Cholesterol modulates acetylcholine receptor diffusion by tuning confinement sojourns and nanocluster stability

Translational motion of neurotransmitter receptors is key for determining receptor number at the synapse and hence, synaptic efficacy. We combine live-cell STORM superresolution microscopy of nicotinic acetylcholine receptor (nAChR) with single-particle tracking, mean-squared displacement (MSD), turning angle, ergodicity, and clustering analyses to characterize the lateral motion of individual molecules and their collective behaviour. nAChR diffusion is highly heterogeneous: subdiffusive, Brownian and, less frequently, superdiffusive. At the single-track level, free walks are transiently interrupted by ms-long confinement sojourns occurring in nanodomains of ~36 nm radius. Cholesterol modulates the time and the area spent in confinement. Turning angle analysis reveals anticorrelated steps with time-lag dependence, in good agreement with the permeable fence model. At the ensemble level, nanocluster assembly occurs in second-long bursts separated by periods of cluster disassembly. Thus, millisecond-long confinement sojourns and second-long reversible nanoclustering with similar cholesterol sensitivities affect all trajectories; the proportion of the two regimes determines the resulting macroscopic motional mode and breadth of heterogeneity in the ensemble population.Fil: Mosqueira, Alejo. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Camino, Pablo A.. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Barrantes, Francisco Jose. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin

Percolation study for the capillary ascent of a liquid through a granular soil

Capillary rise plays a crucial role in the construction of road embankments in flood zones, where hydrophobic compounds are added to the soil to suppress the rising of water and avoid possible damage of the pavement. Water rises through liquid bridges, menisci and trimers, whose width and connectivity depends on the maximal half-length {\lambda} of the capillary bridges among grains. Low {\lambda} generate a disconnect structure, with small clusters everywhere. On the contrary, for high {\lambda}, create a percolating cluster of trimers and enclosed volumes that form a natural path for capillary rise. Hereby, we study the percolation transition of this geometric structure as a function of {\lambda} on a granular media of monodisperse spheres in a random close packing. We determine both the percolating threshold {\lambda}_{c} = (0.049 \pm 0.004)R (with R the radius of the granular spheres), and the critical exponent of the correlation length {\nu} = (0.830 \pm 0.051), suggesting that the percolation transition falls into the universality class of ordinary percolation

Contact forces distribution for a granular material from a Monte Carlo study on a single grain

The force network ensemble is one of the most promising statistical descriptions of granular media, with an entropy accounting for all force configurations at mechanical equilibrium consistent with some external stress. It is possible to define a temperature-like parameter, the angoricity {\alpha}^{-1}, which under isotropic compression is a scalar variable. This ensemble is frequently studied on whole packings of grains; however, previous works have shown that spatial correlations can be neglected in many cases, opening the door to studies on a single grain. Our work develops a Monte Carlo method to sample the force ensemble on a single grain at constant angoricity on two and three-dimensional mono-disperse granular systems, both with or without static friction. The results show that, despite the steric exclusions and the constrictions of Coulomb's limit and repulsive normal forces, the pressure per grain always show a gamma distribution with scale parameter {\nu} = {\alpha}^{-1} and shape parameter k close to k', the number of degrees of freedom in the system. Moreover, the average pressure per grain fulfills an equipartition theorem =k'{\alpha}^{-1} in all cases (in close parallelism with the one for an ideal gas). These results suggest the existence of k' independent random variables (i.e. elementary forces) with identical exponential distributions as the basic elements for describing the force network ensemble at low angoricities under isotropic compression, in analogy with the volume ensemble of granular materials

Interview investigation of insecure attachment styles as mediators between poor childhood care and schizophrenia-spectrum phenomenology

