256 results match your criteria: "CNRS-Universite de Bordeaux[Affiliation]"

Hemispheric asymmetry is a cardinal feature of human brain organization. Altered brain asymmetry has also been linked to some cognitive and neuropsychiatric disorders. Here, the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium presents the largest-ever analysis of cerebral cortical asymmetry and its variability across individuals.

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The Middle to Later Stone Age transition in Africa has been debated as a significant shift in human technological, cultural, and cognitive evolution. However, the majority of research on this transition is currently focused on southern Africa due to a lack of long-term, stratified sites across much of the African continent. Here, we report a 78,000-year-long archeological record from Panga ya Saidi, a cave in the humid coastal forest of Kenya.

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Chirality-controlled crystallization via screw dislocations.

Nat Commun

April 2018

Centre de Recherche Paul-Pascal, CNRS & Université de Bordeaux, 115 Avenue Schweitzer, 33600, Pessac, France.

Chirality plays an important role in science from enantiomeric separation in chemistry to chiral plasmonics in nanotechnology. However, the understanding of chirality amplification from chiral building blocks to ordered helical superstructures remains a challenge. Here, we demonstrate that topological defects, such as screw dislocations, can drive the chirality transfer from particle to supramolecular structure level during the crystallization process.

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Harmful Algal Blooms are worldwide occurrences that can cause poisoning in human seafood consumers as well as mortality and sublethal effets in wildlife, propagating economic losses. One of the most widespread toxigenic microalgal taxa is the dinoflagellate Genus Alexandrium, that includes species producing neurotoxins referred to as PST (Paralytic Shellfish Toxins). Blooms cause shellfish harvest restrictions to protect human consumers from accumulated toxins.

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The vertebrate hedgehog pathway is organized in primary cilia, and hedgehog components relocate into or out of cilia during signaling. Defects in intraflagellar transport (IFT) typically disrupt ciliary assembly and attenuate hedgehog signaling. Determining whether IFT drives the movement of hedgehog components is difficult due to the requirement of IFT for building cilia.

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Wax synthases are involved in the biosynthesis of wax esters, lipids with great industrial potential. Here, we heterologously expressed the native wax synthase MhWS2 from Marinobacter hydrocarbonoclasticus in Saccharomyces cerevisiae and performed comprehensive analysis of its substrate specificity. The enzyme displayed high wax synthase (but no diacylglycerol acyltransferase) activity both in vivo and in vitro.

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Renner-Teller effects in the photoelectron spectra of CNC, CCN, and HCCN.

J Chem Phys

February 2018

Institut des Sciences Moléculaires, UMR 5255 CNRS-Université de Bordeaux, Bât. A12, 351 Cours de la Libération, F-33405 Talence Cedex, France.

Article Synopsis
  • The study derives the line intensity of photoelectron spectra for molecular species displaying Renner-Teller coupling, focusing on CNC, CCN, and HCCN.
  • It investigates the rovibronic energy levels of these radicals and their cations using advanced computational methods.
  • A new model is developed to address the bending mode and rotation, which is then applied to simulate and compare the calculated photoelectron spectra with experimental data.
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Reticulons are integral ER membrane proteins characterised by a reticulon homology domain comprising four transmembrane domains which results in the proteins sitting in the membrane in a W-topology. Here we report on a novel subgroup of reticulons with an extended N-terminal domain and in particular on arabidopsis reticulon 20. Using high resolution confocal microscopy we show that reticulon 20 is located in a unique punctate pattern on the ER membrane.

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The earliest modern humans outside Africa.

Science

January 2018

Zinman Institute of Archaeology, University of Haifa, Haifa, Mount Carmel 3498838, Israel.

To date, the earliest modern human fossils found outside of Africa are dated to around 90,000 to 120,000 years ago at the Levantine sites of Skhul and Qafzeh. A maxilla and associated dentition recently discovered at Misliya Cave, Israel, was dated to 177,000 to 194,000 years ago, suggesting that members of the clade left Africa earlier than previously thought. This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of around 220,000 years ago.

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Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cel-lular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing.

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Necrosis and ethylene-inducing peptide 1-like (NLP) proteins constitute a superfamily of proteins produced by plant pathogenic bacteria, fungi, and oomycetes. Many NLPs are cytotoxins that facilitate microbial infection of eudicot, but not of monocot plants. Here, we report glycosylinositol phosphorylceramide (GIPC) sphingolipids as NLP toxin receptors.

