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关键词： Fire blight   Genome-wide   PbNPF gene family   Pear  

摘要： The Nitrate Transporter 1/Peptide Transporter family (NPF) plays a vital role in transporting a wide range of diverse mobile substrates, including nitrate, peptides, amino acids, dicarboxylates, malate, glucosinolates, indole-3-acetic acid (IAA), abscisic acid (ABA), and jasmonic acid (JA). While systematic characterization of NPF family genes has been achieved in model plants like Arabidopsis and rice, as well as in horticultural crops such as tomato and apple, their orthologs in Pyrus bretschneideri have not been thoroughly investigated. In this study, we identified 85 PbNPF genes in genome through phylogenetic and genomic analyses. Chromosomal location analysis revealed that 82 genes are distributed across 17 chromosomes, while three genes possessing ambiguous localization. Synteny analysis revealed that the expansion of this gene family was mostly caused by whole genome duplication events. Numerous hormone-responsive elements linked to biotic and abiotic stress responses were found using promoter cis-acting element analysis. Several PbNPF genes were markedly down-regulated after Erwinia amylovora infection, according to transcriptome data and qRT-PCR results. Subcellular localization confirmed that PbNPF5.7 is a plasma membrane-localized protein. Notably, PbNPF5.7 acts as a negative regulator of fire blight resistance: silencing PbNPF5.7 markedly enhances resistance to Erwinia amylovora by reducing ROS accumulation and increasing the activities of multiple defense-related enzymes, whereas overexpression of PbNPF5.7 in tobacco significantly increases susceptibility to fire blight. This study offers the first genome-wide characterization of the NPF family in pear and identifies PbNPF5.7 as a negative regulator of fire blight resistance. These findings suggest that members of the pear NPF family may play crucial roles in disease resistance.

关键词： 1-kestose   Fructooligosaccharides   Immobilization   Komagataella phaffii   Levansucrase   Prebiotics  

摘要： Fructooligosaccharides (FOS) are widely recognized prebiotics that selectively stimulate beneficial gut microbiota. Among short-chain FOS, 1-kestose has been reported to exert superior bifidogenic activity compared to longer-chain oligosaccharides, and its enrichment in FOS mixtures is increasingly valued for therapeutic and nutritional applications. However, industrial production of FOS from sucrose often results in mixtures contaminated with residual sucrose and glucose, which diminish prebiotic efficacy and limit use in populations with metabolic disorders. To address this, we developed a recombinant Komagataella phaffii strain expressing a mutated levansucrase (LsdA R171K–H172S) from Gluconoacetobacter diazotrophicus for the synthesis and purification of FOS. Fed-batch culture experiments revealed an imbalance between periplasmic retention and extracellular secretion of the enzyme, despite the presence of a secretion signal. To overcome this limitation, cells were immobilized in calcium alginate beads, enabling simultaneous sucrose hydrolysis and glucose consumption. Optimal biomass loading was determined to be 300 g/L, balancing enzymatic activity and bead stability. Semicontinuous purification was performed in a fixed column at 35 °C with varying carbohydrate concentrations. The highest FOS purity (91.8%) and recovery (90.5%) were achieved at 400 g/L carbohydrate concentration. The resulting solution contained predominantly 1-kestose (79.9%) with 20% nystose, and negligible residual sucrose or glucose. This one-step bioprocess demonstrates an efficient strategy for producing high-purity FOS enriched in 1-kestose, offering advantages over conventional fermentation and purification methods and supporting the development of functional foods with enhanced prebiotic potential.

