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In most actinomycetes, GlnR governs both nitrogen and non-nitrogen metabolisms (e.g., carbon, phosphate, and secondary metabolisms). Although GlnR has been recognized as a global regulator, its regulatory role in central carbon metabolism [e.g., glycolysis, gluconeogenesis, and the tricarboxylic acid (TCA) cycle] is largely unknown. In this study, we characterized GlnR as a direct transcriptional repressor of the pckA gene that encodes phosphoenolpyruvate carboxykinase, catalyzing the conversion of the TCA cycle intermediate oxaloacetate to phosphoenolpyruvate, a key step in gluconeogenesis. Through the transcriptomic and quantitative real-time PCR analyses, we first showed that the pckA transcription was upregulated in the glnR null mutant of Amycolatopsis mediterranei. Next, we proved that the pckA gene was essential for A. mediterranei gluconeogenesis when the TCA cycle intermediate was used as a sole carbon source. Furthermore, with the employment of the electrophoretic mobility shift assay and DNase I footprinting assay, we revealed that GlnR was able to specifically bind to the pckA promoter region from both A. mediterranei and two other representative actinomycetes (Streptomyces coelicolor and Mycobacterium smegmatis). Therefore, our data suggest that GlnR may repress pckA transcription in actinomycetes, which highlights the global regulatory role of GlnR in both nitrogen and central carbon metabolisms in response to environmental nutrient stresses. IMPORTANCE: The GlnR regulator of actinomycetes controls nitrogen metabolism genes and many other genes involved in carbon, phosphate, and secondary metabolisms. Currently, the known GlnR-regulated genes in carbon metabolism are involved in the transport of carbon sources, the assimilation of short-chain fatty acid, and the 2-methylcitrate cycle, although little is known about the relationship between GlnR and the TCA cycle and gluconeogenesis. Here, based on the biochemical and genetic results, we identified GlnR as a direct transcriptional repressor of pckA, the gene that encodes phosphoenolpyruvate carboxykinase, a key enzyme for gluconeogenesis, thus highlighting that GlnR plays a central and complex role for dynamic orchestration of cellular carbon, nitrogen, and phosphate fluxes and bioactive secondary metabolites in actinomycetes to adapt to changing surroundings.
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Proteínas de Bactérias , Regulação Bacteriana da Expressão Gênica , Gluconeogênese , Nitrogênio , Gluconeogênese/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Nitrogênio/metabolismo , Proteínas Repressoras/metabolismo , Proteínas Repressoras/genética , Amycolatopsis/metabolismo , Amycolatopsis/genética , Regiões Promotoras Genéticas , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Fosfoenolpiruvato Carboxiquinase (ATP)/genética , Ciclo do Ácido Cítrico/genética , Actinobacteria/genética , Actinobacteria/metabolismoRESUMO
Bimetallic metal-organic framework (BMOF) exhibits better electrocatalytic performance than mono-MOF, but deciphering the precise anchoring of foreign atoms and revealing the underlying mechanisms at the atomic level remains a major challenge. Herein, a novel binuclear NiFe-MOF with precise anchoring of Fe sites is synthesized. The low-crystallinity (LC)-NiFe0.33 -MOF exhibited abundant unsaturated active sites and demonstrated excellent electrocatalytic oxygen evolution reaction (OER) performance. It achieved an ultralow overpotential of 230 mV at 10 mA cm-2 and a Tafel slope of 41 mV dec-1 . Using a combination of modulating crystallinity, X-ray absorption spectroscopy, and theoretical calculations, the accurate metal sequence of BMOF and the synergistic effect of the active sites are identified, revealing that the adjacent active site plays a significant role in regulating the catalytic performance of the endmost active site. The proposed model of BMOF electrocatalysts facilitates the investigation of efficient OER electrocatalysts and the related catalytic mechanisms.
