Crystal Structure of the Full-Length Feline Immunodeficiency Virus Capsid Protein Shows an N-Terminal β-Hairpin in the Absence of N-Terminal Proline.

Feline immunodeficiency virus (FIV) is a member of the Retroviridae family. It is the causative agent of an acquired immunodeficiency syndrome (AIDS) in cats and wild felines. Its capsid protein (CA) drives the assembly of the viral particle, which is a critical step in the viral replication cycle.

The conformation of the Congo-red ligand bound to amyloid fibrils HET-s(218-289): a solid-state NMR study.

We have previously shown that Congo red (CR) binds site specifically to amyloid fibrils formed by HET-s(218-289) with the long axis of the CR molecule almost parallel to the fibril axis. HADDOCK docking studies indicated that CR adopts a roughly planar conformation with the torsion angle ϕ characterizing the relative orientation of the two phenyl rings being a few degrees. In this study, we experimentally determine the torsion angle ϕ at the center of the CR molecule when bound to HET-s(218-289) amyloid fibrils using solid-state NMR tensor-correlation experiments.

High-resolution mitochondrial DNA analysis sheds light on human diversity, cultural interactions, and population mobility in Northwestern Amazonia.

Objectives: Northwestern Amazonia (NWA) is a center of high linguistic and cultural diversity. Several language families and linguistic isolates occur in this region, as well as different subsistence patterns, with some groups being foragers and others agriculturalists. In addition, speakers of Eastern Tukanoan languages are known for practicing linguistic exogamy, a marriage system in which partners are taken from different language groups.

Molecular dissection of protein-protein interactions between integrin α5β1 and the Helicobacter pylori Cag type IV secretion system.

The more severe strains of the bacterial human pathogen Helicobacter pylori produce a type IV secretion system (cagT4SS) to inject the oncoprotein cytotoxin-associated gene A (CagA) into gastric cells. This syringe-like molecular apparatus is prolonged by an external pilus that exploits integrins as receptors to mediate the injection of CagA. The molecular determinants of the interaction of the cagT4SS pilus with the integrin ectodomain are still poorly understood.

[Children's politics and the hierarchy dilemma].

Hierarchy is a recurrent feature of social life. From an early age, children are confronted with power relationships wherein a dominant individual imposes his/her will to a subordinate individual. Recent research has shown that young children develop sophisticated abilities in understanding power.

Performance of a Multiplex Serological Helicobacter pylori Assay on a Novel Microfluidic Assay Platform.

Infection with () occurs in 50% of the world population, and is associated with the development of ulcer and gastric cancer. Serological diagnostic tests indicate an infection by detecting antibodies directed against proteins. In addition to line blots, multiplex assay platforms provide smart solutions for the simultaneous analysis of antibody responses towards several proteins.

The neural development of conditional reasoning in children: Different mechanisms for assessing the logical validity and likelihood of conclusions.

Scientific and mathematical thinking relies on the ability to evaluate whether conclusions drawn from conditional (if-then) arguments are logically valid. Yet, the neural development of this ability -- termed deductive reasoning -- is largely unknown. Here we aimed to identify the neural mechanisms that underlie the emergence of deductive reasoning with conditional rules in children.

Gradient reconstitution of membrane proteins for solid-state NMR studies.

We here adapted the GRecon method used in electron microscopy studies for membrane protein reconstitution to the needs of solid-state NMR sample preparation. We followed in detail the reconstitution of the ABC transporter BmrA by dialysis as a reference, and established optimal reconstitution conditions using the combined sucrose/cyclodextrin/lipid gradient characterizing GRecon. We established conditions under which quantitative reconstitution of active protein at low lipid-to-protein ratios can be obtained, and also how to upscale these conditions in order to produce adequate amounts for NMR.

Sample Preparation for Membrane Protein Structural Studies by Solid-State NMR.

Conformational studies of membrane proteins remain a challenge in the field of structural biology, and in particular the investigation of the proteins in a native-like lipid environment. Solid-state NMR presents a valuable opportunity for this, and we present here three critical steps in the solid-state NMR sample preparation, i.e.

Hippocampal spatial mechanisms relate to the development of arithmetic symbol processing in children.

Understanding the meaning of abstract mathematical symbols is a cornerstone of arithmetic learning in children. Studies have long focused on the role of spatial intuitions in the processing of numerals. However, it has been argued that such intuitions may also underlie symbols that convey fundamental arithmetic concepts, such as arithmetic operators.

Global realized niche divergence in the African clawed frog .

Although of crucial importance for invasion biology and impact assessments of climate change, it remains widely unknown how species cope with and adapt to environmental conditions beyond their currently realized climatic niches (i.e., those climatic conditions existing populations are exposed to).

Ternary polysaccharide complexes: Colloidal drug delivery systems stabilized in physiological media.

Chitosan-hyaluronan (HYA) polyelectrolyte complexes (PECs) were designed to maintain their colloidal stabilities in physiological ionic strength and pH, via a new concept of ternary complexes. This strategy relied on the formation of a binary PEC between chitosan and a strong polyacid, dextran sulphate (DS) or heparin (HEP), and further functionalization with HYA. The major parameter leading to stabilized colloids was a high ratio of the degrees of polymerization of chitosan versus the strong polyacid.

Social stress contagion in rats: Behavioural, autonomic and neuroendocrine correlates.

The negative emotional consequences associated with life stress exposure in an individual can affect the emotional state of social partners. In this study, we describe an experimental rat model of social stress contagion and its effects on social behaviour and cardiac autonomic and neuroendocrine functions. Adult male Wistar rats were pair-housed and one animal (designated as "demonstrator" (DEM)) was submitted to either social defeat stress (STR) by an aggressive male Wild-type rat in a separate room or just exposed to an unfamiliar empty cage (control condition, CTR), once a day for 4 consecutive days.

