Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases, and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2. The regulator PhoP and its sensor ...Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases, and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2. The regulator PhoP and its sensor kinase PhoR compose a two-component system in B. subtilis. In this study, the phoR- and phoP-knockout mutants were constructed by in-frame deletion and the role of PhoR/PhoP on the production of fengycin was determined. Inactivation of phoR or phoP in B. subtilis decreased its inhibition ability against Botrytis cinerea growth in vitro compared to the strain NCD-2 wild type. The lipopeptides were extracted from strain NCD-2 wild type and its mutant strains by hydrochloric acid precipitate, and the lipopeptides from phoR-null mutant orphoP-null mutant almost lost the inhibition ability against B. cinerea growth compared to the lipopeptides from strain NCD-2 wild type. Fast protein liquid chromatography （FPLC） analysis of the lipopeptides showed that inactivation of phoR or phoP genes reduced the production of fengycin by strain NCD-2. The fengycin production abilities were compared for bacteria under low-phosphate medium （LPM） and high-phosphate medium （HPM）, respectively. Results indicated that the regulation of fengycin production by the PhoR/PhoP two-component system occurred in LPM but not in HPM. Reverse transcriptionaI-PCR confirmed that the fengycin synthetase gene fenC was positively regulated by phoP when cultured in LPM. All of these characteristics could be partially restored by complementation of intact phoR or phoP gene in the mutant. These data indicated that the PhoR/PhoP two-component system greatly regulated fengycin production and antifungal ability in B. subtilis NCD-2 mainly under low-phosphate conditions.展开更多
To address the issues of short setting time and high bleeding rate of A component,which easily cause pipe plugging and poor grouting performance when a two-component grout is injected synchronously behind the Segmenta...To address the issues of short setting time and high bleeding rate of A component,which easily cause pipe plugging and poor grouting performance when a two-component grout is injected synchronously behind the Segmental Lining,the inorganic retarder sodium pyrophosphate(TSPP)and three organic retarders were added to the A component:sodium citrate(SC),sodium tartrate(ST)and glycerol(GLY).The effect law and microscopic mechanism of viscosity,bleeding rate,setting time,gelling time,compressive strength,and stone rate were investigated.The results revealed that the addition of retarders could enhance the stability and setting time of the A component and increase the gelling time,stone rate,and compressive strength of two-component grout.Among them,the performance of the grout with an SC dosage of 0.1% was superior.The bleeding rate of this grout was reduced to 3.5%,the stone rate of the two-component grout was more than 99%,and the early compressive strength and late compressive strength of this grout were increased by approximately 35% and 7%,respectively.The initial and final setting time of the A component with a TSPP dosage of 0.3% was the longest,which was prolonged to 17 and 26 h,respectively.Microscopic analysis revealed that the four retarders hindered the hydration process of cement through complexation and adsorption,and inhibited the hydration of C_(3)S and the crystallisation of CH.Moreover,they reduced the defects caused by the rapid reaction of water glass and CH on the solid phase structure,enabled the microstructure of the stone body to be denser,and subsequently,enhanced the compressive strength.展开更多
Cronobacter sakazakii is an opportunistic foodborne pathogen with remarkable resilience to environmental stressors,posing severe risks in powdered infant formula.Here,we identify the GlrKR two-component system(TCS)as ...Cronobacter sakazakii is an opportunistic foodborne pathogen with remarkable resilience to environmental stressors,posing severe risks in powdered infant formula.Here,we identify the GlrKR two-component system(TCS)as a master regulator that integrates environmental sensing with virulence control.Genetic deletion of either the sensor kinase(glrK)or the response regulator(glrR)markedly attenuates bacterial motility,epithelial cell adherence,and virulence in a neonatal rat model.GlrK is essential for acid and oxidative stress resistance,whereas both GlrK and GlrR suppress desiccation tolerance,revealing a regulatory trade-off between environmental persistence and host invasion.Quantitative proteomics and site-specific mutagenesis uncover enhanced deamidation of OmpA at N101 inΔglrR as a mechanistic basis for impaired adherence.Additionally,GlrKR modulates sensitivity to p-coumaric acid,a plant-derived antimicrobial,via transcriptional control of the efflux pump TolC.These findings establish GlrKR as a central node linking environmental adaptation,antimicrobial defense,and host-pathogen interaction in C.sakazakii,offering a promising target for next-generation food safety interventions.展开更多
Two-component systems(TCSs)play important roles in the regulation of secondary metabolism in Streptomyces.However,so far,few TCSs have been functionally identified in the rapamycin-producing strain,Streptomyces rapamy...Two-component systems(TCSs)play important roles in the regulation of secondary metabolism in Streptomyces.However,so far,few TCSs have been functionally identified in the rapamycin-producing strain,Streptomyces rapamycinicus.In this study,a two-component system(TCS)CseB-C(M271_22640/M271_22645)in S.rapamycinicus NRRL 5491,whose homolog from Streptomyces coelicolor is involved in regulating cell wall integrity and secondary metabolism,was identified to play a dual role in differential regulation of antibiotic biosynthesis,activating rapamycin biosynthesis and simultaneously repressing elaiophylin biosynthesis.We showed that knockout of cseB-C resulted in a drastic reduction in rapamycin production and a significant increase in elaiophylin production.Transcriptional analysis revealed that deletion of cseB-C resulted in a substantial decrease in the transcription of sigE,which clusters together with cseB-C.Introduction of sigE into theΔcseB-C mutant could fully restore rapamycin and elaiophylin production to the wild-type levels,suggesting that the role of CseB-C on rapamycin and elaiophylin biosynthesis is mediated by sigE.Collectively,the results obtained in this study contribute to a better understanding of the regulation of rapamycin and elaiophylin biosynthesis in S.rapamycinicus.展开更多
