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The functions of sucrose transporters (SUTs) differ among family members. The physiological function of SUT1 has been studied intensively, while that of SUT4 in various plant species including tomato (Solanum lycopersicum) is less well-understood. In this study, we characterized the function of tomato SlSUT4 in the regulation of flowering using a combination of molecular and physiological analyses. SlSUT4 displayed transport activity for sucrose when expressed in yeast (Saccharomyces cerevisiae), and it localized at both the plasma membrane and tonoplast. SlSUT4 interacted with SlSUT1, causing partial internalization of the latter, the main phloem loader of sucrose in tomato. Silencing of SlSUT4 promoted SlSUT1 localization to the plasma membrane, contributing to increased sucrose export and thus increased sucrose level in the shoot apex, which promoted flowering. Both silencing of SlSUT4 and spraying with sucrose suppressed gibberellin biosynthesis through repression of ent-kaurene oxidase and gibberellin 20-oxidase-1 (2 genes encoding key enzymes in gibberellin biosynthesis) expression by SlMYB76, which directly bound to their promoters. Silencing of SlMYB76 promoted gibberellin biosynthesis. Our results suggest that SlSUT4 is a functional SUT in tomato; downregulation of SlSUT4 expression enhances sucrose transport to the shoot apex, which promotes flowering by inhibiting gibberellin biosynthesis.
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Solanum lycopersicum , Solanum lycopersicum/genética , Giberelinas , Sacarosa/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Regulación de la Expresión Génica de las PlantasRESUMEN
BACKGROUND: As a significant process of post-transcriptional gene expression regulation in eukaryotic cells, alternative splicing (AS) of exons greatly contributes to the complexity of the transcriptome and indirectly enriches the protein repertoires. A large number of studies have focused on the splicing inclusion of alternative exons and have revealed the roles of AS in organ development and maturation. Notably, AS takes place through a change in the relative abundance of the transcript isoforms produced by a single gene, meaning that exons can have complex splicing patterns. However, the commonly used percent spliced-in (Ψ) values only define the usage rate of exons, but lose information about the complexity of exons' linkage pattern. To date, the extent and functional consequence of splicing complexity of alternative exons in development and evolution is poorly understood. RESULTS: By comparing splicing complexity of exons in six tissues (brain, cerebellum, heart, liver, kidney, and testis) from six mammalian species (human, chimpanzee, gorilla, macaque, mouse, opossum) and an outgroup species (chicken), we revealed that exons with high splicing complexity are prevalent in mammals and are closely related to features of genes. Using traditional machine learning and deep learning methods, we found that the splicing complexity of exons can be moderately predicted with features derived from exons, among which length of flanking exons and splicing strength of downstream/upstream splice sites are top predictors. Comparative analysis among human, chimpanzee, gorilla, macaque, and mouse revealed that, alternative exons tend to evolve to an increased level of splicing complexity and higher tissue specificity in splicing complexity. During organ development, not only developmentally regulated exons, but also 10-15% of non-developmentally regulated exons show dynamic splicing complexity. CONCLUSIONS: Our analysis revealed that splicing complexity is an important metric to characterize the splicing dynamics of alternative exons during the development and evolution of mammals.
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Gorilla gorilla , Pan troglodytes , Masculino , Humanos , Animales , Ratones , Pan troglodytes/genética , Gorilla gorilla/genética , Exones/genética , Empalme Alternativo , Isoformas de Proteínas/genética , Mamíferos/genéticaRESUMEN
The high correlation between rolling bearing composite faults and single fault samples is prone to misclassification. Therefore, this paper proposes a rolling bearing composite fault diagnosis method based on a deep graph convolutional network. First, the acquired raw vibration signals are pre-processed and divided into sub-samples. Secondly, a number of sub-samples in different health states are constructed as graph-structured data, divided into a training set and a test set. Finally, the training set is used as input to a deep graph convolutional neural network (DGCN) model, which is trained to determine the optimal structure and parameters of the network. A test set verifies the feasibility and effectiveness of the network. The experimental result shows that the DGCN can effectively identify compound faults in rolling bearings, which provides a new approach for the identification of compound faults in bearings.