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Shear thinning in non-Brownian suspensions.

Soft Matter

February 2018

ESPCI Paris, PSL Research University, Sciences et Ingénierie de la Matière Molle, CNRS UMR 7615, 10 rue Vauquelin, F-75231 Paris Cedex 05, France. and Université de Bordeaux, Centre de Recherche Paul Pascal, UPR-8641 CNRS, 115 avenue Schweitzer, 33600 Pessac, France.

We study the flow of suspensions of non-Brownian particles dispersed into a Newtonian solvent. Combining capillary rheometry and conventional rheometry, we evidence a succession of two shear thinning regimes separated by a shear thickening one. Through X-ray radiography measurements, we show that during each of those regimes, the flow remains homogeneous and does not involve particle migration.

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Atopic dermatitis (AD) is a chronic and multifactorial inflammatory skin disease involving various dendritic cells such as epidermal Langerhans cells (LC) and inflammatory dendritic epidermal cells (IDECs). Most of the clinical studies was performed on isolated cells, and thus, it would be useful to characterize directly on the human epidermal tissue the first cellular events occurred during the AD. The suction blister method was used to obtain whole epidermis samples and interstitial cutaneous fluids.

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Quantitative approaches for characterizing molecular organization of cell membrane molecules under physiological and pathological conditions profit from recently developed super-resolution imaging techniques. Current tools employ statistical algorithms to determine clusters of molecules based on single-molecule localization microscopy (SMLM) data. These approaches are limited by the ability of SMLM techniques to identify and localize molecules in densely populated areas and experimental conditions of sample preparation and image acquisition.

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Increased rise time of electron temperature during adiabatic plasmon focusing.

Nat Commun

November 2017

Laboratoire Photonique, Numérique et Nanosciences (LP2N), UMR 5298, CNRS-IOGS-Université de Bordeaux, Institut d'Optique d'Aquitaine, 33400, Talence, France.

Decay of plasmons to hot carriers has recently attracted considerable interest for fundamental studies and applications in quantum plasmonics. Although plasmon-assisted hot carriers in metals have already enabled remarkable physical and chemical phenomena, much remains to be understood to engineer devices. Here, we present an analysis of the spatio-temporal dynamics of hot electrons in an emblematic plasmonic device, the adiabatic nanofocusing surface-plasmon taper.

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Unveiling the Ionization Energy of the CN Radical.

J Phys Chem Lett

September 2017

Institut des Sciences Moléculaires, UMR 5255 CNRS-Université de Bordeaux, Bât. A12, 351 cours de la Libération, F-33405 Talence Cedex, France.

The cyano radical is a ubiquitous molecule and was, for instance, one of the first species detected in astrophysical media such as comets or diffuse clouds. In photodissociation regions, the reaction rate of CN + CO → CN + CO is one of the critical parameters defining nitrile chemistry. The enthalpy of this charge transfer reaction is defined as the difference of ionization energies (E) between CN and CO.

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A High-Throughput Time-Domain ThermoReflectance (HT-TDTR) technique was developed to perform fast thermal conductivity measurements with minimum user actions required. This new setup is based on a heterodyne picosecond thermoreflectance system. The use of two different laser oscillators has been proven to reduce the acquisition time by two orders of magnitude and avoid the experimental artefacts usually induced by moving the elements present in TDTR systems.

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Valence shell threshold photoelectron spectroscopy of the CHCN (x = 0-2) and CNC radicals.

J Chem Phys

July 2017

Institut des Sciences Moléculaires, UMR 5255 CNRS-Université de Bordeaux, Bât. A12, 351 Cours de la Libération, F-33405 Talence Cedex, France.

We present the photoelectron spectroscopy of four radical species, CHCN (x = 0-2) and CNC, formed in a microwave discharge flow-tube reactor by consecutive H abstractions from CHCN (CHCN + F → CHCN + HF (x = 1-3)). The spectra were obtained combining tunable vacuum ultraviolet synchrotron radiation with double imaging electron/ion coincidence techniques, which yielded mass-selected threshold photoelectron spectra. The results obtained for HCCN complement existing ones while for the other radicals the data represent the first observation of their (single-photon) ionizing transitions.