Microorganisms utilize complex signal-regulating networks to adapt to environmental changes,and two-component system(TCS)plays a crucial role in bacterial sensing and response to environmental fluctuations.This articl...Microorganisms utilize complex signal-regulating networks to adapt to environmental changes,and two-component system(TCS)plays a crucial role in bacterial sensing and response to environmental fluctuations.This article provides a comprehensive and in-depth multidimensional overview of the RstB/RstA TCS.The RstB/RstA TCS is capable of sensing a variety of external signals,including pH fluctuations,changes in Mg^(2+)concentration,antibiotics and osmotic pressure.And it regulates a variety of physiological processes,including motility,virulence factor expression,biofilm formation,and antibiotic resistance.RstB/RstA TCS might be a critical breakthrough for developing novel antimicrobial strategies to combat bacterial resistance.However,based on the PubMed database,few researches have been conducted on RstB/RstA,and knowledge on this TCS has not been reviewed.Furthermore,the precise regulatory mechanisms of the RstB/RstA system remain largely unexplored,especially in the ocean bacteria.This article integrates the key roles of the RstB/RstA TCS in environmental signal sensing and physiological function regulation.It mainly summarizes the structural composition,multifunctional roles,and regulatory mechanisms of the RstB/RstA system,especially its regulatory role in the marine pathogen Photobacterium damselae subsp.damselae(Pdd).In addition,we also discusse the current limitations of related research,and explore its great potential in the treatment of diseases affecting economically important fish species and human health.This work aims to provide a novel perspective for the study of TCSs in marine bacteria and to offer a theoretical foundation and future directions for further in-depth investigations of this regulatory system.展开更多
Lactiplantibacillus plantarum is a nomadic species that displays adaptive variations in different habitats,partic-ularly in the intestines.Bile salts tolerance is crucial for L.plantarum to survive and exert beneficia...Lactiplantibacillus plantarum is a nomadic species that displays adaptive variations in different habitats,partic-ularly in the intestines.Bile salts tolerance is crucial for L.plantarum to survive and exert beneficial properties in this environment.L.plantarum exhibits varying growth capacities under bile salts exposure;however,the mo-lecular mechanisms responsible for this variation are not fully understood.In this study,comparative genomics analysis was used to elucidate the specific genes in bile salts-tolerant L.plantarum and further investigate the mechanisms that contribute to bacterial survival under bile salts.A total of eighty-seven specific genes were identified in the tolerant strains,which were primarily associated with the two-component system and carbo-hydrate metabolism.Notably,the mutation of a response regulator(agrA)in the two-component system decreased the growth rate of L.plantarum under bile salts exposure,whereas complementation increased tolerance.Metabolomic analysis suggested that the deletion of agrA resulted in the downregulation of pathways associated with bacterial energy metabolism.These findings indicate that L.plantarum responds to harsh envi-ronments by sensing bile salts as signaling molecules and subsequently adjusting complex metabolic pathways as a survival strategy.This provides novel insights into the molecular basis of the two-component system contributing to bile salts tolerance.展开更多
The signal transduction system of microorganisms helps them adapt to changes in their complex living environment.Two-component system(TCS)is a representative signal transduction system that plays a crucial role in reg...The signal transduction system of microorganisms helps them adapt to changes in their complex living environment.Two-component system(TCS)is a representative signal transduction system that plays a crucial role in regulating cellular communication and secondary metabolism.In Gram-negative bacteria,an unorthodox TCS consist-ing of histidine kinase protein GacS(initially called LemA)and response regulatory protein GacA is widespread.It mainly regulates various physiological activities and behaviors of bacteria,such as quorum sensing,secondary metabolism,biofilm formation and motility,through the Gac/Rsm(Regulator of secondary metabolism)signaling cascade pathway.The global regulatory ability of GacS/GacA in cell physiological activities makes it a potential research entry point for developing natural products and addressing antibiotic resistance.In this review,we summarize the progress of research on GacS/GacA from various perspectives,including the reaction mechanism,related regulatory pathways,main functions and GacS/GacA-mediated applications.Hopefully,this review will facilitate further research on GacS/GacA and promote its application in regulating secondary metabolism and as a therapeutic target.展开更多
The management of antibiotic-resistant, bacterial biofilm infections in skin wounds poses an increasingly challenging clinical scenario. Pseudomonas aeruginosa infection is difficult to eradicate because of biofilm fo...The management of antibiotic-resistant, bacterial biofilm infections in skin wounds poses an increasingly challenging clinical scenario. Pseudomonas aeruginosa infection is difficult to eradicate because of biofilm formation and antibiotic resistance. In this study, we identified a new benzothiazole derivative compound, SN12 (IC_(50)= 43.3 nmol/L), demonstrating remarkable biofilm inhibition at nanomolar concentrations in vitro. In further activity assays and mechanistic studies, we formulated an unconventional strategy for combating P. aeruginosa-derived infections by targeting the two-component (Gac/Rsm) system. Furthermore, SN12 slowed the development of ciprofloxacin and tobramycin resistance. By using murine skin wound infection models, we observed that SN12 significantly augmented the antibacterial effects of three widely used antibiotics—tobramycin (100-fold), vancomycin (200-fold), and ciprofloxacin (1000-fold)—compared with single-dose antibiotic treatments for P. aeruginosa infection in vivo. The findings of this study suggest the potential of SN12 as a promising antibacterial synergist, highlighting the effectiveness of targeting the two-component system in treating challenging bacterial biofilm infections in humans.展开更多
