The repertoire of G-protein-coupled receptors in Xenopus tropicalis

<p>Abstract</p> <p>Background</p> <p>The G-protein-coupled receptor (GPCR) superfamily represents the largest protein family in the human genome. These proteins have a variety of physiological functions that give them well recognized roles in clinical medicine. In <it>Xenopus tropicalis</it>, a widely used animal model for physiology research, the repertoire of GPCRs may help link the GPCR evolutionary history in vertebrates from teleost fish to mammals.</p> <p>Results</p> <p>We have identified 1452 GPCRs in the <it>X. tropicalis </it>genome. Phylogenetic analyses classified these receptors into the following seven families: <it>Glutamate</it>, <it>Rhodopsin</it>, <it>Adhesion</it>, <it>Frizzled</it>, <it>Secretin</it>, <it>Taste 2 </it>and <it>Vomeronasal 1</it>. Nearly 70% of <it>X. tropicalis </it>GPCRs are represented by the following three types of receptors thought to receive chemosensory information from the outside world: olfactory, vomeronasal 1 and vomeronasal 2 receptors.</p> <p>Conclusion</p> <p><it>X. tropicalis </it>shares a more similar repertoire of GPCRs with mammals than it does with fish. An examination of the three major groups of receptors related to olfactory/pheromone detection shows that in <it>X. tropicalis</it>, these groups have undergone lineage specific expansion. A comparison of GPCRs in <it>X. tropicalis</it>, teleost fish and mammals reveals the GPCR evolutionary history in vertebrates.</p

Curcumin Enhances Neurogenesis and Cognition in Aged Rats: Implications for Transcriptional Interactions Related to Growth and Synaptic Plasticity

Background: Curcumin has been demonstrated to have many neuroprotective properties, including improvement of cognition in humans and neurogenesis in animals, yet the mechanism of such effects remains unclear. Methodology: We assessed behavioural performance and hippocampal cell proliferation in aged rats after 6- and 12-week curcumin-fortified diets. Curcumin enhanced non-spatial and spatial memory, as well as dentate gyrate cell proliferation as compared to control diet rats. We also investigated underlying mechanistic pathways that might link curcumin treatment to increased cognition and neurogenesis via exon array analysis of cortical and hippocampal mRNA transcription. The results revealed a transcriptional network interaction of genes involved in neurotransmission, neuronal development, signal transduction, and metabolism in response to the curcumin treatment. Conclusions: The results suggest a neurogenesis- and cognition-enhancing potential of prolonged curcumin treatment i

Etude de protéines impliquées dans l'oligomérisation, la sécrétion, l'ancrage membranaire et la localisation fonctionnelle de l'acétylcholinestérase dans le cerveau des mammifères

Both the catalytic domains and the C-terminal t peptides contribute to the capacity of cholinesterases to form and secrete various oligomers. The AChE-PRiMA complex is at least partially contained in lipid rafts, both in the rat brain and in transfected neuroblastoma and COS cells. The potential phosphorylation sites and palmitoylation sites are not required for recruitment of the complex in the rafts. We undertook a search for such potential partners by two-hybrid strategies, both in yeast and in E. coli. Five potential partners were obtained several times, and one of those obtained from the yeast screen appeared also positive in the bacterial screen. This corresponds to a zinc-finger rich protein, which may act as a transcriptional regulator but was also shown to bind a short C-terminal peptide from a membrane receptor. The CutA protein affects the processing of proteins in the secretory pathway, facilitating tetramerization of AChEt.Nous avons construit des protéines chimères dans lesquelles les peptides t ont été échangés entre les deux cholinestérases, et nous avons introduit diverses mutations dans ces peptides. Nous avons montré que le domaine catalytique et le peptide t contribuent à la capacité d'oligomérisation et à la sécrétion des cholinestérases. Nous avons entrepris de rechercher de tels partenaires potentiels, en utilisant la stratégie de double-hybride, chez la levure et chez E. coli, avec la région C-terminale de PRiMA I comme appât et des banques d'ADNc issues de cerveau humain. Cinq partenaires potentiels ont été obtenus plusieurs fois chez la levure Le complexe AChE-PRiMA est au moins partiellement intégré dans des sous-domaines membranaires appelés rafts , aussi bien dans le cerveau de rat que dans des cellules de neuroblastomes ou des cellules COS transfectées. En mutant ces résidus, nous avons montré que les modifications post tranductionelle ne sont pas nécessaires pour le recrutement dans les rafts . Nous avons trouvé que l'expression de la forme longue de mCutA réduit la production d'AChEt et que ceci dépend du peptide C-terminal t. Nous avons également observé que la co-expression avec mCutA augmente la formation de tétramères et facilite la tétramérisation de l'AChEy de manière directe ou indirectePARIS5-BU Méd.Cochin (751142101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Relations réciproques entre les noyaux de l'amygdale et le locus coerulus (influence sur l'apprentissage et la consolidation mnésique)