Background Insecure attachment styles have received theoretical attention and some initial empirical support as mediators between childhood adverse experiences and psychotic phenomena; however, further specificity needs investigating. The present interview study aimed to examine (i) whether two forms of poor childhood care, namely parental antipathy and role reversal, were associated with subclinical positive and negative symptoms and schizophrenia-spectrum personality disorder (PD) traits, and (ii) whether such associations were mediated by specific insecure attachment styles. Method A total of 214 nonclinical young adults were interviewed for subclinical symptoms (Comprehensive Assessment of At-Risk Mental States), schizophrenia-spectrum PDs (Structured Clinical Interview for DSM-IV Axis II Disorders), poor childhood care (Childhood Experience of Care and Abuse Interview), and attachment style (Attachment Style Interview). Participants also completed the Beck Depression Inventory-II and all the analyses were conducted partialling out the effects of depressive symptoms. Results Both parental antipathy and role reversal were associated with subclinical positive symptoms and with paranoid and schizotypal PD traits. Role reversal was also associated with subclinical negative symptoms. Angry-dismissive attachment mediated associations between antipathy and subclinical positive symptoms and both angry-dismissive and enmeshed attachment mediated associations of antipathy with paranoid and schizotypal PD traits. Enmeshed attachment mediated associations of role reversal with paranoid and schizotypal PD traits. Conclusions Attachment theory can inform lifespan models of how adverse developmental environments may increase the risk for psychosis. Insecure attachment provides a promising mechanism for understanding the development of schizophrenia-spectrum phenomenology and may offer a useful target for prophylactic intervention

Some aspects of the production and quality of set yoghurt using fat-substitutes and vegetable oils

Yoghurt is a popular fermented milk product where it is consumed in appreciable quantities in most countries in the world. In the present study the quality of natural set yoghurt was evaluated taking into consideration the following aspects: first, the production of low-calorie products where the milk fat was substituted by modified starches (e.g. Litesse, Lycadex 100 and 200, N-Oil II, Paselli SA2 and P-Fibre 150 C and 285 F) and microparticulated whey protein (e.g. Simplesse 100 dry and wet) because these products minic the fat mouth-feel and contain low energy values when compared with milk fat. Second, the manufacture of dietetic yoghurt by replacing the milk fat with different types of vegetable oils (e.g. olive, corn, sunflower and groundnut) that are high in mono- and poly-unsaturated fatty acids). Yoghurt was made from reconstituted skim milk powder (-14% total solids) fortified with fat-substitutes, vegetable oils or anhydrous milk fat (AMF) at 1.5%., warmed to 6

Disclosure of cholesterol recognition motifs in transmembrane domains of the human nicotinic acetylcholine receptor

Cholesterol influences ion-channel function, distribution and clustering in the membrane, endocytosis, and exocytic sorting of the nicotinic acetylcholine receptor (AChR). We report the occurrence of a cholesterol recognition motif, here coined “CARC”, in the transmembrane regions of AChR subunits that bear extensive contact with the surrounding lipid, and are thus optimally suited to convey cholesterol-mediated signaling from the latter. Three cholesterol molecules could be docked on the transmembrane segments of each AChR subunit, rendering a total of 15 cholesterol molecules per AChR molecule. The CARC motifs contribute each with an energy of interaction between 35 and 52 kJ.mol−1, adding up to a total of about 200 kJ.mol−1 per receptor molecule, i.e. ∼40% of the lipid solvation free energy/ AChR molecule. The CARC motif is remarkably conserved along the phylogenetic scale, from prokaryotes to human, suggesting that it could be responsible for some of the above structural/functional properties of the AChR

Desempenho ambiental e eficiência energética do óleo de pinhão-manso, pela abordagem da avaliação do ciclo de vida.

