Helicoverpa zea is a major target pest of pyramided transgenic crops expressing Cry1,Cry2 and/or Vip3Aa proteins from Bacillus thuringiensis(Bt)in the United States.Laboratory-selected Cry1Ac/Cry2Ab cross resistance a...Helicoverpa zea is a major target pest of pyramided transgenic crops expressing Cry1,Cry2 and/or Vip3Aa proteins from Bacillus thuringiensis(Bt)in the United States.Laboratory-selected Cry1Ac/Cry2Ab cross resistance and fieldevolved practical dual resistance of H.zea to these two toxins have been widely reported.Whether the widespread Cry1Ac/Cy2Ab dual resistance of H.zea has resulted from the selection of one shared or two independent resistance mechanisms by pyramided Bt crops remains unclear.Cadherin is a well-confirmed receptor of Cry1Ac and a suggested receptor of Cry2Ab in at least three Lepidopteran species.To test whether cadherin may serve as one shared mechanism for the cross and dual resistance of H.zea to Cry1Ac and Cry2Ab,we cloned H.zea cadherin(HzCadherin)cDNA and studied its functional roles in the mode of action of Cry1Ac and Cry2Ab by gain-and lossof-function analyses.Heterologous expression of HzCadherin in H.zea midgut,H.zea fat body and Sf9 cells made all three of these cell lines more susceptible to activated Cry1Ac but not activated Cry2Ab,whereas silencing HzCadherin of H.zea midgut and fat body cells significantly reduced the susceptibility to Cry1Ac but not Cry2Ab.Likewise,suppressing HzCadherin with siRNA made H.zea larvae resistant to Cry1Ac.These results clearly demonstrate that HzCadherin is not a receptor for Cry2Ab,and thus it is unlikely to serve as one shared mechanism for the cross and dual resistance of H.zea to Cry1Ac and Cry2Ab.展开更多
Ovarian cancer is among the most lethal gynecological cancers,primarily due to the lack of specific symptoms leading to an advanced-stage diagnosis and resistance to chemotherapy.Drug resistance(DR)poses the most sign...Ovarian cancer is among the most lethal gynecological cancers,primarily due to the lack of specific symptoms leading to an advanced-stage diagnosis and resistance to chemotherapy.Drug resistance(DR)poses the most significant challenge in treating patients with existing drugs.The Food and Drug Administration(FDA)has recently approved three new therapeutic drugs,including two poly(ADP-ribose)polymerase(PARP)inhibitors(olaparib and niraparib)and one vascular endothelial growth factor(VEGF)inhibitor(bevacizumab)for maintenance therapy.However,resistance to these new drugs has emerged.Therefore,understanding the mechanisms of DR and exploring new approaches to overcome them is crucial for effective management.In this review,we summarize the major molecular mechanisms of DR and discuss novel strategies to combat DR.展开更多
Viral diseases are minacious with the potential for causing pandemics and treatment is complicated because of their inherent ability to mutate and become resistant to drugs. Antiviral drug resistance is a persistent p...Viral diseases are minacious with the potential for causing pandemics and treatment is complicated because of their inherent ability to mutate and become resistant to drugs. Antiviral drug resistance is a persistent problem that needs continuous attention by scientists, medical professionals, and government agencies. To solve the problem, an in-depth understanding of the intricate interplay between causes of antiviral drug resistance and potential new drugs specifically natural products is imperative in the interest and safety of public health. This review delves into natural product as reservoir for antiviral agents with the peculiar potentials for addressing the complexities associated with multi-drug resistant and emerging viral strains. An evaluation of the mechanisms underlying antiviral drug activity, antiviral drug resistance is addressed, with emphasis on production of broad-spectrum antiviral agents from natural sources. There is a need for continued natural product-based research, identification of new species and novel compounds.展开更多
The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been ...The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been suggested after the geotechnical characterization of samples of soil was taken. From these, it arises that the studied soil is the most plastically clay (of type A<sub>3</sub>) according to GTR classification. Samples made of small bricks and measured out at 4%, 6% and 8% of binders (molasses, starch or molasses + starch) have been warmed up to different temperatures (100°C, 150°C, 200°C and 250°C) for the rising of the thermic behavior under different conditions and submitted to crushing testings for the estimation of characteristic resistances to the compression. According to the mechanical behavior, we note an improvement of resistances for small bricks measured 4%, 6% and 8%, of molasses respectively of 32.44%, 32.06% and 23.43% against the value of reference for small bricks without molasses. In the same way, the binder (molasses + starch) also reveals an improvement of resistance to the compression of 13.27%, 26.17% and 26.17%. On the contrary, the stabilization with the starch binder did not bring a significative improvement. According to the thermic influence, the heating at 100°C of stabilized small bricks at 4%, 6% and 8% of molasses, reveals a significative improvement of resistances. Moreover, the stabilization with the starch reveals on the contrary a good behavior for heatings at 150°C and 250°C. In short, for the binder (molasses + starch), it is the heating at 200°C that shows some improvements of remarkable resistances. Different analyses of realized statistics also show the effectivity of obtained results. For all realized formulations, the measuring out at 6% of binders (molasses, or molasses + starch) seems as optimal in front of the best thermo-mechanical revealed properties.展开更多
Cucumber is an important vegetable worldwide,and powdery mildew(PM)is a common and serious disease of cucumbers.Breeding disease-resistant cucumber varieties is the most advantageous strategy to control this disease.I...Cucumber is an important vegetable worldwide,and powdery mildew(PM)is a common and serious disease of cucumbers.Breeding disease-resistant cucumber varieties is the most advantageous strategy to control this disease.In recent years,exploration and identification of cucumber PM resistance genes have achieved great advancement,and many genes have been cloned and verified using different methods.However,the resistance mechanism of cucumber PM is still unclear,and many ambiguities need to be elucidated urgently.In this review,we summarized the research advances in PM resistance in cucumbers,including genetic analysis,quantitative trait locus mapping,map-based cloning,transcriptomics,mlo-mediated PM resistance,and mining of noncoding RNAs involved in resistance.Finally,the research directions and the problems that need to be solved in the future were discussed.展开更多