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Doping metals and constructing heterostructures are pivotal strategies to enhance the electrocatalytic activity of metal-organic frameworks (MOFs). Nevertheless, effectively designing MOF-based catalysts that incorporate both doping and multiphase interfaces poses a significant challenge. In this study, a one-step Co-doped and Co3O4-modified Ni-MOF catalyst (named Ni NDC-Co/CP) with a thickness of approximately 5.0 nm was synthesized by a solvothermal-assisted etching growth strategy. Studies indicate that the formation of the Co-O-Ni-O-Co bond in Ni NDC-Co/CP was found to facilitate charge density redistribution more effectively than the Co-O-Ni bimetallic synergistic effect in NiCo NDC/CP. The designating Ni NDC-Co/CP achieved superior oxygen evolution reaction (OER) activity (245 mV @ 10 mA cm-2) and robust long stability (100 h @ 100 mA cm-2) in 1.0 M KOH. Furthermore, the Ni NDC-Co/CP(+)||Pt/C/CP(-) displays pregnant overall water splitting performance, achieving a current density of 10 mA cm-2 at an ultralow voltage of 1.52 V, which is significantly lower than that of commercial electrolyzer using Pt/C and IrO2 electrode materials. In situ Raman spectroscopy elucidated the transformation of Ni NDC-Co to Ni(Co)OOH under an electric field. This study introduces a novel approach for the rational design of MOF-based OER electrocatalysts.
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BACKGROUND: More and more studies showed that gut microbiota was closely related to the development of colorectal cancer (CRC). However, the specific pathway of gut microbiota regulating CRC development is still unknown. METHODS: We collected fecal samples from 14 CRC patients and 20 normal volunteers for 16 S sequencing analysis. At the same time, 14 CRC patients' tumors and their adjacent tissues were collected for the detection of STING pathway related protein level. Mice were injected with azoxymethane (AOM) to establish an animal model of CRC, and antibiotics were given at the same time to evaluate the influence of gut microbiota on STING pathway and whether it was involved in regulating the tumor development of CRC mice. RESULTS: The sequencing results showed that compared with the normal group, the gut microbiota gut microbiota of CRC patients changed significantly at different species classification levels. At the level of genus, Akkermansia, Ligilactobacillus and Subdoligranulum increased the most in CRC patients, while Bacteroides and Dialister decreased sharply. The expression of STING-related protein was significantly down-regulated in CRC tumor tissues. Antibiotic treatment of CRC mice can promote the development of tumor and inhibit the activation of STING pathway. CONCLUSION: Gut microbiota participates in CRC progress by mediating STING pathway activation.
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Neoplasias Colorretais , Progressão da Doença , Microbioma Gastrointestinal , Proteínas de Membrana , Microbioma Gastrointestinal/efeitos dos fármacos , Microbioma Gastrointestinal/fisiologia , Neoplasias Colorretais/microbiologia , Neoplasias Colorretais/patologia , Neoplasias Colorretais/metabolismo , Animais , Camundongos , Humanos , Proteínas de Membrana/metabolismo , Masculino , Feminino , Estudos de Casos e Controles , Pessoa de Meia-Idade , Transdução de Sinais , Prognóstico , Azoximetano/toxicidade , Fezes/microbiologiaRESUMO
A series of novel substituted 4-anilinoquinazolines and their related compounds were designed and prepared by 3D modeling as potential inhibitors of VEGFR-2. Evaluation of VEGFR inhibitory activities suggested that compound I10 was a more potent (IC50 = 0.11 nM) VEGFR-2 inhibitor than most of the listed drugs. Kinase panel assays demonstrated that compound I10 was the selective VEGFR-2 inhibitor. The prediction of 3D modeling unveiled a unique binding mode of this lead compound to VEGFR-2. Compound I10 exhibited remarkable anti-angiogenesis and anti-proliferation in HUVEC at low nanomolar concentrations. PK studies indicated that the lead compound possessed adequate oral bioavailability in various species. In vivo subcutaneous tumor model demonstrated that oral administration of I10 demonstrated potent efficacy in inhibiting tumor growth and angiogenesis. All these results suggested compound I10 is a potential drug candidate for cancer treatment.
