165 research outputs found

    Enhancing a Sense of Competence at Work by Engaging in Proactive Behavior: The Role of Proactive Personality

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    To understand how individuals’ senses of competence are cultivated, scholars have primarily focused on situational factors such as job autonomy and supervisor support. Against this backdrop, we propose that individuals can work as active agents and enhance their sense of competence by initiating actions that aim to master the environment. We adopt the behavioral concordance model and propose that people higher in proactive personality are more likely to engage in proactive behavior that elevates their senses of competence over time. We further propose that such behavioral concordance contributes to boosting a sense of competence is more prominent among those with higher proactive personality. Our predictions are supported by data from 172 employees and their direct supervisors in China, after controlling for the effect of job autonomy and supervisor support for autonomy. Specifically, only those higher in proactive personality engaged in more proactive behavior and increased their sense of competence over time. This study highlights both a self-initiated and a behavioral perspective on understanding the development of a sense of competence

    Dynamic motion of polar skyrmions in oxide heterostructures

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    Polar skyrmions have been widely investigated in oxide heterostructure recently, due to their exotic properties and intriguing physical insights. Meanwhile, so far, the external field-driven motion of the polar skyrmion, akin to the magnetic counterpart, has yet to be discovered. Here, using phase-field simulations, we demonstrate the dynamic motion of the polar skyrmions with integrated external thermal, electrical, and mechanical stimuli. The external heating reduces the spontaneous polarization hence the skyrmion motion barrier, while the skyrmions shrink under the electric field, which could weaken the lattice pinning and interactions between the skyrmions. The mechanical force transforms the skyrmions into c-domain in the vicinity of the indenter center under the electric field, providing the space and driving force needed for the skyrmions to move. This study confirmed that the skyrmions are quasi-particles that can move collectively, while also providing concrete guidance for the further design of polar skyrmion-based electronic devices.Comment: 17 pages, 4 figure

    Zinc-finger domains of the transcriptional repressor KLF15 bind multiple sites in rhodopsin and IRBP promoters including the CRS-1 and G-rich repressor elements

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    BACKGROUND: In the retina, many of the genes that encode components of the visual transduction cascade and retinoid recycling are exclusively expressed in photoreceptor cells and show highly stereotyped temporal and spatial expression patterns. Multiple transcriptional activators of photoreceptor-specific genes have been identified, but little is known about negative regulation of gene expression in the retina. We recently identified KLF15, a member of the Sp/Krüppel-like Factor family of zinc-finger containing transcription factors, as an in vitro repressor of the promoters of the photoreceptor-specific genes rhodopsin and IRBP/Rbp3. To gain further insight into the mechanism of KLF15-mediated regulation of gene expression, we have characterized the binding characteristics and specificity of KLF15's DNA binding domains and defined the KLF15 binding sites in the rhodopsin and IRBP promoters. RESULTS: In EMSA and DNAseI footprinting assays, a KLF15-GST fusion protein containing the C-terminal zinc-finger domains (123 amino acids) showed zinc-dependent and sequence-specific binding to a 9 bp consensus sequence containing a core CG/TCCCC. Both the bovine rhodopsin and IRBP promoters contained multiple KLF15 binding sites that included the previously identified CRS-1 and G-rich repressor elements. KLF15 binding sites were highly conserved between the bovine, human, chimp and dog rhodopsin promoters, but less conserved in rodents. KLF15 reduced luciferase expression by bRho130-luc (containing 4 KLF15 sites) and repressed promoter activation by CRX (cone rod homeobox) and/or NRL (neural retina leucine zipper), although the magnitude of the reduction was smaller than previously reported for a longer bRho225-luc (containing 6 KFL15 sites). CONCLUSION: KLF15 binds to multiple 9 bp consensus sites in the Rhodospin and IRBP promoters including the CRS-1 and G-rich repressor elements. Based on the known expression pattern of KLF15 in non-photoreceptor cells, we hypothesize an in vivo role for KLF15 in repressing photoreceptor-specific gene expression in the inner retina

    Evidence for an iterative module in chain elongation on the azalomycin polyketide synthase.