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Using bacteriophage-derived endolysins as an alternative strategy for fighting drug-resistant bacteria has recently been garnering renewed interest. However, their application is still hindered by their narrow spectra of activity. In our previous work, we demonstrated that the endolysin LysIME-EF1 possesses efficient bactericidal activity against multiple strains of Enterococcus faecalis (E. faecalis). Herein, we observed an 8 kDa fragment and hypothesized that it contributes to LysIME-EF1 lytic activity. To examine our hypothesis, we determined the structure of LysIME-EF1 at 1.75 Å resolution. LysIME-EF1 exhibits a unique architecture in which one full-length LysIME-EF1 forms a tetramer with three additional C-terminal cell-wall binding domains (CBDs) that correspond to the abovementioned 8 kDa fragment. Furthermore, we identified an internal ribosomal binding site (RBS) and alternative start codon within LysIME-EF1 gene, which are demonstrated to be responsible for the translation of the truncated CBD. To elucidate the molecular mechanism for the lytic activity of LysIME-EF1, we combined mutagenesis, lytic activity assays and in vivo animal infection experiments. The results confirmed that the additional LysIME-EF1 CBDs are important for LysIME-EF1 architecture and its lytic activity. To our knowledge, this is the first determined structure of multimeric endolysin encoded by a single gene in E. faecalis phages. As such, it may provide valuable insights into designing potent endolysins against the opportunistic pathogen E. faecalis.
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Bacteriófagos/química , Endopeptidasas/química , Enterococcus faecalis/virología , Genes Virales , Proteínas Virales/química , Bacteriófagos/genética , Cristalografía por Rayos X , Endopeptidasas/genética , Enterococcus faecalis/química , Dominios Proteicos , Proteínas Virales/genéticaRESUMEN
BACKGROUND: The systematic interrogation of reproduction-related genes was key to gain a comprehensive understanding of the molecular mechanisms underlying male reproductive traits in mammals. Here, based on the data collected from the NCBI SRA database, this study first revealed the genes involved in porcine male reproduction as well their uncharacterized transcriptional characteristics. RESULTS: Results showed that the transcription of porcine genome was more widespread in testis than in other organs (the same for other mammals) and that testis had more tissue-specific genes (1210) than other organs. GO and GSEA analyses suggested that the identified test is-specific genes (TSGs) were associated with male reproduction. Subsequently, the transcriptional characteristics of porcine TSGs, which were conserved across different mammals, were uncovered. Data showed that 195 porcine TSGs shared similar expression patterns with other mammals (cattle, sheep, human and mouse), and had relatively higher transcription abundances and tissue specificity than low-conserved TSGs. Additionally, further analysis of the results suggested that alternative splicing, transcription factors binding, and the presence of other functionally similar genes were all involved in the regulation of porcine TSGs transcription. CONCLUSIONS: Overall, this analysis revealed an extensive gene set involved in the regulation of porcine male reproduction and their dynamic transcription patterns. Data reported here provide valuable insights for a further improvement of the economic benefits of pigs as well as future treatments for male infertility.
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Perfilación de la Expresión Génica , Reproducción/genética , Empalme Alternativo , Animales , Evolución Molecular , Redes Reguladoras de Genes , Masculino , Especificidad de Órganos , Porcinos , Testículo/metabolismo , Transcripción GenéticaRESUMEN
A lytic Pseudomonas aeruginosa phage vB_PaeP_LP14 belonging to the family Podoviridae was isolated from infected mink. The microbiological characterization revealed that LP14 was stable at 40 to 50 °C and stable over a broad range of pH (5 to 12). The latent period was 5 min, and the burst size was 785 pfu/infected cell. The whole-genome sequencing showed that LP14 was a dsDNA virus and has a genome of 73,080 bp. The genome contained 93 predicted open reading frames (ORFs), 17 of which have known functions including DNA replication and modification, transcriptional regulation, structural and packaging proteins, and host cell lysis. No tRNA genes were identified. BLASTn analysis revealed that phage LP14 had a high-sequence identity (96%) with P. aeruginosa phage YH6. Both morphological characterization and genome annotation indicate that phage LP14 is a memberof the family Podoviridae genus Litunavirus. The study of phage LP14 will provide basic information for further research on treatment of P. aeruginosa infections.