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Antineoplásicos , Neoplasias , Humanos , Receptor 2 de Fatores de Crescimento do Endotélio Vascular , Neoplasias/tratamento farmacológico , Fosforilação , Inibidores de Proteínas Quinases/química , Proliferação de Células , Antineoplásicos/química , Relação Estrutura-Atividade , Ensaios de Seleção de Medicamentos Antitumorais , Simulação de Acoplamento Molecular , Estrutura MolecularRESUMO
OBJECTIVE: The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion. MATERIALS AND METHODS: The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10 mm (mandibular retromolar space length in root level, RLin2,4,6,8,10) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10 mm (width of the mandibular retromolar space, BW2,4,6,8,10/ width of the second molar distal root, TW2,4,6,8,10) from the CEJ. RESULTS: RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05). CONCLUSIONS: Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization. CLINICAL RELEVANCE: When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization.
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Má Oclusão , Mandíbula , Dente Serotino , Adulto , Feminino , Humanos , Masculino , Tomografia Computadorizada de Feixe Cônico , Mandíbula/diagnóstico por imagem , Dente Molar/diagnóstico por imagem , Dente Serotino/diagnóstico por imagem , Dente Impactado , OdontometriaRESUMO
Completely digital design/completely digital manufacturing (CDD/CDM) workflows have been widely used in orthodontic and orthognathic treatments. This case report introduces a CDD/CDM workflow consisting of clear aligners and virtual planning for a surgery-first approach (SFA) in a patient with a skeletal Class III malocclusion. Following a shortened treatment time of 5 months, the patient's facial appearance improved significantly, and well-balanced occlusion was obtained. SFAs with clear aligners can enable patients to achieve complete esthetic satisfaction during the therapeutic period. The CDD/CDM workflow provided accurate results, improved the clinical outcome, and reduced treatment time.
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Má Oclusão Classe III de Angle , Procedimentos Cirúrgicos Ortognáticos , Estética Dentária , Humanos , Má Oclusão Classe III de Angle/cirurgia , Procedimentos Cirúrgicos Ortognáticos/métodos , Fluxo de TrabalhoRESUMO
Titanium (Ti) implants are widely used in dentistry and orthopedics owing to their excellent corrosion resistance, biocompatibility, and mechanical properties, which have gained increasing attention from the viewpoints of fundamental research and practical applications. Also, numerous studies have been carried out to fine-tune the micro/nanostructures of Ti and/or incorporate chemical elements to improve overall implant performance. Zinc oxide nanoparticles (nano-ZnO) are well-known for their good antibacterial properties and low cytotoxicity along with their ability to synergize with a variety of substances, which have received increasingly widespread attention as biomodification materials for implants. In this review, we summarize recent research progress on nano-ZnO modified Ti-implants. Their preparation methods of nano-ZnO modified Ti-implants are introduced, followed by a further presentation of the antibacterial, osteogenic, and anti-corrosion properties of these implants. Finally, challenges and future opportunities for nano-ZnO modified Ti-implants are proposed.