In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here,we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomona...In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here,we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa;in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation(Dsb)(i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copperbinding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR.The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5’-TTA-N8-TTAA-3’, is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress.展开更多
Listeria monocytogenes is a foodborne pathogen that is ubiquitous in the natural environment.Listeria monocytogenes is capable of forming persistent biofilms in food processing environments,which can lead to persisten...Listeria monocytogenes is a foodborne pathogen that is ubiquitous in the natural environment.Listeria monocytogenes is capable of forming persistent biofilms in food processing environments,which can lead to persistent contamination of foods.It poses a significant threat to human health and food safety.Two-component system(TCS)plays a crucial role in various aspects of bacterial biofilm formation and regulation of virulence factors.The wild-type strain L.monocytogenes 10403S was utilized to build the gene deletion strain ΔvirS/virR and the gene complementation strain CΔvirS/virR.The biofilm assay with crystal violet staining and a motility assay showed that deletion of virS/virR resulted in reduced biofilm formation and motility in L.monocytogenes 10403S.Complementation strain CΔvirS/virR restored the phenotypes to level of wild-type strain.Mutation the 52^(nd) aspartate(Asp52)of VirR with alanine resulted in significantly reduce in both biofilm formation and motility.The GFP reporter system and qRT-PCR demonstrated that deletion virS/virR significantly downregulated the transcriptional level of the chemotactic system cheY,which may be the main reason for the reduced motility and lower biofilm formation capacity of ΔvirS/virR.These findings demonstrated that the two-component system virS/virR positively regulated motility,thereby influencing biofilm formation in L.monocytogenes 10403S.This provides clues to control the biofilm risks of L.monocytogenes in food safety.展开更多
A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble ac...A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU parti-cles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI iso-cyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction be-tween HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.展开更多
The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersio...The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersion relation is obtained analytically by means of the modified lens-type transformation and linear stability analysis.It is shown that a modulational unstable time scale exists for trapped two-component BECs.The modulational properties-which are determined by the wave number,external trapping parameter,intraand inter-species atomic interactions-are modified significantly.The analytical results are confirmed by direct numerical simulation.Our results provide a criterion for judging the occurrence of instability of the trapped two-component BECs in experiment.展开更多
Nickel-coated graphite particles and two-component silicone-rubber were compounded to form a conductive composite system. The electrical volume resistivity of the composites were examined and compared under constant t...Nickel-coated graphite particles and two-component silicone-rubber were compounded to form a conductive composite system. The electrical volume resistivity of the composites were examined and compared under constant tensile strains, cyclic heating-cooling, electric field and repeated cyclic tensile strains in order to study the mechanism of electrical conductivity behaviors of the conductive composites under stress, temperature and current. The results showed that a peak value of the electrical resistivity appeared previously and then gradually increasing with increasing tensile strain. The electrical resistivity displayed positive temperature coefficient effect during the temperature increasing and decreasing. Applying 5A direct current to the conductive composites lesulted in an increase in the electrical resistance immediately, but no changes were detected under lower currents. Under the repeated cyclic strain, the peak value of the electrical resistivity of each cycle increased with the test cycle. All the electrical resistivity changes were attributed to the conductive networks broken-up and rebuilt in the conductive composites.展开更多
We present several families of exact solutions to a system of coupled nonlinear Schrodinger equations. The model describes a binary mixture of two Bose-Einstein condensates in a magnetic trap potential. Using a mappin...We present several families of exact solutions to a system of coupled nonlinear Schrodinger equations. The model describes a binary mixture of two Bose-Einstein condensates in a magnetic trap potential. Using a mapping deformation method, we find exact periodic wave and soliton solutions, including bright and dark soliton pairs.展开更多
In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equat...In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equations is established. Some sufficient conditions for blow-up of the solutions in finite time are given. Moreover, by separation method, the self-similar solutions for the nonlinear shallow water equations are obtained, and which local or global behavior can be determined by the corresponding Emden equation.展开更多
It is shown that the two-component Camassa-Holm and Hunter-Saxton systems are geometrically integrable, namely they describe pseudo-spherical surfaces. As a consequence, their infinite number of conservation laws are ...It is shown that the two-component Camassa-Holm and Hunter-Saxton systems are geometrically integrable, namely they describe pseudo-spherical surfaces. As a consequence, their infinite number of conservation laws are directly constructed. In addition, a class of nonlocal symmetries depending on the pseudo-potentials are obtained.展开更多
