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In this study, vitamin-induced changes in nucleolar structure were evaluated as markers of autoschizis. Human ... [more ▼]Ascorbate and menadione (Apatone) in a ratio of 100:1 kills tumor cells by autoschizis. In this study, vitamin-induced changes in nucleolar structure were evaluated as markers of autoschizis. Human bladder carcinoma (T24) cells were overlain with vitamins or with culture medium. Supernatants were removed at 1-hr intervals from 1 to 4 hr, and the cells were washed with PBS and prepared for assay. Apatone produced marked alterations in nucleolar structure including redistribution of nucleolar components, formation of ring-shaped nucleoli, condensation and increase of the proportion of perinucleolar chromatin, and the enlargement of nucleolar fibrillar centers. Immunogold labeling of the nucleolar rRNA revealed a granular localization in treated and sham-treated cells, and immunogold labeling of the rDNA revealed a shift from the fibrillar centers to the condensed perinucleolar chromatin. Fibrillarin staining shifted from the fibrillar centers and adjacent regions to a more homogeneous staining of the entire nucleolus and was consistent with the percentage of autoschizic cells detected by flow cytometry. Because autoschizis entails sequential reactivation of DNase I and DNase II, and because the fibrillarin redistribution following DNase I and Apatone treatment is identical, it appears that the nucleolar and fibrillarin changes are markers of autoschizis. [less ▲]Detailed reference viewed: 13 (0 ULg) Nucleolar structure across evolution : the transition between bi- and tricompartmentalized nucleoli lies within the class ReptiliaFranck, Claire; Lamaye, Françoise; Thelen, Nicolas et alPoster (2011, January 31)Detailed reference viewed: 21 (7 ULg) Nucleolar structure across evolution : the transition between bi- and tricompartmentalized nucleoli lies within the class ReptiliaThiry, Marc Poster (2011)Detailed reference viewed: 9 (2 ULg) Nucleolar structure across evolution: the transition between bi- and tri-compartmentalized nucleoli lies within the class Reptilia.Lamaye, Francoise; Galliot, Sonia; Alibardi, Lorenzo et alin Journal of Structural Biology (2011), 174(2), 352-9Two types of nucleolus can be distinguished among eukaryotic cells: a tri-compartmentalized nucleolus in amniotes and a bi-compartmentalized nucleolus in all the others. However, though the nucleolus ... [more ▼]Two types of nucleolus can be distinguished among eukaryotic cells: a tri-compartmentalized nucleolus in amniotes and a bi-compartmentalized nucleolus in all the others. However, though the nucleolus' ultrastructure is well characterized in mammals and birds, it has been so far much less studied in reptiles. In this work, we examined the ultrastructural organization of the nucleolus in various tissues from different reptilian species (three turtles, three lizards, two crocodiles, and three snakes). Using cytochemical and immunocytological methods, we showed that in reptiles both types of nucleolus are present: a bi-compartmentalized nucleolus in turtles and a tri-compartmentalized nucleolus in the other species examined in this study. Furthermore, in a given species, the same type of nucleolus is present in all the tissues, however, the importance and the repartition of those nucleolar components could vary from one tissue to another. We also reveal that, contrary to the mammalian nucleolus, the reptilian fibrillar centers contain small clumps of condensed chromatin and that their surrounding dense fibrillar component is thicker. Finally, we also report that Cajal bodies are detected in reptiles. Altogether, we believe that these results have profound evolutionarily implications since they indicate that the point of transition between bipartite and tripartite nucleoli lies at the emergence of the amniotes within the class Reptilia. [less ▲]Detailed reference viewed: 17 (3 ULg) Le nucléole : un organite cellulaire fondamentalLepoint, Alain; Goessens, Guy ; Thiry, Marc in Revue de l'Association Belge des Technologies de Laboratoire (1987), 14Detailed reference viewed: 10 (0 ULg) Nucleolin binds specifically to an AP-1 DNA sequence and represses AP1-dependent transactivation of the matrix metalloproteinase-13 gene.Samuel, Shaija; Twizere, Jean-Claude ; Beifuss, Katherine K et alin Molecular Carcinogenesis (2008), 47(1), 34-46Transcriptional regulation via activator protein-1 (AP-1) protein binding to AP-1 binding sites within gene promoter regions of AP-1 target genes plays a key role in controlling cellular invasion ... [more ▼]Transcriptional regulation via activator protein-1 (AP-1) protein binding to AP-1 binding sites within gene promoter regions of AP-1 target genes plays a key role in controlling cellular invasion, proliferation, and oncogenesis, and is important to pathogenesis of arthritis and cardiovascular disease. To identify new proteins that interact with the AP-1 DNA binding site, we performed the DNA affinity chromatography-based Nucleotide Affinity Preincubation Specificity TEst of Recognition (NAPSTER) assay, and discovered a 97 kDa protein that binds in vitro to a minimal AP-1 DNA sequence element. Mass spectrometric fragmentation sequencing determined that p97 is nucleolin. Immunoblotting of DNA affinity-purified