Bacteria can evolve rapidly by acquiring new traits such as virulence,metabolic properties,and most importantly,antimicrobial resistance,through horizontal gene transfer(HGT).Multidrug resistance in bacteria,especiall...Bacteria can evolve rapidly by acquiring new traits such as virulence,metabolic properties,and most importantly,antimicrobial resistance,through horizontal gene transfer(HGT).Multidrug resistance in bacteria,especially in Gram-negative organisms,has become a global public health threat often through the spread of mobile genetic elements.Conjugation represents a major form of HGT and involves the transfer of DNA from a donor bacterium to a recipient by direct contact.Conjugative plasmids,a major vehicle for the dissemination of antimicrobial resistance,are selfish elements capable of mediating their own transmission through conjugation.To spread to and survive in a new bacterial host,conjugative plasmids have evolved mechanisms to circumvent both host defense systems and compete with co-resident plasmids.Such mechanisms have mostly been studied in model plasmids such as the F plasmid,rather than in conjugative plasmids that confer antimicrobial resistance(AMR)in important human pathogens.A better understanding of these mechanisms is crucial for predicting the flow of antimicrobial resistance-conferring conjugative plasmids among bacterial populations and guiding the rational design of strategies to halt the spread of antimicrobial resistance.Here,we review mechanisms employed by conjugative plasmids that promote their transmission and establishment in Gram-negative bacteria,by following the life cycle of conjugative plasmids.展开更多
Flavobacterium columnare, the etiological agent of colunmaris disease, is one of the most important and widespread bacterial pathogens of freshwater fish. In this study, we constructed two artificial selectable marke...Flavobacterium columnare, the etiological agent of colunmaris disease, is one of the most important and widespread bacterial pathogens of freshwater fish. In this study, we constructed two artificial selectable markers （chloramphenicol and spectinomycin resistance） for gene transfer in F. columnare. These two new artificial selectable markers, which were created by placing the chloramphenicol or spectinomycin resistance gene under the control of the native acs regulatory region of F. columnare, were functional in both F. columnare and Escherichia coli. The integrative/conjugative plasmids constructed by using these markers were introduced into F. columnare G4 via electroporation or conjugation. The integrated plasmid DNA was confirmed by Southern blotting and PCR analysis. These two markers can be employed in future investigations into gene deletion and the pathogenicity of virulence factors in F. columnare.展开更多
Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Ana...Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Analysis of strains data collected in our laboratory revealed that PM typically acquires foreign genes through transformation and conjugation,rather than transformation and fusion.Integrative and conjugative elements(ICEs)are a crucial mechanism that leads to abrupt changes in niche preferences and enhances environmental adaptability for bacteria,with their number far exceeding the number of plasmids and phages(Wozniak and Waldor 2010;Johnson and Grossman 2015;Botelho and Schulenburg 2021).Previous research has shown that the European bovine-sourced strain Pm36950 contains the experimentally transferable resistant ICEPmu1,which could integrate into the host chromosome or forming a circular intermediate(Michael et al.2012).Additionally,a few studies have suggested that PM strains isolated from European bovine and Asian swine might contain ICEs,but these claims lack experimental verification(Klima et al.2014;Moustafa et al.2015;Kadlec et al.2017;Peng et al.2017;Beker et al.2018;Schink et al.2022).Currently,there is no data available on ICE-carrying PM strains isolated from hosts outside of European cattle or Chinses swine.This letter presents a report on a novel ICE identified in the hypervirulent and multidrug-resistant PM HN141014 strain isolated from Chinese duck.The ICE was specifically analyzed for its resistance genes,transferable capacity and host diversity.展开更多
Antimicrobial susceptibility test was performed on 57 clinical isolates of P. aeruginosa and 36 clinical isolates of Acinetobacter with 11 antimicrobial agents including getamicin, amikacin, ciprofloxacin, ofloxacin, ...Antimicrobial susceptibility test was performed on 57 clinical isolates of P. aeruginosa and 36 clinical isolates of Acinetobacter with 11 antimicrobial agents including getamicin, amikacin, ciprofloxacin, ofloxacin, fleroxacin, piperacillin, cefotaxime, cefoperazone/sulbactam, ceftazidime, cefoperazone and doxycycline. Transferable drug resistance plasmid carrying rates of these clinical isolates were also studied. On the basis of the in vitro activities, 52.63%(30/57) of the isolated strains of P. aeruginosa were susceptible to antimicrobial agents selected (except doxycycline), 41.67%(15/36) of the isolated strains of Acinetobacter were susceptible to 11 antimicrobial agents. The sensitivity rate of P.aeruginosa and Acinetobacter to antimicrobial agents selected was 70% or greater to all except doxycycline. Furthermore, the sensitivity rate of P.aeruginosa to amikacin ciprofloxacin, ceftazidime, cefoperazone, cefoperazone/sulbactam, and that of Acinetobacter to cefoperazone/sulbactam, amikacin was more than 90%,among them amikacin, cefoperazone/sulbactam being the most effective. Plasmid analysis showed that 15.79%(9/57) P.aeruginosa strains and 13.89%(5/36) Acinetobacter strains carried plasmid. Conjugative plasmid carrying rates of P. aeruginosa strains and Acinetobacter strains were 7.02%(4/57), 13.89%(5/36), respectively. Conjugative plasmid didn′t play an important role in the formation and dissemination of drug resistance of P. aeruginosa and Acinetobacter.展开更多