The paper deals with analytical models of the elastic energy gradient Wsq representing an energy barrier.The energy barrier is a surface integral of the elastic energy density Wq.The elastic energy density is induced ...The paper deals with analytical models of the elastic energy gradient Wsq representing an energy barrier.The energy barrier is a surface integral of the elastic energy density Wq.The elastic energy density is induced by thermal stresses acting in an isotropic spherical particle(q=p)with the radius R and in a cubic cell of an isotropic matrix(q=m).The spherical particle and the matrix are components of a multi-particle-matrix system representing a model system applicable to a real two-component material of a precipitation-matrix type.The multi-particle-matrix system thus consists of periodically distributed isotropic spherical particles and an isotropic infinite matrix.The infinite matrix is imaginarily divided into identical cubic cells with a central spherical particle in each of the cubic cells.The dimension d of the cubic cell then corresponds to an inter-particle distance.The parameters R,d along with the particle volume fraction v=v(R,d)as a function of R,d represent micro-structural characteristics of a real two-component material.The thermal stresses are investigated within the cubic cell,and accordingly are functions of the microstructural charac-teristics.The thermal stresses originate during a cooling pro-cess as a consequence of the difference am-ap in thermal expansion coefficients between the matrix and the particle,am and ap,respectively.The energy barrier Wsq is used for the determination of the thermal-stress induced strengthening aq.The strengthening represents resistance against com-pressive or tensile mechanical loading for am-ap〉0 or am-ap〈0.respectively.展开更多
Invariant subspace method is exploited to obtain exact solutions of the two- component b-family system. It is shown that the two-component b-family system admits the generalized functional separable solutions. Further...Invariant subspace method is exploited to obtain exact solutions of the two- component b-family system. It is shown that the two-component b-family system admits the generalized functional separable solutions. Furthermore, blow up and behavior of those exact solutions are also investigated.展开更多
This article is concerned with the existence of global attractor of a weakly dissipative generalized two-component μ-Hunter-Saxton （gμHS2） system with viscous terms. Under the period boundary conditions and with t...This article is concerned with the existence of global attractor of a weakly dissipative generalized two-component μ-Hunter-Saxton （gμHS2） system with viscous terms. Under the period boundary conditions and with the help of the Galerkin procedure and compactness method, we first investigate the existence of global solution for the viscous weakly dissipative （gμHS2） system. On the basis of some uniformly prior estimates of the solution to the viscous weakly dissipative （gμHS2） system, we show that the semi-group of the solution operator {S（t）}t≥0 has a bounded absorbing set. Moreover, we prove that the dynamical system {S（t）}t≥0 possesses a global attractor in the Sobolev space H2（S） × H2（S）.展开更多
Ultrasonic Lamb waves are considered as a sensitive and effective tool for nondestructive testing and evaluation of plate-like or pipe-like structures. The nature of multimode and dispersion causes the wave packets to...Ultrasonic Lamb waves are considered as a sensitive and effective tool for nondestructive testing and evaluation of plate-like or pipe-like structures. The nature of multimode and dispersion causes the wave packets to spread, and the modes overlap in both time and frequency domains as they propagate through the structures. By using a two-component laser interferometer technique, in combination with a priori knowledge of the dispersion characteristics and wave structure information of Lamb wave modes, a two-component signal processing technique is presented for implementing dispersion removal and mode separation simultaneously for two modes mixture signals of Lamb waves. The proposed algorithm is first processed and verified using synthetic Lamb wave signals. Then, the two-component displacements test experiment is conducted using different aluminum plate samples. Moreover, we confirm the effectiveness and robustness of this method.展开更多
基金funded by the earmarked fund for the China Agriculture Research System (CARS-18-15)the National Natural Science Foundation of China (31272085,31572051)the Special Fund for Agro-scientific Research in the Public Interest,China (201503109)
文摘Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases, and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2. The regulator PhoP and its sensor kinase PhoR compose a two-component system in B. subtilis. In this study, the phoR- and phoP-knockout mutants were constructed by in-frame deletion and the role of PhoR/PhoP on the production of fengycin was determined. Inactivation of phoR or phoP in B. subtilis decreased its inhibition ability against Botrytis cinerea growth in vitro compared to the strain NCD-2 wild type. The lipopeptides were extracted from strain NCD-2 wild type and its mutant strains by hydrochloric acid precipitate, and the lipopeptides from phoR-null mutant orphoP-null mutant almost lost the inhibition ability against B. cinerea growth compared to the lipopeptides from strain NCD-2 wild type. Fast protein liquid chromatography （FPLC） analysis of the lipopeptides showed that inactivation of phoR or phoP genes reduced the production of fengycin by strain NCD-2. The fengycin production abilities were compared for bacteria under low-phosphate medium （LPM） and high-phosphate medium （HPM）, respectively. Results indicated that the regulation of fengycin production by the PhoR/PhoP two-component system occurred in LPM but not in HPM. Reverse transcriptionaI-PCR confirmed that the fengycin synthetase gene fenC was positively regulated by phoP when cultured in LPM. All of these characteristics could be partially restored by complementation of intact phoR or phoP gene in the mutant. These data indicated that the PhoR/PhoP two-component system greatly regulated fengycin production and antifungal ability in B. subtilis NCD-2 mainly under low-phosphate conditions.
