University of Bordeaux

About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.

Hardwiring the brain: endocannabinoids shape neuronal connectivity.

Abstract: The roles of endocannabinoid signaling during central nervous system development are unknown. We report that CB(1) cannabinoid receptors (CB(1)Rs) are enriched in the axonal growth cones of gamma-aminobutyric acid-containing (GABAergic) interneurons in the rodent cortex during late gestation. Endocannabinoids trigger CB(1)R internalization and elimination from filopodia and induce chemorepulsion and collapse of axonal growth cones of these GABAergic interneurons by activating RhoA. Similarly, endocannabinoids diminish the galvanotropism of Xenopus laevis spinal neurons. These findings, together with the impaired target selection of cortical GABAergic interneurons lacking CB(1)Rs, identify endocannabinoids as axon guidance cues and demonstrate that endocannabinoid signaling regulates synaptogenesis and target selection in vivo.

Super-resolution imaging reveals that AMPA receptors inside synapses are dynamically organized in nanodomains regulated by PSD95.

Abstract: The spatiotemporal organization of neurotransmitter receptors in postsynaptic membranes is a fundamental determinant of synaptic transmission and information processing by the brain. Using four independent super-resolution light imaging methods and EM of genetically tagged and endogenous receptors, we show that, in rat hippocampal neurons, AMPARs are often highly concentrated inside synapses into a few clusters of ∼70 nm that contain ∼20 receptors. AMPARs are stabilized reversibly in these nanodomains and diffuse freely outside them. Nanodomains are dynamic in their shape and position within synapses and can form or disappear within minutes, although they are mostly stable for up to 1 h. AMPAR nanodomains are often, but not systematically, colocalized with clusters of the scaffold protein PSD95, which are generally of larger size than AMPAR nanoclusters. PSD95 expression level regulates AMPAR nanodomain size and compactness in parallel to miniature EPSC amplitude. Monte Carlo simulations further indicate the impact of AMPAR concentration in clusters on the efficacy of synaptic transmission. The observation that AMPARs are highly concentrated in nanodomains, instead of diffusively distributed in the PSD as generally thought, has important consequences on our understanding of excitatory neurotransmission. Furthermore, our results indicate that glutamatergic synaptic transmission is controlled by the nanometer-scale regulation of the size of these highly concentrated nanodomains.

Dinuclear Dysprosium(III) Single-Molecule Magnets with a Large Anisotropic Barrier†

Abstract: Due to the large intrinsic magnetic anisotropy of the lanthanide ions, rare-earth metal systems, and in particular dysprosium (Dy) based materials, have sparked increasing interest in the area of molecular magnetism. In a molecular complex, when such a unique property is combined with a high-spin ground state (S), slow relaxation of the magnetization can be obtained as seen for single-molecule magnets (SMMs). Although, a number of mixed transition-metal/ lanthanide SMMs have been reported, pure lanthanide SMMs are relatively scarce. The latter molecules are rare owing to the difficulty in promoting magnetic interactions in these systems. These interactions are attained by the overlap of bridging ligand orbitals with the 4f orbitals of the lanthanide ions. Thus, ligand design is one of the key components for achieving such interactions in pure lanthanide-based systems. To induce significant magnetic interaction between the lanthanide ions and synthesize high-energy-barrier SMMs, we have been investigating the use of (2-hydroxy-3-methoxyphenyl)methylene (isonicotino)hydrazine (H2hmi) as a rigid chelate in lanthanide chemistry. Such a linear ligand provides O,N,O,O-based multichelating sites that are especially favorable for lanthanide ion complex formation. They can form dinuclear systems using the bridging phenoxide oxygen atom, and the pyridine group promotes the formation of extended networks that can control the organization of the SMM units in the three-dimensional structure. Herein we report the use of the H2hmi ligand to design materials based on ferromagnetically coupled dinuclear dysprosium(III) SMMs with large relaxation barriers. [Dy2(hmi)2(NO3)2(MeOH)2] (1) and [Dy2(hmi)2(NO3)2 (MeOH)2]1·MeCN (2·MeCN) were obtained from a suspension of Dy(NO3)3·5H2O / H2hmi in methanol (treated with triethylamine) and in a 3:1 mixture of acetonitrile and methanol (treated with pyridine), respectively. After two days, pale orange single crystals were obtained, which were kept in contact with the mother liquor to prevent deterioration. Complexes 1 (Figure 1) and 2 (Figure 2) crystallize in monoclinic P21/c and orthorhombic Pbca space groups, respectively. Both complexes have similar dinuclear

Software verification with BLAST

Abstract: Blast (the Berkeley Lazy Abstraction Software verification Tool) is a verification system for checking safety properties of C programs using automatic property-driven construction and model checking of software abstractions. Blast implements an abstract-model check-refine loop to check for reachability of a specified label in the program. The abstract model is built on the fly using predicate abstraction. This model is then checked for reachability. If there is no (abstract) path to the specified error label, Blast reports that the system is safe and produces a succinct proof. Otherwise, it checks if the path is feasible using symbolic execution of the program. If the path is feasible, Blast outputs the path as an error trace, otherwise, it uses the infeasibility of the path to refine the abstract model. Blast short-circuits the loop from abstraction to verification to refinement, integrating the three steps tightly through “lazy abstraction” [5]. This integration can offer significant advantages in performance by avoiding the repetition of work from one iteration of the loop to the next.

Adult hippocampal neurogenesis is involved in anxiety-related behaviors.

Abstract: Adult hippocampal neurogenesis is a unique example of structural plasticity, the functional role of which has been a matter of intense debate. New transgenic models have recently shown that neurogenesis participates in hippocampus-mediated learning. Here, we show that transgenic animals, in which adult hippocampal neurogenesis has been specifically impaired, exhibit a striking increase in anxiety-related behaviors. Our results indicate that neurogenesis plays an important role in the regulation of affective states and could be the target of new treatments for anxiety disorders.