The global dissemination of antibiotic resistance genes(ARGs),especially via plasmid-mediated horizontal transfer,is becoming a pervasive health threat.While our previous study found that herbicides can accelerate the...The global dissemination of antibiotic resistance genes(ARGs),especially via plasmid-mediated horizontal transfer,is becoming a pervasive health threat.While our previous study found that herbicides can accelerate the horizontal gene transfer(HGT)of ARGs in soil bacteria,the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear.Here,the underlying mechanism associ-ated with herbicide-promoted HGT was analyzed by detecting intracellular reactive oxygen species(ROS)production,extracellular polymeric substance composition,cell membrane integrity and proton motive force combined with genome-wide RNA sequencing.Exposure to herbicides induced a series of the above bacterial responses to promote HGT except for the ROS response,including compact cell-to-cell contact by enhancing pilus-encoded gene expression and decreasing cell surface charge,increasing cell membrane permeability,and enhancing the proton motive force,providing additional power for DNA uptake.This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides,which elucidates a new perspective on nonantibiotic agrochemical acceleration of the HGT of ARGs.展开更多
I. INTRODUCTIONIn the preceding paper we have reported that in a forked conjugative thienylpolyenic system with two electron-attracting groups at one end, the structural
In this paper, the following carbonyl-imino bridged compounds and related analogs havebeen synthesized:X= C1, m = 0); and the structural effect of the carbonyl-imino bridges has been studied by means of the UV and oth...In this paper, the following carbonyl-imino bridged compounds and related analogs havebeen synthesized:X= C1, m = 0); and the structural effect of the carbonyl-imino bridges has been studied by means of the UV and other properties of the compounds. A new conception of conjugative segment is put forward. The structural bases for each of the three π-π* bands of (C) are ascertained and verified by modification on structure of segments, such as eliminating, merging, lengthening or shortening of segments. It is demonstrated that both bridges -CO-and -NH- can block the conjugated polarization of the whole molecule so as to form three segments S, M and L of which the λmax each exhibits relative independence. The electronic absorption peaks resulting from different segments can be readily recognized and the existence of each segment can be ascertained. This may provide a new way for structural analysis of bridged compounds.展开更多
The co-occurrence of plasmid-mediated multidrug resistance and hypervirulence in epidemic carbapenem-resistant Klebsiella pneumoniae has emerged as a global public health issue.In this study,an ST23 carbapenem-resista...The co-occurrence of plasmid-mediated multidrug resistance and hypervirulence in epidemic carbapenem-resistant Klebsiella pneumoniae has emerged as a global public health issue.In this study,an ST23 carbapenem-resistant hyper-virulent K.pneumoniae(CR-HvKP)strain VH1-2 was identified from cucumber in China and harbored a novel hybrid plasmid pVH1-2-VIR.The plasmid pVH1-2-VIR carrying both virulence and multidrug-resistance(MDR)genes was likely generated through the recombination of a virulence plasmid and an IncFIIK conjugative MDR plasmid in clinical ST2318622 isolated from a sputum sample.The plasmid pVH1-2-VIR exhibited the capacity for transfer to the clinical ST11 carbapenem-resistant K.pneumoniae(CRKP)strain via conjugation assay.Acquisition of pVH1-2-VIR plasmid directly converted a CRKP into CR-HvKP strain characterized by hypermucoviscosity,heightened virulence for Galleria mellonella larvae,and increased colonization ability in the mouse intestine.The emergence of such a hybrid plasmid may expedite the spread of CR-HvKP strains,posing a significant risk to human health.展开更多
Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts...Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon the introduction of an electron-attractive branching group, just like the case of introducing an electron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the corresponding forked compounds, the equivalent △Ns for a branching group may be calculated with accuracy. Based on the value of this equivalent, the substituentnature of the structural effect of the branching group has been inferred. The electronic absorption maxima for four series of the forked compounds have been cal-culated by means of the extended homologous equation for the corresponding linear compounds.With an appropriate correction for the positional effect of the substituent equivalent, the cal-culated wavelengths agree generally with experimental data within ± 7nm.展开更多
Molecular tailoring of self-assembled hole-transporting monolayers(SAMs)has been proven as an efficient approach for improving the device performance of inverted perovskite solar cells.Herein,a novel SAM with extended...Molecular tailoring of self-assembled hole-transporting monolayers(SAMs)has been proven as an efficient approach for improving the device performance of inverted perovskite solar cells.Herein,a novel SAM with extended conjugation is designed and synthesized,named NaPh-4PACz.Compared to Ph-4PACz,NaPh-4PACz exhibits a larger adsorption energy with the ITO substrate,enabling the formation of a more uniform and dense film,thereby preventing direct contact between the perovskite and ITO.Additionally,NaPh-4PACz also has a stronger interaction with the perovskite,which can reduce buried interface defects and suppress non-radiative recombination.Consequently,NaPh-4PACz-based devices achieved a power conversion efficiency of 25.48%due to their interfacial“adhesive”ability.Importantly,the stability of the NaPh-4PACz-based devices was significantly improved.展开更多