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Antibacterianos/farmacologia , Osteogênese/efeitos dos fármacos , Próteses e Implantes , Titânio/química , Óxido de Zinco/química , Corrosão , Lasers , Nanopartículas , Nanoestruturas , Nanotubos , Propriedades de SuperfícieRESUMO
Hypercapnia in combination with hypoxemia is usually present in severe respiratory disease in the intensive care unit (ICU) and can lead to more severe cognitive dysfunction. Increasing evidence has indicated that the compromised blood-brain barrier (BBB) in the hippocampus in hypoxemia conditions can result in cognitive dysfunction. However, the role and underlying mechanism of hypercapnia in the BBB disruption remains poorly known. A rat model of hypercapnia was first established in this study by intubation and mechanical ventilation with a small-animal ventilator. After this, the cognitive function of the experimental rats was assessed by the Morris water maze test. The BBB permeability was evaluated by the Evans Blue (EB) test and brain water content (BWC). Western blot analysis was carried out to detect the protein expressions of total and nuclear hypoxia-inducible factor-1α (HIF-1α), matrixmetalloproteinase-9 (MMP-9) and Aquaporins-4 (AQP-4) in the hippocampus tissue. Double immunofluorescence further verified the protein expression of different biomarkers was localized in the astrocytes of the hippocampus. Hypercapnia alone did not disrupt the BBB, but it could further enhance the BBB permeability in hypoxemia. Concomitantly, up-regulation of nuclear HIF-1α, AQP-4, MMP-9 protein expression along with increased degradation of the occludin and claudin-5 proteins was found in the hypercapnia rat model, while the total HIF-1α remained unchanged. Interestingly, these changes were independent of the acidosis induced by hypercapnia. Of note, after premedication of 2-Methoxyestradiol (2ME2, an inhibitor of HIF-1α nuclear translocation), the disrupted BBB could be restored resulting in improvement of the cognitive impairment. Meanwhile, accumulation of nuclear HIF-1α, protein expression of AQP-4 and MMP-9 and protein degradation of the occludin and claudin-5 were decreased. Thus, our study demonstrated that hypercapnia can further disrupt the BBB through promoting HIF-1α nuclear translocation and up-regulation of AQP-4 and MMP-9 in hypoxemia. It is therefore suggested that the cascade of hypercapnia-induced nuclear HIF-1α protein translocation in hypoxia-activated astrocytes may be a potential target for ameliorating cognitive impairment.
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Barreira Hematoencefálica/metabolismo , Disfunção Cognitiva/metabolismo , Hipocampo/metabolismo , Hipercapnia/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Hipóxia/metabolismo , Animais , Astrócitos/metabolismo , Astrócitos/patologia , Barreira Hematoencefálica/patologia , Núcleo Celular/metabolismo , Disfunção Cognitiva/patologia , Hipocampo/patologia , Hipercapnia/patologia , Hipóxia/patologia , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
AIMS: To explore the involvement of NOD-like receptor protein 3 (NLRP3) inflammasome and M1 macrophage in root resorption (RR). METHODS: A rat RR model was established by excessive orthodontic force. After different force-loading time, the expression levels of NLRP3, caspase-1, and interleukin-1ß (IL-1ß) and distribution of M1 macrophages were analysed by immunohistochemistry and immunofluorescence staining in vivo. Then, the mechanism of NLRP3 activation was further verified by macrophage and human periodontal ligament cell (hPDLC) co-culture system in vitro. The production levels of NLRP3, caspase-1, pro-caspase-1, and IL-1ß in M1 macrophages in the co-culture system were detected by Western blot, and the polarization of CD68+IL-1ß+ M1 macrophages was detected by immunofluorescence staining. RESULTS: In the rat RR model, NLRP3, caspase-1, IL-1ß, and M1 macrophages were expressed in periodontal ligament, mainly concentrated around RR areas. Force-pre-treated hPDLCs promoted M1 macrophage polarization and the production of NLRP3, caspase-1, and IL-1ß in M1 macrophages in co-culture system. When MCC950, an inhibitor of NLRP3 inflammasome, was added, NLRP3 activation and M1 macrophage polarization were inhibited. CONCLUSIONS: In periodontal tissues, hPDLCs stimulated by force promoted M1 macrophage polarization and increased IL-1ß production by activating NLRP3 inflammasome in M1 macrophages, thus initiating the occurrence of RR.