Burkholderia pseudomallei is the pathogen that causes melioidosis.Melioidosis has a long duration of chronic infection,atypical clinical manifestations at acute onset,and is prone to life-threatening complications and...Burkholderia pseudomallei is the pathogen that causes melioidosis.Melioidosis has a long duration of chronic infection,atypical clinical manifestations at acute onset,and is prone to life-threatening complications and poor prognosis.Understanding the pathogenesis and drug resistance mechanism of Burkholderia pseudomallei will effectively help the diagnosis and treatment of the disease and improve the prognosis.This review focuses on the extracellular movement of Burkholderia pseudomallei in host cells,the way of infecting host cells,virulence factors,and drug resistance mechanisms(efflux pumps,changes in target sites,etc.).This study provides a possible direction for the early diagnosis,treatment and control of melioidosis caused by this bacterium.展开更多
Tuberculosis(TB)is a chronic infectious disease caused by Mycobacterium Tuberculosis(MTB).It is the second largest single cause of death besides novel coronavirus pneumonia.Along with the abuse of antibiotics and exte...Tuberculosis(TB)is a chronic infectious disease caused by Mycobacterium Tuberculosis(MTB).It is the second largest single cause of death besides novel coronavirus pneumonia.Along with the abuse of antibiotics and extensive use of anti-tuberculosis drugs,multidrug-resistant(MDR)TB,drug-resistant(XDR)TB and totally drug-resistant(TDR)TB became obstacles to the tuberculosis eradication worldwide.According to the World Health Organization(WHO)statistics,China is not only a high burden tuberculosis country in the world,but also a country with a serious epidemic of MDR.Traditional drugs fail to meet the needs of tuberculosis control.Therefore,it is urgent to find new targets of anti-tuberculosis drugs and develop new anti-tuberculosis drugs.Hence,this paper systematically summarizes the mechanism of traditional and newly developed anti-tuberculosis drugs,in which stressing the research progress of drug resistance mechanisms.This work provides us with new insights of new anti-tuberculosis drug developments,and may contribute to a reduction in the harm that tuberculosis brings to society.展开更多
Conventional MgO-C bricks(graphite content>14 wt.%)produce a great deal of greenhouse gas emission,while low-carbon MgO-C bricks have serious thermal shock resistance during high-temperature service.To enhance the ...Conventional MgO-C bricks(graphite content>14 wt.%)produce a great deal of greenhouse gas emission,while low-carbon MgO-C bricks have serious thermal shock resistance during high-temperature service.To enhance the high-temperature mechanical property and thermal shock resistance of low-carbon MgO-C bricks,a novel route of introducing ZrSiO_(4) powder into low-carbon MgO-C bricks was reported in such refractories with 2 wt.% flaky graphite.The results indicate that the low-carbon MgO-C brick with 0.5 wt.%ZrSiO_(4) addition has the maximum hot modulus of rupture at 1400℃ and the corresponding specimen fired in the carbon embedded atmosphere has the maximum residual strength ratio(98.6%)after three thermal shock cycles.It is found that some needle-like AlON and plate-like Al_(2)O_(3)-ZrO_(2) composites were in situ formed in the matrices after the low-carbon MgO-C bricks were coked at 1400℃,which can enhance the high-temperature mechanical property and thermal shock resistance due to the effect of fiber toughening and particle toughening.Moreover,CO_(2) emission of the newly developed low-carbon MgO-C bricks is reduced by 58.3% per ton steel after using them as the working lining of a 90 t vacuum oxygen decarburization ladle.展开更多
As an important ecological tree species in northern China, Populus simonii plays a crucial role in maintaining ecological balance and promoting environmental sustainability. The academic community has conducted a seri...As an important ecological tree species in northern China, Populus simonii plays a crucial role in maintaining ecological balance and promoting environmental sustainability. The academic community has conducted a series of in-depth studies on this species, covering key areas such as genomics, survival mechanisms, and genetic breeding. Through the analysis of the genomic structure and function of P. simonii, we have not only revealed the molecular basis for its adaptation to harsh environments but also identified key genes that promote its growth and resistance to pests and diseases. Furthermore, exploring the survival mechanisms of P. simonii has deepened our understanding of its stress resistance traits, including how it effectively copes with abiotic stresses such as drought, salinization, and heavy metal pollution. In genetic breeding, significant progress has been made through the application of modern biotechnology, improving the growth rate and wood quality of P. simonii and enhancing its environmental adaptability and disease resistance. These research findings have not only enriched our knowledge of the biological characteristics of P. simonii but also provided a solid scientific foundation for its application in ecological restoration, forestry production, and environmental management.展开更多
Chlamydia Trachomatis (C.T.) is one of the most common pathogens of human sexually transmitted diseases. Treatment of C.T. infection primarily depends on Tetracyclines, Macrolides and Quinolones, but with the wide use...Chlamydia Trachomatis (C.T.) is one of the most common pathogens of human sexually transmitted diseases. Treatment of C.T. infection primarily depends on Tetracyclines, Macrolides and Quinolones, but with the wide use of antibiotics an increasing number of drug-resistant Chlamydia trachomatis cases have been reported. This review summarizes the resistant conditions and the possible resistance mechanisms of C.T..展开更多