Formamidinium lead iodide(FAPbI_(3))perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection appl...Formamidinium lead iodide(FAPbI_(3))perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection application.However,the presence of larger FA^(+)cation induces to an expansion of the Pb-I octahedral framework,which unfortunately affects both the stability and charge carrier mobility of the corresponding devices.To address this challenge,we develop a novel low-dimensional(HtrzT)PbI_(3) perovskite featuring a conjugated organic cation(1H-1,2,4-Triazole-3-thiol,HtrzT^(+))which matches well with theα-FAPbI_(3) lattices in two-dimensional plane.Benefiting from the matched lattice between(HtrzT)PbI_(3) andα-FAPbI_(3),the anchored lattice enhances the Pb-I bond strength and effectively mitigates the inherent tensile strain of theα-FAPbI_(3) crystal lattice.The X-ray detector based on(HtrzT)PbI_(3)(1.0)/FAPbI_(3) device achieves a remarkable sensitivity up to 1.83×10^(5)μC Gy_(air)^(−1) cm^(−2),along with a low detection limit of 27.6 nGy_(air) s^(−1),attributed to the release of residual stress,and the enhancement in carrier mobility-lifetime product.Furthermore,the detector exhibits outstanding stability under X-ray irradiation with tolerating doses equivalent to nearly 1.17×10^(6) chest imaging doses.展开更多
Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative s...Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative systems has been studied by means of UV, XPS, ^(13) C NMR and quantum chemical calculation. The results show that: 1. There exists the effect of opposite terminal groups exists in phenylpolyenic and other aromatic conjugative systems. 2. When A=B and X=Y are the same, the group (-X=Y) connected at polyenic chain is a terminal group, while the other is an opposite terminal group. When the two groups are different, the one with weaker conjugative power plays the role of the opposite terminal group. 3. The effect of opposite terminal groups increases successively in the order of CN, COMe, CHO, NO_2 and can be quantita- tively described with substitute equivalent △N_s. Theλ_(max) of compound containing an opposite terminal group can be calculated by the homologous equation 10^(-4) =a+b/(1/2)^(2/N＇^(-S)_a), most of the calculated values are in agreement with experiment results.展开更多
HighlightsA novel conjugative plasmid pHJ90-cfr carrying the multiresistance gene cfr was characterized in Proteus vulgaris.A new IS5-family member,ISPmi4,was identified for the first time.Both plasmids and ICEs were ...HighlightsA novel conjugative plasmid pHJ90-cfr carrying the multiresistance gene cfr was characterized in Proteus vulgaris.A new IS5-family member,ISPmi4,was identified for the first time.Both plasmids and ICEs were vital mobile genetic elements for horizontal transmission of cfr gene in Proteus species.展开更多
In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradien...In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.展开更多
The light-driven CO_(2)reduction reaction(CO_(2)RR)to CO is a very effective way to address global warming.To avoid competition with water photolysis,metal-free gas-solid CO_(2)RR catalysts should be investigated.Cova...The light-driven CO_(2)reduction reaction(CO_(2)RR)to CO is a very effective way to address global warming.To avoid competition with water photolysis,metal-free gas-solid CO_(2)RR catalysts should be investigated.Covalent organic frameworks(COFs)offer a promising approach for CO_(2)transformation but lack high efficiency and selectivity in the absence of metals.Here,we have incorporated a pyridine nitrogen component into the imine-COF conjugated structure(Tp Pym).This innovative system has set a record of producing a CO yield of 1565μmol g^(-1)within 6 h.The soft X-ray absorption fine structure measurement proves that Tp Pym has both better conjugation and electron cloud enrichment.The electronic structure distribution delays the charge-carrier recombination,as evidenced by femtosecond transient absorption spectroscopy.The energy band diagram and theoretical calculation show that the conduction-band potential of Tp Pym is lower and the reduction reaction of CO_(2)to CO is more likely to occur.展开更多
π-Conjugated donor-acceptor-donor-acceptor-donor(D-A-D-A-D)type pyrenoviologens(PyV^(2+)),with the 2,7 positions of pyrene serving as connection bridges,were synthesized through SN2 reactions.Specifically,pyrenoviolo...π-Conjugated donor-acceptor-donor-acceptor-donor(D-A-D-A-D)type pyrenoviologens(PyV^(2+)),with the 2,7 positions of pyrene serving as connection bridges,were synthesized through SN2 reactions.Specifically,pyrenoviologen 3c was modified with a methylnaphthalene group,while 3a and 3b were modified with methyl and benzyl groups,respectively,for comparison.These pyrenoviologens exhibit reversible redox properties and strong fluorescence emission.Electrochromic devices(ECDs)were prepared using pyrenoviologens as the active materials.Notably,naphthalene-containing pyrenoviologen 3c,with its DA-D-A-D conjugated structure,possesses more stable free radicals,enabling it to maintain the radical color for a longer duration after power loss.A series of color-changing devices were successfully assembled.Due to the strong fluorescence of pyrenoviologens and the unique electron transfer effect between them and picric acid(PA),a sensor film with good selectivity and high sensitivity for PA in aqueous solution was prepared using pyrenoviologens as the fluorescent probe.Specifically,3c exhibited the highest sensitivity to PA due to its lowest energy gap.The introduction of the D-A-D-A-D structure is a strategic approach to enhancing photoelectric performance and broadening the application of viologens.展开更多