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Inflamassomos , Interleucina-1beta , Proteína 3 que Contém Domínio de Pirina da Família NLR , Reabsorção da Raiz , Animais , Humanos , Interleucina-1beta/metabolismo , Macrófagos , Proteínas NLR , RatosRESUMO
Botrytis cinerea, a ubiquitous necrotrophic plant-pathogenic fungus, is responsible for grey mold and rot disease in a very wide range of plant species. Subtilisin-like proteases (or subtilases) are a very diverse family of serine proteases present in many organisms and are reported to have a broad spectrum of biological functions. Here, we identified two genes encoding subtilisin-like proteases (Bcser1 and Bcser2) in the genome of B. cinerea, both of which contain an inhibitor I9 domain and a peptidase S8 domain. The expression levels of Bcser1 and Bcser2 increased during the sclerotial forming stage, as well as during a later stage of hyphal infection on Arabidopsis thaliana leaves, but the up-regulation of Bcser1 was significantly higher than that of Bcser2. Interestingly, deletion of Bcser1 had no effect on the fungal development or virulence of B. cinerea. However, deletion of Bcser2 or double deletion of Bcser1 and Bcser2 severely impaired the hyphal growth, sclerotial formation and conidiation of B. cinerea. We also found that ∆Bcser2 and ∆Bcser1/2 could not form complete infection cushions and then lost the ability to infect intact plant leaves of Arabidopsis and tomato but could infect wounded plant tissues. Taken together, our results indicate that the subtilisin-like protease Bcser2 is crucial for the sclerotial formation, conidiation, and virulence of B. cinerea.
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Arabidopsis/microbiologia , Botrytis/patogenicidade , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Peptídeo Hidrolases/metabolismo , Doenças das Plantas/microbiologia , Virulência , Arabidopsis/crescimento & desenvolvimento , Botrytis/genética , Botrytis/crescimento & desenvolvimento , Proteínas Fúngicas/genética , Hifas , Peptídeo Hidrolases/genética , Esporos Fúngicos , Subtilisinas/genética , Subtilisinas/metabolismoRESUMO
BACKGROUND: Due to the important role of rifamycin in curing tuberculosis infection, the study on rifamycin has never been stopped. Although RifZ, which locates within the rifamycin biosynthetic cluster, has recently been characterized as a pathway-specific regulator for rifamycin biosynthesis, little is known about the regulation of rifamycin export. RESULTS: In this work, we proved that the expression of the rifamycin efflux pump (RifP) was regulated by RifQ, a TetR-family transcriptional regulator. Deletion of rifQ had little impact on bacterial growth, but resulted in improved rifamycin production, which was consistent with the reverse transcription PCR results that RifQ negatively regulated rifP's transcription. With electrophoretic mobility shift assay and DNase I Footprinting assay, RifQ was found to directly bind to the promoter region of rifP, and a typical inverted repeat was identified within the RifQ-protected sequences. The transcription initiation site of rifP was further characterized and found to be upstream of the RifQ binding sites, well explaining the RifQ-mediated repression of rifP's transcription in vivo. Moreover, rifamycin B (the end product of rifamycin biosynthesis) remarkably decreased the DNA binding affinity of RifQ, which led to derepression of rifamycin export, reducing the intracellular concentration of rifamycin B as well as its toxicity against the host. CONCLUSIONS: Here, we proved that the export of rifamycin B was repressed by RifQ in Amycolatopsis mediterranei, and the RifQ-mediated repression could be specifically relieved by rifamycin B, the end product of rifamycin biosynthesis, based on which a feedback model was proposed for regulation of rifamycin export. With the findings here, one could improve the antibiotic yield by simply inactivating the negative regulator of the antibiotic transporter.
