Clathrin self-assembly is regulated by three light-chain residues controlling the formation of critical salt bridges

Clathrin self-assembly into a polyhedral lattice mediates membrane protein sorting during endocytosis and organelle biogenesis. Lattice formation occurs spontaneously in vitro at low pH and, intracellularly, is triggered by adaptors at physiological pH. To begin to understand the cellular regulation of clathrin polymerization, we analyzed molecular interactions during the spontaneous assembly of recombinant hub fragments of the clathrin heavy chain, which bind clathrin light-chain subunits and mimic the self-assembly of intact clathrin. Reconstitution of hubs using deletion and substitution mutants of the light-chain subunits revealed that the pH dependence of clathrin self-assembly is controlled by only three acidic residues in the clathrin light-chain subunits. Salt inhibition of hub assembly identified two classes of salt bridges which are involved and deletion analysis mapped the clathrin heavy-chain regions participating in their formation. These combined observations indicated that the negatively charged regulatory residues, identified in the light-chain subunits, inhibit the formation of high-affinity salt bridges which would otherwise induce clathrin heavy chains to assemble at physiological pH. In the presence of light chains, clathrin self-assembly depends on salt bridges that form only at low pH, but is exquisitely sensitive to regulation. We propose that cellular clathrin assembly is controlled via the simple biochemical mechanism of reversing the inhibitory effect of the light-chain regulatory sequence, thereby promoting high-affinity salt bridge formation.     

Significance of a first-time atypical Papanicolaou smear in a young, high-risk African-American and Latino-American population

The first atypical Papanicolaou smear in young, sexually active Latino and African-American women of low socioeconomic status may be predictive of underlying cervical neoplasia and human papillomavirus infection of significant quantity. The optimal management of first-time atypia on routine Pap smear has not been established. In many clinics, colposcopically directed sampling of the cervix is recommended only if atypia persists following specific or nonspecific treatment of cervicitis or after an arbitrarily determined time interval. Others recommend immediate colposcopic evaluation. To determine the best approach to the first-time atypical Pap smear in young minority women at high risk for the development of cervical cancer, 250 such patients were evaluated with colposcopically directed biopsy of the cervix prior to any form of therapy. Pap smears were repeated at the time of colposcopy. Histologically, there was evidence of cervical intraepithelial neoplasia in 41% of patients and human papillomavirus infection in 86%. Repeat Pap smears predicted the presence of cervical intraepithelial neoplasia in only 24% of patients. Immediate colposcopic evaluation represents the most prudent approach to the first-time atypical Pap smear in young, high-risk minority women.     

Relation of racial identity attitudes to self-actualization and affective states of Black students.

The relation between racial identity attitudes derived from W. E. Cross's (1971) model of psychological nigrescence, or Black self-actualization, and various affective states hypothesized to be relevant to the racial identification process, were investigated through multiple regression analysis. Cross proposed a model of how a person converts from Negro to Black, a process consisting of 5 distinct psychological stages characterized by different racial identity attitudes. Ss were 166 Black university students, who completed the Personal Orientation Inventory, a racial attitude scale, the SCL-90, and a personal-data information sheet. Both pro-White–anti-Black (preencounter) and pro-Black–anti-White (immersion) attitudes were associated with greater personal distress, as indicated by negative relations between these attitudes and mentally healthy self-actualizing tendencies and by positive relations to feelings of inferiority, anxiety, and hostility. Awakening Black identity (encounter attitudes) was positively related to self-actualization tendencies and negatively related to feelings of inferiority and anxiety. The possibility that cognitive and affective components of racial identity attitudes may evolve via different models is explored. Recommendations for delivery of psychological services to Black populations are discussed. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of the important challenges and opportunities related to modeling of mammalian cell bioreactors

Industrialization of mammalian cell culture has been achieved by integrating knowledge from several applying core concepts of chemical engineering, cellular and molecular biology, and biochemistry. Modeling has been applied to biological and physical processes to gain additional insights into such processes. This article covers modeling of the bioreactor and metabolic processes as it applies to bioprocess. Hydrodynamics of a bioreactor is briefly described while additional focus is given to gas‐liquid mass transfer. Biological modeling is presented in the order of increasing complexity. First steady state models are presented followed by dynamic models, cybernetic models, and finally bioreactor integrated models. The closing discussion summarizes challenges of implementation of model‐based approaches in the biopharmaceutical industry. © 2016 American Institute of Chemical Engineers AIChE J, 63: 398–408, 2017     

Deep feature learning versus shallow feature learning systems for joint use of airborne thermal hyperspectral and visible remote sensing data

Recently, the development of various remote sensing sensors has provided more reliable information and data for identification of different ground classes. Accordingly, multisensory fusion techniques are applied to enhance the process of information extraction from complementary airborne and spaceborne remote sensing data. Most of previous research in the literature has focused on the extraction of shallow features from a specific sensor and on classification of the resulted feature space using decision fusion systems. In recent years, Deep Learning (DL) algorithms have drawn a lot of attention in the machine learning area and have had different remote sensing applications, especially on data fusion. This study presents two different feature-learning strategies for the fusion of hyperspectral thermal infrared (HTIR) and visible remote sensing data. First, a Deep Convolutional Neural Network (DCNN)-Support Vector Machine (SVM) was utilized on the features of two datasets to provide the class labels. To validate the results with other learning strategies, a shallow feature model was used, as well. This model was based on feature fusion and decision fusion that classified and fused the two datasets. A co-registered thermal infrared hyperspectral (HTIR) and Fine Resolution Visible (Vis) RGB imagery was available from Quebec of Canada to examine the effectiveness of the proposed method. Experimental results showed that, except for the computational time, the proposed deep learning model outperformed shallow feature-based strategies in the classification performance that was based on its accuracy.     

