MAGUK SCAFFOLDS ORGANIZE A KEY SYNAPTIC COMPLEX IN HORIZONTAL CELL PROCESSES CONTACTING PHOTORECEPTORS

Synaptic processes and plasticity of synapses are mediated by large suites of proteins. In most cases, many of these proteins are tethered together by synaptic scaffold proteins. Scaffold proteins have a large number and typically a variety of protein interaction domains that allow many different proteins to be assembled into functional complexes. As each scaffold protein has a different set of protein interaction domains and a unique set of interacting partners, the presence of synaptic scaffolds can provide insight into the molecular mechanisms that regulate synaptic processes. In studies of rabbit retina, we found SAP102 and Chapsyn110 selectively localized in the tips of B-type horizontal cell processes where they contact cone and rod photoreceptors. We further identified some known SAP102 binding partners, kainate receptor GluR6/7 and inward rectifier potassium channel Kir2.1, closely associated with SAP102 in the processes of invaginating HCs. In contrast, in the mouse retina we identified Chapsyn110 as the major scaffold in the tips of horizontal cells contacting photoreceptors. Kir2.1 was found to be assembled with SAP102 into a complex with GluR6/7 in photoreceptor invaginations in Rabbit. GluR6/7 and Kir2.1 presumably are involved in synaptic processes that govern cell-to-cell communication, and could both contribute in different ways to synaptic currents that mediate feedback signaling. Notably, we failed to find evidence for the presence of Cx57 or Cx59, but Pannexin1 immunolabeling was positive in the OPL of mouse retina suggesting that it could play a role in ephaptic and pH mediated signaling. Polyamines regulate many ion channels including Kir2.1. During the day polyamine immunolabeling was unexpectedly high in photoreceptor terminals compared to other areas of the retina. If polyamines are released, they may regulate the activity of Kir2.1 channels located in the tips of HCs. Alternatively, the presence of polyamines may potentiate GluR6/7 by reducing the transition to desensitized state causing an increase in channel conductance. The presence of SAP102 and Chapsyn110 and their binding partners in both cone and rod invaginating synapses suggests that whatever mechanism is supported by this protein complex is present in both types of photoreceptors

El Sueño de Brønsted : ácidos fosfóricos quirales

Entre los muchos catalizadores que han aparecido en los últimos años en el espectacular desarrollo de la organocatálisis, los ácidos fosfóricos quirales derivados del 1,1'-Bi-2-naftol (BINOL), han mostrado una excelente aplicabilidad en reacciones de distinta naturaleza, siendo hoy en día, una herramienta esencial en el campo de la síntesis asimétrica. En este trabajo se describen las principales características de éstos, además de ilustrar algunas de las muchas reacciones que han sido desarrolladas en los últimos años

La perspectiva social de las principales plataformas de MOOC a través de Facebook

Facebook, Como roja sociales, offers ONU potente medio de Comunicación Social un Través de la Red, Conectando con Usuarios: intereses comunes. En Este estudio se analizan las cuentas de Facebook de 7 de las Principales de plataformas de MOOC: Coursera, EDX, Futuro Learn, Extensión de Harvard, Miriada X, Stanford en línea y Udacity, con el fin de describir el Modo en Que Estas emplean SUS cuentas de Como Facebook Espacio Digital de Comunicación, Información e Interacción con Usuarios sociales SUS. Para ola, se han utilizado Herramientas de Medición en línea Sobre el Crecimiento y La visibilidad de las cuentas permite, El contents publicado y La interactividad Con Los Seguidores. Los Resultados evidencian Que El Número de Seguidores no es proporcional al Número de Publicaciones y El Nivel de Actividad de las respectivas cuentas. Esto! Evidencia Que es Necesario Tener y desarrollar Estrategias En torno a las redes sociales, ya Que Ello PUEDE Contribuir a la Consolidación de colectivos Interesados ??en el proyecto educativo Que offers Cada plataforma

Prevalence of Nosema microsporidians in commercial bumblebees (Bombus terrestris) is not related to the intensity of their use at the landscape scale

The use of commercial bumblebees to aid crop pollination may result in overcrowding of agricultural landscapes by pollinators. Consequently, transmission of parasites between pollinators via shared flowers may be substantial. In SW Spain, we assessed the initial infection status of commercial Bombus terrestris colonies and then explored spatial and seasonal influences on changes in parasite prevalence across a landscape where bumblebee colonies are intensively used to pollinate berry crops. Colonies were placed inside strawberry greenhouse crops and in woodlands adjacent and distant to crops, in winter and in spring, as representative periods of high and low use of colonies, respectively. Worker bumblebees were collected from colonies upon arrival from a producer and 30 days after being placed in the field. The abdomen of each bumblebee was morphologically inspected for a range of internal parasites. Upon arrival, 71% of the colonies were infected by spores of Nosema. Three bumblebees from two colonies harboured Apicystis bombi spores at the end of their placement in woodlands adjacent to the crops. Nosema colony prevalence did not change significantly either among sites or between seasons. We found no evidence for the density of commercial B. terrestris impacting Nosema prevalence in those commercial colonies, but our results highlight the potential risk for parasites to be transmitted from commercial bumblebees to native pollinators.Peer Reviewe

Habitat use of the wild boar, Sus scrofa Linnaeus 1758, in Los Alerces National Park, Argentina