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    The assembly-line synthases that produce bacterial polyketide natural products follow a modular paradigm in which each round of chain extension is catalysed by a different set or module of enzymes. Examples of deviation from this paradigm, in which a module catalyses either multiple extensions or none are of interest from both a mechanistic and an evolutionary viewpoint. We present evidence that in the biosynthesis of the 36-membered macrocyclic aminopolyol lactones (marginolactones) azalomycin and kanchanamycin, isolated respectively from Streptomyces malaysiensis DSM4137 and Streptomyces olivaceus Tü4018, the first extension module catalyses both the first and second cycles of polyketide chain extension. To confirm the integrity of the azl gene cluster, it was cloned intact on a bacterial artificial chromosome and transplanted into the heterologous host strain Streptomyces lividans, which does not possess the genes for marginolactone production. When furnished with 4-guanidinobutyramide, a specific precursor of the azalomycin starter unit, the recombinant S. lividans produced azalomycin, showing that the polyketide synthase genes in the sequenced cluster are sufficient to accomplish formation of the full-length polyketide chain. This provides strong support for module iteration in the azalomycin and kanchanamycin biosynthetic pathways. In contrast, re-sequencing of the gene cluster for biosynthesis of the polyketide β-lactone ebelactone in Streptomyces aburaviensis has shown that, contrary to a recently-published proposal, the ebelactone polyketide synthase faithfully follows the colinear modular paradigm

    QTL identification and candidate gene identification for monoterpene content in grape (Vitis vinifera L.) berries

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    Great progress has been made during the last decade in clarifying the molecular details of aroma accumulation in grape berries. However, the multigene complex controlling monoterpene accumulation in grape is not well understood. To shed light on this issue, the grapes of 149 F1 progenies from the cross 87-1 (Vitis vinifera L.) × 9-22 (Vitis vinifera L.) were characterized at the mature stage for three representative free monoterpenes during five growing seasons. A total of 202, 184 and 255 polymorphic SSR (simple sequence repeat) markers were contracted on the maternal 87-1, paternal 9-22 and consensus genetic maps, respectively. On the consensus map, we confirmed a major QTL (quantitative trait locus) for free linalool, nerol and α-terpineol content on linkage group (LG) 5, and a stable QTL for free linalool and α-terpineol was detected on LG 10. In addition, two new stable QTLs for free monoterpene (linalool, nerol and α-terpineol) contents were identified on LG 11 and LG 18 that explained up to 42.5 % of the total variance. Eleven promising candidate genes related to pentatricopeptide repeat (PPR)-containing proteins, seed maturation protein, RING finger protein, and AP2/ERF transcription factors might be potentially involved in monoterpene accumulation. The stable QTLs and candidate genes identified in this study provide new insights into free monoterpene accumulation in grape

    Alzheimer’s disease: amyloid-based pathogenesis and potential therapies

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    Alzheimer’s disease is one of the most severe neurodegenerative diseases among elderly people. Different pathogenic factors for Alzheimer’s disease have been posited and studied in recent decades, but no effective treatment has been found, necessitating further studies. In this Viewpoint article, we assess studies on the mechanisms underlying the accumulation of amyloid b (Aβ) peptide and the formation of Aβ oligomers because their accumulation in amyloid plaques in brain tissue has become a well-studied hallmark of Alzheimer’s disease. We focus on the production of Aβ and its impact on the function of synapses and neural circuits, and also discuss the clinical prospects for amyloid-targeted therapies

    Unexpected enzyme-catalysed [4+2] cycloaddition and rearrangement in polyether antibiotic biosynthesis

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    Enzymes that catalyse remarkable Diels–Alder-like [4+2] cyclizations have been previously implicated in the biosynthesis of spirotetronate and spirotetramate antibiotics. Biosynthesis of the polyether antibiotic tetronasin is not expected to require such steps, yet the tetronasin gene cluster encodes enzymes Tsn11 and Tsn15, which are homologous to authentic [4+2] cyclases. Here, we show that deletion of Tsn11 led to accumulation of a late-stage intermediate, in which the two central rings of tetronasin and four of its twelve asymmetric centres remain unformed. In vitro reconstitution showed that Tsn11 catalyses an apparent inverse-electron-demand hetero-Diels–Alder-like [4+2] cyclization of this species to form an unexpected oxadecalin compound that is then rearranged by Tsn15 to form tetronasin. To gain structural and mechanistic insight into the activity of Tsn15, the crystal structure of a Tsn15-substrate complex has been solved at 1.7 Å resolution

    Rhodapentalenes: Pincer Complexes with Internal Aromaticity

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    Summary(#br)Pincer complexes are a remarkably versatile family benefited from their stability, diversity, and tunability. Many of them contain aromatic organic rings at the periphery, and aromaticity plays an important role in their stability and properties, whereas their metallacyclic cores are not aromatic. Herein, we report rhodapentalenes, which can be viewed as pincer complexes in which the metallacyclic cores exhibit considerable aromatic character. Rhodapentalenes show good thermal stability, although the rhodium-carbon bonds in such compounds are fragile. Experimental and computational studies suggest that the stabilization of rigid CCC pincer architectures together with an intrinsic aromaticity is vital for these metallacyclic rhodium species. Dearomatization-aromatization reactions, corresponding to metal-ligand cooperation of classical aromatic pincer complexes, were observed in this system. These findings suggest a new concept for pincer chemistry, the internal aromaticity involving metal d -orbitals, which would be useful for exploiting the nature of construction motif and inspire further applications
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