Significant effects of minor chemical composition changes on the structure and property of (Pb1-ySry)(Mg1/3Nb2/3)0.07ZrxTi0.93-xO3:zLa.

Piezoelectric ceramics with high electrical performances and high Curie temperature (Tc) act as key materials for numerous electromechanical devices such as transducers and actuators. Herein, we report a systematic investigation on the crystal structure, microstructure and electrical properties of Sr and La co-doped Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics with a low Pb(Mg1/3Nb2/3)O3 content, namely, (Pb1-ySry)(Mg1/3Nb2/3)0.07ZrxTi0.93-xO3:zLa. With an increase in the Zr content (x value) from 0.49 to 0.53, its crystal structure evolved from a tetragonal phase to a rhombohedral phase, leading to not only a morphotropic phase boundary (MPB) at around x = 0.51 but also a monotonously decreasing Tc. Meanwhile, a change in either the Sr- or La-doping content (y and z values, respectively) in the range of y = 0.03-0.07 and z = 0.01-0.03 can slightly deviate the structure of MPB, resulting in a significant effect on its electrical properties. As the best results, the optimal composition of x = 0.51, y = 0.05, and z = 0.02 yielded peak electrical performance, with a related room temperature piezoelectric coefficient (d33) of 645 pC N-1, remanent polarization (Pr) of 33.5 µC cm-2, coercive field (Ec) of 8.6 kV cm-1, and Tc of 242 °C. Especially, its piezoelectric properties showed excellent temperature stability, and its d33 value decreased by only 3% from room temperature to 150 °C. This work not only provides an alternative piezoelectric ceramic with outstanding electrical performance for industrial applications, but also reveals a comprehensive perspective on the composition-structure-property relationship of doped Pb[(Mg1/3Nb2/3),Zr,Ti]O3, which is helpful for further work on piezoelectric ceramics.

Psychosocial functioning and its influencing factors in patients with depression post-remission: Implications for assessment and interventions.

BACKGROUND: Enhancing psychosocial functioning is crucial for reducing relapse in depression, but methods for monitoring and recovery are unclear. METHOD: A 1-year follow-up study assessed psychosocial functioning in 182 patients with remitted depression at baseline (T0) as well as at 1, 2, 6, 9, and 12 months post-remission (T1-T5). Using generalized estimating equations (GEE) and multiple linear regression (MLR), we analyzed the impact of changes in psychosocial functioning on relapse/recurrence risk, and assessed the influence of various factors. RESULTS: An increase in psychosocial functioning significantly lowered relapse/recurrence odds by 54.2 %, averaging a risk reduction of 3.1 %. GEE analyses indicated subjective depressive symptoms (ß = -0.315) most significantly impacted psychosocial functioning, followed by social support (ß = 0.236), positive coping (ß = 0.225), and negative automatic thoughts (ß = -0.183). Negative coping and expressed emotion exhibited non-significant effects. MLR revealed that the impact of negative automatic thoughts was most significant at initial remission, but the relative importance of residual subjective depressive symptoms, positive coping, and social support on psychosocial functioning remained stable over time. LIMITATIONS: Predetermined follow-up assessments may not fully capture psychosocial functioning at relapse/recurrence, and the inclusion of factors might not be sufficiently comprehensive. CONCLUSIONS: Recovery of psychosocial functioning significantly reduces relapse risk in post-remission patients with depression more than residual subjective depressive symptoms. The degree of influence of factors on psychosocial functioning can change with the length of remission time.

LncRNAs in the Dlk1-Dio3 Domain Are Essential for Mid-Embryonic Heart Development.

The Dlk1-Dio3 domain is important for normal embryonic growth and development. The heart is the earliest developing and functioning organ of the embryo. In this study, we constructed a transcriptional termination model by inserting termination sequences and clarified that the lack of long non-coding RNA (lncRNA) expression in the Dlk1-Dio3 domain caused the death of maternal insertion mutant (MKI) and homozygous mutant (HOMO) mice starting from E13.5. Parental insertion mutants (PKI) can be born and grow normally. Macroscopically, dying MKI and HOMO embryos showed phenomena such as embryonic edema and reduced heart rate. Hematoxylin and eosin (H.E.) staining showed thinning of the myocardium in MKI and HOMO embryos. In situ hybridization (IHC) and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) showed downregulation of lncGtl2, Rian, and Mirg expression in MKI and HOMO hearts. The results of single-cell RNA sequencing (scRNA-Seq) analysis indicated that the lack of lncRNA expression in the Dlk1-Dio3 domain led to reduced proliferation of epicardial cells and may be an important cause of cardiac dysplasia. In conclusion, this study demonstrates that Dlk1-Dio3 domain lncRNAs play an integral role in ventricular development.