The objective of this work, was to characterize the sands of the quarries of: Bandjoun-Djione, Djengou, Hiala and La’gou I, mainly from their mechanical strengths, the equivalent of sand and the finesse module. In or...The objective of this work, was to characterize the sands of the quarries of: Bandjoun-Djione, Djengou, Hiala and La’gou I, mainly from their mechanical strengths, the equivalent of sand and the finesse module. In order to study the compressive strength of concrete made from these sands, we determined their granularity, fineness modulus and density;the concrete was then formulated by the Dreux-Gorisse method. A total of 72 specimens were constructed with the objective of achieving an average compressive strength of 25 MPa at 28 days. But we have obtained a compressive strength at 28 days, varying from 13.14 MPa to 17.50 MPa. The correction of the modulus of fineness of these sands made it possible to improve the granularity and increase the compressive strength of these concretes by more than 70%. We have thus obtained the compression resistance of 25 MPa aimed for each of the corrected sands.展开更多
One hundred and thirty-eight rice accessions were screened for resistance to the small brown planthopper （SBPH） （Laodelphax striatellus Fallen） by the modified seedbox screening test. Twenty-five rice accessions w...One hundred and thirty-eight rice accessions were screened for resistance to the small brown planthopper （SBPH） （Laodelphax striatellus Fallen） by the modified seedbox screening test. Twenty-five rice accessions with different levels of resistance to SBPH were detected, accounting for 18.1% of the total accessions, which included 2 highly resistant, 9 resistant and 14 moderately resistant varieties. Compared with indica rice, japonica rice was more susceptible to SBPH. Antixenosis test, antibiosis test and correlation analysis were performed to elucidate the resistance mechanism. The resistant check Rathu Heenati （RHT）, highly resistant varieties Mudgo and Kasalath, and resistant variety IR36 expressed strong antixenosis and antibiosis against SBPH, indicating the close relationship between resistance level and these two resistance mechanisms in the four rice varieties. Antibiosis was the dominant resistance pattern in the resistant varieties Daorenqiao and Yangmaogu due to their high antibiosis but low antixenosis. Dular, ASD7 and Milyang 23 had relatively strong antixenosis and antibiosis, indicating the two resistance mechanisms were significant in these three varieties. The resistant DV85 expressed relatively high level of antixenosis but low antibiosis, whereas Zhaiyeqing 8 and Guiyigu conferred only moderate antibiosis and antixenosis to SBPH, suggesting tolerance in these three varieties. Antibiosis and antixenosis governed the resistance to SBPH in the moderately resistant accession 9311. Antixenosis was the main resistance type in V20A. Tolerance was considered to be an important resistance mechanism in Minghui 63 and Yangjing 9538 due to their poor antibiosis and antixenosis resistance. The above accessions with strong antibiosis or antixenosis were the ideal materials for the resistance breeding.展开更多
The Ti fire found in high performance engines promotes the development of burn resistant Ti alloys. The burn resistant mechanism of Ti40 alloy is investigated. Ti40 alloy reveals good burn resistance. Its interfacial ...The Ti fire found in high performance engines promotes the development of burn resistant Ti alloys. The burn resistant mechanism of Ti40 alloy is investigated. Ti40 alloy reveals good burn resistance. Its interfacial products between burning products and the matrix are tenacious, which retard the diffusion of oxygen into the matrix. Two burn resistant mechanisms, that is, fast scatter dispersion of heat and suppression of oxygen diffusion, are proposed.展开更多
Drought and shortage of water resources, which restrict the economy, society development and environmental protection, are key factors in arid zones of China. In the arid zones of Western China, researching plant drou...Drought and shortage of water resources, which restrict the economy, society development and environmental protection, are key factors in arid zones of China. In the arid zones of Western China, researching plant drought resistance mechanism, selecting plant species with higher drought resistance, and developing water-saving techniques, are important for environmental improvement and economic development. This paper reviews research advances on drought resistance mechanism of plant species, based on research of morphological, physiological, and ecological adaptation mechanism of plant species under drought stress, such as anatomical structure of root systems and leaves, photosynthesis, antioxidant enzyme system, malondialdehyde （MDA）, osmotic adjustment, endogenous hormone, drought-induced proteins and δ^13C. Finally, this paper points out the key field of future research.展开更多
Rice planthoppers,including brown planthopper(BPH)and white-backed planthopper(WBPH),are the most destructive pests in Asian rice cultivation regions.Planthopper resistance genes that have been mapped and characterize...Rice planthoppers,including brown planthopper(BPH)and white-backed planthopper(WBPH),are the most destructive pests in Asian rice cultivation regions.Planthopper resistance genes that have been mapped and characterized advance our understanding of underlying resistance mechanisms and facilitate the breeding of resistant varieties,thereby contributing to an efficient pest management strategy.In this study,a novel resistance gene Bph38 derived from the wild rice species Oryza rufipogon Griff.was found to confer high resistance to BPH and WBPH.Conventional mapping was performed to identify regions associated with BPH and WBPH resistance,and two mapping efforts led to the same region on chromosome 4 flanked by markers RM16563 and RM16763.Bulked-segregant analysis and next-generation sequencing were performed using the same population to detect the resistance gene.Conventional mapping narrowed the region to a 12.3-Mb segment,and fine mapping using BC1 F2 recombinants identified a 79-kb segment flanked by markers YM112 and YM190.Near-isogenic lines(NILs)carrying Bph38 in the 9311(indica)and BR54(japonica)genetic backgrounds were developed by crossing and backcrossing with marker-assisted selection.The agronomic traits and BPH and WBPH resistance of the NILs were similar to those of the recurrent parents.Mandatory feeding and host-choice tests revealed that Bph38 showed both antibiotic and antixenotic effects in both insects,with stronger effects in indica-background lines.Further fine mapping and characterization of the major gene may result in map-based cloning of the gene and allow its application in breeding insectresistant rice varieties.展开更多