基金Funded by the National Natural Science Foundation of China(No.52378394)the Fundamental Research Funds for the Central Universities(No.B230201037)。
文摘To address the issues of short setting time and high bleeding rate of A component,which easily cause pipe plugging and poor grouting performance when a two-component grout is injected synchronously behind the Segmental Lining,the inorganic retarder sodium pyrophosphate(TSPP)and three organic retarders were added to the A component:sodium citrate(SC),sodium tartrate(ST)and glycerol(GLY).The effect law and microscopic mechanism of viscosity,bleeding rate,setting time,gelling time,compressive strength,and stone rate were investigated.The results revealed that the addition of retarders could enhance the stability and setting time of the A component and increase the gelling time,stone rate,and compressive strength of two-component grout.Among them,the performance of the grout with an SC dosage of 0.1% was superior.The bleeding rate of this grout was reduced to 3.5%,the stone rate of the two-component grout was more than 99%,and the early compressive strength and late compressive strength of this grout were increased by approximately 35% and 7%,respectively.The initial and final setting time of the A component with a TSPP dosage of 0.3% was the longest,which was prolonged to 17 and 26 h,respectively.Microscopic analysis revealed that the four retarders hindered the hydration process of cement through complexation and adsorption,and inhibited the hydration of C_(3)S and the crystallisation of CH.Moreover,they reduced the defects caused by the rapid reaction of water glass and CH on the solid phase structure,enabled the microstructure of the stone body to be denser,and subsequently,enhanced the compressive strength.
基金supported by Tianjin Key Medical Discipline Con-struction(TJYXZDXK-3-004A-3).
文摘Cronobacter sakazakii is an opportunistic foodborne pathogen with remarkable resilience to environmental stressors,posing severe risks in powdered infant formula.Here,we identify the GlrKR two-component system(TCS)as a master regulator that integrates environmental sensing with virulence control.Genetic deletion of either the sensor kinase(glrK)or the response regulator(glrR)markedly attenuates bacterial motility,epithelial cell adherence,and virulence in a neonatal rat model.GlrK is essential for acid and oxidative stress resistance,whereas both GlrK and GlrR suppress desiccation tolerance,revealing a regulatory trade-off between environmental persistence and host invasion.Quantitative proteomics and site-specific mutagenesis uncover enhanced deamidation of OmpA at N101 inΔglrR as a mechanistic basis for impaired adherence.Additionally,GlrKR modulates sensitivity to p-coumaric acid,a plant-derived antimicrobial,via transcriptional control of the efflux pump TolC.These findings establish GlrKR as a central node linking environmental adaptation,antimicrobial defense,and host-pathogen interaction in C.sakazakii,offering a promising target for next-generation food safety interventions.
基金supported by the Key Research and Development Project of Henan Province(Grant Number 241111111200,231111310700)Open Project Program of National Engineering Research Center of Wheat and Corn Further Processing,Henan University of Technology(Grant Number NL2024004)+2 种基金China Postdoctoral Science Foundation(Grant Number 2024M760793)Natural Science Foundation of Henan(Grant Number 242300421557)National Natural Science Foundation of China(Grant Number 32270095).
文摘Two-component systems(TCSs)play important roles in the regulation of secondary metabolism in Streptomyces.However,so far,few TCSs have been functionally identified in the rapamycin-producing strain,Streptomyces rapamycinicus.In this study,a two-component system(TCS)CseB-C(M271_22640/M271_22645)in S.rapamycinicus NRRL 5491,whose homolog from Streptomyces coelicolor is involved in regulating cell wall integrity and secondary metabolism,was identified to play a dual role in differential regulation of antibiotic biosynthesis,activating rapamycin biosynthesis and simultaneously repressing elaiophylin biosynthesis.We showed that knockout of cseB-C resulted in a drastic reduction in rapamycin production and a significant increase in elaiophylin production.Transcriptional analysis revealed that deletion of cseB-C resulted in a substantial decrease in the transcription of sigE,which clusters together with cseB-C.Introduction of sigE into theΔcseB-C mutant could fully restore rapamycin and elaiophylin production to the wild-type levels,suggesting that the role of CseB-C on rapamycin and elaiophylin biosynthesis is mediated by sigE.Collectively,the results obtained in this study contribute to a better understanding of the regulation of rapamycin and elaiophylin biosynthesis in S.rapamycinicus.