摘要： Calcium-ion batteries (CIBs) are widely regarded as promising alternatives to lithium-ion batteries (LIBs) due to their abundant resources, low-cost, superior safety, high energy density and similar working mechanism; nevertheless, the absence of an exceptional anode material remains a notable obstacle impeding the advancement of CIB technology. In this work, we implemented a through first-principles calculation to estimate the anodic behavior of the emerging 2D TiB_x (x = 1-5) monolayers in CIBs. The projected band structure calculation reveals that the TiB_x (x = 1-5) anodes exhibit remarkable electronic conductivity with intrinsical metallic/semimetallic behavior. It is found that Ca ions are chemically anchored on the surfaces of TiB_x (x = 1-5) anodes with adsorption energies of −3.40 to −0.25 eV. Moreover, the lightweight properties and high affinity of Ca ions endow TiB_x (x = 1-5) anodes with low average open-circuit-voltages of 0.20, 0.43, 0.45, 0.45 and 0.45 V, as well as high theoretical capacities of 608.98, 1028.48, 667.52, 1176.64 and 1051.84 mA h/g. Additionally, Ca ion can diffuse rapidly across the TiB_x (x = 1, 3, 4, 5) anode surfaces with diffusion barriers of 0.20, 0.27, 0.37 and 0.21 eV. In contrast, the TiB₂ anode exhibits a remarkably high diffusion barrier (1.00 eV) for Ca ion, resulting in a low ion mobility. Furthermore, TiB_x (x = 1-5) anodes present small volume expansion during electrochemical cycling with the maximum lattice changes of 3.59%, 4.97%, 1.34%, 4.42% and 1.91%. These exceptional attributes make TiB_x (x = 1, 3, 4, 5) monolayers appealing anode candidates for CIBs. In particular, the TiB₄ anode exhibits the optimal electrochemical performance due to its planar structure and high adsorption energy.

关键词： 1-Propanol   Culture-dependent validation   Environmental factors   Metabolic pathways   Metagenomics   Microbial community  

摘要： 1-Propanol is a crucial flavor compound in Jiang-flavor Baijiu, yet the key microbial pathways and environmental factors controlling its synthesis have not been systematically investigated. Using an integrated approach of metagenomics and culture-dependent techniques, this study identified the key microbes, pathways, and factors controlling 1-propanol synthesis. The highest 1-propanol level was detected in first-round base Baijiu, with rapid accumulation during early pit fermentation. Metagenomics revealed the propanoate pathway as the dominant route, primarily contributed by Limosilactobacillus, while Pichia and Saccharomyces were key providers of pyruvate decarboxylase in the citramalate and threonine pathways. Pure-culture validation confirmed that L. panis MR32 predominantly utilizes 1,2-propanediol as the precursor, while yeasts such as P. kudriavzevii 2J2 and S. cerevisiae LB7A prefer the 2-ketobutyrate pathway. Environmental tests revealed optimal 1-propanol production by L. panis MR32 at pH 5.5 and increasing yields with temperature (25–45 °C). In contrast, most yeasts produced the most 1-propanol at 30 °C, beyond which yields declined, with only P. kudriavzevii 2J2 and I. orientalis IO tolerating high lactic acid. Our findings clarify the microbial division of labor and environmental drivers of 1-propanol formation, enabling targeted fermentation control.

关键词： ACM   all-cause mortality   cTnI   cardiac troponin-I   CV   cardiovascular   EQW   weekly exenatide   GLP-1   glucagon-like peptide-1   hHF   hospitalization for heart failure   HR   hazard ratio   MACE   major adverse cardiovascular event   NT-proBNP   N-terminal pro B-type natriuretic peptide   RCS   restricted cubic spline  

摘要： In the EXSCEL trial, exenatide did not reduce major adverse cardiovascular events (MACE), but heterogeneity of benefit and the role of cardiac biomarkers remain uncertain. We evaluated the prognostic value of baseline and 1-year changes in N-terminal pro B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin I (cTnI), and whether baseline biomarker concentrations modified exenatide effects.

