625 research outputs found

    Synthese, Assemblierung und intrazellulärer Transport von Mitgliedern der cys-loop- und P2X-Familie liganden-gesteuerter Ionenkanäle

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    The results presented here strongly indicate that ubiquitination of the recombinant human alpha1 GlyR at the plasma membrane of Xenopus oocytes is involved in receptor internalisation and degradation. Ubiquitination of the human alpha1 GlyR has been demonstrated by radio-iodination of plasma membrane-boundalpha1 GlyRs, whose subunits differed in molecular weight by additional 7, 14 or 21 kDa, corresponding to the molecular weights of one, two and three conjugated ubiquitin molecules, respectively, and by co-isolation of the non-tagged human alpha1 GlyR through hexahistidyl-tagged ubiquitin. Ubiquitin conjugated GlyRs where prominent at the plasma membrane, but could be hardly detected in total cell homogenates, indicating that ubiquitination takes place exclusively at the plasma membrane. Ubiquitination of the alpha1 GlyR at the plasma membrane was no longer detectable when the ten lysine residues of the cytoplasmic loop between transmembrane segments M3 and M4 were replaced by arginines. Despite this proteolytic cleavage continued to take place at the same extent as with the wild type alpha1 GlyR, suggesting that removal of GlyRs from the plasma membrane and routing to lysosomes for degradation were not dependent on ubiquitination. Also replacing a tyrosine in position 339, which was speculated to be part of an additional endocytosis motif, did not lead to a significant reduction of cleavage of the GlyR alpha1 subunits. However, a mutant lacking both, ubiquitination sites and 339Y, was significantly less processed. These results may suggest that the GlyR alpha1 subunit harbors at least two endocytosis motifs, which may act independently to regulate the density of alpha1 GlyR. Apparently, each of the two signals may be capable of compensating entirely the loss of the other. Part two of this Dissertation demonstrates that the correct topology of the glycine receptor alpha1 subunit depends critically on six positively charged residues within a basic cluster, RFRRKRR, located in the large cytoplasmic loop following the C-terminal end of M3. Neutralization of one or more charges of this cluster, but not of other charged residues in the M3-M4 loop, led to an aberrant translocation into the endoplasmic reticulum lumen of the M3-M4 loop. However, when two of the three basic charges located in the ectodomain linking M2 and M3 were neutralized, in addition to two charges of the basic cluster, endoplasmic reticulum disposition of the M3-M4 loop was prevented. We conclude that a high density of basic residues C-terminal to M3 is required to compensate for the presence of positively charged residues in the M2-M3 ectodomain, which otherwise impair correct membrane integration of the M3 segment. Part three of this Dissertation describes my contribution (blue native PAGE analysis of metabolically labeled alpha7 and 5HT3A receptors and the examination of the glycosylation state of metabolically labeled alpha7 subunits) to a work on the limited assembly capacity of Xenopus oocytes for nicotinic alpha7 subunits. While 5HT3A subunits combined efficiently to pentamers, alpha7 subunits existed in various assembly states including trimers, tetramers, pentamers, and aggregates. Only alpha7 subunits that completed the assembly process to homopentamers acquired complex-type carbohydrates and appeared at the cell surface. We conclude that Xenopus oocytes have a limited capacity to guide the assembly of alpha7 subunits, but not 5HT3A subunits to homopentamers. Accordingly, ER retention of imperfectly assembled alpha7 subunits rather than inefficient routing of fully assembled alpha7 receptors to the cell surface limits surface expression levels of alpha7 nicotinic acetylcholine receptors. Part four of this Dissertation describes my contribution (the biochemical analysis of the human P2X2 and P2X6 subtypes) to studies on the quaternary structure of P2X receptors. Armaz Aschrafi, the main author of the paper showed that subsequent to isolation under non-denaturing conditions from Xenopus oocytes the His-rP2X2 protein migrated on blue native PAGE predominantly in an aggregated form. The only discrete protein band detectable could be assigned to homotrimers of the His-rP2X2 subunit. Because of the exceptional assembly-behaviour of the rP2X2 protein compared to the rP2X1, rP2X3, rP2X4 and rP2X5 proteins, its human orthologue was investigated in the same manner. In contrast to rP2X2 subunits, hP2X2 subunits migrated under virtually identical conditions in a single defined assembly state, which could be clearly assigned to a trimer. P2X6 subunits represent the sole P2X subtype that is unable to form functional homomeric receptors in Xenopus oocytes. The blue native PAGE analysis of metabolically labeled hP2X6 receptors and the examination of the glycosylation state revealed that hP2X6 subunits form tetramers and aggregates that are not exported to the plasma membrane of Xenopus oocytes

    Vacuum Evaporation.

