5,189 research outputs found

    Purification and characterization of a cold-adapted α-amylase produced by Nocardiopsis sp. 7326 isolated from Prydz Bay, Antarctic

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    This is the author accepted manuscript. The final version is available from Springer via the DOI in this record. An actinomycete strain 7326 producing cold-adapted α-amylase was isolated from the deep sea sediment of Prydz Bay, Antarctic. It was identified as Nocardiopsis based on morphology, 16S rRNA gene sequence analysis, and physiological and biochemical characteristics. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram activity staining of purified amylase showed a single band equal to a molecular mass of about 55 kDa. The optimal activity temperature of Nocardiopsis sp. 7326 amylase was 35°C, and the activity decreased dramatically at temperatures above 45°C. The enzyme was stable between pH 5 and 10, and exhibited a maximal activity at pH 8.0. Ca2+, Mn2+, Mg2+, Cu2+, and Co2+stimulated the activity of the enzyme significantly, and Rb2+, Hg2+, and EDTA inhibited the activity. The hydrolysates of soluble starch by the enzyme were mainly glucose, maltose, and maltotriose. This is the first report on the isolation and characterization of cold-adapted amylase from Nocardiopsis sp.National Natural Science Funds of Chin

    Molecular cloning and expression of a cold-adapted lipase gene from an antarctic deep sea psychrotrophic bacterium Pseudomonas sp. 7323

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    This is the author accepted manuscript. The final version is available from Springer via the DOI in this record .A psychrotrophic bacterium producing a cold-adapted lipase was isolated from the deep-sea sediment of Prydz Bay, Antarctic and identified as a Pseudomonas strain. Determination of the nucleotide sequence of the gene encoding a lipase from Pseudomonas sp. 7323 (lipA) revealed that LipA is composed of 617 amino acid residues with a calculated molecular weight of 64,466 Da. LipA has a GXSXG motif, which is conserved in lipases/esterases and generally contains the active-site serine. The lipase purified from the Escherichia coli transformant (rLipA) by metal-chelating chromatography exhibited the same electrophoretic mobility as did the wild-type lipase (wLipA) purified from strain 7323, and both enzymes were quite similar in physicochemical properties. The optimal temperature and pH value for the lipases activity were 30°C and 9.0, respectively. They were unstable at temperatures above 25°C and only retained half of their highest activity after incubation at 60°C for 5 min. These results indicated that the enzymes were typical alkaline cold-adapted enzymes. Both enzymes were particularly activated by Ca2+. Additionally, the enzymes hydrolyzed p-nitrophenyl caprate and tributyrin at the highest velocity among the other p-nitrophenyl esters and triglycerides.Hi-Tech research and development program of Chin

    The research progress on the mechanism of adenosine A1 receptor-mediated calcitonin gene-related peptide to relieve migraine

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    Currently, the pathogenesis of migraine is unclear. The trigeminal vascular reflex theory is the dominant pathogenesis theory, and its core parts are neurogenic inflammation and pain sensitisation. Calcitonin gene related peptide (CGRP) is the most powerful vasodilating peptide in brain circulation. It is also a marker of trigeminal nerve microvascular activation that plays a synergistic role in the pathogenesis of migraine. Adenosine A1 receptor (A1R) can inhibit the release of CGRP in the trigeminal nerve vascular system to alleviate migraine by mediating adenosine. This review summarises the progress of research on the alleviation of migraine by using A1R-mediated CGRP

    Reduced glutamine synthetase activity alters the fecundity of female Bactrocera dorsalis (Hendel)

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    Glutamine synthetase (GS) is a key enzyme in glutamine synthesis and is associated with multiple physiological processes in insects, such as embryonic development, heat shock response, and fecundity regulation. However, little is known about the influence of GS on female fecundity in the oriental fruit fly, Bactrocera dorsalis. Based on the cloning of BdGSs, mitochondrial BdGSm and cytoplasmic BdGSc, we determined their expressions in the tissues of adult B. dorsalis. BdGSm was highly expressed in the fat body, while BdGSc was highly expressed in the head and midgut. Gene silencing by RNA interference against two BdGSs isoforms suppressed target gene expression at the transcriptional level, leading to a reduced ovarian size and lower egg production. The specific inhibitor L-methionine S-sulfoximine suppressed enzyme activity, but only the gene expression of BdGSm was suppressed. A similar phenotype of delayed ovarian development occurred in the inhibitor bioassay. Significantly lower expression of vitellogenin and vitellogenin receptor was observed when GS enzyme activity was suppressed. These data illustrate the effects of two GS genes on adult fecundity by regulating vitellogenin synthesis in different ways

    A novel Internet of Things-supported intelligent education management system implemented via collaboration of knowledge and data

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    The past decade has witnessed great progress in the Internet of Things (IoT), which can provide integrated platforms for data with various formats and to serve different parts of human society. Although IoT-supported education management systems have achieved some successful applications, most existing systems cannot perform intelligent information processing, such as autonomous planning and optimal scheduling. To remedy this gap, this work proposes a novel IoT-supported intelligent education management system that is implemented via collaboration of knowledge and data. First, the macroscopic architecture is designed according to field knowledge of education management, and a clustering-based data analysis algorithm is utilized to visualize real-time classroom characteristics. Then, statistics of learning status are generated, and personalized following plans are accordingly suggested to different specific users. Finally, the functions of the designed smart education management system are tested via computer simulation operations. The obtained results show that the proposal can work well under a real-time data stream and is expected to serve as a typical education management application in smart cities. Through verification, it is found that the integration of general education and professional courses is the ideal starting point for the design of the elements of an optimal course structure for engineering practice majors. In particular, we should strengthen the reform of the following course types: introduction to design, general education, concentrated practice, comprehensive design and peak courses

    Evaluation of ChatGPT-Generated Medical Responses: A Systematic Review and Meta-Analysis

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    Large language models such as ChatGPT are increasingly explored in medical domains. However, the absence of standard guidelines for performance evaluation has led to methodological inconsistencies. This study aims to summarize the available evidence on evaluating ChatGPT's performance in medicine and provide direction for future research. We searched ten medical literature databases on June 15, 2023, using the keyword "ChatGPT". A total of 3520 articles were identified, of which 60 were reviewed and summarized in this paper and 17 were included in the meta-analysis. The analysis showed that ChatGPT displayed an overall integrated accuracy of 56% (95% CI: 51%-60%, I2 = 87%) in addressing medical queries. However, the studies varied in question resource, question-asking process, and evaluation metrics. Moreover, many studies failed to report methodological details, including the version of ChatGPT and whether each question was used independently or repeatedly. Our findings revealed that although ChatGPT demonstrated considerable potential for application in healthcare, the heterogeneity of the studies and insufficient reporting may affect the reliability of these results. Further well-designed studies with comprehensive and transparent reporting are needed to evaluate ChatGPT's performance in medicine

    (E)-N′-(4-Meth­oxy­benzyl­idene)-3-nitro­benzohydrazide

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    In the title compound, C15H13N3O4, the two substituted benzene rings form a dihedral angle of 5.0 (3)°. In the crystal, inter­molecular N—H⋯O hydrogen bonds link mol­ecules into chains along the b axis
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