Changes in Early Cortical Visual Processing Predict Enhanced Reactivity in Deaf Individuals

Individuals with profound deafness rely critically on vision to interact with their environment. Improvement of visual performance as a consequence of auditory deprivation is assumed to result from cross-modal changes occurring in late stages of visual processing. Here we measured reaction times and event-related potentials (ERPs) in profoundly deaf adults and hearing controls during a speeded visual detection task, to assess to what extent the enhanced reactivity of deaf individuals could reflect plastic changes in the early cortical processing of the stimulus. We found that deaf subjects were faster than hearing controls at detecting the visual targets, regardless of their location in the visual field (peripheral or peri-foveal). This behavioural facilitation was associated with ERP changes starting from the first detectable response in the striate cortex (C1 component) at about 80 ms after stimulus onset, and in the P1 complex (100–150 ms). In addition, we found that P1 peak amplitudes predicted the response times in deaf subjects, whereas in hearing individuals visual reactivity and ERP amplitudes correlated only at later stages of processing. These findings show that long-term auditory deprivation can profoundly alter visual processing from the earliest cortical stages. Furthermore, our results provide the first evidence of a co-variation between modified brain activity (cortical plasticity) and behavioural enhancement in this sensory-deprived population

Human, Nature, Dynamism: The Effects of Content and Movement Perception on Brain Activations during the Aesthetic Judgment of Representational Paintings

Movement perception and its role in aesthetic experience have been often studied, within empirical aesthetics, in relation to the human body. No such specificity has been defined in neuroimaging studies with respect to contents lacking a human form. The aim of this work was to explore, through functional magnetic imaging (f MRI), how perceived movement is processed during the aesthetic judgment of paintings using two types of content: human subjects and scenes of nature. Participants, untutored in the arts, were shown the stimuli and asked to make aesthetic judgments. Additionally, they were instructed to observe the paintings and to rate their perceived movement in separate blocks. Observation highlighted spontaneous processes associated with aesthetic experience, whereas movement judgment outlined activations specifically related to movement processing. The ratings recorded during aesthetic judgment revealed that nature scenes received higher scored than human content paintings. The imaging data showed similar activation, relative to baseline, for all stimuli in the three tasks, including activation of occipito-temporal areas, posterior parietal, and premotor cortices. Contrast analyses within aesthetic judgment task showed that human content activated, relative to nature, precuneus, fusiform gyrus, and posterior temporal areas, whose activation was prominent for dynamic human paintings. In contrast, nature scenes activated, relative to human stimuli, occipital and posterior parietal cortex/precuneus, involved in visuospatial exploration and pragmatic coding of movement, as well as central insula. Static nature paintings further activated, relative to dynamic nature stimuli, central and posterior insula. Besides insular activation, which was specific for aesthetic judgment, we found a large overlap in the activation pattern characterizing each stimulus dimension (content and dynamism) across observation, aesthetic judgment, and movement judgment tasks. These findings support the idea that the aesthetic evaluation of artworks depicting both human subjects and nature scenes involves a motor component, and that the associated neural processes occur quite spontaneously in the viewer. Furthermore, considering the functional roles of posterior and central insula, we suggest that nature paintings may evoke aesthetic processes requiring an additional proprioceptive and sensori-motor component implemented by “motor accessibility” to the represented scenario, which is needed to judge the aesthetic value of the observed painting

Cell-free expression of GPCRs: the endothelin system

The human endothelin receptors, ETA and ETB, are two members of the G-protein coupled receptors family (GPCRs) and they are key players in cardiovascular regulation. The characterization of their functionality in vitro has been limited by the possibility to obtain high quality samples using conventional expression systems. The Cell-Free expression system is an alternative technique for the production of membrane protein as well as GPCRs and can overcome some of the limitations that are commonly encountered using an in vivo approach. Cell-Free expression protocols for the two receptors ETA and ETB have been optimized by implementing post- and co-translational association to lipid bilayers. The efficiency of the reconstitution or association to liposomes and nanodiscs has systematically been studied and the ligand binding properties of the two receptors have been analyzed using a set of different complementary techniques. In several different conditions a high affinity binding of the peptide ligand ET-1 to both endothelin receptors could be obtained and the highest activity values were detected in sample prepared using a co-translational approach in presence of nanodiscs. Furthermore, the characteristic differential binding pattern of selected agonists and antagonists to the two receptors was confirmed. In samples obtained from several Cell-Free expression conditions, two intrinsic properties of the functionally folded ETB receptor, such as the proteolytic processing based on conformational recognition as well as the formation of SDS-resistant complexes with the peptide ligand ET-1, were detected. ETA and ETB are able to induce in vivo the activation of hetrotrimeric G proteins upon stimulation with an agonist, leading to the dissociation of the heterotrimeric complex and the exchange of GDP to GTP in the Galpha subunit. The Cell-Free expression system was chosen for the production of two G alpha subunit, Galpha s and Galpha q. Soluble expression of the two proteins was achieved and the production of active Galpha s was confirmed using fluorescent as well as radioactive assays. In conclusion, the obtained results document a new process for the production of ligand binding competent endothelin receptors, as well as Galpha proteins, using a Cell-Free expression system. The combination of this expression system and the nanodiscs technology appears to be a promising tool for the further characterization of membrane proteins as well as GPCRs