DKK1-SE recruits AP1 to activate the target gene DKK1 thereby promoting pancreatic cancer progression.

Super-enhancers are a class of DNA cis-regulatory elements that can regulate cell identity, cell fate, stem cell pluripotency, and even tumorigenesis. Increasing evidence shows that epigenetic modifications play an important role in the pathogenesis of various types of cancer. However, the current research is far from enough to reveal the complex mechanism behind it. This study found a super-enhancer enriched with abnormally active histone modifications in pancreatic ductal adenocarcinoma (PDAC), called DKK1-super-enhancer (DKK1-SE). The major active component of DKK1-SE is component enhancer e1. Mechanistically, AP1 induces chromatin remodeling in component enhancer e1 and activates the transcriptional activity of DKK1. Moreover, DKK1 was closely related to the malignant clinical features of PDAC. Deletion or knockdown of DKK1-SE significantly inhibited the proliferation, colony formation, motility, migration, and invasion of PDAC cells in vitro, and these phenomena were partly mitigated upon rescuing DKK1 expression. In vivo, DKK1-SE deficiency not only inhibited tumor proliferation but also reduced the complexity of the tumor microenvironment. This study identifies that DKK1-SE drives DKK1 expression by recruiting AP1 transcription factors, exerting oncogenic effects in PDAC, and enhancing the complexity of the tumor microenvironment.

Crystal structure of lipase from Pseudomonas aeruginosa reveals an unusual catalytic triad conformation.

The Pseudomonas aeruginosa lipase PaL catalyzes the stereoselective hydrolysis of menthyl propionate to produce L-menthol. The lack of a three-dimensional structure of PaL has so far prevented a detailed understanding of its stereoselective reaction mechanism. Here, the crystal structure of PaL was determined at a resolution of 1.80 Å by single-wavelength anomalous diffraction. In the apo-PaL structure, the catalytic His302 is located in a long loop on the surface that is solvent exposed. His302 is distant from the other two catalytic residues, Asp274 and Ser164. This configuration of catalytic residues is unusual for lipases. Using metadynamics simulations, we observed that the enzyme undergoes a significant conformational change upon ligand binding. We also explored the catalytic and stereoselectivity mechanisms of PaL by all-atom molecular dynamics simulations. These findings could guide the engineering of PaL with an improved diastereoselectivity for L-menthol production.

Understanding the Effects of Anode Catalyst Conductivity and Loading on Catalyst Layer Utilization and Performance for Anion Exchange Membrane Water Electrolysis.

Anion exchange membrane water electrolysis (AEMWE) is a promising technology to produce hydrogen from low-cost, renewable power sources. Recently, the efficiency and durability of AEMWE have improved significantly due to advances in the anion exchange polymers and catalysts. To achieve performances and lifetimes competitive with proton exchange membrane or liquid alkaline electrolyzers, however, improvements in the integration of materials into the membrane electrode assembly (MEA) are needed. In particular, the integration of the oxygen evolution reaction (OER) catalyst, ionomer, and transport layer in the anode catalyst layer has significant impacts on catalyst utilization and voltage losses due to the transport of gases, hydroxide ions, and electrons within the anode. This study investigates the effects of the properties of the OER catalyst and the catalyst layer morphology on performance. Using cross-sectional electron microscopy and in-plane conductivity measurements for four PGM-free catalysts, we determine the catalyst layer thickness, uniformity, and electronic conductivity and further use a transmission line model to relate these properties to the catalyst layer resistance and utilization. We find that increased loading is beneficial for catalysts with high electronic conductivity and uniform catalyst layers, resulting in up to 55% increase in current density at 2 V due to decreased kinetic and catalyst layer resistance losses, while for catalysts with lower conductivity and/or less uniform catalyst layers, there is minimal impact. This work provides important insights into the role of catalyst layer properties beyond intrinsic catalyst activity in AEMWE performance.

