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(110) Production(s) de LORMAN V.
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Regular Cell Pattern Organization and Optimized Cell Death Process in Non-proliferative Epithelium
Auteur(s): Azzag K., Martinand-Mari Camille, Maury Benoit, Rousset François, Sahuquet Alain, Rochal S.B., Mennessier G., Mangeat Paul, Baghdiguian Stephen, Lorman V.
Conference: PhysCell2009 (Primosten, HR, 2009-09-06)
Actes de conférence: Proceedings of PhysCell2009, Physics of Cells: From the Edge to the Heart, vol. p.p.143 (2009)
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Tubular Liquid Membrane Instabilities and Protein Coupling Mediated by Critical Modes
Auteur(s): Monnier Sylvain, Rochal S.B., Lorman V., Parmeggiani A.
Conference: PhysCell2009 (Primosten, HR, 2009-09-06)
Actes de conférence: Proceedings of PhysCell2009, Physics of Cells: From the Edge to the Heart, vol. p.p.54 (2009)
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Topological control of life and death in non-proliferative epithelia.
Auteur(s): Martinand-Mari Camille, Maury Benoit, Rousset François, Sahuquet Alain, Mennessier G., Rochal Sergei, Lorman V., Mangeat Paul, Baghdiguian Stephen
(Article) Publié:
Plos One, vol. 4 p.e4202 (2009)
Texte intégral en Openaccess :
Ref HAL: hal-00367911_v1
PMID 19145253
DOI: 10.1371/journal.pone.0004202
WoS: 000265479800008PubMed Central: 2625397
Exporter : BibTex | endNote
14 Citations
Résumé: Programmed cell death is one of the most fascinating demonstrations of the plasticity of biological systems. It is classically described to act upstream of and govern major developmental patterning processes (e.g. inter-digitations in vertebrates, ommatidia in Drosophila). We show here the first evidence that massive apoptosis can also be controlled and coordinated by a pre-established pattern of a specific 'master cell' population. This new concept is supported by the development and validation of an original model of cell patterning. Ciona intestinalis eggs are surrounded by a three-layered follicular organization composed of 60 elongated floating extensions made of as many outer and inner cells, and indirectly spread through an extracellular matrix over 1200 test cells. Experimental and selective ablation of outer and inner cells results in the abrogation of apoptosis in respective remaining neighbouring test cells. In addition incubation of outer/inner follicular cell-depleted eggs with a soluble extract of apoptotic outer/inner cells partially restores apoptosis to apoptotic-defective test cells. The 60 inner follicular cells were thus identified as 'apoptotic master' cells which collectively are induction sites for programmed cell death of the underlying test cells. The position of apoptotic master cells is controlled by topological constraints exhibiting a tetrahedral symmetry, and each cell spreads over and can control the destiny of 20 smaller test cells, which leads to optimized apoptosis signalling.
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Physics Approach to Protein Arrangements in Icosahedral Viral Capsids: beyond the Caspar and Klug Model
Auteur(s): Lorman V., Rochal S.B.
Conference: Protein Folds in Infectious and Neurodegenerative Diseases (Aussois, FR, 2009-04-25)
Actes de conférence: Jacques-Monod Conference "Protein Folds in Infectious and Neurodegenerative Diseases, vol. p.p.61 (2009)
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Theory of a Reconstructive Structural Transformation in Capsides of Icosahedral Viruses
Auteur(s): Rochal S.B., Lorman V.
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 80 p.051905 (2009)
Ref HAL: hal-00590703_v1
PMID 20365004
DOI: 10.1103/PhysRevE.80.051905
WoS: 000272309500070
Exporter : BibTex | endNote
2 Citations
Résumé: A theory of a reconstructive structural transformation in icosahedral capsid shells is developed for a whole family of virulent human viruses. It is shown that the reversible rearrangement of proteins during the virus maturation transformation is driven by the variation in the wave number l associated with the protein density distribution function. The collective displacement field of protein centers from their positions in the initial (procapsid) and the final (capsid) two-dimensional icosahderal structures is derived. The amplitude of the displacement field is shown to be small and it minimizes the calculated free energy of the transformation. The theory allows us to propose a continuous thermodynamical mechanism of the reconstructive procapsid-to-capsid transformation. In the frame of the density-wave approach, we also propose to take an equivalent plane-wave vector as a common structural feature for different icosahedral capsid shells formed by the same proteins. Using these characteristics, we explain the relation between the radii of the procapsid and capsid shells and generalize it to the case of the viral capsid polymorphism.
Commentaires: 6 pages
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Dual symmetry in bent-core liquid crystals and unconventional superconductors
Auteur(s): Mettout B., Lorman V.
(Article) Publié:
Symmetry, vol. 2 p.15-39 (2010)
Texte intégral en Openaccess :
Ref HAL: hal-00553794_v1
DOI: 10.3390/sym2010015
WoS: 000208831600002
Exporter : BibTex | endNote
1 Citation
Résumé: We extend the Landau theory of bent-core mesophases and d-wave high-Tc superconductors by considering additional secondary pseudo-proper order parameters. These systems exhibit a remarkable analogy relating their symmetry groups, list of phases and an infinite set of physical tensors. This analogy lies upon an internal dual structure shared by the two theories. We study the dual operator transforming rotations into translations in liquid crystals, and gauge symmetries into rottions in superconductors. It is used to classify the bent-core line defects, and to analyze the electronic gap structure of lamellar d-wave superfluids.
Commentaires: 25 pages
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Landau theory of crystallization and the capsid structures of small icosahedral viruses
Auteur(s): Lorman V., Rochal S.B.
(Article) Publié:
Physical Review B, vol. 77 p.224109 (2008)
Ref HAL: hal-00378231_v1
DOI: 10.1103/PhysRevB.77.224109
WoS: 000257289300028
Exporter : BibTex | endNote
25 Citations
Résumé: A new approach to the capsid structures of small viruses with spherical topology and icosahedral symmetry is proposed. It generalizes Landau theory of crystallization to describe icosahedral viral shells self-assembled from identical asymmetric proteins. An explicit method which predicts the positions of centers of mass for the proteins constituting the shell is discussed in detail. The method is based on irreducible density distribution function which generates the protein positions. The universal form of the density distribution function which contains no fitting parameter permits to classify the capsids structures of small viruses. The theory describes in a uniform way both the structures satisfying the well-known Caspar and Klug geometrical model for capsid construction and those violating it. A group theory analysis of the Caspar and Klug model and of the “quasiequivalence” principle for protein environments in viral capsids is given. The molecular basis of difference in protein environments and peculiarities in the assembly thermodynamics are also discussed.
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