Objective: To investigate the antimicrobial susceptibility of 97 clinical Staphylococcus aureus(S. aureus) strains against 14 antimicrobials and corresponding resistance mechanisms.Methods: The antimicrobial susceptib...Objective: To investigate the antimicrobial susceptibility of 97 clinical Staphylococcus aureus(S. aureus) strains against 14 antimicrobials and corresponding resistance mechanisms.Methods: The antimicrobial susceptibility of the isolates was determined using a disk diffusion method and antimicrobial resistance genes were screened by polymerase chain reaction. Mutations responsible for ciprofloxacin and rifampicin resistance were investigated by polymerase chain reaction and DNA sequencing.Results: All isolates were found to be susceptible to vancomycin. Various rates of resistance to penicillin(83.5%), ampicillin(77.3%), erythromycin(63.9%), tetracycline(16.5%), amoxicillin/clavulanic acid(16.5%), ciprofloxacin(15.5%), trimethoprim/sulfamethoxazole(15.5%), oxacillin(13.4%), fusidic acid(12.4%), rifampin(6.2%), clindamycin(6.2%), gentamicin(6.2%) and mupirocin(5.2%) were determined. In addition,different combinations of resistance genes were identified among resistant isolates.Ciprofloxacin resistant isolates had mutations in codon 84(Ser84 Leu) and 106(Gly106 Asp) in the gyr A gene. Mutations in grl A were mostly related to Ser80 Phe substitution. Leu466 Ser mutation in the rpo B gene was detected in all rifampin resistant isolates. All methicillin resistant S. aureus isolates were SCCmec type V.Conclusions: In conclusion, it was determined that the isolates were resistant to different classes of antimicrobials at varying rates and resistance was mediated by different genetic mechanisms. Therefore, continuous monitoring of resistance in S. aureus strains is necessary to control their resistance for clinically important antimicrobials.展开更多
Carbapenem resistance presents a major challenge for the global public health network, as clinical infections caused by carbapenem-resistant organisms(CRO) are frequently associated with significant morbidity and mort...Carbapenem resistance presents a major challenge for the global public health network, as clinical infections caused by carbapenem-resistant organisms(CRO) are frequently associated with significant morbidity and mortality. Ceftazidime–avibactam(CAZ–AVI) is a novel cephalosporin/β-lactamase inhibitor combination offering an important advance in the treatment of CRO infections. CAZ–AVI has been reported to inhibit the activities of Ambler classes A, C, and some class D enzymes. However, bacterial resistance has been emerging shortly after the introduction of this combination in clinical use, with an increasing trend. Understanding these resistance mechanisms is crucial for guiding the development of novel treatments and aiding in the prediction of underlying resistance mechanisms. This review aims to systematically summarize the epidemiology of CAZ–AVI-resistant strains and recently identified resistance mechanisms of CAZ–AVI, with a focus on the production of β-lactamase variants, the hyperexpression of β-lactamases, reduced permeability, and overexpressed efflux pumps. The various mechanisms of CAZ–AVI resistance that have emerged within a short timescale emphasize the need to optimize the use of current agents, as well as the necessity for the surveillance of CAZ–AVI-resistant pathogens.展开更多
Before 1980s,the circular suspension spring in automobile subjected to torsion fatigue load,under the cyclic normal tensile stresses,the majority of fatigue fracture occurred was in normal tensile fracture mode（NTFM...Before 1980s,the circular suspension spring in automobile subjected to torsion fatigue load,under the cyclic normal tensile stresses,the majority of fatigue fracture occurred was in normal tensile fracture mode（NTFM）and the fracture surface was under 45°diagonal.Because there exists the interaction between the residual stresses induced by shot peening and the applied cyclic normal tensile stresses in NTFM,which represents as＂stress strengthening mechanism＂,shot peening technology could be used for improving the fatigue fracture resistance（FFR）of springs.However,since 1990s up to date,in addition to regular NTFM,the fatigue fractures occurred of peened springs from time to time are in longitudinal shear fracture mode（LSFM）or transverse shear fracture mode（TSFM）with the increase of applied cyclic shear stresses,which leads to a remarkable decrease of FFR.However,LSFM/TSFM can be avoided effectively by means of shot peening treatment again on the peened springs.The phenomena have been rarely happened before.At present there are few literatures concerning this problem.Based upon the results of force analysis of a spring,there is no interaction between the residual stresses by shot peening and the applied cyclic shear stresses in shear fracture.This;means that the effect of＂stress strengthening mechanism＂for improving the FFR of LSFM/TSFM is disappeared basically.During shot peening,however,both of residual stress and cyclic plastic deformed microstructure are induced synchronously like＂twins＂in the surface layer of a spring.It has been found for the first time by means of force analysis and experimental results that the modified microstructure in the＂twins＂as a＂structure strengthening mechanism＂can improve the FFR of LSFM/TSFM.At the same time,it is;also shown that the optimum technology of shot peening strengthening must have both＂stress strengthening mechanism＂and＂structure strengthening mechanism＂simultaneously so that the FFR of both NTFM and LSFM/TSFM can be improved by shot peening.展开更多
[ Objective ] The paper was to explore the induced resistance of tomato against gray mold （Botrytis cinerea） by salicylic acid. [ Method ] SA was used as an inducer to treat tomato seedlings, the effects of SA on my...[ Objective ] The paper was to explore the induced resistance of tomato against gray mold （Botrytis cinerea） by salicylic acid. [ Method ] SA was used as an inducer to treat tomato seedlings, the effects of SA on mycelial diameter and spore germination of B. cinerea were studied, and the changes of 4 defense enzyme activities containing catalase （CAT）, peroxidase （POD）, polyphenol oxidase （PPO） and phenylalanine ammonia lyase （PAL）, as well as malondialdehyde （MDA） content during the production process of induced resistance were also measured. [ Result] SA had no inhibitory effect against spore germination and myce- lial growth of B. cinerea within the concentration range, and the relative induced effect had different degrees of improvement after treatment. The induced effect was the best as B. cinerea was challenged to inoculate at the third day after using 150 mg/L SA in tomato plants, and the duration of resistance was 10 -15 d. After treated by SA, CAT, POD, PPO and PAL first increased and then decreased in systemic induced resistance against B. cinerea, which were significantly higher than control. Meanwhile, MDA content showed ascendant trend in wavy line form. [ Conclusion ] The use of SA within a certain concentration range is safe; CAT, POD, PPO and PAL activities have positive correlation with induced resistance against B. cinerea, the increase of MDA content also has close relationship with the imvrovement of disease resistance.展开更多