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Bacteriófagos , Podoviridae , Fagos Pseudomonas , Animales , Bacteriófagos/genética , ADN Viral/genética , Genoma Viral , Sistemas de Lectura Abierta , Podoviridae/genética , Fagos Pseudomonas/genética , Pseudomonas aeruginosa/genéticaRESUMEN
Chromatin accessibility and post-transcriptional histone modifications play important roles in gene expression regulation. However, little is known about the joint effect of multiple chromatin modifications on the gene expression level in plants, despite that the regulatory roles of individual histone marks such as H3K4me3 in gene expression have been well-documented. By using machine-learning methods, we systematically performed gene expression level prediction based on multiple chromatin modifications data in Arabidopsis and rice. We found that as few as four histone modifications were sufficient to yield good prediction performance, and H3K4me3 and H3K36me3 being the top two predictors with known functions related to transcriptional initiation and elongation, respectively. We demonstrated that the predictive powers differed between protein-coding and non-coding genes as well as between CpG-enriched and CpG-depleted genes. We also showed that the predictive model trained in one tissue or species could be applied to another tissue or species, suggesting shared underlying mechanisms. More interestingly, the gene expression levels of conserved orthologs are easier to predict than the species-specific genes. In addition, chromatin state of distal enhancers was moderately correlated to gene expression but was dispensable if given the chromatin features of the proximal regions of genes. We further extended the analysis to transcription factor (TF) binding data. Strikingly, the combinatorial effects of only a few TFs were roughly fit to gene expression levels in Arabidopsis. Overall, by using quantitative modeling, we provide a comprehensive and unbiased perspective on the epigenetic and TF-mediated regulation of gene expression in plants.
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Cromatina/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/metabolismo , Factores de Transcripción/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Epigénesis Genética , Código de Histonas , Oryza/metabolismoRESUMEN
Protein-DNA interactions play important roles in regulations of many vital cellular processes, including transcription, translation, DNA replication and recombination. Sequence variants occurring in these DNA binding proteins that alter protein-DNA interactions may cause significant perturbations or complete abolishment of function, potentially leading to diseases. Developing a mechanistic understanding of impacts of variants on protein-DNA interactions becomes a persistent need. To address this need we introduce a new computational method PremPDI that predicts the effect of single missense mutation in the protein on the protein-DNA interaction and calculates the quantitative binding affinity change. The PremPDI method is based on molecular mechanics force fields and fast side-chain optimization algorithms with parameters optimized on experimental sets of 219 mutations from 49 protein-DNA complexes. PremPDI yields a very good agreement between predicted and experimental values with Pearson correlation coefficient of 0.71 and root-mean-square error of 0.86 kcal mol-1. The PremPDI server could map mutations on a structural protein-DNA complex, calculate the associated changes in binding affinity, determine the deleterious effect of a mutation, and produce a mutant structural model for download. PremPDI can be applied to many tasks, such as determination of potential damaging mutations in cancer and other diseases. PremPDI is available at http://lilab.jysw.suda.edu.cn/research/PremPDI/.
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Algoritmos , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , ADN/metabolismo , Mutación Missense , Sustitución de Aminoácidos , Biología Computacional , ADN/genética , Proteínas de Unión al ADN/química , Bases de Datos Genéticas , Humanos , Modelos Lineales , Simulación de Dinámica Molecular , Unión Proteica/genética , TermodinámicaRESUMEN
A temperate bacteriophage, IME1320_01, was induced by mitomycin C treatment from Corynebacterium striatum. This phage possesses a double-stranded DNA genome of 40,086 bp with a G+C content of 58%. A total of 53 putative open reading frames (ORFs) were identified in its genome. BLASTn analysis revealed that IME1320_01 had the highest sequence similarity to Corynebacterium striatum strain 216, with a genome homology coverage of 44% and highest sequence identity of 95%. The termini of the phage genome was non-redundant, with a 13-nt 3'-protruding cohesive end. To the best of our knowledge, phage IME1320_01 is the first inducible phage to be identified in Corynebacterium striatum.