Sws2 Gene Positively Regulates Melanin Production in Plectropomus leopardus Skin via Direct Regulation of the Synthesis of Retinoic Acid.

Opsins are a class of transmembrane proteins encoded by opsin genes, and they play a variety of functional roles. Short wavelength-sensitive opsin 2 (sws2), one of the five classes of visual opsin genes, mainly senses blue light. Previous research has indicated that sws2 is essential for melanocyte formation in fish; however, its specific role in skin color differentiation remains to be elucidated. Here, we identified the sws2 gene in a prized reef-dwelling fish, Plectropomus leopardus. The full-length P. leopardus sws2 gene encodes a protein consisting of 351 amino acids, and exhibits substantial homology with other fish species. The expression of the sws2 gene was widespread across P. leopardus tissues, with high expression in eye and skin tissues. Through immunohistochemistry and in situ hybridization analyses, we discovered that the sws2 gene was primarily localized in the rod and cone cells of the retina, and epidermal cells of the skin. Furthermore, dsRNA interference was used for sws2 gene knockdown in living P. leopardus to elucidate its function in skin color differentiation. Black-color-related genes, melanin contents, and tyrosinase activity in the skin significantly decreased after sws2 knockdown (p < 0.05), but red-color-related genes and carotenoid and lutein contents significantly increased (p < 0.05). Retinoic acid injection produced the opposite results. Our results suggested that the sws2 gene influences P. leopardus skin color regulation by affecting vitamin synthesis and melanin-related gene expression levels. This study establishes a foundation for elucidating the molecular mechanisms by which sws2 regulates melanocyte formation in fish skin.

Sources of acellular oxidative potential of water-soluble fine ambient particulate matter in the midwestern United States.

Ambient fine particulate matter (PM2.5) is associated with numerous health complications, yet the specific PM2.5 chemical components and their emission sources contributing to these health outcomes are understudied. Our study analyzes the chemical composition of PM2.5 collected from five distinct locations at urban, roadside and rural environments in midwestern region of the United States, and associates them with five acellular oxidative potential (OP) endpoints of water-soluble PM2.5. Redox-active metals (i.e., Cu, Fe, and Mn) and carbonaceous species were correlated with most OP endpoints, suggesting their significant role in OP. We conducted a source apportionment analysis using positive matrix factorization (PMF) and found a strong disparity in the contribution of various emission sources to PM2.5 mass vs. OP. Regional secondary sources and combustion-related aerosols contributed significantly (> 75 % in total) to PM2.5 mass, but showed weaker contribution (43-69 %) to OP. Local sources such as parking emissions, industrial emissions, and agricultural activities, though accounting marginally to PM2.5 mass (< 10 % for each), significantly contributed to various OP endpoints (10-50 %). Our results demonstrate that the sources contributing to PM2.5 mass and health effects are not necessarily same, emphasizing the need for an improved air quality management strategy utilizing more health-relevant PM2.5 indicators.

Inter-continental variability in the relationship of oxidative potential and cytotoxicity with PM2.5 mass.

Most fine ambient particulate matter (PM2.5)-based epidemiological models use globalized concentration-response (CR) functions assuming that the toxicity of PM2.5 is solely mass-dependent without considering its chemical composition. Although oxidative potential (OP) has emerged as an alternate metric of PM2.5 toxicity, the association between PM2.5 mass and OP on a large spatial extent has not been investigated. In this study, we evaluate this relationship using 385 PM2.5 samples collected from 14 different sites across 4 different continents and using 5 different OP (and cytotoxicity) endpoints. Our results show that the relationship between PM2.5 mass vs. OP (and cytotoxicity) is largely non-linear due to significant differences in the intrinsic toxicity, resulting from a spatially heterogeneous chemical composition of PM2.5. These results emphasize the need to develop localized CR functions incorporating other measures of PM2.5 properties (e.g., OP) to better predict the PM2.5-attributed health burdens.

Chemical composition-induced evolution of the structure, domain and electrical properties of Sm-doped (1 - x)Pb(Ni1/3Nb2/3)O3-xPbTiO3.