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    Investigating the neural basis of learning using brain-computer interfaces

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    Learning a new skill requires one to produce new patterns of activity among networks of neurons. This applies not only to physical skills, such as learning to play a new sport, but also to abstract skills, such as learning to play chess. An abstract skill that we can use to study the neural mechanisms of learning, in general, is controlling a brain-computer interface (BCI). BCIs were conceived of as assistive devices to help people with paralysis, limb-loss, or other neurological disorder, but they have also proven effective as tools to study the neural basis of sensory-motor control and learning. We tested the ability of subjects to generate neural activity patterns required to control arbitrary BCI decoders. We found that the subjects could more easily learn to control the decoder when they could use existing patterns of neural activity than when they needed to generate new patterns. We also analyzed the way in which subjects adapted their neural activity during learning. We found that neural activity adapts in a way that is consistent with the learning-related performance improvements and that the trial-to-trial variability of neural activity decreased as performance improved. We tested how specific properties of BCI decoders, which translate neural activity into movements of the effector, influence the ability to learn to control a BCI by incorporating dimensionality reduction into a Kalman filter and assessing how performance related to the number of latent dimensions. We found that the subjects could use a standard Kalman filter just as well as a Kalman filter that incorporates dimensionality reduction. However, as the dimensionality of the model increased, performance improved up to an asymptotic level. Lastly, we tested whether increasing the difficulty of a task would lead the subjects to learn to demonstrate better BCI performance. We implemented an instructed path task that required the animals to move a cursor along re-defined paths, and we found that this task motivated one monkey to improve his performance. In all, these studies help to uncover what contributes to BCI control, and they help pave the way for transitioning BCIs from the lab to the clinic

    TH2 T CELLS ARE REQUIRED FOR BIOMATERIAL-MEDIATED FUNCTIONAL MUSCLE REGENERATION

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    Regenerative medicine therapies that primarily target stem cells have achieved limited success. An alternative strategy is to focus on immune cells, the first responders to traumatic wounds, which can interact directly with biomaterial scaffolds. Here, we investigate how biomaterial scaffolds shape the immune microenvironment in non-traumatic subcutaneous and traumatic muscle wounds (VML) and ultimately impact tissue regeneration. A diverse population of immune cells is recruited into scaffolds and the surrounding area, including macrophages, dendritic cells, T lymphocytes and B lymphocytes. The scaffolds induced a pro-regenerative type-2 response, which, in the VML is characterized by an mTOR/Rictor-dependent Th2 pathway and IL-4-dependent macrophage polarization, critical for functional muscle regeneration. Targeting the adaptive components of the immune system during the process of biomaterials design may support the development of future therapies that efficiently control immune balance in tissues, ultimately stimulating tissue repair

    An exploratory study into teaching for social responsibility in apparel and textiles university programs

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    Doctor of PhilosophyDepartment of Educational LeadershipMajor Professor Not ListedThe purpose of this research was to investigate social responsibility in the apparel and textiles field through the lens of the faculty, including how they define social responsibility and incorporate it into the curriculum. This research explored how faculty who identify as teaching from a social responsibility perspective interpret the term, curriculum topics they address, their pedagogical approaches to instructional design of this curriculum, and the ways they assess student learning. As part of this research an interdisciplinary body of literature was examined within the context of teaching for social responsibility. Education was found to play a major role in encouraging young designers and industry professionals to embrace social responsibility, sustainable fashion, and to consider the product lifecycle (Moorhouse & Moorhouse, 2017). The quantitative research design for this study used a survey method. Analysis included frequency distributions, percentage ratios, and inductive analysis for the open-ended question data. This study aimed to improve the understanding for why and how apparel and textiles instructors include social responsibility in their curriculum. The findings showed that apparel and textiles instructors perceived social responsibility topics as important to the curriculum and that their personal experiences and beliefs influence how they define social responsibility. In addition, the results produced an updated and more inclusive list of social responsibility topics relevant to the current state of the apparel and textiles field. The results provided information about which instructional methods and assessment measures faculty use in their courses when teaching social responsibility topics. The findings aid in supporting faculty to include social responsibility in their teaching. Lastly, the results from this study can inform strategies to develop future curriculum design

    Perfluoroalkylated amphiphiles with a morpholinophosphate or a dimorpholinophosphate polar head group

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    Some previously synthesized (perfluoroalkyl)alkyldimorpholinophosphates, CnF2n+1CmH2mOP(O)-[N(CH2CH2)(2)O](2), were found remarkably to stabilize heat sterilizable water-in-fluorocarbon reverse emulsions and to have a strong proclivity to self-aggregate into microtubular assemblies when dispersed in water. This series has now been extended in order to allow structure-property relationships to be established and product optimization to be achieved. A new series of even more fluorophilic compounds consisting in bis[(perfluoroalkyl)alkyl]monomorpholinophosphates, (CnF2n+1CmH2mO)(2)P(O)N(CH2CH2)(2)O, was also synthesized. Preliminary surfactant activity and biocompatibility data are presented and compared to data obtained with non-fluorinated analogues

    Network platform for sound information analyzis

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    A new technique of audio information processing for automatic analysis and classification of records, including speech, has been proposed. The technique is based on information representation in the form of associative semantic (cognitive) network structure and deals with amplitude and frequency layers both

    Исследование закономерностей развития структурно-химической неоднородности в разнородном сварном соединении трубопроводного переходника

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    Данная работа посвящена исследованию структурно-химической неоднородности (СХН) трубопроводного переходника из разнородных сталей, выполненного аргонодуговой сваркой (АрДС). При помощи оптического микроскопа получены фотографии СХН и ее размеры. СХН выражается в появлении прослоек (карбидной и ферритной) с разным химическим составом. Приведены графики роста ширин прослоек от времени выдержки и температуры.This paper is devoted to the comparison of the structural and chemical inhomogeneity (SCI) of adapters made of dissimilar steels, made by tungsten insert gas (TIG). By means of optical microscope, photographs of the SCI and its dimensions were obtained. SCI is expressed in the appearance of interlayers (carbide and ferritic) with different chemical composition. Graphs of the growth of the widths of the interlayers from the time of exposure and temperature are given
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