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Actinobacteria/genética , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Rifamicinas/metabolismo , Actinobacteria/metabolismo , Antibacterianos/biossíntese , Antibacterianos/metabolismo , Vias Biossintéticas/genética , Família Multigênica , Rifamicinas/biossíntese , Transativadores/genéticaRESUMO
Rifamycin and its derivatives are particularly effective against the pathogenic mycobacteria Mycobacterium tuberculosis and Mycobacterium leprae Although the biosynthetic pathway of rifamycin has been extensively studied in Amycolatopsis mediterranei, little is known about the regulation in rifamycin biosynthesis. Here, an in vivo transposon system was employed to identify genes involved in the regulation of rifamycin production in A. mediterranei U32. In total, nine rifamycin-deficient mutants were isolated, among which three mutants had the transposon inserted in AMED_0655 (rifZ, encoding a LuxR family regulator). The rifZ gene was further knocked out via homologous recombination, and the transcription of genes in the rifamycin biosynthetic gene cluster (rif cluster) was remarkably reduced in the rifZ null mutant. Based on the cotranscription assay results, genes within the rif cluster were grouped into 10 operons, sharing six promoter regions. By use of electrophoretic mobility shift assay and DNase I footprinting assay, RifZ was proved to specially bind to all six promoter regions, which was consistent with the fact that RifZ regulated the transcription of the whole rif cluster. The binding consensus sequence was further characterized through alignment using the RifZ-protected DNA sequences. By use of bionformatic analysis, another five promoters containing the RifZ box (CTACC-N8-GGATG) were identified, among which the binding of RifZ to the promoter regions of both rifK and orf18 (AMED_0645) was further verified. As RifZ directly regulates the transcription of all operons within the rif cluster, we propose that RifZ is a pathway-specific regulator for the rif cluster.IMPORTANCE To this day, rifamycin and its derivatives are still the first-line antituberculosis drugs. The biosynthesis of rifamycin has been extensively studied, and most biosynthetic processes have been characterized. However, little is known about the regulation of the transcription of the rifamycin biosynthetic gene cluster (rif cluster), and no regulator has been characterized. Through the employment of transposon screening, we here characterized a LuxR family regulator, RifZ, as a direct transcriptional activator for the rif cluster. As RifZ directly regulates the transcription of the entire rif cluster, it is considered a pathway-specific regulator for rifamycin biosynthesis. Therefore, as the first regulator characterized for direct regulation of rif cluster transcription, RifZ may provide a new clue for further engineering of high-yield industrial strains.
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Actinomycetales/genética , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Rifamicinas/biossíntese , Transativadores/genética , Transativadores/metabolismo , Actinomycetales/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Vias Biossintéticas/genética , Elementos de DNA Transponíveis , Técnicas de Inativação de Genes , Recombinação Homóloga , Família Multigênica , Mutação , Fases de Leitura Aberta , Óperon , Regiões Promotoras Genéticas , Homologia de Sequência de AminoácidosRESUMO
Using native signal peptide, an alkaliphilic actinomycete xylanase XynK was overexpressed in Escherichia coli and secreted into the culture medium completely. At its optimum catalytic temperature of 55 °C, the cellulose-free xylanase exhibits high activity and stability at pH 7.0-11.0. In comparison with the well-studied actinomycete xylanase from Streptomyces lividans, as an alkaliphilic xylanase, XynK exhibited different biochemical and catalytic characteristics. With the aid of site-directed mutagenesis, some residues were demonstrated to be important to the activity, stability, or substrate binding of the enzyme. The pH stability of mutants H131S and W135A both decreased obviously under high pH values. Combined with their K(m) parameters and homology model analysis, His131 was proposed to be important to both substrate binding and enzyme catalyzing, whereas Trp135 significantly influenced enzyme stability. Good stability under alkaline condition, as well as high secretory expression implies good potentials of the alkaline xylanase in various industrial applications. In addition, results from site-directed mutagenesis provide useful information for further pH stability mechanisms investigation.
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Endo-1,4-beta-Xilanases/química , Endo-1,4-beta-Xilanases/metabolismo , Endo-1,4-beta-Xilanases/genética , Estabilidade Enzimática/fisiologia , Escherichia coli/enzimologia , Escherichia coli/genética , Concentração de Íons de Hidrogênio , Mutagênese Sítio-Dirigida , Especificidade por Substrato/genética , Especificidade por Substrato/fisiologiaRESUMO
This study explores the potential of the dumbbell solvent as a minimal model for understanding electrolyte solutions in polar solvents. Our investigation involves a comparative analysis of the dumbbell model and the Stockmayer model, focusing on ion solvation and ion-ion correlations. We examine electrolytes containing symmetric monovalent salts dissolved in polar solvents while varying the ion density and solvent polarity. Both models predict an augmented solvent coordination number around ions as the solvent polarity increases, with the dumbbell solvent displaying a more pronounced effect. Notably, radial distribution functions (RDFs) between solvent and ions yield differing trends; Stockmayer models exhibit a nonmonotonic relationship due to strong dipole-dipole interactions at higher polarity, while RDFs for ions and dumbbell solvents consistently rise. In response to increased solvent polarity, Stockmayer solvents within the ion's solvation shell undergo continuous dipole orientation shifts, whereas the dumbbell solvent predominantly adopts pointing-away dipole orientations, diminishing pointing-to orientations. This underscores the significance of the interplay between the solvent molecular orientation and dipole rotation. Both models qualitatively predict ion pairing and clustering behaviors across varying solvent dipole strengths and salt concentrations. The Stockmayer solvent generally provides stronger electrostatic screening than the dumbbell solvent due to its neglect of the coupling between molecular orientation and dipole rotation. What's more, at a high dipole moment regime, ion-ion correlations in Stockmayer solvent can become stronger with increasing dipole moment due to stronger solvent-solvent correlations. This study underscores the effectiveness of the dumbbell solvent model in systematically elucidating the fundamental principles governing electrolytes and offers potential applications in the rational design of electrolyte systems.