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Corynebacterium/virología , Genoma Viral/genética , Siphoviridae/genética , Activación Viral/efectos de los fármacos , Composición de Base/genética , ADN Viral/genética , Mitomicina/farmacología , Sistemas de Lectura Abierta/genética , Análisis de Secuencia de ADN , Siphoviridae/clasificación , Siphoviridae/aislamiento & purificaciónRESUMEN
This work describes the characterization and genome annotation of a new lytic Enterococcus faecalis siphovirus, vB_EfaS_AL3 (referred to as AL3), isolated from wastewater samples collected in Liaoning Province, China. The genome of phage AL3 is composed of linear double-stranded DNA that is 40,789 bp in length with a G + C content of 34.84% and 61 putative protein-coding genes. Phylogenetic and comparative genomic analyses indicate that phage AL3 should be considered a novel phage.
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Bacteriófagos/genética , Enterococcus faecalis/virología , Genoma Viral , Filogenia , Análisis de Secuencia de ADN , Aguas Residuales/virología , Bacteriólisis , Composición de Base , China , ADN/química , ADN/genética , ADN Viral/química , ADN Viral/genética , Microscopía Electrónica de Transmisión , Anotación de Secuencia Molecular , Ensayo de Placa Viral , Virión/ultraestructuraRESUMEN
A novel virulent bacteriophage vB_SpuP_Spp16 (hereafter designated Spp16) that infects Salmonella enterica serovar pullorum was isolated. Transmission electron microscopy showed that Spp16 possessed an isometric polyhedral head (60 nm in diameter) and a short tail (10 nm in length) belonging to the family Podoviridae. Its complete genome was determined to be 41,832 bp, with a 39.46% GC content by next-generation sequencing. The genome contains 53 proposed open reading frames that are involved in DNA replication and modification, transcriptional regulation, phage structural and packaging proteins and bacterial lysis. No transfer RNA genes were identified. The termini of genome were determined using our previously proposed termini identification method, which suggests that this phage has redundant termini with 421 bp direct terminal repeats. BLASTn analysis revealed the highest sequence similarity with Yersinia phage phi80-18, with a genome coverage of 33% and highest sequence identity of 69%. The phylogenetic analysis indicated that Spp16 forms a distinct branch of the subfamily Autographivirinae. Comparative genomics analysis showed that the phage Spp16 should be regarded as a new subcluster within the GAP227-like cluster in the Autographivirinae subfamily. The phage Spp16 has an obligate lytic life cycle demonstrated by experimental data and genomic analysis. These results suggest that Spp16 may be a proper candidate to control diseases caused by Salmonella enterica serovar pullorum.
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Genoma Viral , Fagos de Salmonella/genética , Salmonella enterica/virología , Filogenia , Fagos de Salmonella/clasificación , Fagos de Salmonella/aislamiento & purificación , Fagos de Salmonella/ultraestructura , Especificidad de la EspecieRESUMEN
Enterococcus faecalis is one of the main bacteria in the human and animal intestine but is also classed as an opportunistic pathogen. During normal growth, E. faecalis produces natural antibiotics and is conducive to human health. As ectopic parasites, E. faecalis is capable of causing infective endocarditis, neonatal sepsis, bloodstream infections, bacteremia, and intraabdominal infections. With the incidence of antibiotic resistance reaching crisis point, it is imperative to find alternative treatments for multidrug-resistant infections. Using phage for pathogen control is a promising treatment option to combat bacterial resistance. In this study, a lytic phage, designated vB_EfaP_IME195, was isolated from hospital sewage using a clinical multidrug-resistant Enterococcus faecalis strain as an indicator. The one-step growth curve with the optimal multiplicity of infection of (MOI) 0.01 revealed a latent period of ~ 30 min and a burst size of ~ 120 plaque-forming units (pfu) per cell. Transmission electron microscopy showed that the phage belongs to the family Podoviridae. Phage vB_EfaP_IME195 has a linear, double-stranded DNA genome of 18,607 bp with a G + C content of 33% and 27 coding sequences (GenBank accession no. KT932700). Run-off sequencing experiments showed that the phage has a unique 59-bp inverted repeat sequences at the terminal ends. BLASTn analysis revealed that vB_EfaP_IME195 shares 92% identity (93% genome coverage) with unpublished E. faecalis phage Idefix. This study reported a novel E. faecalis phage with unique genome termini containing inverted repeats. The isolation and characterization of this novel lytic E. faecalis phage provides the basis for the development of new therapeutic agents like phage cocktails for multidrug-resistant E. faecalis infection, and its unique genomic feature would also provide valuable knowledge and insight for further phage genome analysis.