Les présentes études ont été réalisées pour explorer l interaction fonctionnelle entre le noyau noradrénergique Locus Coeruleus(LC) et le noyau latéral basal de l amygdale (BLA) in vivo, pendant l apprentissage et la consolidation mnésique. Les neurones du BLA et du LC ont été enregistrés simultanément alors que le rat anesthésié recevait des chocs électriques sur une patte. Tous les neurones du LC ont montré une réponse excitatrice multiphasique suivie d une inhibition prolongée. Les réponses des cellules du BLA furent majoritairement inhibitrices, avec une levée d inhibition pendant la phase réfractaire du LC. Des stimulations électriques directes du LC ont aussi entraîné une réponse inhibitrice dans le BLA, partiellement bloquée par l infusion locale du timolol, un antagoniste du récepteur bêta adrénergique. Il s agit de la première démonstration des effets in vivo de l activation du système noradrénergique sur l activité neuronale dans le BLA. L apprentissage de l évitement passif a été adopté comme tâche dans l étude comportementale. L enregistrement des neurones du BLA pendant la phase pre-apprentissage (habituation), l apprentissage et pendant les cent minutes qui suivent l apprentissage et le test de rétention montre que l activité neuronale du BLA augmente pendant le phase d habituation et pendant les cent minutes suivant le test, mais pas en période post-habituation, ni post-apprentissage. Ces résultats suggèrent que la mémoire réactivée lors du test subit un processus de reconsolidation. L étude du sommeil tend à corroborer ces résultats. Le nombre d épisodes du sommeil paradoxal (REM) et la proportion de REM sur la durée totale du sommeil augmentent uniquement après le test. Tous ces résultats impliquent que le BLA puisse jouer un rôle important dans la consolidation et la reconsolidation de la mémoire et que l influence du BLA sur la mémoire agit en concert avec le LC.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Graphene in Ionic Liquids: Collective van der Waals Interaction and Hindrance of Self-Assembly Pathway

Over the past decade, there has been much controversy regarding the microscopic mechanism by which the π-electron-rich carbon nanomaterials such as graphene and carbon nanotubes can be dispersed in ionic liquids. Through a combination of a quantum mechanical calculation on the level of density functional theory, an extensive molecular dynamics study on the time scale of microseconds, and a kinetic analysis at the experimental time scale, we have demonstrated that collective van der Waals forces between ionic liquids and graphene are able to describe both the short-ranged cation−π interaction and the long-ranged dispersion interaction and this microscopic interaction drives two graphene plates trapped in their metastable state while two graphene plates easily self-assemble into graphite in water

Graphene in Ionic Liquids: Collective van der Waals Interaction and Hindrance of Self-Assembly Pathway

Over the past decade, there has been much controversy regarding the microscopic mechanism by which the π-electron-rich carbon nanomaterials such as graphene and carbon nanotubes can be dispersed in ionic liquids. Through a combination of a quantum mechanical calculation on the level of density functional theory, an extensive molecular dynamics study on the time scale of microseconds, and a kinetic analysis at the experimental time scale, we have demonstrated that collective van der Waals forces between ionic liquids and graphene are able to describe both the short-ranged cation−π interaction and the long-ranged dispersion interaction and this microscopic interaction drives two graphene plates trapped in their metastable state while two graphene plates easily self-assemble into graphite in water

Advances in the pathogenesis of Alzheimer’s disease: a re-evaluation of amyloid cascade hypothesis

Abstract Alzheimer’s disease (AD) is a common neurodegenerative disease characterized clinically by progressive deterioration of memory, and pathologically by histopathological changes including extracellular deposits of amyloid-beta (A-beta) peptides forming senile plaques (SP) and the intracellular neurofibrillary tangles (NFT) of hyperphosphorylated tau in the brain. This review focused on the new developments of amyloid cascade hypothesis with details on the production, metabolism and clearance of A-beta, and the key roles of some important A-beta-related genes in the pathological processes of AD. The most recent research advances in genetics, neuropathology and pathogenesis of the disease were also discussed.</p

Enhanced Ferromagnetism and Tunable Magnetism in Fe3GeTe2Monolayer by Strain Engineering

Recent discovery of intrinsic ferromagnetism in Fe3GeTe2 (FGT) monolayer [ Deng, Y.; et al. Nature 2018, 563, 94-99; Fei, Z.; et al. Nat. Mater. 2018, 17, 778-782 ] not only extended the family of two-dimensional (2D) magnetic materials but also stimulated further interest in the possibility to tune their magnetic properties without changing the chemical composition or introducing defects. By means of density functional theory computations, we explore strain effects on the magnetic properties of the FGT monolayer. We demonstrate that the ferromagnetism can be largely enhanced by the tensile strain in the FGT monolayer due to the competitive effects of direct exchange and superexchange interaction. The average magnetic moments of Fe atoms increase monotonically with an increase in biaxial strain from -5 to 5% in FGT monolayer. The intriguing variation of magnetic moments with strain in the FGT monolayer is related to the charge transfer induced by the changes in the bond lengths. Given the successful fabrication of the FGT monolayer, the strain-tunable ferromagnetism in the FGT monolayer can stimulate the experimental effort in this field. This work also suggests an effective route to control the magnetic properties of the FGT monolayer. The pronounced magnetic response toward the biaxial strain can be used to design the magnetomechanical coupling spintronics devices based on FGT.Peer reviewe