Exploring glycosignatures of pathogenic bacteria: the sweet side of biological recognition

Póster presentado en el 65th Congress of the Hellenic Society of Biochemistry and Molecular Biology celebrado en Tesalónica (Grecia) los días del 28-30 de noviembre de 2014Glycan chains are gaining importance as recognition signals in numerous processes related to health and disease. In particular, specific glycosylation patterns are frequently found to be associated with pathogenesis, including pathogen-host interactions. Bacterial surfaces are coated with distinct signature carbohydrate structures, most prominently capsular polysaccharides and lipopolysaccharides (LPS), which are targeted by host receptors for triggering defence responses or are exploited by the pathogen as mechanism of attachment to the host-cell surface. We have established a proof-of-concept for the use of designer¿s microarrays in the exploration of glycosylation motifs of the bacterial surface. Non-typable Haemophilus influenzae (NTHi), an opportunistic pathogen frequently isolated from respiratory samples from chronic obstructive pulmonary disease patients, was selected as case-study. A library of mutant strains of the clinical isolate 375 lacking specific glycosyltransferases involved in the synthesis of the lipooligosaccharide (LOS) was generated. Isolated LOSs were quantified, characterised by polyacrylamide gel electrophoresis, and immobilised in the microarrays as probes, alongside the corresponding whole bacteria strains. As pattern-reading tool, a panel of plant lectins with well-defined oligosaccharide-binding specificities was used. A fingerprint-like binding profile for each NTHi strain was observed, and competition assays with lectin-specific haptens confirmed carbohydrate-dependent recognition. For selected bacteria-lectin pairs, a real-time kinetics study was performed with the novel biosensor platform Quartz Crystal Microgravimetry (QCM). Both microarray and QCM techniques allowed the evaluation of glycans¿ accessibility on the bacterial surface, a factor of significant impact on their biomarker potential and their recognition by endogenous lectins of the innate immune system. Typification of bacterial glycosignatures by this newly described approach may be of particular relevance when characterising clinical isolates or mutant libraries in order to establish virulence correlations.Peer Reviewe

Exploring glycosignatures of nontypeable Haemophilus influenzae and recognition by human surfactant protein D

Trabajo presentado al EMBO workshop on Cell Biology of Animal Lectins, celebrado en Rehovot (Israel) del 21 al 26 de junio de 2015.Peer Reviewe

Organic Salt Hydrate as a Novel Paradigm for Thermal Energy Storage

The use of inorganic salt hydrates for thermochemical energy storage (TCS) applications is widely investigated. One of the drawbacks that researchers face when studying this class of materials is their tendency to undergo deliquescence phenomena. We here proposed and investigated, for the first time, the possibility of using organic salt hydrates as a paradigm for novel TCS materials with low water solubility, that is, more resistance to deliquescence, a tendency to coordinate a high number of water molecules and stability under operating conditions. The organic model compound chosen in this study was calcium; 7-[[2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-3-[(2-methyl-5,6-dioxo-1H-1,2,4-triazin-3-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, known as calcium ceftriaxone, hereafter named CaHS (calcium hydrated salt), a water-insoluble organic salt, which can combine up to seven water molecules. The CaHS was prepared by precipitation from the water-soluble disodium triaxone. The thermal behavior of CaHS, in terms of stability and dehydration–hydration cyclability, was assessed. The material can operate in the temperature range of 30–150 °C, suitable for TCS. No deliquescence phenomena occurred upon exposure to a relative humidity (RH) between 10 and 100%. Its heat storage capacity, so far unknown, was measured to be ~595.2 kJ/kg (or ~278.6 kWh/m3). The observed heat storage capacity, thermal stability, and good reversibility after dehydration–hydration cycles highlight the potential of this class of materials, thus opening new research paths for the development and investigation of innovative organic salt hydrates

Dissecting bacterial ligands for lectins: from isolated molecules to the entire pathogen surface

