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It is well established that cell-intrinsic signaling through the receptor tyrosine kinase KIT is critical for the development of neural crest–derived melanocytes. Nevertheless, it is not entirely clear whether Kit acts exclusively in a melanocyte-autonomous manner or in addition indirectly through other cell types. To address this question in vivo, we generated a targeted allele of Kit that allowed for CRE recombinase-mediated deletion of the transmembrane domain of KIT. Mice carrying one copy of the targeted allele and expressing CRE under the melanoblast/melanocyte-specific tyrosinase promoter exhibited a white spotting phenotype that was even more extensive compared with that found in mice heterozygous for a Kit-null allele. This phenotype is unlikely the result of sequestration of KIT ligand by neighboring cells or by potentially secreted forms of KIT because the spotting phenotype could not be rescued by overexpression of KITL. Likewise, overexpression of endothelin-3 or hepatocyte growth factor was unable to rescue melanocytes in these mice. Although the severity of the observed phenotype remains to be explained, the findings indicate that melanocyte-selective impairment of Kit is sufficient to interfere with normal melanocyte development.
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We investigated the course of language processing in the context of a verification task that required numerical estimation and comparison. Participants listened to sentences with complex quantifiers that contrasted in Polarity, a logical property (e.g., more-than-half, less-than-half), and then performed speeded verification on visual scenarios that displayed a proportion between 2 discrete quantities. We varied systematically not only the sentences, but also the visual materials, in order to study their effect on the verification process. Next, we used the same visual scenarios with analogous non-verbal probes that featured arithmetical inequality symbols (). This manipulation enabled us to measure not only Polarity effects, but also, to compare the effect of different probe types (linguistic, non-linguistic) on processing.
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The high accumulation of silicon (Si) protects plants from biotic and abiotic stresses. Two different types of Si transporter [Low Silicon 1 (Lsi1) and 2 (Lsi2)] involved in the uptake and distribution of Si have been identified. Lsi1, a Si permeable channel, belongs to the Nod26-like major intrinsic protein (NIP) III subgroup of the aquaporin membrane protein family with a distinct selectivity, whereas Lsi2, an efflux Si transporter, belongs to an uncharacterized anion transporter family. These transporters are localized to the plasma membrane, but, in different plant species, show different expression patterns and tissue or cellular localizations that are associated with different levels of Si accumulation. A recent mathematical modeling study revealed that cooperation of Lsi1 and Lsi2, which show a polarized localization, is required for the efficient transport of Si in rice.
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The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulate their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier. Here, we present the dodecameric structure of SpeG from V. cholerae in a ligand-free form in three different conformational states: open, intermediate and closed. All structures were crystallized in C2 space group symmetry and contain six monomers in the asymmetric unit cell. Two hexamers related by crystallographic 2-fold symmetry form the SpeG dodecamer. The open and intermediate states have a unique open dodecameric ring. This SpeG dodecamer is asymmetric except for the one 2-fold axis and is unlike any known dodecameric structure. Using a fluorescence thermal shift assay, size-exclusion chromatography with multi-angle light scattering, small-angle X-ray scattering analysis, negative-stain electron microscopy and structural analysis, we demonstrate that this unique open dodecameric state exists in solution. Our combined results indicate that polyamines trigger conformational changes and induce the symmetric closed dodecameric state of the protein when they bind to their allosteric sites.
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With the increasing resolution of digital elevation models (DEMs), computational efficiency problems have been encountered when extracting the drainage network of a large river basin at billion-pixel scales. The efficiency of the most time-consuming depression-filling pretreatment has been improved by using the O(NlogN) complexity least-cost path search method, but the complete extraction steps following this method have not been proposed and tested. In this paper, an improved O(NlogN) algorithm was proposed by introducing a size-balanced binary search tree (BST) to improve the efficiency of the depression-filling pretreatment further. The following extraction steps, including the flow direction determination and the upslope area accumulation, were also redesigned to benefit from this improvement. Therefore, an efficient and comprehensive method was developed. The method was tested to extract drainage networks of 31 river basins with areas greater than 500,000km2 from the 30-m-resolution ASTER GDEM and two sub-basins with areas of approximately 1000km2 from the 1-m-resolution airborne LiDAR DEM. Complete drainage networks with both vector features and topographic parameters were obtained with time consumptions in O(NlogN) complexity. The results indicate that the developed method can be used to extract entire drainage networks from DEMs with billions of pixels with high efficiency.