As the two typical basic binary solid solutions of the relaxor-PbTiO3 family, Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) has been widely investigated, whereas Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) has not. Here, 1.5 mol% Sm-doped (1 - x)Pb(Ni1/3Nb2/3)O3-xPbTiO3, (1 - x)PNN-xPT:0.015Sm with x = 0.33-0.39, ceramics have been prepared and the chemical composition-induced evolution of crystal structure, domain, and electrical properties investigated systematically. With increasing PT content, evolution of the rhombohedral-tetragonal structure was observed. A rhombohedral-tetragonal morphotropic phase boundary occurred around x = 0.36-0.37, which showed a peak piezoelectric property with piezoelectric constant d33 = 531 pC N-1 and planar electromechanical coupling factor kp = 0.37 at room temperature. At the same time, the x = 0.36 composition showed improved ferroelectric behavior with remanent polarization Pr = 13.4 µC cm-2 and coercive field Ec = 3.2 kV cm-1. Interestingly, different from its PMN-PT counterpart, there is no temperature-driven phase transition between room temperature and the Curie temperature for (1 - x)PNN-xPT:0.015Sm. These parameters indicated that the PNN-PT system is worthy of more attention and is a promising platform for further development of high-performance piezo/ferroelectric materials.

Discovery, characterization and mechanism of a Microbacterium esterase for key d-biotin chiral intermediate synthesis.

Esterases are crucial biocatalysts in chiral compound synthesis. Herein, a novel esterase EstSIT01 belonging to family V was identified from Microbacterium chocolatum SIT101 through genome mining and phylogenetic analysis. EstSIT01 demonstrated remarkable efficiency in asymmetrically hydrolyzing meso-dimethyl ester [Dimethyl cis-1,3-Dibenzyl-2-imidazolidine-4,5-dicarboxyate], producing over 99% yield and 99% enantiomeric excess (e.e.) for (4S, 5R)-monomethyl ester, a crucial chiral intermediate during the synthesis of d-biotin. Notably, the recombinant E. coli expressing EstSIT01 exhibited over 40-fold higher activity than that of the wild strain. EstSIT01 displays a preference for short-chain p-NP esters. The optimal temperature and pH were 45 °C and 10.0, with Km and kcat values of 0.147 mmol/L and 5.808 s- 1, respectively. Molecular docking and MD simulations suggest that the high stereoselectivity for meso-diester may attribute to the narrow entrance tunnel and unique binding pocket structure. Collectively, EstSIT01 holds great potential for preparing chiral carboxylic acids and esters.

Amorphous Iridium Oxide-Integrated Anode Electrodes with Ultrahigh Material Utilization for Hydrogen Production at Industrial Current Densities.

Herein, ionomer-free amorphous iridium oxide (IrOx) thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells (PEMECs) via low-cost, environmentally friendly, and easily scalable electrodeposition at room temperature. Combined with a Nafion 117 membrane, the IrOx-integrated electrode with an ultralow loading of 0.075 mg cm-2 delivers a high cell efficiency of about 90%, achieving more than 96% catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane (2 mg cm-2). Additionally, the IrOx electrode demonstrates superior performance, higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes. Notably, the remarkable performance could be mainly due to the amorphous phase property, sufficient Ir3+ content, and rich surface hydroxide groups in catalysts. Overall, due to the high activity, high cell efficiency, an economical, greatly simplified and easily scalable fabrication process, and ultrahigh material utilization, the IrOx electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.

Intrahepatic cholangiocarcinoma with FGFR alterations: A series of Chinese cases with an emphasis on their clinicopathologic and genetic features.

Intrahepatic Cholangiocarcinoma (iCCA) with FGFR alterations is relatively rare, and its identification is important in the era of targeted therapy. We collected a large series of FGFR-altered cases in the Chinese population and characterized their clinicopathological and genetic features. Among the 18 FGFR-altered cases out of 260 iCCAs, 10 were males and 8 were females, ranging in age from 35 to 74 years (mean, 57.3 years; median, 58 years). Pathologically, they include 9 cases of large duct (LD, 50 %) and small duct (SD, 50 %) types each. All of them (100 %, 18/18) showed microsatellite stable (MSS) and low tumor mutation burden (TMB). Genetically, FGFR alterations involved FGFR1 (20 %), FGFR2 (70 %), and FGFR3 (10 %), with FGFR2 rearrangement accounting for the most (11/18). The most frequently altered genes/biological processes were development/proliferation-related pathways (44 %), chromatin organization (20 %), and tumor suppressors (32 %). Our study further revealed the clinicopathological and genetic features of FGFR-altered iCCA and demonstrated that its occurrence may show regional or ethnic variability and is less common in the Chinese population. A significant number of LD-type iCCA cases also have FGFR alterations rather than the SD type.