A two-step equal channel angular extrusion（ECAE） procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were...A two-step equal channel angular extrusion（ECAE） procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were studied. The results show that the average grain size of pure Mg decreases with decreasing extrusion temperature. After ECAE processing at 473 K, fine and equiaxed grains（~9 μm） are obtained. The sample processed at 473 K exhibits the excellent mechanical properties, whereas the sample processed at 633 K has the lowest corrosion rate. The improved corrosion resistance and mechanical properties of pure Mg by ECAE are ascribed to grain refinement and microstructural modification.展开更多
基金funded by the USDA National Institute of Food and Agriculture (Hatch Grant ARZT-1360890-H31-164 and multi-state grant ARZ-T1370680-R31-172 (NC246))the National Natural Science Foundation of China (NSFC)–Henan Joint Major Grant (U2004206)+2 种基金the State Key Laboratory of Cotton Biology Open Fund, Zhengzhou University, China (CB2020A06)the Henan Agriculture Research System, China (HARS22-09-G3)the earmarked fund for China Agriculture Research System (CARS-27)
文摘Helicoverpa zea is a major target pest of pyramided transgenic crops expressing Cry1,Cry2 and/or Vip3Aa proteins from Bacillus thuringiensis(Bt)in the United States.Laboratory-selected Cry1Ac/Cry2Ab cross resistance and fieldevolved practical dual resistance of H.zea to these two toxins have been widely reported.Whether the widespread Cry1Ac/Cy2Ab dual resistance of H.zea has resulted from the selection of one shared or two independent resistance mechanisms by pyramided Bt crops remains unclear.Cadherin is a well-confirmed receptor of Cry1Ac and a suggested receptor of Cry2Ab in at least three Lepidopteran species.To test whether cadherin may serve as one shared mechanism for the cross and dual resistance of H.zea to Cry1Ac and Cry2Ab,we cloned H.zea cadherin(HzCadherin)cDNA and studied its functional roles in the mode of action of Cry1Ac and Cry2Ab by gain-and lossof-function analyses.Heterologous expression of HzCadherin in H.zea midgut,H.zea fat body and Sf9 cells made all three of these cell lines more susceptible to activated Cry1Ac but not activated Cry2Ab,whereas silencing HzCadherin of H.zea midgut and fat body cells significantly reduced the susceptibility to Cry1Ac but not Cry2Ab.Likewise,suppressing HzCadherin with siRNA made H.zea larvae resistant to Cry1Ac.These results clearly demonstrate that HzCadherin is not a receptor for Cry2Ab,and thus it is unlikely to serve as one shared mechanism for the cross and dual resistance of H.zea to Cry1Ac and Cry2Ab.
基金This study received support for Open Access Publikationskosten from the DFG.
文摘Ovarian cancer is among the most lethal gynecological cancers,primarily due to the lack of specific symptoms leading to an advanced-stage diagnosis and resistance to chemotherapy.Drug resistance(DR)poses the most significant challenge in treating patients with existing drugs.The Food and Drug Administration(FDA)has recently approved three new therapeutic drugs,including two poly(ADP-ribose)polymerase(PARP)inhibitors(olaparib and niraparib)and one vascular endothelial growth factor(VEGF)inhibitor(bevacizumab)for maintenance therapy.However,resistance to these new drugs has emerged.Therefore,understanding the mechanisms of DR and exploring new approaches to overcome them is crucial for effective management.In this review,we summarize the major molecular mechanisms of DR and discuss novel strategies to combat DR.
文摘Viral diseases are minacious with the potential for causing pandemics and treatment is complicated because of their inherent ability to mutate and become resistant to drugs. Antiviral drug resistance is a persistent problem that needs continuous attention by scientists, medical professionals, and government agencies. To solve the problem, an in-depth understanding of the intricate interplay between causes of antiviral drug resistance and potential new drugs specifically natural products is imperative in the interest and safety of public health. This review delves into natural product as reservoir for antiviral agents with the peculiar potentials for addressing the complexities associated with multi-drug resistant and emerging viral strains. An evaluation of the mechanisms underlying antiviral drug activity, antiviral drug resistance is addressed, with emphasis on production of broad-spectrum antiviral agents from natural sources. There is a need for continued natural product-based research, identification of new species and novel compounds.
文摘The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been suggested after the geotechnical characterization of samples of soil was taken. From these, it arises that the studied soil is the most plastically clay (of type A<sub>3</sub>) according to GTR classification. Samples made of small bricks and measured out at 4%, 6% and 8% of binders (molasses, starch or molasses + starch) have been warmed up to different temperatures (100°C, 150°C, 200°C and 250°C) for the rising of the thermic behavior under different conditions and submitted to crushing testings for the estimation of characteristic resistances to the compression. According to the mechanical behavior, we note an improvement of resistances for small bricks measured 4%, 6% and 8%, of molasses respectively of 32.44%, 32.06% and 23.43% against the value of reference for small bricks without molasses. In the same way, the binder (molasses + starch) also reveals an improvement of resistance to the compression of 13.27%, 26.17% and 26.17%. On the contrary, the stabilization with the starch binder did not bring a significative improvement. According to the thermic influence, the heating at 100°C of stabilized small bricks at 4%, 6% and 8% of molasses, reveals a significative improvement of resistances. Moreover, the stabilization with the starch reveals on the contrary a good behavior for heatings at 150°C and 250°C. In short, for the binder (molasses + starch), it is the heating at 200°C that shows some improvements of remarkable resistances. Different analyses of realized statistics also show the effectivity of obtained results. For all realized formulations, the measuring out at 6% of binders (molasses, or molasses + starch) seems as optimal in front of the best thermo-mechanical revealed properties.
基金supported by the National Natural Science Foundation of China(Grant No.31701915)Zhejiang Province Public Welfare Technology Application Research Project(Grant No.LGN19C150007).