The fluorescence imaging (FLI) in the second near-infrared window (NIR-II, 1000–1700nm) has attracted considerable attention in the past decade. In contrast to conventional NIR-I window excitation (808nm/980nm), FLI ...The fluorescence imaging (FLI) in the second near-infrared window (NIR-II, 1000–1700nm) has attracted considerable attention in the past decade. In contrast to conventional NIR-I window excitation (808nm/980nm), FLI with NIR-II window excitation (1064nm/other wavelength beyond 1000nm) can afford deeper tissue penetration depth with high clarity due to the merits of suppressed photon scattering and diminished autofluorescence. In this review, we have summarized NIR-II window excitable/emissive organic/polymeric fluorophores recently developed. The characteristics of these fluorophores such as chemical structures and photophysical properties have also been critically discussed. Furthermore, the latest development of noninvasive in vivo FLI with NIR-II excitation was highlighted. The ideal imaging results emphasized the importance of NIR-II excitation of these fluorophores in enabling deep tissue penetration and high-resolution imaging. Finally, a perspective on the challenges and prospects of NIR-II excitable/emissive organic/polymeric fluorophores was also discussed. We expected this review will be served as a source of inspiration for researchers, stimulating the creation of novel NIR-II excitable fluorophores and fostering the development of bioimaging applications.展开更多
Urothelial carcinoma(UC)is the 9th most common and the 13th most deadly cancer worldwide1.Despite the availability of platinum-based chemotherapy and immune checkpoint inhib-itors(ICIs),the 5-year survival rate of pat...Urothelial carcinoma(UC)is the 9th most common and the 13th most deadly cancer worldwide1.Despite the availability of platinum-based chemotherapy and immune checkpoint inhib-itors(ICIs),the 5-year survival rate of patients with metastatic UC(mUC)remains poor(10-15%)2.展开更多
A comprehensive understanding of the relevance between molecular structure and passivation ability to screen efficient modifiers is essential for enhancing the performance of perovskite solar cells(PSCs).Here,three si...A comprehensive understanding of the relevance between molecular structure and passivation ability to screen efficient modifiers is essential for enhancing the performance of perovskite solar cells(PSCs).Here,three similarπ-πstacking molecules namely benzophenone(BPN),diphenyl sulfone(DPS),and diphenyl sulfoxide(DPSO)are used as back-interface modifiers in carbon-based CsPbBr_(3)PSCs.After investigation,the results demonstrate the positive effect of the p-πconjugation characteristic inπ-πstacking molecules on maximizing their passivation ability.The p-πco njugation of DPSO enables a higher coordinative activity of oxygen atom in its S=O group than that in 0=S=O group of DPS and C=O group of BPN,which gives a superior passivation effect of DPSO on defects of perovskite films.The modification of DPSO also significantly improves the p-type behavior of perovskite films and the back-interfacial energetics matching,inducing an increase of hole extraction and a decrease of energy loss.Finally,the unencapsulated carbon-based CsPbBr_(3)PSCs with DPSO achieve a maximum power conversion efficiency of 10.60%and outstanding long-term stability in high-temperature,high-humidity(85℃,85%relative humidity)air environment.This work provides insights into the influence of the structure ofπ-πstacking molecules on their ability to improve the perovskite films quality and therefore the PSCs performance.展开更多
BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD)is the most common chronic liver disease worldwide.Its prevalence is closely linked to the dramatic rise in obesity and non-communicable diseas...BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD)is the most common chronic liver disease worldwide.Its prevalence is closely linked to the dramatic rise in obesity and non-communicable diseases.MASLD exhibits a progressive trajectory that may culminate in development of hepatic cirrhosis,thereby predisposing affected individuals to an elevated likelihood of hepatocarcinogenesis.Diet,especially dietary fatty acids,serves as a key link between nutrient intake and MASLD pathogenesis.AIM To explore the impact of various omega-6 fatty acid subtypes on the pathogenesis and therapeutic strategies of MASLD.METHODS A systematic literature search was conducted across Web of Science,PubMed,Cochrane Central,Scopus,and Embase databases from inception through June 2024 to identify all original studies linking different subtypes of omega-6 polyunsaturated fatty acids to the pathogenesis and management of MASLD.The search strategy explored the linkage between omega-6 polyunsaturated fatty acids and their subtypes,including linoleic acid(LA),gamma-linolenic acid(GLA),arachidonic acid,conjugated LA,and docosapentaenoic acid,in relation to MASLD and cardiometabolic risk.RESULTS By employing the specified search strategy,a total of 83 articles were identified as potentially eligible.During the title,abstract,and full-text screening phases,27 duplicate records were removed,leaving 56 records for relevance screening.Of these,43 records were excluded for reasons such as irrelevance and language restrictions(limited to English),resulting in 13 full-text articles being included for detailed assessment(10 human studies,1 animal study,and 2 review articles).Although certain subtypes,as GLA,dihomo-GLA,omega-6-derived oxylipins,and most arachidonic acid-derived eicosanoids,exhibit pro-inflammatory effects,our findings suggest that other subtypes such as LA,cis-9,trans-11 conjugated LA,and docosapentaenoic acid have beneficial effects on fatty liver,cardiometabolic risk factors,and inflammation,even at high intake levels.CONCLUSION The varying health effects of omega-6 fatty acids,ranging from anti-inflammatory to pro-inflammatory impacts on the liver,leave the question of their recommendation for MASLD patients unresolved.This underscores the importance of careful selection when considering omega-6 supplementation.展开更多
基金the Wellcome Trust,BBSRC,and the National Natural Science Foundation of China(81802065,102908/Z/13/Z).