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2D metal-organic frameworks (MOFs) have emerged as potential candidates for electrocatalytic oxygen evolution reactions (OER) due to their inherent properties like abundant coordination unsaturated active sites and efficient charge transfer. Herein, a versatile and massively synthesizable self-etching assembly strategy wherein nickel-iron foam (NFF) acts as a substrate and a metal ion source. Specifically, by etching the nickel-iron foam (NFF) surface using ligands and solvents, Ni/Fe metal ions are activated and subsequently reacted under hydrothermal conditions, resulting in the formation of self-supporting nanosheet arrays, eliminating the need for external metal salts. The obtained 33 % NiFeMOF/NFF exhibits remarkable OER performance with ultra-low overpotentials of 188/231â mV at 10/100â mA cm-2, respectively, outperforming most recently reported catalysts. Besides, the built 33 % NiFeMOF/NFF(+)||Pt/C(-) electrolyzer presents low cell voltages of 1.55/1.83â V at 10/100â mA cm-2, superior to the benchmark RuO2 (+)||Pt/C(-), implying good industrialization prospects. The excellent catalytic activity stems from the modulation of the electronic spin state of the Ni active site by the introduction of Fe, which facilitates the adsorption process of oxygen-containing intermediates and thus enhances the OER activity. This innovative approach offers a promising pathway for commercial-scale sustainable energy solutions.
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Sepsis-induced myocardial dysfunction (SMD) is the major cause of death in sepsis. Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3)-mediated pyroptosis contributes to the occurrence and development of SMD. Although Apelin confers direct protection against SMD, the potential mechanisms remain unclear. This study aimed to determine whether Apelin protects against SMD via regulation of NLRP3-mediated pyroptosis of cardiomyocytes. Experimental SMD was induced in wild-type (WT) control mice and Apelin knockout (Apelin-/-) mice by cecal ligation and puncture (CLP). Neonatal mouse cardiomyocytes (NMCs) were treated with lipopolysaccharide (LPS) to simulate the physiological environment of SMD in vitro. The expression of Apelin was greatly decreased in the plasma from septic patients and septic mouse heart. Knockout of Apelin aggravated SMD, evidenced by decreased cardiac function, and increased cardiac fibrosis and NLRP3 inflammasome and pyroptosis levels in CLP-treated Apelin-/- mice compared with WT mice. Overexpression of Apelin activated the AMPK pathway and thereby inhibited NLRP3 inflammasome-mediated pyroptosis of NMCs induced by LPS in vitro These protective effects were partially abrogated by AMPK inhibitor. In conclusion, Apelin attenuated SMD by inhibiting NLRP3-mediated pyroptosis via activation of the AMPK pathway. Apelin may serve as a promising therapeutic target for SMD.
