0 ULg)
See detailLocalisation ultrastructurale du rDNA et du rRNA dans le nucléole
Thiry, Marc ULg

Scientific conference (1991)

Detailed reference viewed: 5 (1 ULg)
Peer Reviewed
See detailLocating transcribed and non-transcribed rDNA spacer sequences within the nucleolus by in situ hybridization and immunoelectron microscopy.
Thiry, Marc ULg; Thiry-Blaise, L.

in Nucleic Acids Research (1991), 19(1), 11-5

Immunoelectron microscopy and in situ hybridization have been used to investigate the precise location of transcribed and non-transcribed rDNA spacer sequences. Whereas a 5'-external transcribed spacer ... [more ▼]

Immunoelectron microscopy and in situ hybridization have been used to investigate the precise location of transcribed and non-transcribed rDNA spacer sequences. Whereas a 5'-external transcribed spacer sequence is predominantly visualized in the fibrillar centers of nucleoli, a non-transcribed spacer sequence is preferentially detected in the interstices, in close contact with the fibrillar centers and which interrupt the surrounding dense fibrillar component. Occasionally these two spacers are also observed in clumps of dense nucleolus-associated chromatin. These observations provide insights into the organization of ribosomal repeats within the nucleolus. [less ▲]

Detailed reference viewed: 3 (0 ULg)
Peer Reviewed
See detailDNase I-sensitive sites within the nuclear architecture visualized by immunoelectron microscopy.
Thiry, Marc ULg

in DNA & Cell Biology (1991), 10(3), 169-80

Nick-translation using mild digestion with DNase I allows preferential labeling of actively transcribing or potentially active genes, as compared with inactive genes. We have adapted this method to the ... [more ▼]

Nick-translation using mild digestion with DNase I allows preferential labeling of actively transcribing or potentially active genes, as compared with inactive genes. We have adapted this method to the level of electron microscopy to see the DNase I-sensitive regions in situ in Ehrlich tumor cells. In interphase cells treated with very low concentrations of DNase I, labeled sequences are found at the borders and in the close vicinity of condensed chromatin blocks. Labeling of condensed areas of chromatin requires higher DNase I concentrations and longer incubation in the nick-translation medium. In the nucleolus, the first sites to be nick-translated are the fibrillar centers and the interstices surrounding them, whereas the dense fibrillar component never contains labeled sequences. When cells are pretreated with actinomycin D, only a few perinucleolar clumps of condensed chromatin are labeled under the same conditions. This method provides a new tool for studying the functional organization of chromatin within a cell. The precise location of nick-translated sites in nucleolar components observed could change classical views concerning the functional organization of the nucleolus. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Peer Reviewed
See detailDigital three-dimensional visualization of cellular organelles studied by medium- and high-voltage electron microscopy.
Beorchia, A.; Ploton, D.; Menager, M. et al

in Journal of Microscopy (1991), 163(Pt 2), 221-31

Tilted thick sections (one-half to several micrometers) of biological specimens observed with medium- to high-voltage electron microscopes are extremely useful for the study of the three-dimensional (3-D ... [more ▼]

Tilted thick sections (one-half to several micrometers) of biological specimens observed with medium- to high-voltage electron microscopes are extremely useful for the study of the three-dimensional (3-D) structure of organelles. If high resolution in 3-D visualization and 3-D reconstruction is needed, many images corresponding to various angles of rotation and tilt must be recorded. This necessitates very time-consuming work--including eventual photographic processing--before good positioning of the object is defined. We have developed software which permits very rapid and precise determination of the tilt-axis, the registration of tilted views, 3-D measurements and 3-D visualization. Images are digitized either from negative films or directly with a camera fitted to the microscope. The application of the software is performed in minutes and allows for a rapid check of the quality of the tilt-series and of the features of interest of the object. Application of the software to the study of the 3-D structure of active components of the nucleolus stained with silver is shown. [less ▲]

Detailed reference viewed: 18 (0 ULg)
Peer Reviewed
See detailIn situ nick translation at the electron microscopic level: a tool for studying the location of DNAse I-sensitive regions within the cell.
Thiry, Marc ULg

in Journal of Histochemistry and Cytochemistry : Official Journal of the Histochemistry Society (1991), 39(6), 871-4

The in situ nick translation method was adapted to the ultrastructural level, to study the location of DNAse I-sensitive sequences within the cell. Ultra-thin sections of Lowicryl-embedded cells were ... [more ▼]

The in situ nick translation method was adapted to the ultrastructural level, to study the location of DNAse I-sensitive sequences within the cell. Ultra-thin sections of Lowicryl-embedded cells were incubated in a medium containing DNAse I, DNA polymerase I, and all four deoxyribonucleotides, some being biotinylated. The nick-translated sites were then visualized by an indirect immunogold labeling technique. The resulting labeling pattern is closely dependent on the DNAse I concentration in the nick-translation medium. The method reveals with great precision the specific DNAse I-sensitive regions within the nucleus. This technique can be used to discriminate between active and inactive regions of interphase chromatin. [less ▲]