The impact of the COVID-19 pandemic on dietary behaviors among school-age children, adolescents, and young adults: a systematic review and meta-analysis.

CONTEXT: The COVID-19 pandemic has had a global impact on food security and nutrition, both in the short and long term. The influence on school-age children, adolescents, and young adults may be particularly significant and long-lasting. OBJECTIVE: This systematic review and meta-analysis aimed to quantify the impact of the COVID-19 pandemic on dietary habits among school-age children, adolescents, and young adults worldwide. DATA SOURCES: PubMed, Web of Science, and Embase were searched from inception to October 5, 2023. DATA EXTRACTION: We included observational studies published in English that reported dietary quality scores and dietary intake quantities during and before the COVID-19 pandemic among school-age children, adolescents, and young adults. We included a total of 22 cohort studies and 20 cross-sectional studies of high or moderate quality. DATA ANALYSIS: We conducted a meta-analysis, expressing dietary quality scores and dietary intake quantities as standardized mean differences (SMD) with 95% confidence intervals (CIs). For studies with low heterogeneity, we used a fixed-effects model; otherwise, we applied a random-effects model. The Newcastle-Ottawa Scale was employed by 2 reviewers independently to evaluate methodological quality. The analysis indicated that, overall, juice intake increased (SMD = 0.12, 95% CI: 0.04 to 0.20), while alcohol consumption reduced during the COVID-19 pandemic (SMD = -0.28, 95% CI: -0.47 to -0.08). However, the age-stratified results varied. Among school-age children, intake of fruit, dairy products, sugar, and juice increased. Adolescents showed an increase in meal frequency and vegetable intake. Young adults showed reduced carbohydrate and alcohol intakes, while protein and dairy product intakes increased, based on limited included studies. CONCLUSION: Dietary changes in school-age children from before to during the pandemic were mixed, while dietary behavior changes in adolescents and young adults tended to be more positive. Considering the lasting effects of negative dietary behaviors, attention should be given to addressing the increased sugar and juice intakes. It is also crucial that caregivers and researchers monitor whether positive dietary behaviors will rebound after returning to normal study and life. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42023420923.

Enantiodivergent kinetic resolution of 4-substituted 1,2,3,4-tetrahydroquinolines employing amine oxidase.

Optically pure 1,2,3,4-tetrahydroquinolines (THQs) represent a class of important motifs in many natural products and pharmaceutical agents. While recent advances on redox biocatalysis have demonstrated the great potential of amine oxidases, all the transformations focused on 2-substituted THQs. The corresponding biocatalytic method for the preparation of chiral 4-substituted THQs is still challenging due to the poor activity and stereoselectivity of the available enzyme. Herein, we developed a biocatalytic kinetic resolution approach for enantiodivergent synthesis of 4-phenyl- or alkyl-substituted THQs. Through structure-guided protein engineering of cyclohexylamine oxidase derived from Brevibacterium oxidans IH-35 A (CHAO), the variant of CHAO (Y215H/Y214S) displayed improved specific activity toward model substrate 4-phenyl substituted THQ (0.14 U/mg, 13-fold higher than wild-type CHAO) with superior (R)-stereoselectivity (E > 200). Molecular dynamics simulations show that CHAO Y215H/Y214S allows a suitable substrate positioning in the expanded binding pocket to be facilely accessed, enabling enhanced activity and stereoselectivity. Furthermore, a series of 4-alkyl-substituted THQs can be transformed by CHAO Y215H/Y214S, affording R-isomers with good yields (up to 50 %) and excellent enantioselectivity (up to ee > 99 %). Interestingly, the monoamine oxidase from Pseudomonas fluorescens Pf0-1 (PfMAO1) with opposite enantioselectivity was also mined. Together, this system enriches the kinetic resolution methods for the synthesis of chiral THQs.

Human P2X7 receptor variants Gly150Arg and Arg276His polymorphisms have differential effects on risk association and cellular functions in pancreatic cancer.