文摘Bacteria can evolve rapidly by acquiring new traits such as virulence,metabolic properties,and most importantly,antimicrobial resistance,through horizontal gene transfer(HGT).Multidrug resistance in bacteria,especially in Gram-negative organisms,has become a global public health threat often through the spread of mobile genetic elements.Conjugation represents a major form of HGT and involves the transfer of DNA from a donor bacterium to a recipient by direct contact.Conjugative plasmids,a major vehicle for the dissemination of antimicrobial resistance,are selfish elements capable of mediating their own transmission through conjugation.To spread to and survive in a new bacterial host,conjugative plasmids have evolved mechanisms to circumvent both host defense systems and compete with co-resident plasmids.Such mechanisms have mostly been studied in model plasmids such as the F plasmid,rather than in conjugative plasmids that confer antimicrobial resistance(AMR)in important human pathogens.A better understanding of these mechanisms is crucial for predicting the flow of antimicrobial resistance-conferring conjugative plasmids among bacterial populations and guiding the rational design of strategies to halt the spread of antimicrobial resistance.Here,we review mechanisms employed by conjugative plasmids that promote their transmission and establishment in Gram-negative bacteria,by following the life cycle of conjugative plasmids.
基金Supported by the National Basic Research Program of China(973Program)(No.2009CB118703)
文摘Flavobacterium columnare, the etiological agent of colunmaris disease, is one of the most important and widespread bacterial pathogens of freshwater fish. In this study, we constructed two artificial selectable markers （chloramphenicol and spectinomycin resistance） for gene transfer in F. columnare. These two new artificial selectable markers, which were created by placing the chloramphenicol or spectinomycin resistance gene under the control of the native acs regulatory region of F. columnare, were functional in both F. columnare and Escherichia coli. The integrative/conjugative plasmids constructed by using these markers were introduced into F. columnare G4 via electroporation or conjugation. The integrated plasmid DNA was confirmed by Southern blotting and PCR analysis. These two markers can be employed in future investigations into gene deletion and the pathogenicity of virulence factors in F. columnare.
基金supported by the earmarked fund for China Agriculture Research System(CARS-42-17)the Sichuan Veterinary Medicine and Drug Innovation Group of China Agricultural Research System(SCCXTD-2021-18)。
文摘Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Analysis of strains data collected in our laboratory revealed that PM typically acquires foreign genes through transformation and conjugation,rather than transformation and fusion.Integrative and conjugative elements(ICEs)are a crucial mechanism that leads to abrupt changes in niche preferences and enhances environmental adaptability for bacteria,with their number far exceeding the number of plasmids and phages(Wozniak and Waldor 2010;Johnson and Grossman 2015;Botelho and Schulenburg 2021).Previous research has shown that the European bovine-sourced strain Pm36950 contains the experimentally transferable resistant ICEPmu1,which could integrate into the host chromosome or forming a circular intermediate(Michael et al.2012).Additionally,a few studies have suggested that PM strains isolated from European bovine and Asian swine might contain ICEs,but these claims lack experimental verification(Klima et al.2014;Moustafa et al.2015;Kadlec et al.2017;Peng et al.2017;Beker et al.2018;Schink et al.2022).Currently,there is no data available on ICE-carrying PM strains isolated from hosts outside of European cattle or Chinses swine.This letter presents a report on a novel ICE identified in the hypervirulent and multidrug-resistant PM HN141014 strain isolated from Chinese duck.The ICE was specifically analyzed for its resistance genes,transferable capacity and host diversity.
文摘Antimicrobial susceptibility test was performed on 57 clinical isolates of P. aeruginosa and 36 clinical isolates of Acinetobacter with 11 antimicrobial agents including getamicin, amikacin, ciprofloxacin, ofloxacin, fleroxacin, piperacillin, cefotaxime, cefoperazone/sulbactam, ceftazidime, cefoperazone and doxycycline. Transferable drug resistance plasmid carrying rates of these clinical isolates were also studied. On the basis of the in vitro activities, 52.63%(30/57) of the isolated strains of P. aeruginosa were susceptible to antimicrobial agents selected (except doxycycline), 41.67%(15/36) of the isolated strains of Acinetobacter were susceptible to 11 antimicrobial agents. The sensitivity rate of P.aeruginosa and Acinetobacter to antimicrobial agents selected was 70% or greater to all except doxycycline. Furthermore, the sensitivity rate of P.aeruginosa to amikacin ciprofloxacin, ceftazidime, cefoperazone, cefoperazone/sulbactam, and that of Acinetobacter to cefoperazone/sulbactam, amikacin was more than 90%,among them amikacin, cefoperazone/sulbactam being the most effective. Plasmid analysis showed that 15.79%(9/57) P.aeruginosa strains and 13.89%(5/36) Acinetobacter strains carried plasmid. Conjugative plasmid carrying rates of P. aeruginosa strains and Acinetobacter strains were 7.02%(4/57), 13.89%(5/36), respectively. Conjugative plasmid didn′t play an important role in the formation and dissemination of drug resistance of P. aeruginosa and Acinetobacter.
基金This work was supported by the National Natural Science Foundation of China(31972521)the Fujian Agriculture and Forest University Program for Distinguished Young Scholar(No.XJQ2017001).
文摘The global dissemination of antibiotic resistance genes(ARGs),especially via plasmid-mediated horizontal transfer,is becoming a pervasive health threat.While our previous study found that herbicides can accelerate the horizontal gene transfer(HGT)of ARGs in soil bacteria,the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear.Here,the underlying mechanism associ-ated with herbicide-promoted HGT was analyzed by detecting intracellular reactive oxygen species(ROS)production,extracellular polymeric substance composition,cell membrane integrity and proton motive force combined with genome-wide RNA sequencing.Exposure to herbicides induced a series of the above bacterial responses to promote HGT except for the ROS response,including compact cell-to-cell contact by enhancing pilus-encoded gene expression and decreasing cell surface charge,increasing cell membrane permeability,and enhancing the proton motive force,providing additional power for DNA uptake.This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides,which elucidates a new perspective on nonantibiotic agrochemical acceleration of the HGT of ARGs.