The aim of this work was to study the patterns of habitat use of the wild boar in Los Alerces National Park, Argentina. We surveyed 262 transects, totaling 26.2 km, searching for fresh signs of the species. The wild boar used low elevations more intensively (600 to 700 m asl) than higher elevations, and forests of Nothofagus dombeyi and N. antarctica with understory dominated by Chusquea culeou than other vegetation types. The occurrence of signs among elevation strips and vegetation types was different between summer and autumn. Our results might be helpful for park managers and park rangers in developing wild boar control plans.Fil: Schiaffini, Mauro Ignacio. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Laboratorio de Investigaciones en Evolución y Biodiversidad; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vila, Alejandro R.. Wildlife Conservation Society; Estados Unido

Evidence for a Dinuclear Active Site in the Metallo-β-lactamase BcII with Substoichiometric Co(II): A New Model for Uptake

Metallo-β-lactamases are zinc-dependent enzymes that constitute one of the main resistance mechanisms to β-lactam antibiotics. Metallo-β-lactamases have been characterized both in mono- and dimetallic forms. Despite many studies, the role of each metal binding site in substrate binding and catalysis is still unclear. This is mostly due to the difficulties in assessing the metal content and site occupancy in solution. For this reason, Co(II) has been utilized as a useful probe of the active site structure. We have employed UV-visible, EPR, and NMR spectroscopy to study Co(II) binding to the metallo-β-lactamase BcII from Bacillus cereus. The spectroscopic features were attributed to the two canonical metal binding sites, the 3H (His116, His118, and His196) and DCH (Asp120, Cys221, and His263) sites. These data clearly reveal the coexistence of mononuclear and dinuclear Co(II)-loaded forms at Co(II)/enzyme ratios as low as 0.6. This picture is consistent with the macroscopic dissociation constants here determined from competition binding experiments. A spectral feature previously assigned to the DCH site in the dinuclear species corresponds to a third, weakly bound Co(II) site. The present work emphasizes the importance of using different spectroscopic techniques to follow the metal content and localization during metallo-β-lactamase turnover

Asp-120 Locates Zn2 for Optimal Metallo-β-lactamase Activity

Metallo-β-lactamases are zinc-dependent hydrolases that inactivate β-lactam antibiotics, rendering bacteria resistant to them. Asp-120 is fully conserved in all metallo-β-lactamases and is central to catalysis. Several roles have been proposed for Asp-120, but so far there is no agreed consensus. We generated four site-specifically substituted variants of the enzyme BcII from Bacillus cereus as follows: D120N, D120E, D120Q, and D120S. Replacement of Asp-120 by other residues with very different metal ligating capabilities severely impairs the lactamase activity without abolishing metal binding to the mutated site. A kinetic study of these mutants indicates that Asp-120 is not the proton donor, nor does it play an essential role in nucleophilic activation. Spectroscopic and crystallographic analysis of D120S BcII, the least active mutant bearing the weakest metal ligand in the series, reveals that this enzyme is able to accommodate a dinuclear center and that perturbations in the active site are limited to the Zn2 site. It is proposed that the role of Asp-120 is to act as a strong Zn2 ligand, locating this ion optimally for substrate binding, stabilization of the development of a partial negative charge in the β-lactam nitrogen, and protonation of this atom by a zinc-bound water molecule

3D objects reconstruction from frontal images: an example with guitars

This work deals with the automatic 3D reconstruction of objects from frontal RGB images. This aims at a better understanding of the reconstruction of 3D objects from RGB images and their use in immersive virtual environments. We propose a complete workflow that can be easily adapted to almost any other family of rigid objects. To explain and validate our method, we focus on guitars. First, we detect and segment the guitars present in the image using semantic segmentation methods based on convolutional neural networks. In a second step, we perform the final 3D reconstruction of the guitar by warping the rendered depth maps of a fitted 3D template in 2D image space to match the input silhouette. We validated our method by obtaining guitar reconstructions from real input images and renders of all guitar models available in the ShapeNet database. Numerical results for different object families were obtained by computing standard mesh evaluation metrics such as Intersection over Union, Chamfer Distance, and the F-score. The results of this study show that our method can automatically generate high-quality 3D object reconstructions from frontal images using various segmentation and 3D reconstruction techniques.Postprint (published version

Super-resolution generative adversarial networks of randomly-seeded fields

Reconstruction of field quantities from sparse measurements is a problem arising in a broad spectrum of applications. This task is particularly challenging when the mapping between sparse measurements and field quantities is performed in an unsupervised manner. Further complexity is added for moving sensors and/or random on–off status. Under such conditions, the most straightforward solution is to interpolate the scattered data onto a regular grid. However, the spatial resolution achieved with this approach is ultimately limited by the mean spacing between the sparse measurements. In this work, we propose a super-resolution generative adversarial network framework to estimate field quantities from random sparse sensors. The algorithm exploits random sampling to provide incomplete views of the high-resolution underlying distributions. It is hereby referred to as the randomly seeded super-resolution generative adversarial network (RaSeedGAN). The proposed technique is tested on synthetic databases of fluid flow simulations, ocean surface temperature distribution measurements and particle-image velocimetry data of a zero-pressure-gradient turbulent boundary layer. The results show excellent performance even in cases with high sparsity or noise level. This generative adversarial network algorithm provides full-field high-resolution estimation from randomly seeded fields with no need of full-field high-resolution representations for training.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 949085) received by S.D. NOAA High Resolution SST data provided by the NOAA/OAR/ESRL PSL