Commissariat à l'énergie atomique et aux énergies alternatives

About: Commissariat à l'énergie atomique et aux énergies alternatives is a based out in . It is known for research contribution in the topics: Layer (electronics) & Signal. The organization has 9958 authors who have published 9212 publications receiving 132235 citations.

Role of cyclic and pseudo-cyclic electron transport in response to dynamic light changes in Physcomitrella patens.

Abstract: Photosynthetic organisms support cell metabolism by harvesting sunlight and driving the electron transport chain at the level of thylakoid membranes. Excitation energy and electron flow in the photosynthetic apparatus is continuously modulated in response to dynamic environmental conditions. Alternative electron flow around photosystem I plays a seminal role in this regulation contributing to photoprotection by mitigating overreduction of the electron carriers. Different pathways of alternative electron flow coexist in the moss Physcomitrella patens, including cyclic electron flow mediated by the PGRL1/PGR5 complex and pseudo-cyclic electron flow mediated by the flavodiiron proteins FLV. In this work, we generated P. patens plants carrying both pgrl1 and flva knock-out mutations. A comparative analysis of the WT, pgrl1, flva, and pgrl1 flva lines suggests that cyclic and pseudo-cyclic processes have a synergic role in the regulation of photosynthetic electron transport. However, although both contribute to photosystem I protection from overreduction by modulating electron flow following changes in environmental conditions, FLV activity is particularly relevant in the first seconds after a light change whereas PGRL1 has a major role upon sustained strong illumination.

New in vivo avatars of diffuse intrinsic pontine gliomas (DIPG) from stereotactic biopsies performed at diagnosis.

Abstract: // Alexandre Plessier 1, * , Ludivine Le Dret 1, * , Pascale Varlet 2 , Kevin Beccaria 3 , Joelle Lacombe 2 , Sebastien Meriaux 4 , Francoise Geffroy 4 , Laurence Fiette 5 , Patricia Flamant 5 , Fabrice Chretien 2, 5 , Thomas Blauwblomme 3 , Stephanie Puget 3 , Jacques Grill 1, 6 , Marie-Anne Debily 1, 7, ** and David Castel 1, 6, ** 1 UMR8203 “Vectorologie & Therapeutiques Anticancereuses”, CNRS, Gustave Roussy, Universite Paris-Sud, Universite Paris-Saclay, Villejuif, France 2 Department of Neuropathology, Hopital Sainte-Anne, Universite Paris V Descartes, Sorbonne Paris Cite, Paris, France 3 Department of Pediatric Neurosurgery, Hopital Necker-Enfants Malades, Universite Paris V Descartes, Sorbonne Paris Cite, Paris, France 4 UNIRS, Neurospin, I2BM, Direction de la Recherche Fondamentale, Commissariat a l’Energie Atomique et aux Energies Alternatives, Gif-sur-Yvette, France 5 Institut Pasteur, Histopathology and Animal Models, Universite Paris V Descartes, Sorbonne Paris Cite, Paris, France 6 Departement de Cancerologie de l’Enfant et de l’Adolescent, Gustave Roussy, Universite Paris-Sud, Universite Paris-Saclay, Villejuif, France 7 Universite d’Evry-Val d’Essonne, Evry, France * These two co-authors contributed equally to the work ** Co-senior authors Correspondence to: David Castel, email: david.castel@gustaveroussy.fr Marie-Anne Debily, email: marie-anne.debily@gustaveroussy.fr Keywords: brain tumor model, child, tumor-initiating cell, infiltrative midline glioma with histone H3-K27M mutation, bioluminescence Received: August 04, 2016 Accepted: January 10, 2017 Published: February 02, 2017 ABSTRACT Diffuse Instrinsic Pontine Glioma is the most aggressive form of High Grade Gliomas in children. The lack of biological material and the absence of relevant models have hampered the development of new therapeutics. Their extensive infiltration of the brainstem renders any surgical resection impossible and until recently biopsies were considered not informative enough and therefore not recommended. Thus, most models were derived from autopsy material. We aimed to develop relevant in vivo DIPG models that mimic this specific disease and its molecular diversity from tumor material obtained at diagnosis. Eight patient-derived orthotopic xenograft models were obtained after direct stereotactic injection of a mixed cell suspension containing tumor cells and stromal cells in the brainstem or thalamus of nude mice and serially passaged thereafter. In parallel, we developed 6 cell-derived xenograft models after orthotopic injection of tumor-initiating cells cultured from stereotactic biopsies. Cells were modified to express luciferase to enable longitudinal tumor growth monitoring, and fluorescent reporter proteins to trace the tumor cells in the brain. These models do not form a tumor mass, they are invasive, show the H3K27 trimethylation loss in vivo and the tumor type diversity observed in patients in terms of histone H3 mutations and lineage markers. Histological and MRI features at 11.7 Tesla show similarities with treatment naive human DIPG, and in this respect, both direct and indirect orthotopic xenograft looked alike. These DIPG models will therefore constitute valuable tools for evaluating new therapeutic approaches in this devastating disease.