文摘I. INTRODUCTIONIn the preceding paper we have reported that in a forked conjugative thienylpolyenic system with two electron-attracting groups at one end, the structural
基金Project supported by the National Natural Science Foundation of China.
文摘In this paper, the following carbonyl-imino bridged compounds and related analogs havebeen synthesized:X= C1, m = 0); and the structural effect of the carbonyl-imino bridges has been studied by means of the UV and other properties of the compounds. A new conception of conjugative segment is put forward. The structural bases for each of the three π-π* bands of (C) are ascertained and verified by modification on structure of segments, such as eliminating, merging, lengthening or shortening of segments. It is demonstrated that both bridges -CO-and -NH- can block the conjugated polarization of the whole molecule so as to form three segments S, M and L of which the λmax each exhibits relative independence. The electronic absorption peaks resulting from different segments can be readily recognized and the existence of each segment can be ascertained. This may provide a new way for structural analysis of bridged compounds.
基金supported in part by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(32121004)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2019BT02N054)+4 种基金Laboratory of Lingnan Modern Agriculture Project(NT2021006)Guangdong Major Project of Basic and Applied Basic Research(grant 2020B0301030007)Innovation Team Project of Guangdong University(2019KCXTD001),the 111 Project(grant D20008)Natural Science Foundation of Shandong Province of China(ZR2022MC001)the Scientific and Technological Projects of Qingdao(19‐6‐1‐94‐nsh).
文摘The co-occurrence of plasmid-mediated multidrug resistance and hypervirulence in epidemic carbapenem-resistant Klebsiella pneumoniae has emerged as a global public health issue.In this study,an ST23 carbapenem-resistant hyper-virulent K.pneumoniae(CR-HvKP)strain VH1-2 was identified from cucumber in China and harbored a novel hybrid plasmid pVH1-2-VIR.The plasmid pVH1-2-VIR carrying both virulence and multidrug-resistance(MDR)genes was likely generated through the recombination of a virulence plasmid and an IncFIIK conjugative MDR plasmid in clinical ST2318622 isolated from a sputum sample.The plasmid pVH1-2-VIR exhibited the capacity for transfer to the clinical ST11 carbapenem-resistant K.pneumoniae(CRKP)strain via conjugation assay.Acquisition of pVH1-2-VIR plasmid directly converted a CRKP into CR-HvKP strain characterized by hypermucoviscosity,heightened virulence for Galleria mellonella larvae,and increased colonization ability in the mouse intestine.The emergence of such a hybrid plasmid may expedite the spread of CR-HvKP strains,posing a significant risk to human health.
文摘Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon the introduction of an electron-attractive branching group, just like the case of introducing an electron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the corresponding forked compounds, the equivalent △Ns for a branching group may be calculated with accuracy. Based on the value of this equivalent, the substituentnature of the structural effect of the branching group has been inferred. The electronic absorption maxima for four series of the forked compounds have been cal-culated by means of the extended homologous equation for the corresponding linear compounds.With an appropriate correction for the positional effect of the substituent equivalent, the cal-culated wavelengths agree generally with experimental data within ± 7nm.
基金supported by the National Natural Science Foundation of China(61904053,22279033)the National Key Research and Development Program of China(2023YFB4204502)+2 种基金the 111 Project(B16016)the Fundamental Research Funds for the Central Universities(2025MS043)the Special Foundation for Carbon Peak Carbon Neutralization Technology Innovation Program of Jiangsu Province(BE2022026).
文摘Molecular tailoring of self-assembled hole-transporting monolayers(SAMs)has been proven as an efficient approach for improving the device performance of inverted perovskite solar cells.Herein,a novel SAM with extended conjugation is designed and synthesized,named NaPh-4PACz.Compared to Ph-4PACz,NaPh-4PACz exhibits a larger adsorption energy with the ITO substrate,enabling the formation of a more uniform and dense film,thereby preventing direct contact between the perovskite and ITO.Additionally,NaPh-4PACz also has a stronger interaction with the perovskite,which can reduce buried interface defects and suppress non-radiative recombination.Consequently,NaPh-4PACz-based devices achieved a power conversion efficiency of 25.48%due to their interfacial“adhesive”ability.Importantly,the stability of the NaPh-4PACz-based devices was significantly improved.
基金supports from the National Natural Science Foundation of China(22375220,U2001214,22471302)the Guangdong Basic and Applied Basic Research Foundation(2024B1515020101)Open Project Fund from State Key Laboratory of Optoelectronic Materials and Technologies(OEMT-2024-KF-08).