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Occurrence and Biosynthesis of Alkyl Hydroxycinnamates in Plant Lipid Barriers.

Plants (Basel)

June 2017

Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA.

The plant lipid barriers cuticle and suberin represent one of the largest biological interfaces on the planet. They are comprised of an insoluble polymeric domain with associated organic solvent-soluble waxes. Suberin-associated and plant cuticular waxes contain mixtures of aliphatic components that may include alkyl hydroxycinnamates (AHCs).

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Root Aliphatic Suberin Analysis Using Non-extraction or Solvent-extraction Methods.

Bio Protoc

June 2017

Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS - Université de Bordeaux, INRA Bordeaux Aquitaine, Villenave d'Ornon, France.

Here we describe both non-extraction and solvent-extraction methods for root aliphatic suberin analysis. The non-extraction method is fast as roots are directly depolymerized using acidic transmethylation. However, suberin aliphatic components are isolated together with all the other acyl chains making up the lipids (, membranes) present in roots.

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Fast Diffusion of Long Guest Rods in a Lamellar Phase of Short Host Particles.

Phys Rev Lett

April 2017

Centre de Recherche Paul-Pascal, CNRS & Université de Bordeaux, 115 Avenue Schweitzer, F-33600 Pessac, France.

We investigate the dynamic behavior of long guest rodlike particles immersed in liquid crystalline phases formed by shorter host rods, tracking both guest and host particles by fluorescence microscopy. Counterintuitively, we evidence that long rods diffuse faster than short rods forming the one-dimensional ordered smectic-A phase. This results from the larger and noncommensurate size of the guest particles as compared to the wavelength of the energy landscape set by the lamellar stack of liquid slabs.

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Cohesin mediates sister chromatid cohesion which is essential for chromosome segregation and repair. Sister chromatid cohesion requires an acetyl-transferase (Eso1 in fission yeast) counteracting Wpl1, promoting cohesin release from DNA We report here that Wpl1 anti-cohesion function includes an additional mechanism. A genetic screen uncovered that Protein Phosphatase 4 (PP4) mutants allowed cell survival in the complete absence of Eso1.

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Diversity of Amyloid Motifs in NLR Signaling in Fungi.

Biomolecules

April 2017

Non-Self Recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095 CNRS Université de Bordeaux, 1 rue Camille Saint Saëns, 33077 Bordeaux CEDEX, France.

Amyloid folds not only represent the underlying cause of a large class of human diseases but also display a variety of functional roles both in prokaryote and eukaryote organisms. Among these roles is a recently-described activity in signal transduction cascades functioning in host defense and programmed cell death and involving Nod-like receptors (NLRs). In different fungal species, prion amyloid folds convey activation signals from a receptor protein to an effector domain by an amyloid templating and propagation mechanism.

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Bax mitochondrial relocation is linked to its phosphorylation and its interaction with Bcl-xL.

Microb Cell

December 2016

Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS & Université de Bordeaux, CS61390, 146 Rue Léo Saignat, 33077 Bordeaux, France.

The heterologous expression of Bax, and other Bcl-2 family members, in the yeast , has proved to be a valuable reporter system to investigate the molecular mechanisms underlying their interaction with mitochondria. By combining the co-expression of Bax and Bcl-xL mutants with analyzes of their localization and interaction in mitochondria and post-mitochondrial supernatants, we showed that the ability of Bax and Bcl-xL to interact is dependent both on Bax phosphorylation - mimicked by a substitution S184D - and by Bax and Bcl-xL localization. This, and previous data, provide the molecular basis for a model of dynamic equilibrium for Bax localization and activation, regulated both by phosphorylation and Bcl-xL.

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VDAC regulates AAC-mediated apoptosis and cytochrome release in yeast.

Microb Cell

August 2016

Centro de Biologia Molecular e Ambiental (CBMA), Departamento de Biologia, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.

Mitochondrial outer membrane permeabilization is a key event in apoptosis processes leading to the release of lethal factors. We have previously shown that absence of the ADP/ATP carrier (AAC) proteins (yeast orthologues of mammalian ANT proteins) increased the resistance of yeast cells to acetic acid, preventing MOMP and the release of cytochrome from mitochondria during acetic acid - induced apoptosis. On the other hand, deletion of (yeast voltage-dependent anion channel - VDAC) increased the sensitivity of yeast cells to acetic acid.

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