Characterization of three vasopressin receptor 2 variants: an apparent polymorphism (V266A) and two loss-of-function mutations (R181C and M311V).

Arginine vasopressin (AVP) is released from the posterior pituitary and controls water homeostasis. AVP binding to vasopressin V2 receptors (V2Rs) located on kidney collecting duct epithelial cells triggers activation of Gs proteins, leading to increased cAMP levels, trafficking of aquaporin-2 water channels, and consequent increased water permeability and antidiuresis. Typically, loss-of-function V2R mutations cause nephrogenic diabetes insipidus (NDI), whereas gain-of-function mutations cause nephrogenic syndrome of inappropriate antidiuresis (NSIAD). Here we provide further characterization of two mutant V2Rs, R181C and M311V, reported to cause complete and partial NDI respectively, together with a V266A variant, in a patient diagnosed with NSIAD. Our data in HEK293FT cells revealed that for cAMP accumulation, AVP was about 500- or 30-fold less potent at the R181C and M311V mutants than at the wild-type receptor respectively (and about 4000- and 60-fold in COS7 cells respectively). However, in contrast to wild type V2R, the R181C mutant failed to increase inositol phosphate production, while with the M311V mutant, AVP exhibited only partial agonism in addition to a 37-fold potency decrease. Similar responses were detected in a BRET assay for β-arrestin recruitment, with the R181C receptor unresponsive to AVP, and partial agonism with a 23-fold decrease in potency observed with M311V in both HEK293FT and COS7 cells. Notably, the V266A V2R appeared functionally identical to the wild-type receptor in all assays tested, including cAMP and inositol phosphate accumulation, β-arrestin interaction, and in a BRET assay of receptor ubiquitination. Each receptor was expressed at comparable levels. Hence, the M311V V2R retains greater activity than the R181C mutant, consistent with the milder phenotype of NDI associated with this mutant. Notably, the R181C mutant appears to be a Gs protein-biased receptor incapable of signaling to inositol phosphate or recruiting β-arrestin. The etiology of NSIAD in the patient with V266A V2R remains unknown

Quaternary structure predictions of transmembrane proteins starting from the monomer: a docking-based approach

BACKGROUND: We introduce a computational protocol for effective predictions of the supramolecular organization of integral transmembrane proteins, starting from the monomer. Despite the demonstrated constitutive and functional importance of supramolecular assemblies of transmembrane subunits or proteins, effective tools for structure predictions of such assemblies are still lacking. Our computational approach consists in rigid-body docking samplings, starting from the docking of two identical copies of a given monomer. Each docking run is followed by membrane topology filtering and cluster analysis. Prediction of the native oligomer is therefore accomplished by a number of progressive growing steps, each made of one docking run, filtering and cluster analysis. With this approach, knowledge about the oligomerization status of the protein is required neither for improving sampling nor for the filtering step. Furthermore, there are no size-limitations in the systems under study, which are not limited to the transmembrane domains but include also the water-soluble portions. RESULTS: Benchmarks of the approach were done on ten homo-oligomeric membrane proteins with known quaternary structure. For all these systems, predictions led to native-like quaternary structures, i.e. with C(α)-RMSDs lower than 2.5 Å from the native oligomer, regardless of the resolution of the structural models. CONCLUSION: Collectively, the results of this study emphasize the effectiveness of the prediction protocol that will be extensively challenged in quaternary structure predictions of other integral membrane proteins

2010 M&A Update

Most of 2009 was slow for mergers and acquisitions (M&A), due to financial turmoil and economic uncertainty that carried over from late 2008. But the deal market rebounded in the fourth quarter of 2009 and 2010 appears to be much better for M&A than 2009. Yet while the global economy shows signs of recovery, and many buyers and sellers are flush with cash, M&A activity may begin slowly in the United States in 2011 due to uncertainty about the business outlook and potential tax changes. In this article, we briefly review M&A activity in the first half of 2010, and look back on 2009. We comment on current deal making, suggest factors that may influence future deals, and conclude with expectations for the future

Student interpreters predict meaning while simultaneously interpreting - even before training

