27 research outputs found
Applying Hierarchical Clustering to Broad Absorption Line ProïŹles for Quasar ClassiïŹcation
The region immediately surrounding an actively accreting supermassive black hole at the centre of a massive galaxy, the accretion disk, produces an enormous amount of radiation resulting in a luminous, short-lived phenomenon called a quasar. About 20% of quasars show broad, blue-shifted absorption features in their UV spectra, indicative of an outïŹowing wind from the accretion disk. These winds can remove angular momentum from the accretion disk, thereby contributing to the growth of the central black hole. Understanding these winds will help us to better constrain the details of how black holes grow during the quasar phase. The structures of the absorption features are sensitive to the properties (ionization state, velocity proïŹle, and thickness) of the winds. Consequently, the broad absorption line proïŹles of these objects show great diversity in depth and velocity width. Using a sample of 1,084 broad absorption line quasar spectra from the Sloan Digital Sky Survey, we apply an agglomerative hierarchical clustering algorithm to group spectra by similar C IV absorption line shapes. For each cluster, we compose median spectra and compare the shapes of the C IV broad absorption lines with the properties of prominent, broad emission lines. In agreement with results in the literature, low-velocity, deep troughs are found preferentially in objects for which the radiation from the accretion disk is more energetic. The link between broad absorption line properties and those of emission lines holds promise for allowing us to constrain the structure and dynamics of the outïŹowing winds
Inhibition of Neuroepithelial Patched-Induced Apoptosis by Sonic Hedgehog
International audienc
Dependence receptors: mechanisms of an announced death.
Present adress Chantal Thibert : Université Joseph Fourrier, Grenoble F-38042, France, INSERM U836, Grenoble Institut des Neurosciences, Team 2 Neurodegenerescence and PlasticityInternational audienceDependence receptors form a family of functionally related receptors which are all able to induce two completely opposite intracellular signals depending on the availability of their ligand. Indeed, in its presence, they mediate a positive, classical signal transduction of survival, differentiation or migration but without it, they trigger a negative signal which leads to cell death. The molecular mechanisms involved in triggering cell death in the absence of ligand are starting to be unravelled: dependence receptors are recruited at well-defined domains at the plasma membrane, they trigger cell death through a monomeric form, they are cleaved by caspases and they recruit a caspase activating complex
Mise au point de la transgenĂšse chez le ver Ă soie Bombyx mori L et perspectives d'applications
La transgenĂšse est une mĂ©thode puissante pour Ă©tudier la fonction de gĂšnes ou pour confĂ©rer des traits gĂ©nĂ©tiques utiles Ă des organismes. Au cours de ma thĂšse, j'ai testĂ© l'aptitude du transposon piggyBac (dĂ©couvert chez le lĂ©pidoptĂšre Trichoplusia ni) Ă intĂ©grer des gĂšnes dans les chromosomes de cellules d'insectes en culture. J'ai ensuite appliquĂ© ce systĂšme Ă l'intĂ©gration stable et transmissible Ă la descendance d'un gĂšne d'intĂ©rĂȘt dans le gĂ©nome du ver Ă soie Bombyx mori L. Ce systĂšme utilise deux vecteurs; l'un vĂ©hicule un gĂšne d'intĂ©rĂȘt (le gĂšne rapporteur gfp sous le contrĂŽle du promoteur du gĂšne de l'actine cytoplasmique BmA3) placĂ© entre les extrĂ©mitĂ©s inversĂ©es rĂ©pĂ©tĂ©es de l'Ă©lĂ©ments piggyBac ; l'autre est un vecteur assistant non-autonome qui code la transposase de piggyBac sous le contrĂŽle du mĂȘme promoteur. La co-injection des deux vecteurs dans l'Ćuf au stade prĂ©blastodermique aboutit Ă la transformation de gamĂštes chez environ 2% des individus injectĂ©s. L'analyse de l'ADN gĂ©nomique des larves transgĂ©niques a rĂ©vĂ©lĂ© que l'expression de la fluorescence rĂ©sultait d'insertions souvent multiples du transgĂšne ; celui-ci est par ailleurs hĂ©ritĂ© de façon mendĂ©lienne au cours des gĂ©nĂ©rations. J'ai donc pu montrer que ce systĂšme est efficace pour la transformation germinale du ver Ă soie. J'ai donc pu montrer que ce systĂšme est efficace pour la transformation germinale du ver Ă soie. J'ai entrepris d'exploiter la transgenĂšse pour inhiber par interfĂ©rence d'ARN l'expression de gĂšnes fortement exprimĂ©s dans la glande sĂ©ricigĂšne. L'application au gĂšne codant la Fibroine, la protĂ©ine majoritaire de la soie, si elle est rĂ©alisable, permettrait de substituer cette protĂ©ine par des protĂ©ines d'intĂ©rĂȘt textile et pharmaceutique.LYON1-BU.Sciences (692662101) / SudocSudocFranceF
Quantitation of Platelet Glycoprotein IV (CD36) in Healthy Subjects and in Patients with Essential Thrombocythemia Using an Immunocapture Assay
Functions of LKB1 in neural crest development: The story unfolds
International audienceNeural crest cells (NCCs) are highly motile, multipotent, embryonic cells that delaminate from the dorsal edges of the neural tube. NCCs follow stereotypical long-range migratory pathways to reach target organs during development, where they give rise to multiple derivatives. The identification of reservoirs of neural crest stem cells that persist to adulthood has recently aroused renewed interest in the biology of NCCs. In this context, several recent studies have demonstrated the essential role of the metabolic kinase LKB1 in NCC establishment. This review surveys how LKB1 governs the formation and maintenance of several neural crest derivatives, including facial bones, melanocytes, Schwann cells, and the enteric nervous system. We also detail the underlying molecular mechanisms that involve downstream effectors of LKB1, in particular the contribution of the AMPK-mTOR signaling pathway to both polarity and metabolic processes. Collectively, these recent discoveries open promising perspectives for new therapeutic applications for the treatment of neural crest disorders
MĂȘme lâeffet Warburg est oxydable
Au cours du dĂ©veloppement tumoral, les cellules malignes reprogramment leur mĂ©tabolisme pour rĂ©pondre Ă la demande en biosynthĂšses conditionnant lâaugmentation de leur biomasse et pour sâadapter aux propriĂ©tĂ©s de leur microenvironnement. Les avancĂ©es rĂ©centes de la recherche ont rĂ©vĂ©lĂ© lâĂ©tonnante flexibilitĂ© des cellules cancĂ©reuses qui alternent entre un mĂ©tabolisme glycolytique aĂ©robie (appelĂ© effet Warburg) et un mĂ©tabolisme oxydatif en fonction de leurs conditions de dĂ©veloppement, une plasticitĂ© mĂ©tabolique requĂ©rant une mutualisation de leurs ressources Ă©nergĂ©tiques. Dans cette revue, nous prĂ©sentons ces nouvelles dĂ©couvertes et discutons dâun modĂšle dĂ©crivant la tumeur comme un Ă©cosystĂšme mĂ©tabolique Ă©volutif tout en insistant sur les applications thĂ©rapeutiques qui en dĂ©coulent