References of "Thiry, Marc"
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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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See detailIdentification des sites de la transcription des gènes ribosomiques dans le nucléole de la cellule tumorale d'Ehrlich
Thiry, Marc ULg

in Bulletin de l'Association des Anatomistes (1990), 74

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See detailImmunoelectron microscope localization of DNase I sensitive sequences within the cell nucleus
Thiry, Marc ULg

in Cell Biology International Reports (1990), 14

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See detailLocalization of DNase I sensitive sequences in specific regions of nuclear architecture
Thiry, Marc ULg

in Archives Internationales de Physiologie et de Biochimie (1990), 98

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See detailComputerized three dimensional visualization of silver stained nucleolar organizer regions studied by high voltage electron microscopy
Ploton, Dominique; Beorchia, A; Ménager, Monique et al

in Biology of the Cell (1990), 69

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See detailNick translation : un outil pour la microscopie électronique
Thiry, Marc ULg

Scientific conference (1990)

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See detailElectron microscope localization of ribosomal RNA and DNA after in situ hybridization
Thiry, Marc ULg; Thiry-Blaise, Lydia

in Harris, J R; Zbarsky, I B (Eds.) Nuclear structure and function (1990)

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See detailSpatial distribution of DNA and histones within Ehrlich tumor cell nucleoli by immunoelectron microscopy
Thiry, Marc ULg

in Harris, J R; Zbarsky, I B (Eds.) Nuclear structure and function (1990)

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See detailUltrastructural cytochemistry of the mammalian cell nucleolus.
Derenzini, Massimo; Thiry, Marc ULg; Goessens, Guy ULg

in Journal of Histochemistry and Cytochemistry : Official Journal of the Histochemistry Society (1990), 38(9), 1237-56

In the present review on the organization of the mammalian cell nucleolus, we report and discuss data obtained during the past 10 years by means of cytochemical and immunocytochemical ultrastructural ... [more ▼]

In the present review on the organization of the mammalian cell nucleolus, we report and discuss data obtained during the past 10 years by means of cytochemical and immunocytochemical ultrastructural techniques. Particular emphasis is placed on the following topics: location of the nucleolus organizer regions in interphasic nucleolar components, structure of nucleolar chromatin in situ, and the structure-function relationship of the nucleolar components. The cytochemical and immunocytochemical results are compared and the concordant data are stressed for each topic. [less ▲]

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See detailUltrastructural and cytochemical studies on extranucleolar bodies in rat oocytes at the preovulatory follicle stage.
Antoine, Nadine ULg; Thiry, Marc ULg; Goessens, Guy ULg

in Biology of the Cell (1989), 65(1), 61-6

At the antral follicle stage, the nucleolus is entirely composed of a homogeneous proteinic compact mass. This nucleolar compaction during oogenesis seems to be a general feature in mammalian oocytes ... [more ▼]

At the antral follicle stage, the nucleolus is entirely composed of a homogeneous proteinic compact mass. This nucleolar compaction during oogenesis seems to be a general feature in mammalian oocytes. However, when oocyte maturation is induced by gonadotropin hormone (LH), oocytes enter into preovulatory stage. All the nucleoli are vacuolated and extranucleolar bodies appear in the germinal vesicle near the nucleolar mass. Based on the results obtained by ultrastructural cytochemical stainings, we postulate that these extranucleolar bodies originate from the nucleolar mass itself. The presence of the extranucleolar bodies could reflect the extrusion of nucleolar material, essentially ribonucleoproteins, into the ooplasm. This material could persist after fertilization in the pronuclei until the resumption of transcription at the early stage of embryogenesis. [less ▲]

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