Detailed reference viewed: 9 (0 ULg)
Peer Reviewed
See detailCytochemical distinction of various nucleolar components in insect cells.
Thiry, Marc ULg; Schoonbroodt, Stéphanie ULg; Goessens, Guy ULg

in Biology of the Cell (1991), 72(1-2), 133-40

The fine structure of the insect Sf9 cell nucleolus has been investigated by means of different cytochemical and immunocytochemical techniques at the electron microscope level. Apart from a few ... [more ▼]

The fine structure of the insect Sf9 cell nucleolus has been investigated by means of different cytochemical and immunocytochemical techniques at the electron microscope level. Apart from a few perinucleolar condensed chromatin clumps, the insect cell nucleolus comprises two compartments. The first of these consists of a roundish compact zone formed of fibrillar material. The other is composed of fibrillar and granular structures organized into a network separated by interstitial spaces. But, unlike mammalian cell nucleoli, any fibrillar center has been observed in the Sf9 cell nucleolus, even after actinomycin D treatment. We also show that the compact fibrillar zone of Sf9 cell nucleoli contains silver-stainable material and DNA. In actinomycin D-treated cells, a preferential contact of this compact fibrillar zone with condensed chromatin has been visualized. Finally, silver-stainable material has been found to persist throughout the whole mitosis. These results suggest that the compact fibrillar zone at the insect Sf9 cell nucleolus should, at least partly, correspond to the fibrillar center of mammalian cell nucleoli. [less ▲]

Detailed reference viewed: 19 (1 ULg)
Peer Reviewed
See detailLocalization of nucleolar chromatin by immunocytochemistry and in situ hybridization at the electron microscopic level.
Thiry, Marc ULg; Scheer, U.; Goessens, Guy ULg

in Electron Microscopy Reviews (1991), 4(1), 85-110

Nucleoli are the morphological expression of the activity of a defined set of chromosomal segments bearing rRNA genes. The topological distribution and composition of the intranucleolar chromatin as well ... [more ▼]

Nucleoli are the morphological expression of the activity of a defined set of chromosomal segments bearing rRNA genes. The topological distribution and composition of the intranucleolar chromatin as well as the definition of nucleolar structures in which enzymes of the rDNA transcription machinery reside have been investigated in mammalian cells by various immunogold labelling approaches at the ultrastructural level. The precise intranucleolar location of rRNA genes has been further specified by electron microscopic in situ hybridization with a non-autoradiographic procedure. Our results indicate that the fibrillar centers are the sole nucleolar structures where rDNA, core histones, RNA polymerase I and DNA topoisomerase I are located together. Taking into account the potential value and limitations of immunoelectron microscopic techniques, we propose that transcription of the rRNA genes takes place within the confines of the fibrillar centers, probably close to the boundary regions to the surrounding dense fibrillar component. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Peer Reviewed
See detailDistinguishing the sites of pre-rRNA synthesis and accumulation in Ehrlich tumor cell nucleoli.
Thiry, Marc ULg; Goessens, Guy ULg

in Journal of Cell Science (1991), 99 ( Pt 4)

The precise location of transcribing rRNA genes within Ehrlich tumor cell nucleoli has been investigated using two approaches: high-resolution autoradiography of cells pulse-labelled with tritiated ... [more ▼]

The precise location of transcribing rRNA genes within Ehrlich tumor cell nucleoli has been investigated using two approaches: high-resolution autoradiography of cells pulse-labelled with tritiated uridine, varying the exposure time, and in situ-in vitro transcription coupled with an immunogold labelling procedure. When autoradiographic preparations are exposed for a short time, silver grains are found associated almost exclusively with interphasic cell nucleoli. Labelling of extranucleolar areas requires longer exposure. Within the nucleolus, the first sites to be revealed are in the dense fibrillar component. Prolonging exposure increases labelling over the dense fibrillar component, with label becoming more and more apparent over the fibrillar centers. Under these conditions, however, labelling does not extend into the granular component, and no background is observed. Initiation of transcription on ultrathin cell sections occurs preferentially at the borders of condensed chromatin blocks and in their close vicinity. The condensed chromatin areas themselves remain unlabelled. Inside most nucleoli, gold-particle clusters are mainly detected in the fibrillar centers, especially at their periphery, whereas the dense fibrillar component and the granular component remain devoid of label. These results, together with previous observations made on the same cell type, clearly indicate that the fibrillar centers are the sites of rRNA gene transcription in Ehrlich tumor cell nucleoli, while the dense fibrillar component is the site of pre-rRNA accumulation. [less ▲]

Detailed reference viewed: 16 (1 ULg)