material with anti-nucleolin antibodies confirmed this identification. Nucleolin also binds the AP-1 site in gel shift assays. Nucleolin interacts in NAPSTER with the AP-1 site within the promoter sequence of the metalloproteinase-13 gene (MMP-13), and binds in vivo in chromatin immunoprecipitation assays in the vicinity of the AP-1 site in the MMP-13 promoter. Overexpression of nucleolin in human HeLa cervical carcinoma cells significantly represses AP-1 dependent gene transactivation of a minimal AP-1 reporter construct and of an MMP-13 promoter reporter sequence. This is the first report of nucleolin binding and transregulation at the AP-1 site. [less ▲]Detailed reference viewed: 55 (1 ULg) The Nucleolonema of Plant and Animal Cells: A ComparisonDeltour, Roger ; Motte, Patrick in Biology of the Cell (1990), 68(1), 5-11Depending on the author and the animal or plant origin of the material under study, the term "nucleolonema" is used in different contexts and thus indicates nucleolar ultrastructures that are different ... [more ▼]Depending on the author and the animal or plant origin of the material under study, the term "nucleolonema" is used in different contexts and thus indicates nucleolar ultrastructures that are different. In this paper, we attempt to clarify this state of affairs and to propose a definition for the plant cell nucleolonema. [less ▲]Detailed reference viewed: 19 (1 ULg) The nucleolus during the cell cycle.Thiry, Marc ; Goessens, Guy Book published by R.G. Landes Company, Chapman and Hall (1996)Detailed reference viewed: 23 (1 ULg) The nucleolus in reptiles: Ultrastructural studiesLamaye, F; Thiry, Marc Poster (2008)Detailed reference viewed: 1 (0 ULg) The nucleolus of the teleost fish Barbus barbus (L.) : an example of nucleolus without fibrillar centerThiry, Marc Poster (2003)Detailed reference viewed: 2 (0 ULg) Nucleolus-associated bodies in meristematic cells of Pisum sativumJennane, A; Thiry, Marc ; Goessens, Gin Cell Biology International (1998), 22Detailed reference viewed: 6 (0 ULg) Nucleolus-associated bodies in meristematic cells of Pisum sativum : ultrastructural and quantitative studiesJennane; Thiry, Marc ; Goessens, GPoster (1998)Detailed reference viewed: 1 (0 ULg) The nucleolus: structure/function relationship in RNA metabolism.Hernandez-Verdun, Daniele; Roussel, Pascal; Thiry, Marc et alin Wiley Interdisciplinary Reviews. RNA (2010), 1(3), 415-31The nucleolus is the ribosome factory of the cells. This is the nuclear domain where ribosomal RNAs are synthesized, processed, and assembled with ribosomal proteins. Here we describe the classical ... [more ▼]The nucleolus is the ribosome factory of the cells. This is the nuclear domain where ribosomal RNAs are synthesized, processed, and assembled with ribosomal proteins. Here we describe the classical tripartite organization of the nucleolus in mammals, reflecting ribosomal gene transcription and pre-ribosomal RNA (pre-rRNA) processing efficiency: fibrillar center, dense fibrillar component, and granular component. We review the nucleolar organization across evolution from the bipartite organization in yeast to the tripartite organization in humans. We discuss the basic principles of nucleolar assembly and nucleolar structure/function relationship in RNA metabolism. The control of nucleolar assembly is presented as well as the role of pre-existing machineries and pre-rRNAs inherited from the previous cell cycle. In addition, nucleoli carry many essential extra ribosomal functions and are closely linked to cellular homeostasis and human health. The last part of this review presents recent advances in nucleolar dysfunctions in human pathology such as cancer and virus infections that modify the nucleolar organization. [less ▲]Detailed reference viewed: 23 (3 ULg) The nucleolus: When 2 became 3.Thiry, Marc ; Lamaye, Françoise ; Lafontaine, Denis L. J.in Nucleus (2011), 2(4), Though the nucleolus is considered today as a multifunctional domain, its primary function is ribosome biogenesis. We have shown at the ultrastructural level that there are primarily two types of ... [more ▼]Though the nucleolus is considered today as a multifunctional domain, its primary function is ribosome biogenesis. We have shown at the ultrastructural level that there are primarily two types of nucleolar organization: nucleoli containing three components in amniotes and two components in all other eukaryotes. In a recent report we made the additional, and surprising, finding that both types of nucleolar arrangement are found among living reptiles, viz. a bicompartmentalized nucleolus in turtles and a tricompartmentalized nucleolus in lizards, crocodiles and snakes. This latter organization occurs regardless of the species, the tissue or the developmental stages analyzed. These results are compatible with the view that the transition between bipartite and tripartite nucleoli coincided with the emergence of the amniotes within the Reptilia. They also support the previous hypothesis that turtles are primitive reptiles. The emergence in amniote vertebrates of a third nucleolar compartment might have imparted novel regulatory functions to the nucleolus, as well as perhaps, expanding the adaptability of ribosome synthesis to an ever changing environment, thus, enhancing the overall fitness of amniotic vertebrates. [less ▲]Detailed reference viewed: 21 (6 ULg) Nucleon nucleon interaction in a chiral constituent quark modelBartz, Daniel ; Stancu, Floarea in Nuclear Physics A (2002), A699(1-2), 316-319We study the nucleon-nucleon interaction within a chiral constituent quark model where the hyperfine interaction is due to pseudoscalar meson exchange. We calculate the S-3(1) and S-1(0) phase shifts by ... [more ▼]We study the nucleon-nucleon interaction within a chiral constituent quark model where the hyperfine interaction is due to pseudoscalar meson exchange. We calculate the S-3(1) and S-1(0) phase shifts by using the resonating group method. Their behaviour clearly indicates the presence of a strong repulsive core at short distance. This is due to the spin-flavour symmetry of the interaction and to the quark interchange between the two interacting nucleons. We add a sigma-meson exchange quark-quark interaction which provides a medium range attraction necessary to describe the S-1(0) phase shift. We also explore the role of a tensor interaction at the quark level. [less ▲]Detailed reference viewed: 19 (5 ULg) Nucleon nucleon interaction in a chiral constituent quark modelStancu, Floarea ; Pepin, S.; Glozman, L Yain Physical Review. C : Nuclear Physics (1997), C56We study the short-range nucleon-nucleon interaction in a chiral constituent quark model by diagonalizing a Hamiltonian comprising a linear confinement and a Goldstone boson exchange interaction between ... [more ▼]We study the short-range nucleon-nucleon interaction in a chiral constituent quark model by diagonalizing a Hamiltonian comprising a linear confinement and a Goldstone boson exchange interaction between quarks. The six-quark harmonic oscillator basis contains up to two excitation quanta. We show that the highly dominant configuration is $\mid s^4p^2[42]_O [51]_{FS}>$ due to its specific flavour-spin symmetry. Using the Born-Oppenheimer approximation we find a strong effective repulsion at zero separation between nucleons in both $^3S_1$ and $^1S_0$ channels. The symmetry structure of the highly dominant configuration implies the existence of a node in the S-wave relative motion wave function at short distances. The amplitude of the oscillation of the wave function at short range will be however strongly suppressed. We discuss the mechanism leading to the effective short-range repulsion within the chiral constituent quark model as compared to that related with the one-gluon exchange interaction. [less ▲]Detailed reference viewed: 43 (3 ULg) Nucleon nucleon scattering in a chiral constituent quark modelBartz, Daniel ; Stancu, Floarea in Physical Review. C : Nuclear Physics (2001), C63We study the nucleon-nucleon interaction in a chiral constituent quark model by using the resonating group method, convenient for treating the interaction between composite particles. The calculated phase ... [more ▼]We study the nucleon-nucleon interaction in a chiral constituent quark model by using the resonating group method, convenient for treating the interaction between composite particles. The calculated phase shifts for the $^3S_1$ and $^1S_0$ channels show the presence of a strong repulsive core due to the combined effect of the quark interchange and the spin-flavour structure of the effective quark-quark interaction. Such a symmetry structure stems from the pseudoscalar meson exchange between the quarks and is a consequence of the spontaneous breaking of the chiral symmetry. We perform single and coupled channel calculations and show the role of coupling of the $\Delta\Delta$ and hidden color $CC$ channels on the behaviour of the phase shifts. [less ▲]Detailed reference viewed: 6 (3 ULg) The Nucleon-Nucleon Problem in Quark ModelsStancu, Floarea in Few-Body Systems (2003), 14In the first part we summarize the status of the nucleon-nucleon (NN) problem in the context of Hamiltonian based constituent quark models and present results for the $\ell = 0$ phase shifts obtained from ... [more ▼]In the first part we summarize the status of the nucleon-nucleon (NN) problem in the context of Hamiltonian based constituent quark models and present results for the $\ell = 0$ phase shifts obtained from the Goldstone-boson exchange model by applying the resonating group method. The second part deals with the construction of local shallow and deep equivalent potentials based on a Superymmetric Quantum Mechanics approach. [less ▲]Detailed reference viewed: 17 (2 ULg) Nucleon-Nucleus Potential at Low and Intermediate Energy in a Dirac-Hartree ModelJaminon, Martine ; Mahaux, Claude ; Rochus, Pierre in Physical Review Letters (1979), 43We calculate the average nucleon-nucleus potential from the Dirac-Hartree model, extended to positive energy. The sole input is a one-boson-exchange nucleon-nucleon interaction which reproduces ground ... [more ▼]We calculate the average nucleon-nucleus potential from the Dirac-Hartree model, extended to positive energy. The sole input is a one-boson-exchange nucleon-nucleon interaction which reproduces ground-state properties. We obtain fair agreement with empirical values. Between 170 and 400 MeV, the calculated potential is repulsive in the nuclear interior but still attractive at the surface. This shape is related to the scalar and vector nature of the exchanged bosons. [less ▲]Detailed reference viewed: 29 (8 ULg)