BACKGROUND: The purinergic P2X7 receptor (P2X7R) plays an important role in the crosstalk between pancreatic stellate cells (PSCs) and cancer cells, thus promoting progression of pancreatic ductal adenocarcinoma (PDAC). Single nucleotide polymorphisms (SNPs) in the P2X7R have been reported for several cancers, but have not been explored in PDAC. MATERIALS AND METHODS: Blood samples from PDAC patients and controls were genotyped for 11 non-synonymous SNPs in P2X7R and a risk analysis was performed. Relevant P2X7R-SNP GFP variants were expressed in PSCs and cancer cells and their function was assayed in the following tests. Responses in Ca2+ were studied with Fura-2 and dye uptake with YO-PRO-1. Cell migration was monitored by fluorescence microscopy. Released cytokines were measured with MSD assay. RESULTS: Risk analysis showed that two SNPs 474G>A and 853G>A (rs28360447, rs7958316), that lead to the Gly150Arg and Arg276His variants, had a significant but opposite risk association with PDAC development, protecting against and predisposing to the disease, respectively. In vitro experiments performed on cancer cells and PSCs expressing the Gly150Arg variant showed reduced intracellular Ca2+ response, fluorescent dye uptake, and cell migration, while the Arg276His variant reduced dye uptake but displayed WT-like Ca2+ responses. As predicted, P2X7R was involved in cytokine release (IL-6, IL-1ß, IL-8, TNF-α), but the P2X7R inhibitors displayed varied effects. CONCLUSION: In conclusion, we provide evidence for the P2X7R SNPs association with PDAC and propose that they could be considered as potential biomarkers.

Improving the production of carbamoyltobramycin by an industrial Streptoalloteichus tenebrarius through metabolic engineering.

Tobramycin is an essential and extensively used broad-spectrum aminoglycoside antibiotic obtained through alkaline hydrolysis of carbamoyltobramycin, one of the fermentation products of Streptoalloteichus tenebrarius. To simplify the composition of fermentation products from industrial strain, the main byproduct apramycin was blocked by gene disruption and constructed a mutant mainly producing carbamoyltobramycin. The generation of antibiotics is significantly affected by the secondary metabolism of actinomycetes which could be controlled by modifying the pathway-specific regulatory proteins within the cluster. Within the tobramycin biosynthesis cluster, a transcriptional regulatory factor TobR belonging to the Lrp/AsnC family was identified. Based on the sequence and structural characteristics, tobR might encode a pathway-specific transcriptional regulatory factor during biosynthesis. Knockout and overexpression strains of tobR were constructed to investigate its role in carbamoyltobramycin production. Results showed that knockout of TobR increased carbamoyltobramycin biosynthesis by 22.35%, whereas its overexpression decreased carbamoyltobramycin production by 10.23%. In vitro electrophoretic mobility shift assay (EMSA) experiments confirmed that TobR interacts with DNA at the adjacent tobO promoter position. Strains overexpressing tobO with ermEp* promoter exhibited 36.36% increase, and tobO with kasOp* promoter exhibited 22.84% increase in carbamoyltobramycin titer. When the overexpressing of tobO and the knockout of tobR were combined, the production of carbamoyltobramycin was further enhanced. In the shake-flask fermentation, the titer reached 3.76 g/L, which was 42.42% higher than that of starting strain. Understanding the role of Lrp/AsnC family transcription regulators would be useful for other antibiotic biosynthesis in other actinomycetes. KEY POINTS: • The transcriptional regulator TobR belonging to the Lrp/AsnC family was identified.  • An oxygenase TobO was identified within the tobramycin biosynthesis cluster. • TobO and TobR have significant effects on the synthesis of carbamoyltobramycin.

Reconstructing dynamics correlation network to simultaneously improve activity and stability of 2,3-butanediol dehydrogenase by design of distal interchain disulfide bonds.