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Bacteriófagos/genética , Enterococcus faecalis/virología , Genoma Viral , Genómica , Bacteriófagos/aislamiento & purificación , Bacteriófagos/ultraestructura , Secuencia de Bases , Biología Computacional/métodos , Evolución Molecular , Genómica/métodos , Secuenciación de Nucleótidos de Alto Rendimiento , Especificidad del Huésped , Sistemas de Lectura AbiertaRESUMEN
Cancer is a complex disease that is driven by genetic alterations. There has been a rapid development of genome-wide techniques during the last decade along with a significant lowering of the cost of gene sequencing, which has generated widely available cancer genomic data. However, the interpretation of genomic data and the prediction of the association of genetic variations with cancer and disease phenotypes still requires significant improvement. Missense mutations, which can render proteins non-functional and provide a selective growth advantage to cancer cells, are frequently detected in cancer. Effects caused by missense mutations can be pinpointed by in silico modeling, which makes it more feasible to find a treatment and reverse the effect. Specific human phenotypes are largely determined by stability, activity, and interactions between proteins and other biomolecules that work together to execute specific cellular functions. Therefore, analysis of missense mutations' effects on proteins and their complexes would provide important clues for identifying functionally important missense mutations, understanding the molecular mechanisms of cancer progression and facilitating treatment and prevention. Herein, we summarize the major computational approaches and tools that provide not only the classification of missense mutations as cancer drivers or passengers but also the molecular mechanisms induced by driver mutations. This review focuses on the discussion of annotation and prediction methods based on structural and biophysical data, analysis of somatic cancer missense mutations in 3D structures of proteins and their complexes, predictions of the effects of missense mutations on protein stability, protein-protein and protein-nucleic acid interactions, and assessment of conformational changes in protein conformations induced by mutations.
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Mutación Missense/genética , Neoplasias/genética , Animales , Biología Computacional/métodos , Humanos , Neoplasias/metabolismo , Conformación Proteica , Estabilidad ProteicaRESUMEN
Objective: To disrupt spa7074, which encodes a member of the TetR family transcriptional factors, in biocontrol strain Act12 and characterize the secondary metabolites in the mutant strain. Methods: We disrupted the gene spa7074 by homologous recombination. The secondary metabolites of the mutant strain Δspa7074 and Act12 were detected by HPLC. The structure was analyzed by MS and NMR. Results: Compared to the wild-type strain, the production of some unknown compounds in the mutant strain Δspa7074 increased obviously. We purified one of the compounds and identified as oligomycin D by MS and NMR analysis. Conclusion: An oligomycin D-producing strain Δspa7074 was derived via genetic engineering.