文摘Formamidinium lead iodide(FAPbI_(3))perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection application.However,the presence of larger FA^(+)cation induces to an expansion of the Pb-I octahedral framework,which unfortunately affects both the stability and charge carrier mobility of the corresponding devices.To address this challenge,we develop a novel low-dimensional(HtrzT)PbI_(3) perovskite featuring a conjugated organic cation(1H-1,2,4-Triazole-3-thiol,HtrzT^(+))which matches well with theα-FAPbI_(3) lattices in two-dimensional plane.Benefiting from the matched lattice between(HtrzT)PbI_(3) andα-FAPbI_(3),the anchored lattice enhances the Pb-I bond strength and effectively mitigates the inherent tensile strain of theα-FAPbI_(3) crystal lattice.The X-ray detector based on(HtrzT)PbI_(3)(1.0)/FAPbI_(3) device achieves a remarkable sensitivity up to 1.83×10^(5)μC Gy_(air)^(−1) cm^(−2),along with a low detection limit of 27.6 nGy_(air) s^(−1),attributed to the release of residual stress,and the enhancement in carrier mobility-lifetime product.Furthermore,the detector exhibits outstanding stability under X-ray irradiation with tolerating doses equivalent to nearly 1.17×10^(6) chest imaging doses.
文摘Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative systems has been studied by means of UV, XPS, ^(13) C NMR and quantum chemical calculation. The results show that: 1. There exists the effect of opposite terminal groups exists in phenylpolyenic and other aromatic conjugative systems. 2. When A=B and X=Y are the same, the group (-X=Y) connected at polyenic chain is a terminal group, while the other is an opposite terminal group. When the two groups are different, the one with weaker conjugative power plays the role of the opposite terminal group. 3. The effect of opposite terminal groups increases successively in the order of CN, COMe, CHO, NO_2 and can be quantita- tively described with substitute equivalent △N_s. Theλ_(max) of compound containing an opposite terminal group can be calculated by the homologous equation 10^(-4) =a+b/(1/2)^(2/N＇^(-S)_a), most of the calculated values are in agreement with experiment results.
基金supported by the National Key Research and Development Program of China(2022YFF0710505)the Central Public-interest Scientific Institution Basal Research Fund,China(1610302022001)。
文摘HighlightsA novel conjugative plasmid pHJ90-cfr carrying the multiresistance gene cfr was characterized in Proteus vulgaris.A new IS5-family member,ISPmi4,was identified for the first time.Both plasmids and ICEs were vital mobile genetic elements for horizontal transmission of cfr gene in Proteus species.
基金Supported by the Science and Technology Project of Guangxi(Guike AD23023002)。
文摘In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.
基金supported by the National Natural Science Foundation of China(Nos.22375031,22202037,22472023)the Fundamental Research Funds for the Central Universities(Nos.2412023YQ001,2412023QD019,2412024QD014)+1 种基金supported by grants from the seventh batch of Jilin Province Youth Science and Technology Talent Lifting Project(No.QT202305)Science and Technology Development Plan Project of Jilin Province,China(No.20240101192JC)。
文摘The light-driven CO_(2)reduction reaction(CO_(2)RR)to CO is a very effective way to address global warming.To avoid competition with water photolysis,metal-free gas-solid CO_(2)RR catalysts should be investigated.Covalent organic frameworks(COFs)offer a promising approach for CO_(2)transformation but lack high efficiency and selectivity in the absence of metals.Here,we have incorporated a pyridine nitrogen component into the imine-COF conjugated structure(Tp Pym).This innovative system has set a record of producing a CO yield of 1565μmol g^(-1)within 6 h.The soft X-ray absorption fine structure measurement proves that Tp Pym has both better conjugation and electron cloud enrichment.The electronic structure distribution delays the charge-carrier recombination,as evidenced by femtosecond transient absorption spectroscopy.The energy band diagram and theoretical calculation show that the conduction-band potential of Tp Pym is lower and the reduction reaction of CO_(2)to CO is more likely to occur.
基金supported by the Shaanxi Province Technological Innovation Guidance Special(No.2022QFY08-01)the National Key Research and Development Program of China(No.2021YFB3200702)+5 种基金Natural Science Foundation of China(Nos.22201228,22205172,52203240 and 22175138)China Postdoctoral Science Foundation(Nos.2022M712530,2023T160506,and 2022M712497)Fundamental Research Funds for the Central Universities(No.xzy012022017)Young Talent Fund of Association for Science and Technology in Shaanxi(No.20230624)Shaanxi Province Postdoctoral Science Foundation(No.2023b SHTBZZ04)the Youth Innovation Team of Shaanxi Universities。
文摘π-Conjugated donor-acceptor-donor-acceptor-donor(D-A-D-A-D)type pyrenoviologens(PyV^(2+)),with the 2,7 positions of pyrene serving as connection bridges,were synthesized through SN2 reactions.Specifically,pyrenoviologen 3c was modified with a methylnaphthalene group,while 3a and 3b were modified with methyl and benzyl groups,respectively,for comparison.These pyrenoviologens exhibit reversible redox properties and strong fluorescence emission.Electrochromic devices(ECDs)were prepared using pyrenoviologens as the active materials.Notably,naphthalene-containing pyrenoviologen 3c,with its DA-D-A-D conjugated structure,possesses more stable free radicals,enabling it to maintain the radical color for a longer duration after power loss.A series of color-changing devices were successfully assembled.Due to the strong fluorescence of pyrenoviologens and the unique electron transfer effect between them and picric acid(PA),a sensor film with good selectivity and high sensitivity for PA in aqueous solution was prepared using pyrenoviologens as the fluorescent probe.Specifically,3c exhibited the highest sensitivity to PA due to its lowest energy gap.The introduction of the D-A-D-A-D structure is a strategic approach to enhancing photoelectric performance and broadening the application of viologens.
基金supported by the National Nature Science Foundation of China(Nos.62075079,62305127,61975200)the Natural Science Foundation of Jilin Province(20230508135RC)the Science and Technology Development Foundation of Changchun City(23GZZ15).