The complete enzyme catalytic cycle includes substrate binding, chemical reaction and product release, in which different dynamic conformations are adopted. Due to the complex relationship among enzyme activity, stability and dynamics, the directed evolution of enzymes for improved activity or stability commonly leads to a trade-off in stability or activity. It hence remains a challenge to engineer an enzyme to have both enhanced activity and stability. Here, we have attempted to reconstruct the dynamics correlation network involved with active center to improve both activity and stability of a 2,3-butanediol dehydrogenase (2,3-BDH) by introducing inter-chain disulfide bonds. A computational strategy was first applied to evaluate the effect of introducing inter-chain disulfide bond on activity and stability of three 2,3-BDHs, and the N258C mutation of 2,3-BDH from Corynebacterium glutamicum (CgBDH) was proved to be effective in improving both activity and stability. In the results, CgBDH-N258C showed a different unfolding curve from the wild type, with two melting temperatures (Tm) of 68.3 °C and 50.8 °C, 19.7 °C and 2 °C higher than 48.6 °C of the wild type. Its half-life was also improved by 14.8-fold compared to the wild type. Catalytic efficiency (kcat/Km) of the mutant was increased by 7.9-fold toward native substrate diacetyl and 8.8-fold toward non-native substrate 2,5-hexanedione compared to the wild type. Molecular dynamics simulations revealed that an interaction network formed by Cys258, Arg162, Ala144 and the catalytic residues was reconstructed in the mutant and the dynamics change caused by the disulfide bond could be propagated through the interactions network. This improved the enzyme stability and activity by decreasing the flexibility and locking more "reactive" pose, respectively. Further construction of mutations including A144G showing a 44-fold improvement in catalytic efficiency toward meso-2,3-BD confirmed the role of modifying dynamics correlation network in tunning enzyme activity and selectivity. This study provided important insights into the relationship among dynamics, enzyme catalysis and stability, and will be useful in the designing new enzymes with co-evolution of stability, activity and selectivity.

Detection and differentiation of seven porcine respiratory pathogens using a multiplex ligation-dependent probe amplification assay.

Respiratory diseases due to viral or bacterial agents, either alone or in combination, cause substantial economic burdens to the swine industry worldwide. Rapid and reliable detection of causal pathogens is crucial for effective epidemiological surveillance and disease management. This research aimed to employ the multiplex ligation-dependent probe amplification (MLPA) assay for simultaneous detection of seven distinct pathogens causing respiratory problems in swine, porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), porcine respiratory coronavirus (PRCV), porcine circovirus type 2 (PCV2), Pasteurella multocida, Actinobacillus pleuropneumoniae, and Glässerella parasuis. The results indicated no probe cross-reactivity among the seven target agents with other swine pathogens. The detection limits ranged from 5 to 34 copies per assay for the target organisms. The MLPA assay was evaluated with 88 samples and compared to real-time or multiplex PCR for the target pathogens. The MLPA assay demonstrated high relative test sensitivities (100 %) and reasonable to good relative specificities at 62.5 %, 95.1 %, 86.8 %, and 97.6 % for PRRSV, P. multocida, G. parasuis, and PCV2, respectively, relative to comparator PCR assays. In 71 samples where MLPA and comparator PCR assays matched exactly, infections were detected in 64 samples (90.1 %), with PRRSV being the most commonly found virus and 50.7 % of the samples showing co-infection with two to five of the pathogens. This approach serves as a valuable tool for conducting differential diagnoses and epidemiological investigations of pathogen prevalence within swine populations.

Interfacial Metal-Support Interaction and Catalytic Performance of Perovskite LaCrO3-Supported Ru Catalyst.

Interfacial metal-support interaction (MSI) significantly affects the dispersion of active metals on the surface of the catalyst support and impacts catalyst performance. Understanding MSI is crucial for developing highly active and stable catalysts with a low metal loading, particularly for noble metal catalysts. In this work, we synthesized LaRuxCr1-xO3 catalysts with low Ru loading (x = 0.005, 0.01, and 0.02) using the sol-gel self-combustion method. We found that all of the Ru atoms immediately above or below the metal-support interface are closely bonded to the perovskite LaCrO3 surface lattice through Ru-O bonds, enhancing the MSI via interfacial reaction and charge transfer mechanisms. We identified a variety of Ru species, including small 3D Ru nanoparticles, 2D dispersed Ru surface atoms, and even 0D Ru single atoms. These highly dispersed Ru species exhibit high activity and stability under dry reforming of methane (DRM) conditions. The LaRu0.01Cr0.99O3 catalyst with very low Ru loading (0.42 wt %) was stable over a 50 h DRM test and the carbon deposition was negligible. The CH4 and CO2 conversions at 750 °C reached 83 and 86%, respectively, approaching the theoretical thermodynamic equilibrium values.