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Metabolismo Secundario , Streptomyces/genética , Streptomyces/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Recombinación Homóloga , Espectrometría de Masas , Mutación , Rutamicina/química , Rutamicina/aislamiento & purificación , Rutamicina/metabolismo , Streptomyces/química , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Based on Resource-based theory and Internal Control (IC) theory, this study elucidates the impacts of corporate digital transformation on total factor productivity, and IC effectiveness, as well as the mechanism among digital transformation, IC and total factor productivity. The results show that digital transformation promotes total factor productivity and IC effectiveness. And effective IC has a significant mediating effect for the impact of digital transformation on total factor productivity. Heterogeneity discussion shows that compared with high-tech enterprises, in non-high-tech ones, digital transformation increases total factor productivity, and more significantly enhances IC effectiveness, presenting a mechanism that digital transformation facilitates IC, and increases total factor productivity. For non-high-tech enterprises, with higher heterogeneity of executive education backgrounds, digital transformation promotes IC effectiveness and total factor productivity, showing the transmission effect among digital transformation, IC and total factor productivity. Finally, it is suggested that the regulatory authorities advance digital infrastructure construction, to reinforce IC and risk prevention, thereby increase total factor productivity. And enterprises grasp the opportunity of digital economy development, promote the mechanism that digital transformation facilitates IC effectiveness, and increases total factor productivity. Non-high-tech ones motivate digital elements' governance efficacy, optimize executive structure, coordinately promote digital strategy, and help the national economy acquire high-quality development. The study provides enlightenments to achieve high-quality development.
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Desarrollo Económico , Organizaciones , ChinaRESUMEN
Diamond is known as the ultimate semiconductor material for electric devices with excellent properties such as an ultra-wide bandgap (5.47 eV), high carrier mobility (electron mobility 4000 cm2/V·s, hole mobility 3800 cm2/V·s), high critical breakdown electric field (20 MV/cm), and high thermal conductivity (22 W/cm·K), showing good prospects in high-power applications. The lack of n-type diamonds limits the development of bipolar devices; most of the research focuses on p-type Schottky barrier diodes (SBDs) and unipolar field-effect transistors (FETs) based on terminal technology. In recent years, breakthroughs have been made through the introduction of new structures, dielectric materials, heterogeneous epitaxy, etc. Currently, diamond devices have shown promising applications in high-power applications, with a BV of 10 kV, a BFOM of 874.6 MW/cm2, and a current density of 60 kA/cm2 already realized. This review summarizes the research progress of diamond materials, devices, and specific applications, with a particular focus on the development of SBDs and FETs and their use in high-power applications, aiming to provide researchers with the relevant intuitive parametric comparisons. Finally, the paper provides an outlook on the parameters and development directions of diamond power devices.
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As the most stable phase of gallium oxide, ß-Ga2O3 can enable high-quality, large-size, low-cost, and controllably doped wafers by the melt method. It also features a bandgap of 4.7-4.9 eV, a critical electric field strength of 8 MV/cm, and a Baliga's figure of merit (BFOM) of up to 3444, which is 10 and 4 times higher than that of SiC and GaN, respectively, showing great potential for application in power devices. However, the lack of effective p-type Ga2O3 limits the development of bipolar devices. Most research has focused on unipolar devices, with breakthroughs in recent years. This review mainly summarizes the research progress fora different structures of ß-Ga2O3 power diodes and gives a brief introduction to their thermal management and circuit applications.
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OBJECTIVES: This study aimed to screen the potential risk factors for academic burnout among adolescents during the COVID-19 pandemic, develop and validate a predictive tool based on the risk factors for predicting academic burnout. DESIGN: This article presents a cross-sectional study. SETTING: This study surveyed two high schools in Anhui Province, China. PARTICIPANTS: A total of 1472 adolescents were enrolled in this study. OUTCOME MEASURES: The questionnaires included demographic characteristic variables, living and learning states and adolescents' academic burnout scale. Least absolute shrinkage and selection operator and multivariate logistic regression analyses were employed to screen the risk factors for academic burnout and develop a predictive model. The receiver operating characteristic (ROC) curve and decision curve analysis (DCA) were used to assess the accuracy and discrimination of the nomogram. RESULTS: In this study, 21.70% of adolescents reported academic burnout. Multivariable logistic regression analysis showed that single-child family (OR=1.742, 95% CI: 1.243 to 2.441, p=0.001), domestic violence (OR=1.694, 95% CI: 1.159 to 2.476, p=0.007), online entertainment (>8 hours/day, OR=3.058, 95% CI: 1.634 to 5.720, p<0.001), physical activity (<3 hours/week, OR=1.686, 95% CI: 1.032 to 2.754, p=0.037), sleep duration (<6 hours/night, OR=2.342, 95% CI: 1.315 to 4.170, p=0.004) and academic performance (<400 score, OR=2.180, 95% CI: 1.201 to 3.958, p=0.010) were independent significant risk factors associated with academic burnout. The area under the curve of ROC with the nomogram was 0.686 in the training set and 0.706 in the validation set. Furthermore, DCA demonstrated that the nomogram had good clinical utility for both sets. CONCLUSIONS: The developed nomogram was a useful predictive model for academic burnout among adolescents during the COVID-19 pandemic. It is essential to emphasise the importance of mental health and promote a healthy lifestyle among adolescents during the future pandemic.
