2,978 research outputs found

    Cloning and Functional Analysis of three Cold Regulated <em>CBF</em> Genes in the Overwintering Crucifer <em>Boechera stricta</em>

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    In this research, we isolated three CBF (C-repeat-Binding Factors) genes from two genotypes of Boechera stricta with contrasting freezing tolerance and characterized their structure and expression patterns in response to cold treatment. An amino acid sequence comparison revealed that the CBF genes in B. stricta showed high conservation in the AP2 domain and PKKP/RAGR motif like other cold adaptable Brassicaceae. The pairwise sequence alignment of the CBF genes isolated from two genotypes of B. stricta showed non-synonymous mutations in CBF 2 and 3. Gene expression analysis demonstrated that CBF genes in B. stricta have expression patterns similar to CBFs in A. thaliana in response to cold treatment, while differential expression at the molecular level in CBF and COR genes was presented between two genotypes of B. stricta. Our results suggest that signal transduction of three CBF genes can be one of the central pathways in the development of freezing tolerance in B. stricta

    Revealing the role of local stress on the depolarization of BNT-BT-based relaxors

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    Canonical relaxors exhibit an electric-field-induced phase transition between a macroscopically nonpolar and polar phase that can be tuned from being stable at low temperature to being reversible at high temperature. The reversibility of this phase change determines the electromechanical performance and large strains can be achieved if the polar phase is intrinsically unstable. This paper is on the thermal depolarization characteristics of a BNT-BT-based multiphase relaxor ceramic observed through the transition temperature from field-induced polar to nonpolar state. It is shown that the progress of detexturization strongly depends on the crystallographic phase. In the more susceptible phase, it becomes significant about 40 °C below the macroscopically observed transition temperature. Additionally, the surface domain structure vanishes at lower temperatures than expected from both dielectric and structural measurements. The development of strong interfacial stresses aiding depolarization, and a mismatch in chemical pressure between surface and bulk, are discussed as the origins for the observed effects. Tailoring of interfacial stresses through chemical adaption of crystallographic phase fractions opens up a pathway to optimize the strain performance of actuator materials and can become a useful tool to stabilize metastable crystallographic phases as well as for property tuning in piezotronics, Mott insulators and multiferroics

    Direct measurement of the intermolecular forces confining a single molecule in an entangled polymer solution

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    We use optical tweezers to directly measure the intermolecular forces acting on a single polymer imposed by surrounding entangled polymers (115 kbp DNA, 1 mg/ml). A tube-like confining field was measured in accord with the key assumption of reptation models. A time-dependent harmonic potential opposed transverse displacement, in accord with recent simulation findings. A tube radius of 0.8 microns was determined, close to the predicted value (0.5 microns). Three relaxation modes (~0.4, 5 and 30 s) were measured following transverse displacement, consistent with predicted relaxation mechanisms.Comment: 11 pages, 3 figure

    Mechanical properties of ZnO epitaxial layers grown on a- and c-axis sapphire

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    The mechanical properties of zinc oxide epitaxial layers grown on a- and c-axis sapphire have been studied by spherical nanoindentation and cross-sectional transmission electron microscopy. As-grown threading dislocations, which are characteristic of epitaxialmaterial, combined with the presence of the much harder, underlying substrate are found to have a significant effect on the mechanical behavior of ZnO epilayers as compared to bulk material. Epilayer material is found to be significantly harder than its bulk counterpart. For a-axis epilayers, analysis of load–unload data yields a hardness of 6.6±1.2GPa, and 5.75±0.8GPa for c-axis layers. We attribute this increased hardness to strain compensation via the presence of as-grown defects. These defects inhibit the slip mechanism responsible for relative softness of bulk single crystals. The absence of pop-in events from analyzed continuous-load nanoindentation data is further evidence for strain compensation by native defects within the epilayers. Large variations in the spread of collected data are indicative of inhomegenity in the epilayers.The University of Sydney, for constructive comments and support. The work at UF is partially supported by the AFOSR under Grant Nos. F49620-03-1-0370 sT.S.d and NSF DMR 0400416

    The RNA polymerase II C-terminal domain-interacting domain of yeast Nrd1 contributes to the choice of termination pathway and couples to RNA processing by the nuclear exosome