文摘Cucumber is an important vegetable worldwide,and powdery mildew(PM)is a common and serious disease of cucumbers.Breeding disease-resistant cucumber varieties is the most advantageous strategy to control this disease.In recent years,exploration and identification of cucumber PM resistance genes have achieved great advancement,and many genes have been cloned and verified using different methods.However,the resistance mechanism of cucumber PM is still unclear,and many ambiguities need to be elucidated urgently.In this review,we summarized the research advances in PM resistance in cucumbers,including genetic analysis,quantitative trait locus mapping,map-based cloning,transcriptomics,mlo-mediated PM resistance,and mining of noncoding RNAs involved in resistance.Finally,the research directions and the problems that need to be solved in the future were discussed.
基金Supported by the National Natural Science Foundation of China(No.82260001)Key Special Project Supported by the National Key R&D Plan of the Ministry of Science and Technology(No.2022YFC2305004)。
文摘Burkholderia pseudomallei is the pathogen that causes melioidosis.Melioidosis has a long duration of chronic infection,atypical clinical manifestations at acute onset,and is prone to life-threatening complications and poor prognosis.Understanding the pathogenesis and drug resistance mechanism of Burkholderia pseudomallei will effectively help the diagnosis and treatment of the disease and improve the prognosis.This review focuses on the extracellular movement of Burkholderia pseudomallei in host cells,the way of infecting host cells,virulence factors,and drug resistance mechanisms(efflux pumps,changes in target sites,etc.).This study provides a possible direction for the early diagnosis,treatment and control of melioidosis caused by this bacterium.
基金Fundamental Research Program of Shanxi province(No.202103021223339,20210302124435)Shanxi Scholarship Council of China(No.2022-175)+1 种基金Fundamental Research Program of Shanxi Datong University(No.2019Q2,2019Q4)Doctoral Scientific Research Foundation of Shanxi Datong University(No.2018-B-13,2018-B-28)。
文摘Tuberculosis(TB)is a chronic infectious disease caused by Mycobacterium Tuberculosis(MTB).It is the second largest single cause of death besides novel coronavirus pneumonia.Along with the abuse of antibiotics and extensive use of anti-tuberculosis drugs,multidrug-resistant(MDR)TB,drug-resistant(XDR)TB and totally drug-resistant(TDR)TB became obstacles to the tuberculosis eradication worldwide.According to the World Health Organization(WHO)statistics,China is not only a high burden tuberculosis country in the world,but also a country with a serious epidemic of MDR.Traditional drugs fail to meet the needs of tuberculosis control.Therefore,it is urgent to find new targets of anti-tuberculosis drugs and develop new anti-tuberculosis drugs.Hence,this paper systematically summarizes the mechanism of traditional and newly developed anti-tuberculosis drugs,in which stressing the research progress of drug resistance mechanisms.This work provides us with new insights of new anti-tuberculosis drug developments,and may contribute to a reduction in the harm that tuberculosis brings to society.
基金Enterprise Research and Development Project of Beijing Lirr High-Temperature Materials Co.,Ltd.(2020-02)Key Scientific Research Project for Universities and Colleges in Henan Province(19A430028)+1 种基金the Excellent Youth Research Project of Anhui Province(2022AH030135)the PhD Research Funding of Suzhou University(2021BSK041).
文摘Conventional MgO-C bricks(graphite content>14 wt.%)produce a great deal of greenhouse gas emission,while low-carbon MgO-C bricks have serious thermal shock resistance during high-temperature service.To enhance the high-temperature mechanical property and thermal shock resistance of low-carbon MgO-C bricks,a novel route of introducing ZrSiO_(4) powder into low-carbon MgO-C bricks was reported in such refractories with 2 wt.% flaky graphite.The results indicate that the low-carbon MgO-C brick with 0.5 wt.%ZrSiO_(4) addition has the maximum hot modulus of rupture at 1400℃ and the corresponding specimen fired in the carbon embedded atmosphere has the maximum residual strength ratio(98.6%)after three thermal shock cycles.It is found that some needle-like AlON and plate-like Al_(2)O_(3)-ZrO_(2) composites were in situ formed in the matrices after the low-carbon MgO-C bricks were coked at 1400℃,which can enhance the high-temperature mechanical property and thermal shock resistance due to the effect of fiber toughening and particle toughening.Moreover,CO_(2) emission of the newly developed low-carbon MgO-C bricks is reduced by 58.3% per ton steel after using them as the working lining of a 90 t vacuum oxygen decarburization ladle.
文摘As an important ecological tree species in northern China, Populus simonii plays a crucial role in maintaining ecological balance and promoting environmental sustainability. The academic community has conducted a series of in-depth studies on this species, covering key areas such as genomics, survival mechanisms, and genetic breeding. Through the analysis of the genomic structure and function of P. simonii, we have not only revealed the molecular basis for its adaptation to harsh environments but also identified key genes that promote its growth and resistance to pests and diseases. Furthermore, exploring the survival mechanisms of P. simonii has deepened our understanding of its stress resistance traits, including how it effectively copes with abiotic stresses such as drought, salinization, and heavy metal pollution. In genetic breeding, significant progress has been made through the application of modern biotechnology, improving the growth rate and wood quality of P. simonii and enhancing its environmental adaptability and disease resistance. These research findings have not only enriched our knowledge of the biological characteristics of P. simonii but also provided a solid scientific foundation for its application in ecological restoration, forestry production, and environmental management.
文摘Chlamydia Trachomatis (C.T.) is one of the most common pathogens of human sexually transmitted diseases. Treatment of C.T. infection primarily depends on Tetracyclines, Macrolides and Quinolones, but with the wide use of antibiotics an increasing number of drug-resistant Chlamydia trachomatis cases have been reported. This review summarizes the resistant conditions and the possible resistance mechanisms of C.T..
文摘The objective of this work, was to characterize the sands of the quarries of: Bandjoun-Djione, Djengou, Hiala and La’gou I, mainly from their mechanical strengths, the equivalent of sand and the finesse module. In order to study the compressive strength of concrete made from these sands, we determined their granularity, fineness modulus and density;the concrete was then formulated by the Dreux-Gorisse method. A total of 72 specimens were constructed with the objective of achieving an average compressive strength of 25 MPa at 28 days. But we have obtained a compressive strength at 28 days, varying from 13.14 MPa to 17.50 MPa. The correction of the modulus of fineness of these sands made it possible to improve the granularity and increase the compressive strength of these concretes by more than 70%. We have thus obtained the compression resistance of 25 MPa aimed for each of the corrected sands.