基金supported by the Young Taishan Scholars Program of Shandong Province(No.tsqn202103029)the Natural Science Foundation of Shandong Province(No.ZR2024JQ035)+2 种基金the National Natural Science Foundation of China(Nos.42176108,32370030)the Science&Technology Innovation Project of Laoshan Laboratory(No.LSKJ202203205)the Fundamental Research Funds for the Central Universities(Nos.202442001,202561037)。
文摘Microorganisms utilize complex signal-regulating networks to adapt to environmental changes,and two-component system(TCS)plays a crucial role in bacterial sensing and response to environmental fluctuations.This article provides a comprehensive and in-depth multidimensional overview of the RstB/RstA TCS.The RstB/RstA TCS is capable of sensing a variety of external signals,including pH fluctuations,changes in Mg^(2+)concentration,antibiotics and osmotic pressure.And it regulates a variety of physiological processes,including motility,virulence factor expression,biofilm formation,and antibiotic resistance.RstB/RstA TCS might be a critical breakthrough for developing novel antimicrobial strategies to combat bacterial resistance.However,based on the PubMed database,few researches have been conducted on RstB/RstA,and knowledge on this TCS has not been reviewed.Furthermore,the precise regulatory mechanisms of the RstB/RstA system remain largely unexplored,especially in the ocean bacteria.This article integrates the key roles of the RstB/RstA TCS in environmental signal sensing and physiological function regulation.It mainly summarizes the structural composition,multifunctional roles,and regulatory mechanisms of the RstB/RstA system,especially its regulatory role in the marine pathogen Photobacterium damselae subsp.damselae(Pdd).In addition,we also discusse the current limitations of related research,and explore its great potential in the treatment of diseases affecting economically important fish species and human health.This work aims to provide a novel perspective for the study of TCSs in marine bacteria and to offer a theoretical foundation and future directions for further in-depth investigations of this regulatory system.
基金supported by the National Natural Science Foundation of China[No.U23A20259,32394051 and 32122067]supported by the Fundamental Research Funds for the Central Universities JUSRP622013Collaborative innovation center of food safety and quality control in Jiangsu Province.
文摘Lactiplantibacillus plantarum is a nomadic species that displays adaptive variations in different habitats,partic-ularly in the intestines.Bile salts tolerance is crucial for L.plantarum to survive and exert beneficial properties in this environment.L.plantarum exhibits varying growth capacities under bile salts exposure;however,the mo-lecular mechanisms responsible for this variation are not fully understood.In this study,comparative genomics analysis was used to elucidate the specific genes in bile salts-tolerant L.plantarum and further investigate the mechanisms that contribute to bacterial survival under bile salts.A total of eighty-seven specific genes were identified in the tolerant strains,which were primarily associated with the two-component system and carbo-hydrate metabolism.Notably,the mutation of a response regulator(agrA)in the two-component system decreased the growth rate of L.plantarum under bile salts exposure,whereas complementation increased tolerance.Metabolomic analysis suggested that the deletion of agrA resulted in the downregulation of pathways associated with bacterial energy metabolism.These findings indicate that L.plantarum responds to harsh envi-ronments by sensing bile salts as signaling molecules and subsequently adjusting complex metabolic pathways as a survival strategy.This provides novel insights into the molecular basis of the two-component system contributing to bile salts tolerance.
基金supported by the National Natural Science Foundation of China(42176108,31870023)the Young Taishan Scholars Program of Shandong Province(tsqn202103029)the Fundamental Research Funds for the Central Universities(201941009).
文摘The signal transduction system of microorganisms helps them adapt to changes in their complex living environment.Two-component system(TCS)is a representative signal transduction system that plays a crucial role in regulating cellular communication and secondary metabolism.In Gram-negative bacteria,an unorthodox TCS consist-ing of histidine kinase protein GacS(initially called LemA)and response regulatory protein GacA is widespread.It mainly regulates various physiological activities and behaviors of bacteria,such as quorum sensing,secondary metabolism,biofilm formation and motility,through the Gac/Rsm(Regulator of secondary metabolism)signaling cascade pathway.The global regulatory ability of GacS/GacA in cell physiological activities makes it a potential research entry point for developing natural products and addressing antibiotic resistance.In this review,we summarize the progress of research on GacS/GacA from various perspectives,including the reaction mechanism,related regulatory pathways,main functions and GacS/GacA-mediated applications.Hopefully,this review will facilitate further research on GacS/GacA and promote its application in regulating secondary metabolism and as a therapeutic target.
基金National Natural Science Foundation of China(No.22177039 and 82304274)National Key R&D Program of China(No.2021YFC2300400)China Postdoctoral Science Foundation(No.55350658).