Solid-state NMR and EPR Spectroscopy of Mn -Substituted ATP-Fueled Protein Engines.

Paramagnetic metal ions deliver structural information both in EPR and solid-state NMR experiments, offering a profitable synergetic approach to study bio-macromolecules. We demonstrate the spectral consequences of Mg / Mn substitution and the resulting information contents for two different ATP:Mg -fueled protein engines, a DnaB helicase from Helicobacter pylori active in the bacterial replisome, and the ABC transporter BmrA, a bacterial efflux pump. We show that, while EPR spectra report on metal binding and provide information on the geometry of the metal centers in the proteins, paramagnetic relaxation enhancements identified in the NMR spectra can be used to localize residues at the binding site.

Structural Insights into Helicobacter pylori Cag Protein Interactions with Host Cell Factors.

The most virulent strains of Helicobacter pylori carry a genomic island (cagPAI) containing a set of 27-31 genes. The encoded proteins assemble a syringe-like apparatus to inject the cytotoxin-associated gene A (CagA) protein into gastric cells. This molecular device belongs to the type IV secretion system (T4SS) family albeit with unique characteristics.

Structural and Molecular Biology of Type IV Secretion Systems.

Type IV secretion systems (T4SSs) are nanomachines that Gram-negative, Gram-positive bacteria, and some archaea use to transport macromolecules across their membranes into bacterial or eukaryotic host targets or into the extracellular milieu. They are the most versatile secretion systems, being able to deliver both proteins and nucleoprotein complexes into targeted cells. By mediating conjugation and/or competence, T4SSs play important roles in determining bacterial genome plasticity and diversity; they also play a pivotal role in the spread of antibiotic resistance within bacterial populations.

A novel 2-step ALD route to ultra-thin MoS films on SiO through a surface organometallic intermediate.

The lack of scalable-methods for the growth of 2D MoS crystals, an identified emerging material with applications ranging from electronics to energy storage, is a current bottleneck against its large-scale deployment. We report here a two-step ALD route with new organometallic precursors, Mo(NMe) and 1,2-ethanedithiol (HS(CH)SH) which consists in the layer-by-layer deposition of an amorphous surface Mo(iv) thiolate at 50 °C, followed by a subsequent annealing at higher temperature leading to ultra-thin MoS nanocrystals (∼20 nm-large) in the 1-2 monolayer range. In contrast to the usual high-temperature growth of 2D dichalcogenides, where nucleation is the key parameter to control both thickness and uniformity, our novel two-step ALD approach enables chemical control over these two parameters, the growth of 2D MoS crystals upon annealing being ensured by spatial confinement and facilitated by the formation of a buffer oxysulfide interlayer.

Francisella tularensis IglG Belongs to a Novel Family of PAAR-Like T6SS Proteins and Harbors a Unique N-terminal Extension Required for Virulence.

The virulence of Francisella tularensis, the etiological agent of tularemia, relies on an atypical type VI secretion system (T6SS) encoded by a genomic island termed the Francisella Pathogenicity Island (FPI). While the importance of the FPI in F. tularensis virulence is clearly established, the precise role of most of the FPI-encoded proteins remains to be deciphered.

GaAs nanowires with oxidation-proof arsenic capping for the growth of an epitaxial shell.

We propose an arsenic-capping/decapping method, allowing the growth of an epitaxial shell around the GaAs nanowire (NW) core which is exposed to an ambient atmosphere, and without the introduction of impurities. Self-catalyzed GaAs NW arrays were firstly grown on Si(111) substrates by solid-source molecular beam epitaxy. Aiming for protecting the active surface of the GaAs NW core, the arsenic-capping/decapping method has been applied.

Cross-linguistic patterns in the acquisition of quantifiers.

Learners of most languages are faced with the task of acquiring words to talk about number and quantity. Much is known about the order of acquisition of number words as well as the cognitive and perceptual systems and cultural practices that shape it. Substantially less is known about the acquisition of quantifiers.

Zinc-Stabilized Chitosan-Chondroitin Sulfate Nanocomplexes for HIV-1 Infection Inhibition Application.

Polyelectrolyte complexes (PECs) constituted of chitosan and chondroitin sulfate (ChonS) were formed by the one-shot addition of default amounts of polyanion to an excess of polycation. Key variables of the formulation process (e.g.

Flow around a rotating, semi-infinite cylinder in an axial stream.

This paper concerns steady, high-Reynolds-number flow around a semi-infinite, rotating cylinder placed in an axial stream and uses boundary-layer type of equations which apply even when the boundary-layer thickness is comparable to the cylinder radius, as indeed it is at large enough downstream distances. At large rotation rates, it is found that a wall jet appears over a certain range of downstream locations. This jet strengthens with increasing rotation, but first strengthens then weakens as downstream distance increases, eventually disappearing, so the flow recovers a profile qualitatively similar to a classical boundary layer.

GaAs Core/SrTiO3 Shell Nanowires Grown by Molecular Beam Epitaxy.

We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of the nanowire facets. Reflection high energy electron diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to determine the structural, chemical, and morphological properties of the heterostructured nanowires.

Two phases of aging separated by the Smurf transition as a public path to death.

Aging's most obvious characteristic is the time dependent increase of an individual's probability to die. This lifelong process is accompanied by a large number of molecular and physiological changes. Although numerous genes involved in aging have been identified in the past decades its leading factors have yet to be determined.