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The enzyme 6-phospho-ß-glucosidase is an important member of the glycoside hydrolase family 1 (GH1). However, its catalytic mechanisms, especially the key residues determining substrate specificity and affinity, are poorly understood. A metagenome-derived gene sequence, encoding a novel 6-phospho-ß-glucosidase designated Pbgl25-217, was isolated and characterized. The optimal conditions for enzymatic activity were 37°C and pH 7; Ca(2+), Mg(2+), and Mn(2+) stabilized the activity of Pbgl25-217, whereas Ni(2+), Fe(2+), Zn(2+), Cu(2+), and Fe(3+) inhibited its activity. The Km and Vmax of Pbgl25-217 were 4.8 mM and 1,987.0 U mg(-1), respectively. Seven conserved residues were recognized by multiple alignments and were tested by site-directed mutagenesis for their functions in substrate recognition and catalytic reaction. The results suggest that residues S427, Lys435, and Tyr437 act as "gatekeepers" in a phosphate-binding loop and play important roles in phosphate recognition. This functional identification may provide insights into the specificity of 6-phospho-ß-glycosidases in GH1 and be useful for designing further directed evolution.
Assuntos
Glucosidases/genética , Glucosidases/metabolismo , Microbiologia Industrial , Metagenoma , Sequência Conservada , Análise Mutacional de DNA , Ativadores de Enzimas/metabolismo , Inibidores Enzimáticos/metabolismo , Estabilidade Enzimática , Glucosidases/química , Concentração de Íons de Hidrogênio , Cinética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Análise de Sequência de DNA , TemperaturaRESUMO
BACKGROUND: Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication, breathing and the temporomandibular joint. The use of mandibular advancement (MA) devices has recently emerged as an adolescent mandibular retraction treatment; however, current studies regarding the effect thereof are relatively few, and there is lack of sufficient clinical support. AIM: To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents. METHODS: This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021. The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software. The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology. RESULTS: There was no significant difference in the length and position of maxilla before and after the treatment. The position of the mandible moved 3.13 mm, the length increased 4.14 mm, the mandibular ramus length increased 4.09 mm, the body length increased 4.25 mm, and the position of the condyle moved 1.03 mm forward after treatment. Additionally, changes in the incisor sagittal position and labial inclination were observed. The position of the upper incisor point moved back 1.33 mm, without statistical difference, the inclination and tooth angle decreased by 3.44° and 4.06°, respectively; the position of the lower incisor point was moved 2.98 mm, and the inclination and tooth angle increased by 2.62° and 1.23°, respectively. Furthermore, changes in the incisor overjet and molar relationship were seen. Overjet decreased by 4.31 mm, of which 1.78 mm was due to dental factors, accounting for 41.3% of the effect as opposed to 58.7% due to skeletal factors. Molar relationship improved 3.87 mm, with 1.34 mm due to dental factors, and dental and skeletal factors were accounted for 34.6% and 65.4% of the effect, respectively. CONCLUSION: For adolescent patients with mandible retraction, invisalign MA can effectively promote the mandible growth, and it was proven to be mainly due to skeletal effects.
RESUMO
The role of CD3+CD56+ natural killer T (NKT) cells and its co-signaling molecules in patients with sepsis-associated encephalopathy (SAE) is unknown. In this prospective observational cohort study, we initially recruited 260 septic patients and eventually analyzed 90 patients, of whom 57 were in the SAE group and 37 were in the non-SAE group. Compared to the non-SAE group, 28-day mortality was significantly increased in the SAE group (33.3% vs. 12.1%, p = 0.026), while the mean fluorescence intensity (MFI) of CD86 in CD3+CD56+ NKT cells was significantly lower (2065.8 (1625.5 ~ 3198.8) vs. 3117.8 (2278.1 ~ 5349), p = 0.007). Multivariate analysis showed that MFI of CD86 in NKT cells, APACHE II score, and serum albumin were independent risk factors for SAE. Furthermore, the Kaplan-Meier survival analysis indicated that the mortality rate was significantly higher in the high-risk group than in the low-risk group (χ2 = 14.779, p < 0.001). This study showed that the decreased expression of CD86 in CD3+CD56+ NKT cells is an independent risk factor of SAE; thus, a prediction model including MFI of CD86 in NKT cells, APACHE II score, and serum albumin can be constructed for diagnosing SAE and predicting prognosis.