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Agotamiento Psicológico , COVID-19 , Pueblos del Este de Asia , Nomogramas , Estudiantes , Adolescente , Humanos , Agotamiento Psicológico/epidemiología , COVID-19/epidemiología , COVID-19/psicología , Estudios Transversales , Pueblos del Este de Asia/psicología , Pueblos del Este de Asia/estadística & datos numéricos , Pandemias , Estudiantes/psicología , Factores de Riesgo , Medición de RiesgoRESUMEN
The α-amino acid ester acyltransferase (SAET) from Sphingobacterium siyangensis is one of the enzymes with the highest catalytic ability for the biosynthesis of l-alanyl-l-glutamine (Ala-Gln) with unprotected l-alanine methylester and l-glutamine. To improve the catalytic performance of SAET, a one-step method was used to rapidly prepare the immobilized cells (SAET@ZIF-8) in the aqueous system. The engineered Escherichia coli (E. coli) expressing SAET was encapsulated into the imidazole framework structure of metal organic zeolite (ZIF-8). Subsequently, the obtained SAET@ZIF-8 was characterized, and the catalytic activity, reusability and storage stability were also investigated. Results showed that the morphology of the prepared SAET@ZIF-8 nanoparticles was basically the same as that of the standard ZIF-8 materials reported in literature, and the introduction of cells did not significantly change the morphology of ZIF-8. After repeated use for 7 times, SAET@ZIF-8 could still retain 67% of the initial catalytic activity. Maintained at room temperature for 4 days, 50% of the original catalytic activity of SAET@ZIF-8 could be retained, indicating that SAET@ZIF-8 has good stability for reuse and storage. When used in the biosynthesis of Ala-Gln, the final concentration of Ala-Gln reached 62.83 mmol/L (13.65 g/L) after 30 min, the yield reached 0.455 g/(L·min), and the conversion rate relative to glutamine was 62.83%. All these results suggested that the preparation of SAET@ZIF-8 is an efficient strategy for the biosynthesis of Ala-Gln.
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Escherichia coli , Zeolitas , Escherichia coli/genética , Glutamina , Zeolitas/química , AminoácidosRESUMEN
In this study, we isolated a lytic Pseudomonas aeruginosa phage (vB_PaeP_ASP23) from the sewage of a mink farm, characterized its complete genome and analyzed the function of its putative lysin and holin. Morphological characterization and genome annotation showed that phage ASP23 belonged to the Krylovirinae family genus Phikmvvirus, and it had a latent period of 10 min and a burst size of 140 pfu/infected cell. In minks challenged with P. aeruginosa, phage ASP23 significantly reduced bacterial counts in the liver, lung, and blood. The whole-genome sequencing showed that its genome was a 42,735-bp linear and double-stranded DNA (dsDNA), with a G + C content of 62.15%. Its genome contained 54 predicted open reading frames (ORFs), 25 of which had known functions. The lysin of phage ASP23 (LysASP), in combination with EDTA, showed high lytic activity against P. aeruginosa L64. The holin of phage ASP23 was synthesized by M13 phage display technology, to produce recombinant phages (HolASP). Though HolASP exhibited a narrow lytic spectrum, it was effective against Staphylococcus aureus and Bacillus subtilis. However, these two bacteria were insensitive to LysASP. The findings highlight the potential of phage ASP23 to be used in the development of new antibacterial agents.