Resumo: A sociedade vem buscando cada vez mais fontes renováveis de energia para substituição dos combustíveis fósseis, devido ao seu inevitável esgotamento futuro e à sua contribuição ao fenômeno do aquecimento global. Em função disso, o incentivo para a produção de combustíveis de base vegetal cresceu no Brasil, merecendo atenção, dentre as culturas oleaginosas, o pinhão-manso (Jatropha curcas L.), conhecido por sua elevada produção de óleo, alta rusticidade e adaptabilidade a condições de solo e clima nos quais a produção de alimentos é impraticável. Visando o desenvolvimento de tal cultura para a produção de biodiesel, os seus impactos ambientais potenciais devem ser analisados. No presente trabalho, diferentes eficiências de produção de grãos e óleo de pinhão-manso e diferentes opções de aproveitamento de resíduos foram estudados, por meio da metodologia de Avaliação do Ciclo que Vida (ACV), buscando-se identificar as alternativas mais sustentáveis para esta cadeia produtiva. No que se refere à Demanda Cumulativa de Energia e às Mudanças Climáticas, a produtividade agrícola e a eficiência da extração de óleo foram determinantes para o bom desempenho do sistema. O cenário de aproveitamento de resíduos mais favorável foi o que empregou resíduos agrícolas e industriais em substituição aos fertilizantes. Abstract: The seek for renewable energy sources to replace fossil fuels, due to its inevitable future depletion and its contribution to the global warming phenomenon, is a worldwide pursuit. As a result, the incentive for the production of plant-based fuels expanded in Brazil, deserving attention, among oilseed crops, the jatropha (Jatropha curcas L.), known for its high oil yield, high rusticity and adaptability to conditions of soil and climate in which food production is impracticable. Aiming at the development of the jatropha crop for the production of biodiesel, its potential environmental impacts should be evaluated. In this study, efficiency of jatropha grain production and of oil production, and options for reuse of the residues were evaluated, using the methodology of Life Cycle Assessment (LCA), seeking to identify more sustainable alternatives to this production chain. Concerning the impact categories of Cumulative Energy Demand and Climate Change, the crop yield and the efficiency of oil extraction were crucial to the performance of the whole system. Considering the reuse of residues, the scenario where the agricultural and industrial residues were used to replace fertilizers shown to be more favorable

The Influence of Parental Dietary Behaviors and Practices on Children’s Eating Habits

Poor dietary habits established during childhood might persist into adulthood, increasing the risk of developing obesity and obesity-related complications such as Type 2 Diabetes Mellitus. It has been found that early modifications in eating habits, especially during childhood, might promote health and decrease the risk of developing diseases during later life. Various studies found a great influence of parental dietary habits on dietary behaviors of their children regardless of demographic characteristics such as gender, age, socioeconomic status and country; however, the exact mechanism is still not clear. Therefore, in this review, we aimed to investigate both parents' and children's dietary behaviors, and to provide evidence for the potential influence of parents' dietary behaviors and practices on certain children's eating habits. Family meals were found to contribute the most in modeling children's dietary habits as they represent an important moment of control and interaction between parents and their children. The parental practices that influenced their children most were role modeling and moderate restriction, suggesting that the increase of parental encouragement and decrease of excessive pressure could have a positive impact in their children's dietary behaviors. This narrative review highlights that parental child-feeding behaviors should receive more attention in research studies as modifiable risk factors, which could help to design future dietary interventions and policies to prevent dietary-related diseases

Imaging the Electrocyte of Torpedo Marmorata by Scanning Force Microscopy

Scanning force microscopy (SFM) and scanning electron microscopy (SEM) were used to examine the tissue structure of the electric organ of Torpedo marmorata in air and in liquid after applying fracturing and cryosectioning techniques and chemical fixation. The electric organ is organized in columns of stacked electrocytes, arranged in a honeycomb pattern. The columns were cut along a plane normal to the cell stack and thin sections were transferred to polylysine coated glass coverslips. The polarity of the electrocytes was made apparent by immunofluorescence microscopy directed to different domains of the acetylcholine receptor (AChR), thus revealing the innervated face of the cell. SFM and SEM both showed cell surfaces to be overlaid by a network of collagen fibers by their characteristic banding pattern with about 64 nm periodicity and about 2.5 nm corrugation amplitude. In liquid, significantly lower structural resolution was achieved by SFM, probably due to sample elasticity