Spectral dependency of superconducting single photon detectors

Abstract: We investigate the effect of varying both incoming optical wavelength and width of NbN nanowires on the superconducting single photon detectors (SSPD) detection efficiency The SSPD are current biased close to critical value and temperature fixed at 42 K, far from transition The experimental results are found to verify with a good accuracy predictions based on the “hot spot model,” whose size scales with the absorbed photon energy With larger optical power inducing multiphoton detection regime, the same scaling law remains valid, up to the three-photon regime We demonstrate the validity of applying a limited number of measurements and using such a simple model to reasonably predict any SSPD behavior among a collection of nanowire device widths at different photon wavelengths These results set the basis for designing efficient single photon detectors operating in the infrared (2–5 μm range)

Enhanced triacylglycerol production in the diatom Phaeodactylum tricornutum by inactivation of a Hotdog-fold thioesterase gene using TALEN-based targeted mutagenesis

Abstract: In photosynthetic oleaginous microalgae, acyl-CoA molecules are used as substrates for the biosynthesis of membrane glycerolipids, triacylglycerol (TAG) and other acylated molecules. Acyl-CoA can also be directed to beta-oxidative catabolism. They can be utilized by a number of lipid metabolic enzymes including endogenous thioesterases, which catalyze their hydrolysis to release free fatty acids. Acyl-CoA availability thus plays fundamental roles in determining the quantity and composition of membrane lipids and storage lipids. Here, we have engineered the model diatom Phaeodactylum tricornutum to produce significantly increased TAGs by disruption of the gene encoding a Hotdog-fold thioesterase involved in acyl-CoA hydrolysis (ptTES1). This plastidial thioesterase can hydrolyze both medium- and long-chain fatty acyl-CoAs, but has the highest activity toward long-chain saturated and monounsaturated fatty acyl-CoAs. The maximum rate was found with oleoyl-CoA, which is hydrolyzed at 50 nmol/min/mg protein. The stable and targeted interruption of acyl-CoA thioesterase gene was achieved using a genome editing technique, transcription activator-like effector nucleases (TALENs). Disruption of native ptTES1 gene resulted in a 1.7-fold increase in TAG content when algal strains were grown in nitrogen-replete media for 8 days, whereas the content of other lipid classes, including phosphoglycerolipids and galactoglycerolipids, remained almost unchanged. The engineered algal strain also exhibited a marked change in fatty acid profile, including a remarkable increase in 16:0 and 16:1 and a decrease in 20:5. Nitrogen deprivation for 72 h further increased TAG content and titer of the engineered strain, reaching 478 μg/109 cells and 4.8 mg/L, respectively. Quantitative determination of in vivo acyl-CoAs showed that the total acyl-CoA pool size was significantly higher in the engineered algal strain than that in the wild type. This study supports the role of ptTES1 in free fatty acid homeostasis in the plastid of Phaeodactylum and demonstrates the potential of TALEN-based genome editing technique to generate an enhanced lipid-producing algal strain through blocking acyl-CoA catabolism.

Measurement of jet shapes in top-quark pair events at √s = 7 TeV using the ATLAS detector

Abstract: A measurement of jet shapes in top-quark pair events using 1.8 fb(-1) of pp collision data recorded by the ATLAS detector at the LHC is presented. Samples of top-quark pair events are selected in b ...