文摘The management of antibiotic-resistant, bacterial biofilm infections in skin wounds poses an increasingly challenging clinical scenario. Pseudomonas aeruginosa infection is difficult to eradicate because of biofilm formation and antibiotic resistance. In this study, we identified a new benzothiazole derivative compound, SN12 (IC_(50)= 43.3 nmol/L), demonstrating remarkable biofilm inhibition at nanomolar concentrations in vitro. In further activity assays and mechanistic studies, we formulated an unconventional strategy for combating P. aeruginosa-derived infections by targeting the two-component (Gac/Rsm) system. Furthermore, SN12 slowed the development of ciprofloxacin and tobramycin resistance. By using murine skin wound infection models, we observed that SN12 significantly augmented the antibacterial effects of three widely used antibiotics—tobramycin (100-fold), vancomycin (200-fold), and ciprofloxacin (1000-fold)—compared with single-dose antibiotic treatments for P. aeruginosa infection in vivo. The findings of this study suggest the potential of SN12 as a promising antibacterial synergist, highlighting the effectiveness of targeting the two-component system in treating challenging bacterial biofilm infections in humans.
基金supported by the National Key R&D Program of China(2016YFA0501503)the National Mega-project for Innovative Drugs of China(2019ZX09721001-004-003)+2 种基金the National Natural Science Foundation of China(31670136 31870127 and 81861138047)the Science and Technology Commission of Shanghai Municipality(19JC1416400)the State Key Laboratory of Drug Research(SIMM2003ZZ-03).
文摘In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here,we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa;in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation(Dsb)(i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copperbinding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR.The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5’-TTA-N8-TTAA-3’, is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress.
基金supported by the National Natural Science Foundation of China(grant numbers 31802208)Science and Technology Research Project of Education Department of Hubei Province(grant numbers Q20221302).
文摘Listeria monocytogenes is a foodborne pathogen that is ubiquitous in the natural environment.Listeria monocytogenes is capable of forming persistent biofilms in food processing environments,which can lead to persistent contamination of foods.It poses a significant threat to human health and food safety.Two-component system(TCS)plays a crucial role in various aspects of bacterial biofilm formation and regulation of virulence factors.The wild-type strain L.monocytogenes 10403S was utilized to build the gene deletion strain ΔvirS/virR and the gene complementation strain CΔvirS/virR.The biofilm assay with crystal violet staining and a motility assay showed that deletion of virS/virR resulted in reduced biofilm formation and motility in L.monocytogenes 10403S.Complementation strain CΔvirS/virR restored the phenotypes to level of wild-type strain.Mutation the 52^(nd) aspartate(Asp52)of VirR with alanine resulted in significantly reduce in both biofilm formation and motility.The GFP reporter system and qRT-PCR demonstrated that deletion virS/virR significantly downregulated the transcriptional level of the chemotactic system cheY,which may be the main reason for the reduced motility and lower biofilm formation capacity of ΔvirS/virR.These findings demonstrated that the two-component system virS/virR positively regulated motility,thereby influencing biofilm formation in L.monocytogenes 10403S.This provides clues to control the biofilm risks of L.monocytogenes in food safety.
文摘A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU parti-cles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI iso-cyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction be-tween HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11764039,11847304,11865014,11475027,11274255 and 11305132the Natural Science Foundation of Gansu Province under Grant No 17JR5RA076the Scientific Research Project of Gansu Higher Education under Grant No 2016A-005
文摘The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersion relation is obtained analytically by means of the modified lens-type transformation and linear stability analysis.It is shown that a modulational unstable time scale exists for trapped two-component BECs.The modulational properties-which are determined by the wave number,external trapping parameter,intraand inter-species atomic interactions-are modified significantly.The analytical results are confirmed by direct numerical simulation.Our results provide a criterion for judging the occurrence of instability of the trapped two-component BECs in experiment.
基金Funded by Wuhan Science and Technology Bureau (No.200710321090-18)
文摘Nickel-coated graphite particles and two-component silicone-rubber were compounded to form a conductive composite system. The electrical volume resistivity of the composites were examined and compared under constant tensile strains, cyclic heating-cooling, electric field and repeated cyclic tensile strains in order to study the mechanism of electrical conductivity behaviors of the conductive composites under stress, temperature and current. The results showed that a peak value of the electrical resistivity appeared previously and then gradually increasing with increasing tensile strain. The electrical resistivity displayed positive temperature coefficient effect during the temperature increasing and decreasing. Applying 5A direct current to the conductive composites lesulted in an increase in the electrical resistance immediately, but no changes were detected under lower currents. Under the repeated cyclic strain, the peak value of the electrical resistivity of each cycle increased with the test cycle. All the electrical resistivity changes were attributed to the conductive networks broken-up and rebuilt in the conductive composites.
基金Project supported by the National Natural Science Foundation of China（Grant Nos 10575087 and 10302018）, and the Natural Science Foundation of Zhejiang Province, China （Grant No Y605056）.
文摘We present several families of exact solutions to a system of coupled nonlinear Schrodinger equations. The model describes a binary mixture of two Bose-Einstein condensates in a magnetic trap potential. Using a mapping deformation method, we find exact periodic wave and soliton solutions, including bright and dark soliton pairs.
基金supported by NSF of China (11071266)partially supported by Scholarship Award for Excellent Doctoral Student granted by Ministry of Educationpartially supported by the found of Chongqing Normal University (13XLB006)
文摘In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equations is established. Some sufficient conditions for blow-up of the solutions in finite time are given. Moreover, by separation method, the self-similar solutions for the nonlinear shallow water equations are obtained, and which local or global behavior can be determined by the corresponding Emden equation.