文摘The fluorescence imaging (FLI) in the second near-infrared window (NIR-II, 1000–1700nm) has attracted considerable attention in the past decade. In contrast to conventional NIR-I window excitation (808nm/980nm), FLI with NIR-II window excitation (1064nm/other wavelength beyond 1000nm) can afford deeper tissue penetration depth with high clarity due to the merits of suppressed photon scattering and diminished autofluorescence. In this review, we have summarized NIR-II window excitable/emissive organic/polymeric fluorophores recently developed. The characteristics of these fluorophores such as chemical structures and photophysical properties have also been critically discussed. Furthermore, the latest development of noninvasive in vivo FLI with NIR-II excitation was highlighted. The ideal imaging results emphasized the importance of NIR-II excitation of these fluorophores in enabling deep tissue penetration and high-resolution imaging. Finally, a perspective on the challenges and prospects of NIR-II excitable/emissive organic/polymeric fluorophores was also discussed. We expected this review will be served as a source of inspiration for researchers, stimulating the creation of novel NIR-II excitable fluorophores and fostering the development of bioimaging applications.
基金supported by the Beijing Natural Science Foundation(Grant No.L244024)National Natural Science Foundation of China(Grant Nos.82172604 and 82473199)CSCO Clinical Oncology Research Foundation(Grant No.Y-2022HER2AZMS-0258).
文摘Urothelial carcinoma(UC)is the 9th most common and the 13th most deadly cancer worldwide1.Despite the availability of platinum-based chemotherapy and immune checkpoint inhib-itors(ICIs),the 5-year survival rate of patients with metastatic UC(mUC)remains poor(10-15%)2.
基金financial supports from the Natural Science Foundation of Shandong Province(ZR2021ME037)the National Natural Science Foundation of China(52472259,22179051 and 61604143)+2 种基金the National Key Research and Development Program of China(2021YFE0111000)the Special Fund of Taishan Scholar Program of Shandong Province(tsqnz20221141)the Foundation of Key Laboratory of Advanced Technique&Preparation for Renewable Energy Materials,Ministry of Education,Yunnan Normal University(OF2022-02)。
文摘A comprehensive understanding of the relevance between molecular structure and passivation ability to screen efficient modifiers is essential for enhancing the performance of perovskite solar cells(PSCs).Here,three similarπ-πstacking molecules namely benzophenone(BPN),diphenyl sulfone(DPS),and diphenyl sulfoxide(DPSO)are used as back-interface modifiers in carbon-based CsPbBr_(3)PSCs.After investigation,the results demonstrate the positive effect of the p-πconjugation characteristic inπ-πstacking molecules on maximizing their passivation ability.The p-πco njugation of DPSO enables a higher coordinative activity of oxygen atom in its S=O group than that in 0=S=O group of DPS and C=O group of BPN,which gives a superior passivation effect of DPSO on defects of perovskite films.The modification of DPSO also significantly improves the p-type behavior of perovskite films and the back-interfacial energetics matching,inducing an increase of hole extraction and a decrease of energy loss.Finally,the unencapsulated carbon-based CsPbBr_(3)PSCs with DPSO achieve a maximum power conversion efficiency of 10.60%and outstanding long-term stability in high-temperature,high-humidity(85℃,85%relative humidity)air environment.This work provides insights into the influence of the structure ofπ-πstacking molecules on their ability to improve the perovskite films quality and therefore the PSCs performance.
文摘BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD)is the most common chronic liver disease worldwide.Its prevalence is closely linked to the dramatic rise in obesity and non-communicable diseases.MASLD exhibits a progressive trajectory that may culminate in development of hepatic cirrhosis,thereby predisposing affected individuals to an elevated likelihood of hepatocarcinogenesis.Diet,especially dietary fatty acids,serves as a key link between nutrient intake and MASLD pathogenesis.AIM To explore the impact of various omega-6 fatty acid subtypes on the pathogenesis and therapeutic strategies of MASLD.METHODS A systematic literature search was conducted across Web of Science,PubMed,Cochrane Central,Scopus,and Embase databases from inception through June 2024 to identify all original studies linking different subtypes of omega-6 polyunsaturated fatty acids to the pathogenesis and management of MASLD.The search strategy explored the linkage between omega-6 polyunsaturated fatty acids and their subtypes,including linoleic acid(LA),gamma-linolenic acid(GLA),arachidonic acid,conjugated LA,and docosapentaenoic acid,in relation to MASLD and cardiometabolic risk.RESULTS By employing the specified search strategy,a total of 83 articles were identified as potentially eligible.During the title,abstract,and full-text screening phases,27 duplicate records were removed,leaving 56 records for relevance screening.Of these,43 records were excluded for reasons such as irrelevance and language restrictions(limited to English),resulting in 13 full-text articles being included for detailed assessment(10 human studies,1 animal study,and 2 review articles).Although certain subtypes,as GLA,dihomo-GLA,omega-6-derived oxylipins,and most arachidonic acid-derived eicosanoids,exhibit pro-inflammatory effects,our findings suggest that other subtypes such as LA,cis-9,trans-11 conjugated LA,and docosapentaenoic acid have beneficial effects on fatty liver,cardiometabolic risk factors,and inflammation,even at high intake levels.CONCLUSION The varying health effects of omega-6 fatty acids,ranging from anti-inflammatory to pro-inflammatory impacts on the liver,leave the question of their recommendation for MASLD patients unresolved.This underscores the importance of careful selection when considering omega-6 supplementation.