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    The RNA polymerase II (RNApII) C-terminal domain (CTD)- interacting domain (CID) proteins are involved in two distinct RNApII termination pathways and recognize different phosphorylated forms of CTD. To investigate the role of differential CTD-CID interactions in the choice of termination pathway, we altered the CTD-binding specificity of Nrd1 by domain swapping. Nrd1 with the CID from Rtt103 (Nrd1(CIDRtt103)) causes read-through transcription at many genes, but can also trigger termination where multiple Nrd1/Nab3-binding sites and the Ser(P)-2 CTD co-exist. Therefore, CTD-CID interactions target specific termination complexes to help choose an RNApII termination pathway. Interactions of Nrd1 with bothCTDand nascent transcripts contribute to efficient termination by the Nrd1 complex. Surprisingly, replacing the Nrd1 CID with that from Rtt103 reduces binding to Rrp6/Trf4, and RNA transcripts terminated by Nrd1(CIDRtt103) are predominantly processed by core exosome. Thus, the Nrd1 CID couples Ser(P)-5 CTD not only to termination, but also to RNA processing by the nuclear exosome

    Visual Depth Mapping from Monocular Images using Recurrent Convolutional Neural Networks

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    A reliable sense-and-avoid system is critical to enabling safe autonomous operation of unmanned aircraft. Existing sense-and-avoid methods often require specialized sensors that are too large or power intensive for use on small unmanned vehicles. This paper presents a method to estimate object distances based on visual image sequences, allowing for the use of low-cost, on-board monocular cameras as simple collision avoidance sensors. We present a deep recurrent convolutional neural network and training method to generate depth maps from video sequences. Our network is trained using simulated camera and depth data generated with Microsoft's AirSim simulator. Empirically, we show that our model achieves superior performance compared to models generated using prior methods.We further demonstrate that the method can be used for sense-and-avoid of obstacles in simulation

    Germline mutations of the STK11 gene in Korean Peutz–Jeghers syndrome patients

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    Peutz–Jeghers syndrome (PJS) is an autosomal dominantly inherited disease characterized by hamartomatous gastrointestinal polyps and mucocutaneous pigmentation, with an increased risk for various neoplasms, including gastrointestinal cancer. Recently, the PJS gene encoding the serine/threonine kinase STK11 (also named LKB1) was mapped to chromosome 19p13.3, and germline mutations were identified in PJS patients. We screened a total of ten Korean PJS patients (nine sporadic cases and one familial case including two patients) to investigate the germline mutations of the STK11 gene. By polymerase chain reaction–single-strand conformation polymorphism and DNA sequencing analysis, three kinds of mis-sense mutation and a frame-shift mutation were identified: codon 232 (TCC to CCC) in exon 5, codon 256 (GAA to GCA) in exon 6, codon 324 (CCG to CTG) in exon 8, and a guanine insertion at codon 342 resulting in a premature stop codon in exon 8. These mis-sense variants were not detected in 100 control DNA samples. Furthermore, we found an intronic mutation at the dinucleotide sequence of a splice-acceptor site: a one base substitution from AG to CG in intron 1, which may cause aberrant splicing. Most reported germline mutations of the STK11 gene in PJS patients were frame-shift or non-sense mutations resulting in truncated proteins. Together, these findings indicate that germline mis-sense mutations of the STK11 gene are found in PJS patients in addition to truncating mutations. The effects of these mutations on protein function require further examination. In summary, we found germline mutations of the STK11 gene in five out of ten Korean PJS patients. © 2000 Cancer Research Campaig

    Prognostic relevance of a T-type calcium channels gene signature in solid tumours: A correlation ready for clinical validation

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    BackgroundT-type calcium channels (TTCCs) mediate calcium influx across the cell membrane. TTCCs regulate numerous physiological processes including cardiac pacemaking and neuronal activity. In addition, they have been implicated in the proliferation, migration and differentiation of tumour tissues. Although the signalling events downstream of TTCC-mediated calcium influx are not fully elucidated, it is clear that variations in the expression of TTCCs promote tumour formation and hinder response to treatment.MethodsWe examined the expression of TTCC genes (all three subtypes; CACNA-1G, CACNA-1H and CACNA-1I) and their prognostic value in three major solid tumours (i.e. gastric, lung and ovarian cancers) via a publicly accessible database.ResultsIn gastric cancer, expression of all the CACNA genes was associated with overall survival (OS) among stage I-IV patients (all pConclusionsAlterations in CACNA gene expression are linked to tumour prognosis. Gastric cancer represents the most promising setting for further evaluation
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