基金Supported by the China NSF for Distinguished Young Scholars under Grant No.10925104
文摘It is shown that the two-component Camassa-Holm and Hunter-Saxton systems are geometrically integrable, namely they describe pseudo-spherical surfaces. As a consequence, their infinite number of conservation laws are directly constructed. In addition, a class of nonlocal symmetries depending on the pseudo-potentials are obtained.
基金supported by the Slovak Research and Development Agency under the contracts No.COST-0022-06,No.COST-0042-06,No.APVV-51-061505,No.APVV-0034-07,No.APVV-0171-06by the 6th FP EU NESPA+16 种基金by FP7-REGPOT-2007-3 DEMATEN 204953(05/08-04/11)by IMPROVING 229625by HANCOC-MNT.ERA-NET 01/09-12/11by NANOSMART Centre of Excellence(01/2007-12/2010)Slovak Academy of Sciencesby the Slovak Grant Agency VEGA(2/7197/27,2/7194/27,2/7195/27,1/4107/07)by iNTeg-Risk CP-IP 213345-2by European Structural Fund-Center of Excellence(Progressive Materials with Nano-and Submicron-Structure):ITMS NFP code 262200120019by COST Action 536by COST Action 538by OTKA Foundation(No.T043704,T043685,T 048593,T 63609)by HPRT-CT-2000-00037by EC5 Center of Excellence ICAI-CT-2000-70029by OTKA Postdoctoral Research Grant(D38478)by Swedish Research Council(No.621-2002-4299)by NSF-OTKA-MTA(No.MTA:96 OTKA:049953)by GVOP-3.2.1.-2004-04-0224/3.0by János Bolyai Research Grant.96/OTKA:049953,OTKA 63609
文摘The paper deals with analytical models of the elastic energy gradient Wsq representing an energy barrier.The energy barrier is a surface integral of the elastic energy density Wq.The elastic energy density is induced by thermal stresses acting in an isotropic spherical particle(q=p)with the radius R and in a cubic cell of an isotropic matrix(q=m).The spherical particle and the matrix are components of a multi-particle-matrix system representing a model system applicable to a real two-component material of a precipitation-matrix type.The multi-particle-matrix system thus consists of periodically distributed isotropic spherical particles and an isotropic infinite matrix.The infinite matrix is imaginarily divided into identical cubic cells with a central spherical particle in each of the cubic cells.The dimension d of the cubic cell then corresponds to an inter-particle distance.The parameters R,d along with the particle volume fraction v=v(R,d)as a function of R,d represent micro-structural characteristics of a real two-component material.The thermal stresses are investigated within the cubic cell,and accordingly are functions of the microstructural charac-teristics.The thermal stresses originate during a cooling pro-cess as a consequence of the difference am-ap in thermal expansion coefficients between the matrix and the particle,am and ap,respectively.The energy barrier Wsq is used for the determination of the thermal-stress induced strengthening aq.The strengthening represents resistance against com-pressive or tensile mechanical loading for am-ap〉0 or am-ap〈0.respectively.
基金supported by NSFC(11471260)the Foundation of Shannxi Education Committee(12JK0850)
文摘Invariant subspace method is exploited to obtain exact solutions of the two- component b-family system. It is shown that the two-component b-family system admits the generalized functional separable solutions. Furthermore, blow up and behavior of those exact solutions are also investigated.
基金partially supported by NNSF of China(11571126,11701198)China Postdoctoral Science Foundation funded project(2017M622397)
文摘This article is concerned with the existence of global attractor of a weakly dissipative generalized two-component μ-Hunter-Saxton （gμHS2） system with viscous terms. Under the period boundary conditions and with the help of the Galerkin procedure and compactness method, we first investigate the existence of global solution for the viscous weakly dissipative （gμHS2） system. On the basis of some uniformly prior estimates of the solution to the viscous weakly dissipative （gμHS2） system, we show that the semi-group of the solution operator {S（t）}t≥0 has a bounded absorbing set. Moreover, we prove that the dynamical system {S（t）}t≥0 possesses a global attractor in the Sobolev space H2（S） × H2（S）.
基金Project supported by the National Natural Science Foundation of China(Grant No.11374230)
文摘Ultrasonic Lamb waves are considered as a sensitive and effective tool for nondestructive testing and evaluation of plate-like or pipe-like structures. The nature of multimode and dispersion causes the wave packets to spread, and the modes overlap in both time and frequency domains as they propagate through the structures. By using a two-component laser interferometer technique, in combination with a priori knowledge of the dispersion characteristics and wave structure information of Lamb wave modes, a two-component signal processing technique is presented for implementing dispersion removal and mode separation simultaneously for two modes mixture signals of Lamb waves. The proposed algorithm is first processed and verified using synthetic Lamb wave signals. Then, the two-component displacements test experiment is conducted using different aluminum plate samples. Moreover, we confirm the effectiveness and robustness of this method.