Prediction has long been considered advantageous in simultaneous interpreting, as it may allow interpreters to comprehend more rapidly and focus on their own production. However, evidence of prediction in simultaneous interpreting to date is relatively limited. In addition, it is unclear whether training in simultaneous interpreting influences predictive processing during a simultaneous interpreting task. We report on a longitudinal eyetracking study which measured the timing and extent of prediction in students before and after two semesters of training in simultaneous interpreting. The students simultaneously interpreted sentences containing a highly predictable word as they viewed a screen containing four pictures, one of which depicted a highly predictable object. They made predictive eye movements to the highly predictable object both before and after their training in simultaneous interpreting. However, we did not find evidence that training influenced the timing or the magnitude of their prediction

Correlating the Energetics and Atomic Motions of the Metal-Insulator Transition of M1 Vanadium Dioxide

Materials that undergo reversible metal-insulator transitions are obvious candidates for new generations of devices. For such potential to be realised, the underlying microscopic mechanisms of such transitions must be fully determined. In this work we probe the correlation between the energy landscape and electronic structure of the metal-insulator transition of vanadium dioxide and the atomic motions occurring using first principles calculations and high resolution X-ray diffraction. Calculations find an energy barrier between the high and low temperature phases corresponding to contraction followed by expansion of the distances between vanadium atoms on neighbouring sub-lattices. X-ray diffraction reveals anisotropic strain broadening in the low temperature structure's crystal planes, however only for those with spacings affected by this compression/expansion. GW calculations reveal that traversing this barrier destabilises the bonding/anti-bonding splitting of the low temperature phase. This precise atomic description of the origin of the energy barrier separating the two structures will facilitate more precise control over the transition characteristics for new applications and devices.Comment: 11 Pages, 8 Figure

New insights on the interaction between thiophene derivatives and Au surfaces: the case of 3,4-ethylenedioxythiophene and the relevant polymer.

The nature of the interface between electrogenerated poly(3,4-ethylenedioxythiophene) and the Au substrate is studied in detail. In particular, the adsorption of the relevant monomer, namely, 3,4-ethylenedioxythiophene, is investigated and compared with that of other thiophene derivatives. Different deposition procedures have been adopted: very thin films of the thiophene derivatives have been obtained through chemisorption processes from vapor and liquid phases, on Au polycrystalline substrates, Au nano particles possessing different size, and a Au(111) single crystal. Different techniques, operating both in situ and ex situ, have been employed for the characterization of these deposits, that is, X-ray photoemission and surface enhanced Raman spectroscopy. The results show that the poly(3,4-ethylenedioxythiophene)/metal interface is far from being simply constituted by unreacted molecules in contact with the substrate; rather, the formation of oligothiophene species and sulfur atoms at the interface has been ascertained

WHY LESS IS MORE: AN EYE TRACKING STUDY ON IDEA PRESENTATION AND ATTRIBUTE ATTENDANCE IN IDEA SELECTION

Innovation contests often result in several hundred ideas generated. Raters have to process this huge amount of ideas that consist of attributes like idea descriptions and various types of feedback infor-mation with limited cognitive resources in order to separate good from bad ideas. It is not clear to what extent raters attend the available information during idea selection. In order to improve our un-derstanding of how to best support raters in idea selection, this study investigated the influence of vari-ations of the presentation mode (two versus four ideas per screen) on the attention paid to information on idea attributes using eye-tracking. We investigated attributes that refer to idea descriptions, feed-back about the content of ideas (creativity score, tags) and about the community comprising the idea-tors and the crowd (historical success of the ideator, likes). The results of our study show that with fewer alternatives per screen, feedback attributes received more attendance, while we found no signifi-cant difference for the processing of idea descriptions. These findings provide first insights into the information-processing behaviour of raters and can inform the design of selection platforms and theory building on the effects of feedback in idea selection

In situ atomic force microscopy in the study of electrogeneration of polybithiophene on Pt electrode

Electrochemical AFM technique has been used for the in situ study of the electrogeneration-deposition process of polybithiophene at varying the polymerisation conditions, such as supporting electrolyte, i.e., LiClO4 or tetrabutylammonium hexafluorophosphate, and polymerisation procedure, i.e., either potentiostatic or potentiodynamic method. In order to better follow the evolution of the morphology of the deposit, particularly during the early stages of the polymer film growth, a suitable home-made electrochemical cell has been used