关键词： Tin(IV) complexes   Lead(IV) complexes   Organotin(IV)   Organolead(IV)   Naphthalene-1,4-dione   Anthracene-9,10-dione  

摘要： In this paper, two proligands derived from the naphthalene-1,4-dione framework: 2-hydroxy-1,4-naphthoquinone, named lawsone (HL¹) and, 2-(2-(tosylamino)phenylamino)-3-chloro-naphthalene-1,4-dione, (H₂L²) were used to obtain tin(IV) compounds of formula [R₂SnL¹Cl], R = methyl (1), phenyl (2), [{Cp(CO)₂Fe}Sn(L¹)₂] (3) and [R₂SnL²], R = methyl (4) or Cp(CO)₂Fe (5). In order to increase the number of fussed rings, two new proligands containing the four fused 1H-anthra[1,2-d]imidazole-6,11-dione framework were also synthesized. H₂L³ incorporates a 2-hydroxyphenyl substituent on the imidazole ring and H₂L⁴ incorporates a 2-(tosylamino)phenyl group. Also tin(IV) compounds of formula R₂SnLⁿ, n = 3 or 4; R = methyl (6 and 8) or Cp(CO)₂Fe (7 and 9) were obtained. All the compounds were characterized by spectroscopic techniques, IR and ¹H NMR spectroscopy, and Mass spectrometry (FAB). The compounds [Me₂SnL²] (4), [{Cp(CO)₂Fe}₂SnL²] (5), and [{Cp(CO)₂Fe}₂SnL³] (7) were studied by single crystal x-ray diffraction and their structures are presented. For complex 2 we have obtained a new compound in the recrystallization process with CH₂Cl₂, because the coordinated 1,4-naphthoquinone-2-olate anion, (L¹)⁻, reacts with solvent to give a new ligand, the dianion of the 3,3′-methylene bilawsone, (L¹-CH₂-L¹)²⁻. The crystal structure of the [Ph₆Sn₄

关键词： Cycle   Stability   Turán number  

摘要： Starting from the stability theorem of Erdős and Simonovits, there have been interesting studies on stability of graphs forbidding certain substructures in terms of edge numbers, minimum degrees or numbers of cliques. In this paper we obtain strong structural stability of $C_{2k+1}$-free in terms of the number of copies of $C_4$. Let $\mathcal{N}(F,G)$ be the number of copies of F in G. We show that a $C_{2k+1}$-free graph G must be very close to $K_{\lfloor \frac{n}{2}\rfloor ,\lceil \frac{n}{2}\rceil }$ when

来源 ScienceDirectJournal ScienceCitationIndex... 详细信息

关键词： AMS   36Cl   Nuclear waste   Radiochemistry  

摘要： The detection limit for ³⁶Cl (T_1/2 = 0.301 My) using mass spectrometry techniques is primarily constrained by the system’s ability to discriminate between ³⁶Cl and its stable isobar ³⁶S. Conventional accelerator mass spectrometry (AMS) systems typically operating at terminal voltages of 3 MV and above, achieve background levels for the isotopic ratio of ³⁶Cl/³⁵Cl on the order of 10⁻¹⁵ using techniques based on the stopping power difference. However, compact AMS systems are limited in their ability to discriminate heavy isobars due to their lower operating terminal voltages (i.e., 1 MV and below). Driven by the need to study ³⁶Cl in low- and intermediate-level nuclear waste (LILW), for which ³⁶Cl/³⁵Cl atom ratios on the order of 10⁻⁹ represent the detection limit of radiometric techniques, the performance of the 1 MV AMS system for the analysis of ³⁶Cl at the Centro Nacional de Aceleradores (CNA, Seville, Spain) was investigated in this work. Two strategies were adopted: (i) optimisation of radiochemistry and control of the ³⁶S signal using ³³S as a proxy, and (ii) exploitation of the partial overlap between the ³⁶Cl and ³⁶S signals in a ΔE–Eres gas detector. These approaches yielded background levels of approximately 10⁻⁹ and 10⁻¹⁰, respectively. To enable these experiments, the stripping process of chlorine in helium gas at terminal voltages below 1 MV was investigated. Results from standard samples and blanks are presented in this paper.