Analysis and modeling of modified styrene–acrylonitrile/carboxylated acrylonitrile butadiene rubber nanocomposites filled with graphene and graphene oxide: Interfacial interaction and nonlinear elastoplastic behavior

Nonlinear elastoplastic behavior of the nanocomposites based on the styrene–acrylonitrile/carboxylated acrylonitrile butadiene rubber (SAN/XNBR) blend was investigated using experimental and theoretical analysis. Graphene, graphene oxide nanoparticles, and glycidyl methacrylate-grafted-XNBR (XNBR-g-GMA) as a compatibilizer were incorporated in the SAN/XNBR blends. In this regard, the focus of this study is on modeling of the stress–strain behavior of these nanocomposites, considering the effect of the interfacial interactions made by compatibilizer. For this purpose, field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) techniques were used to investigate the relationship between microstructure and mechanical properties of nanocomposites. In addition, FESEM and TEM images showed that the presence of a compatibilizer could influence the dispersion and localization of the nanoparticles. According to the tensile test results, the presence of the compatibilizer increased the mechanical properties of the nanocomposites, specifically elongation at break. Considering the nanocomposite containing compatibilizer and graphene oxide, the elongation at break increased about 570% compared with the nanocomposite without compatibilizer. Better dispersion of graphene oxide and the creation of chemical interaction among components in the presence of the XNBR-g-GMA compatibilizer could be the reasons for these improvements, as confirmed by TEM. The usage of the Bergstrom–Boyce model for analyzing the nonlinear elastoplastic behavior of the nanocomposites illustrated proper conformity with the experimental data in the elastic region. However, there are some deviations in the viscoplastic region, particularly close to the breaking elongation region.     

Wind-driven ventilation improvement with plan typology alteration: A CFD case study of traditional Turkish architecture

Aligned with achieving the goal of net-zero buildings, the implementation of energy-saving techniques in minimizing energy demands is proving more vital than at any time. As practical and economic options, passive strategies in ventilation developed over thousands of years have shown great potential for the reduction of residential energy demands, which are often underestimated in modern building’s construction. In particular, as a cost-effective passive strategy, wind-driven ventilation via windows has huge potential in the enhancement of the indoor air quality (IAQ) of buildings while simultaneously reducing their cooling load. This study aims to investigate the functionality and applicability of a common historical Turkish architectural element called “Cumba” to improve the wind-driven ventilation in modern buildings. A case study building with an archetypal plan and parameters was defined as a result of a survey over 111 existing traditional samples across Turkey. Buildings with and without Cumba were compared in different scenarios by the development of a validated CFD microclimate model. The results of simulations clearly demonstrate that Cumba can enhance the room’s ventilation rate by more than two times while harvesting wind from different directions. It was also found that a flexible window opening strategy can help to increase the mean ventilation rate by 276%. Moreover, the room’s mean air velocity and ventilation rate could be adjusted to a broad range of values with the existence of Cumba. Thus, this study presents important findings about the importance of plan typology in the effectiveness of wind-driven ventilation strategies in modern dwellings.     

Designing the Gastronomic Quarter

Throughout the world, urban gastronomic quarters, centred on fresh-food markets, have been pulled back from the brink of extinction. Susan Parham explains how movements like Slow Food and Slow Cities in Italy, and the international demand for organic produce, have started to challenge the global food network of production and consumption. The growing revitalisation of urban quarters around produce markets not only serves customers seeking fresh produce, food products and lively cafés and restaurants, but also offers valuable lessons in urban design.     

A proposed mechanism of action of textile/Al2O3–TiO2 bimetal oxide nanocomposite as an antimicrobial agent

The textile/Al₂O₃–TiO₂ bimetal oxide nanocomposite has been developed as an antimicrobial agent, but its antimicrobial mechanism has still not been clarified. The Al₂O₃–TiO₂ bimetal oxide nanoparticle has been reported as a radical scavenger. This study focuses on investigating the antimicrobial mechanism of the textile/Al₂O₃–TiO₂ bimetal oxide nanocomposite against Escherichia coli and their interaction with cell envelope biomolecules. L-α-Phosphatidyl ethanolamine (PE) is used as a model of bacteria to investigate the antimicrobial mechanism of this nanocomposite. The antimicrobial activity of the textile/Al₂O₃–TiO₂ bimetal oxide nanocomposite was investigated by using attenuated total reflectance/Fourier transform infrared (ATR-FTIR) and UV–Vis, while the toxicity of this nanocomposite was also examined through tissue culture test against a fibroblast skin cell. The ATR-FTIR used was able to confirm the destroyed cell envelope of the bacteria. The amounts of reactive oxygen species (ROS) were analyzed by UV–Vis spectroscopy and the toxicity of this nanocomposite was also examined by reacting tissue culture against the fibroblast skin cell. Overall, the antimicrobial mechanism of this textile nanocomposite was first by the attachment of this nanocomposite through the attachment of this nanoparticle to the surface of PE (as the model of bacteria) by hydrogen binding, and then nanoparticles can destroy the cell wall of bacteria through oxidation reaction by the produced ROS. Finally, these nanoparticles scavenged the ROS free radical. Therefore, the attached nanoparticles attached on textile can kill bacteria without any ROS free radical remaining in human body. These results suggest that the antimicrobial mechanism of this nanocomposite is mostly different due to the scavenger ability of this nanocomposite and its lower toxicity.