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Plasma membranes (PMs) are heterogeneous lipid bilayers comprising diverse subdomains. These sites can be labeled by various proteins in vivo and may serve as hotspots for signal transduction. They are found at apical, basal, and lateral membranes of polarized cells, at cell equatorial planes, or almost isotropically distributed throughout the PM. Recent advances in imaging technologies and understanding of mechanisms that allow proteins to target specific sites in PMs have provided insights into the dynamics and complexity of their specific segregation. Here we present a comprehensive overview of the different types of membrane microdomain and describe the molecular modes that determine site-directed targeting of membrane-resident proteins at the PM.
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Hierarchical ZnO nanoporous/nanowire architectures immobilized on a substrate were prepared by a facile two-step electrochemical technique. The layer optical properties have been characterized by absorption spectroscopy and photoluminescence measurements. The structures strongly absorbed UV light and had a high structural quality. The porosity of the hierarchical layers could be tuned by changing the duration of the second growth step. The photocatalytic activity of ZnO films was higher than that of arrayed ZnO nanowire layers and mesoporous ZnO films. The photocatalytic activity for 4-chlorophenol degradation could be enhanced by developing hierarchical structures with a high percentage exposure of polar (0001) facets, high specific surface area and good accessibility of the pollutant to the oxide surface. The modeling by density functional theory (DFT) of the degradation of 4-chlorophenol molecules by OH radicals lead to several important results, namely that the hydroxylation of the aromatic ring and its opening can occur in parallel releasing hydroperoxyl radical and hydroxyl radical, respectively. The restored OH radical can either further oxidize the primary ring opening product or attack another molecule of 4-chlorophenol. These computational results are in good agreement with the photocatalytic degradation observations made using both ZnO and TiO2 photocatalysts.
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We present a detailed exploration of VideoHandles, a novel interaction technique to support rapid review of wearable video camera data by re-performing gestures as a search query. The availability of wearable video capture devices has led to a significant increase in activity logging across a range of domains. However, searching through and reviewing footage for data curation can be a laborious and painstaking process. We showcase the use of gestures as search queries to support review and navigation of video data. By exploring example action-camera footage across a range of activities, we propose two video data navigation styles using gestures: prospective gesture tagging and retrospective gesture searching. This paper builds on our earlier VideoHandles work, reporting details of our interaction design and implementation, and presenting two additional evaluations. We demonstrate that VideoHandles is a viable interaction technique, returning promising results in its prototype form.
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Our research considers the role that new technologies could play in supporting emotional and non-verbal interactions between musicians during co-present music making. To gain a better understanding of the underlying affective and communicative processes that occur during such interactions, we carried out an exploratory study where we collected self-report and continuous behavioural and physiological measures from pairs of improvising drummers. Our analyses revealed interesting relationships between creative decisions and changes in heart rate. Self-reported measures of creativity, engagement, and energy were correlated with body motion; whilst EEG beta-band activity was correlated with self-reported positivity and leadership. Regarding co-visibility, lack of visual contact between musicians had a negative influence on self reported creativity. The number of glances between musicians was positively correlated with rhythmic synchrony, and the average length of glances was correlated with self-reported boredom. Our results indicate that ECG, motion, and glance measurements could be particularly suitable for the investigation of collaborative music making.
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Magnetic Antidot Lattice (MAL) arrays of Co have been prepared in micron range using ultraviolet (UV) lithography technique with different shapes and sizes. Magnetization reversal in such MAL systems has been studied by magneto-optic Kerr effect (MOKE) based microscopy by varying the angle between the easy axis and the external magnetic field. The domain images evidence that the magnetization reversal along easy axis is highly dominated by nucleation of domains which is subsequently accompanied by domain wall motion. We have observed that with increase in active magnetic area domain size increases but on the contrary coercivity decreases. The presence of periodic holes turns the MALs magnetically hard when compared to similar thickness of continuous thin film. The magnetization relaxation along easy axis for the Co MAL at constant dc field fits very well with the exponential law of Fatuzzo–Labrune indicating domain nucleated dominant process.
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