文摘One hundred and thirty-eight rice accessions were screened for resistance to the small brown planthopper （SBPH） （Laodelphax striatellus Fallen） by the modified seedbox screening test. Twenty-five rice accessions with different levels of resistance to SBPH were detected, accounting for 18.1% of the total accessions, which included 2 highly resistant, 9 resistant and 14 moderately resistant varieties. Compared with indica rice, japonica rice was more susceptible to SBPH. Antixenosis test, antibiosis test and correlation analysis were performed to elucidate the resistance mechanism. The resistant check Rathu Heenati （RHT）, highly resistant varieties Mudgo and Kasalath, and resistant variety IR36 expressed strong antixenosis and antibiosis against SBPH, indicating the close relationship between resistance level and these two resistance mechanisms in the four rice varieties. Antibiosis was the dominant resistance pattern in the resistant varieties Daorenqiao and Yangmaogu due to their high antibiosis but low antixenosis. Dular, ASD7 and Milyang 23 had relatively strong antixenosis and antibiosis, indicating the two resistance mechanisms were significant in these three varieties. The resistant DV85 expressed relatively high level of antixenosis but low antibiosis, whereas Zhaiyeqing 8 and Guiyigu conferred only moderate antibiosis and antixenosis to SBPH, suggesting tolerance in these three varieties. Antibiosis and antixenosis governed the resistance to SBPH in the moderately resistant accession 9311. Antixenosis was the main resistance type in V20A. Tolerance was considered to be an important resistance mechanism in Minghui 63 and Yangjing 9538 due to their poor antibiosis and antixenosis resistance. The above accessions with strong antibiosis or antixenosis were the ideal materials for the resistance breeding.
文摘The Ti fire found in high performance engines promotes the development of burn resistant Ti alloys. The burn resistant mechanism of Ti40 alloy is investigated. Ti40 alloy reveals good burn resistance. Its interfacial products between burning products and the matrix are tenacious, which retard the diffusion of oxygen into the matrix. Two burn resistant mechanisms, that is, fast scatter dispersion of heat and suppression of oxygen diffusion, are proposed.
基金supported by the Key Project of Research Institute of Forestry,Chinese Academy of Forestry(ZD200908)the National Eleventh "Five-year Plan" Science and Technology Funded Project of the State Forestry Administration,P.R.of China (2006BAD26B0101)
文摘Drought and shortage of water resources, which restrict the economy, society development and environmental protection, are key factors in arid zones of China. In the arid zones of Western China, researching plant drought resistance mechanism, selecting plant species with higher drought resistance, and developing water-saving techniques, are important for environmental improvement and economic development. This paper reviews research advances on drought resistance mechanism of plant species, based on research of morphological, physiological, and ecological adaptation mechanism of plant species under drought stress, such as anatomical structure of root systems and leaves, photosynthesis, antioxidant enzyme system, malondialdehyde （MDA）, osmotic adjustment, endogenous hormone, drought-induced proteins and δ^13C. Finally, this paper points out the key field of future research.
基金supported by National Key Research and Development Program of China(2016YFD0100600)the National Program on Research and Development of Transgenic Plants(2014ZX0800911B)+2 种基金the National Natural Science Foundation of China(31160276 and 31560423)the Guangxi Innovation-Driven Development Special Funding Project(Guike-AA17204070)the State Key Laboratory of Hybrid Rice(KF201905)。
文摘Rice planthoppers,including brown planthopper(BPH)and white-backed planthopper(WBPH),are the most destructive pests in Asian rice cultivation regions.Planthopper resistance genes that have been mapped and characterized advance our understanding of underlying resistance mechanisms and facilitate the breeding of resistant varieties,thereby contributing to an efficient pest management strategy.In this study,a novel resistance gene Bph38 derived from the wild rice species Oryza rufipogon Griff.was found to confer high resistance to BPH and WBPH.Conventional mapping was performed to identify regions associated with BPH and WBPH resistance,and two mapping efforts led to the same region on chromosome 4 flanked by markers RM16563 and RM16763.Bulked-segregant analysis and next-generation sequencing were performed using the same population to detect the resistance gene.Conventional mapping narrowed the region to a 12.3-Mb segment,and fine mapping using BC1 F2 recombinants identified a 79-kb segment flanked by markers YM112 and YM190.Near-isogenic lines(NILs)carrying Bph38 in the 9311(indica)and BR54(japonica)genetic backgrounds were developed by crossing and backcrossing with marker-assisted selection.The agronomic traits and BPH and WBPH resistance of the NILs were similar to those of the recurrent parents.Mandatory feeding and host-choice tests revealed that Bph38 showed both antibiotic and antixenotic effects in both insects,with stronger effects in indica-background lines.Further fine mapping and characterization of the major gene may result in map-based cloning of the gene and allow its application in breeding insectresistant rice varieties.