Trabajo presentado en el 19th European Carbohydrate Symposium EuroCarb, celebrado en Barcelona (España), del 2 al 6 de julio de 2017Bacterial glycocalyx components are intimately associated with virulence and commonly used for strain typification. Up until recently, analysis of their recognition by lectins and antibodies was commonly performed following isolation of selected constituents from the pathogen surface. Of note, in these ligand-targeted approaches, the natural presentation and accessibility of glycans along with possible cooperativity of neighbour molecules are not considered, an aspect particularly relevant in the case of weak binders. We recently developed a combined approach of static microarrays and QCM biosensor assays under flow, based on the use of entire bacteria, and demonstrated its usefulness for detection and real-time monitoring of lectin recognition processes [1]. We benefitted from the availability of a panel of nontypeable Heamophilus influenzae (strain NTHi375) mutants, defective for selected lipooligosaccharide (LOS)-specific enzymes, and focused our studies on the effect of LOS truncation in lectin binding to the bacteria. Intriguingly, LOS truncation gave rise to distinct binding profiles for Viscum album and Ricinus communis agglutinins, pointing to the recognition of different Gal-bearing targets. Besides the LOS molecule, a variety of glycoconjugates can be present at the bacterial surface, also encompassing glycoproteins of great significance in pathogenesis. In particular, in NTHi375, hmw loci code for two heavily glycosylated adhesins that are absent in other NTHi strains, as e.g. Rd KW20, a noninvasive laboratory strain. In this work, we pursued the dissection of bacterial surface ligands recognised by these two lectins. To this aim, we comparatively examined their binding to NTHi375, an NTHi375Δomp5 mutant suspected to overexpress LOS, Rd KW20, and an isogenic Rd KW20 mutant expressing HMW1, using our combined bacteria-based microarray and QCM approach. In parallel, recognition of the isolated NTHi375 and Rd KW20 LOSs, whose structures are known to be different, was also examined using LOS-based microarrays. Furthermore, saturation transfer difference NMR experiments allowed the identification of the sugar residues involved in the recognition. Altogether, the results revealed strain- and lectin-specific binding patterns, from the level of LOS molecules to the intact bacterial surface.This work was supported by the Marie Curie Initial Training Networks DYNANO (PITN-GA-2011-289033), GLYCOPHARM (PITN-GA-2012-317297) and WntsApp (PITN-GA-2013- 608180), the CIBER of Respiratory Diseases (CIBERES) – an initiative from the Spanish Institute of Health Carlos III (ISCIII), and the Spanish Ministry of Economy and Competitiveness (grants CTQ2015-64597-C2- 2-P, BFU2012-36825, BFU2015-70052-R, SAF2012-31166 and SAF2015-66520-R). I.K. was funded by a Marie Curie contract from the European Commission.Peer reviewe

Combined Bacteria Microarray and Quartz Crystal Microbalance Approach for Exploring Glycosignatures of Nontypeable Haemophilus influenzae and Recognition by Host Lectins

Recognition of bacterial surface epitopes by host receptors plays an important role in the infectious process and is intimately associated with bacterial virulence. Delineation of bacteria-host interactions commonly relies on the detection of binding events between purified bacteria- and host-target molecules. In this work, we describe a combined microarray and quartz crystal microbalance (QCM) approach for the analysis of carbohydrate-mediated interactions directly on the bacterial surface, thus preserving the native environment of the bacterial targets. Nontypeable Haemophilus influenzae (NTHi) was selected as a model pathogenic species not displaying a polysaccharide capsule or O-antigen-containing lipopolysaccharide, a trait commonly found in several important respiratory pathogens. Here, we demonstrate the usefulness of NTHi microarrays for exploring the presence of carbohydrate structures on the bacterial surface. Furthermore, the microarray approach is shown to be efficient for detecting strain-selective binding of three innate immune lectins, namely, surfactant protein D, human galectin-8, and Siglec-14, to different NTHi clinical isolates. In parallel, QCM bacteria-chips were developed for the analysis of lectin-binding kinetics and affinity. This novel QCM approach involves capture of NTHi on lectin-derivatized chips followed by formaldehyde fixation, rendering the bacteria an integrated part of the sensor chip, and subsequent binding assays with label-free lectins. The binding parameters obtained for selected NTHi-lectin pairs provide further insights into the interactions occurring at the bacterial surface.We gratefully acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (Grants BFU2012-36825, BFU2015-70052-R, SAF2012-31166, and SAF2015-66520-R), the Department of Health of the Navarra Government (ref 359/2012), the CIBER of Respiratory Diseases (CIBERES), an initiative from the Spanish Institute of Health Carlos III (ISCIII), and the Marie Curie Initial Training Networks DYNANO (Grant PITN-GA-2011-289033), GLYCOPHARM (Grant PITN-GA-2012-317297), and WntsApp (GA-No. 608180, FP7-PEOPLE-2013). I.K. and D.P. were funded by Marie Curie contracts from the European Commission.Peer Reviewe

Performances Recovery of Flax Fiber Reinforced Composites after Salt-Fog Aging Test

In the present paper, the performance recovery under conditions of discontinuous exposure to a marine environment of a natural fiber-reinforced composite (NFRC) reinforced by flax fibers was assessed. In particular, this laminate was initially exposed to salt-fog for 15 and 30 days, and then stored in a controlled air condition for up to 21 days. The flax fiber-reinforced composite showed coupled reversible and irreversible aging phenomena during the wet stage, as well as evidencing a significant mechanical recovery during the dry stage. Unlike the stiffness, the laminate showed a noticeable recovery of its flexural strength. This behavior affected the composite material toughness. A simplified approach was applied to define a topological map of the material toughness at varying drying times. The results highlight that the composite shows maximum toughness at intermediate drying times thanks to the strength recovery, in addition to its residual plasticity. This approach allows us to better determine that the strength is more closely related to reversible degradation phenomena, whereas the stiffness is mainly correlated to irreversible ones, implying relevant effects on the toughness of the composite exposed to a wet/dry cycle