基金supported by the Scientific Research Projects Unit of Mustafa Kemal University,Hatay,Turkey(Project no:47)
文摘Objective: To investigate the antimicrobial susceptibility of 97 clinical Staphylococcus aureus(S. aureus) strains against 14 antimicrobials and corresponding resistance mechanisms.Methods: The antimicrobial susceptibility of the isolates was determined using a disk diffusion method and antimicrobial resistance genes were screened by polymerase chain reaction. Mutations responsible for ciprofloxacin and rifampicin resistance were investigated by polymerase chain reaction and DNA sequencing.Results: All isolates were found to be susceptible to vancomycin. Various rates of resistance to penicillin(83.5%), ampicillin(77.3%), erythromycin(63.9%), tetracycline(16.5%), amoxicillin/clavulanic acid(16.5%), ciprofloxacin(15.5%), trimethoprim/sulfamethoxazole(15.5%), oxacillin(13.4%), fusidic acid(12.4%), rifampin(6.2%), clindamycin(6.2%), gentamicin(6.2%) and mupirocin(5.2%) were determined. In addition,different combinations of resistance genes were identified among resistant isolates.Ciprofloxacin resistant isolates had mutations in codon 84(Ser84 Leu) and 106(Gly106 Asp) in the gyr A gene. Mutations in grl A were mostly related to Ser80 Phe substitution. Leu466 Ser mutation in the rpo B gene was detected in all rifampin resistant isolates. All methicillin resistant S. aureus isolates were SCCmec type V.Conclusions: In conclusion, it was determined that the isolates were resistant to different classes of antimicrobials at varying rates and resistance was mediated by different genetic mechanisms. Therefore, continuous monitoring of resistance in S. aureus strains is necessary to control their resistance for clinically important antimicrobials.
基金supported by the National Key Research and Development Program of China (2017YFC1200200)Major Infectious Diseases such as AIDS and Viral Hepatitis Prevention and Control Technology Major Projects (2018ZX10712-001)+1 种基金National Natural Science Foundation of China (81702045 and 81902030)Shenzhen Basic Research projects (JCYJ20190807144409307)
文摘Carbapenem resistance presents a major challenge for the global public health network, as clinical infections caused by carbapenem-resistant organisms(CRO) are frequently associated with significant morbidity and mortality. Ceftazidime–avibactam(CAZ–AVI) is a novel cephalosporin/β-lactamase inhibitor combination offering an important advance in the treatment of CRO infections. CAZ–AVI has been reported to inhibit the activities of Ambler classes A, C, and some class D enzymes. However, bacterial resistance has been emerging shortly after the introduction of this combination in clinical use, with an increasing trend. Understanding these resistance mechanisms is crucial for guiding the development of novel treatments and aiding in the prediction of underlying resistance mechanisms. This review aims to systematically summarize the epidemiology of CAZ–AVI-resistant strains and recently identified resistance mechanisms of CAZ–AVI, with a focus on the production of β-lactamase variants, the hyperexpression of β-lactamases, reduced permeability, and overexpressed efflux pumps. The various mechanisms of CAZ–AVI resistance that have emerged within a short timescale emphasize the need to optimize the use of current agents, as well as the necessity for the surveillance of CAZ–AVI-resistant pathogens.
文摘Before 1980s,the circular suspension spring in automobile subjected to torsion fatigue load,under the cyclic normal tensile stresses,the majority of fatigue fracture occurred was in normal tensile fracture mode（NTFM）and the fracture surface was under 45°diagonal.Because there exists the interaction between the residual stresses induced by shot peening and the applied cyclic normal tensile stresses in NTFM,which represents as＂stress strengthening mechanism＂,shot peening technology could be used for improving the fatigue fracture resistance（FFR）of springs.However,since 1990s up to date,in addition to regular NTFM,the fatigue fractures occurred of peened springs from time to time are in longitudinal shear fracture mode（LSFM）or transverse shear fracture mode（TSFM）with the increase of applied cyclic shear stresses,which leads to a remarkable decrease of FFR.However,LSFM/TSFM can be avoided effectively by means of shot peening treatment again on the peened springs.The phenomena have been rarely happened before.At present there are few literatures concerning this problem.Based upon the results of force analysis of a spring,there is no interaction between the residual stresses by shot peening and the applied cyclic shear stresses in shear fracture.This;means that the effect of＂stress strengthening mechanism＂for improving the FFR of LSFM/TSFM is disappeared basically.During shot peening,however,both of residual stress and cyclic plastic deformed microstructure are induced synchronously like＂twins＂in the surface layer of a spring.It has been found for the first time by means of force analysis and experimental results that the modified microstructure in the＂twins＂as a＂structure strengthening mechanism＂can improve the FFR of LSFM/TSFM.At the same time,it is;also shown that the optimum technology of shot peening strengthening must have both＂stress strengthening mechanism＂and＂structure strengthening mechanism＂simultaneously so that the FFR of both NTFM and LSFM/TSFM can be improved by shot peening.
文摘[ Objective ] The paper was to explore the induced resistance of tomato against gray mold （Botrytis cinerea） by salicylic acid. [ Method ] SA was used as an inducer to treat tomato seedlings, the effects of SA on mycelial diameter and spore germination of B. cinerea were studied, and the changes of 4 defense enzyme activities containing catalase （CAT）, peroxidase （POD）, polyphenol oxidase （PPO） and phenylalanine ammonia lyase （PAL）, as well as malondialdehyde （MDA） content during the production process of induced resistance were also measured. [ Result] SA had no inhibitory effect against spore germination and myce- lial growth of B. cinerea within the concentration range, and the relative induced effect had different degrees of improvement after treatment. The induced effect was the best as B. cinerea was challenged to inoculate at the third day after using 150 mg/L SA in tomato plants, and the duration of resistance was 10 -15 d. After treated by SA, CAT, POD, PPO and PAL first increased and then decreased in systemic induced resistance against B. cinerea, which were significantly higher than control. Meanwhile, MDA content showed ascendant trend in wavy line form. [ Conclusion ] The use of SA within a certain concentration range is safe; CAT, POD, PPO and PAL activities have positive correlation with induced resistance against B. cinerea, the increase of MDA content also has close relationship with the imvrovement of disease resistance.
基金financially supported by the National Natural Science Foundation of China (Nos. 81330031 and 81271701)
文摘A two-step equal channel angular extrusion（ECAE） procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were studied. The results show that the average grain size of pure Mg decreases with decreasing extrusion temperature. After ECAE processing at 473 K, fine and equiaxed grains（~9 μm） are obtained. The sample processed at 473 K exhibits the excellent mechanical properties, whereas the sample processed at 633 K has the lowest corrosion rate. The improved corrosion resistance and mechanical properties of pure Mg by ECAE are ascribed to grain refinement and microstructural modification.
