A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires h...A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.展开更多
The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identific...The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identification methods usually relies either solely nonlinear iterative algorithms or manually trial and error. Therefore, the identification process can be rather time consuming and effort taking. As a result, these methods are not ideal for engineering applications. To come up with a more practical method, a three-stage identification method is proposed. Periodic loading and identification simulations are carried out to verify the effectiveness of the proposed method. Noises are added to the simulated data to test the performance of the proposed method when dealing with noise contaminated data. The simulation results indicate that the proposed method is able to give satisfying results when the noise levels are set to be 0.01, 0.03, 0.05 and 0.07. In addition, the proposed method is also applied to experimental data and compared with an existing method. The experimental data is acquired through a periodic loading test. The experiment results suggest that the proposed method features better accuracy compared with the existing method. An effective approach is proposed for identifying the model parameters of the stranded wire helical spring.展开更多
CRISPR/Cpf1 has emerged recently as an effective tool for genome editing in many organisms,but its use in pigs to generate precise genetic modifications has seldom been described.Myostatin(MSTN)is a well-characterized...CRISPR/Cpf1 has emerged recently as an effective tool for genome editing in many organisms,but its use in pigs to generate precise genetic modifications has seldom been described.Myostatin(MSTN)is a well-characterized negative regulator of muscle development,and natural mutations in this gene cause a double-muscled phenotype in many species.However,to the best of our knowledge,no naturally occurring mutation in MSTN has been found in pigs.In addition,no living pig models with sophisticated modifications orthologous to natural mutations in MSTN have yet been reported.In this study,we exploited the CRISPR/Cpf1 system to introduce a predefined modification orthologous to the natural MSTN mutation found in Belgian Blue cattle(thus known as the Belgian Blue mutation).Our research demonstrated that the cutting efficiency of CRISPR/Cpf1 was 12.3%in mixed porcine fetal fibroblasts in drug free medium,and 41.7%in clonal colonies obtained using G418 selection.Then,the Cpf1-sgRNA vector,ssODN template,and a self-excision cassette were co-transfected into porcine fetal fibroblasts.After G418 selection,8 clonal colonies were examined and 5 with genetic modification were found.Of these 5,2 harbored the precise 11-bp deletion.Using 1 heterozygous clonal colony,2 cloned Duroc piglets were successfully generated,which was heterozygous for the Belgian Blue mutation.In summary,our results demonstrate that CRISPR/Cpf1 system can be used efficiently to generate double-stranded breaks,and also to mediate homologous recombination to introduce precise genomic modifications in pigs.展开更多
A large portion of world＇s natural gas reserves are ＂stranded＂ resources, the drive to monetize these resources leads to the development of gas-to-liquids （GTL） and liquefied natural gas （LNG） technologies. LNG...A large portion of world＇s natural gas reserves are ＂stranded＂ resources, the drive to monetize these resources leads to the development of gas-to-liquids （GTL） and liquefied natural gas （LNG） technologies. LNG has the advantage of having been developed for the past 40 years and having an excellent safety record. GTL on the other hand is another option with substantial benefits, but its development stage and commercial viability are far behind LNG. This paper presents a techno-economic comparison of GTL with LNG, including technical development, plant efficiency, market potential for the products, and capital cost for the infrastructure. The aim is to give an overall view on both LNG and GTL and provide a perspective on the profitability of these two technologies.展开更多
Dear Editor,Torque Teno virus(TTV)is a nonenveloped human DNA virus that was isolated from the serum of a patient with transfusion-transmitted hepatitis with unknown etiology in 1997(Nishizawa et al.,1997).TTV is the ...Dear Editor,Torque Teno virus(TTV)is a nonenveloped human DNA virus that was isolated from the serum of a patient with transfusion-transmitted hepatitis with unknown etiology in 1997(Nishizawa et al.,1997).TTV is the first human virus with a single-stranded circular DNA genome to be identified,and is recently classified as the Alphatorquevirus genus of the Anelloviridae family by the International Committee on Taxonomy of Viruses(ICTV)(King et al.,2011).TTV shows very high genetic展开更多
Dear Editor,Rabbit hemorrhagic disease(RHD)is a highly contagious disease of both wild and domesticated rabbits(Oryctolagus cuniculus).The causative agent of the disease is the rabbit hemorrhagic disease virus(RHDV),b...Dear Editor,Rabbit hemorrhagic disease(RHD)is a highly contagious disease of both wild and domesticated rabbits(Oryctolagus cuniculus).The causative agent of the disease is the rabbit hemorrhagic disease virus(RHDV),belongs to the genus Lagovirus within the family Caliciviridae(Granzow et al.,1996;Ohlinger et al.,1990).It is a small and non-enveloped virus with a 7.5 kb single stranded positive sense RNA genome(Meyers et al.,1991;Meyers et al.,2000).Based on an analysis of VP60展开更多
One of the most promising tools for the control of fungal plant diseases is spray-induced gene silencing(SIGS).In SIGS,small interfering RNA(siRNA)or double-stranded RNA(dsRNA)targeting essential or virulence-related ...One of the most promising tools for the control of fungal plant diseases is spray-induced gene silencing(SIGS).In SIGS,small interfering RNA(siRNA)or double-stranded RNA(dsRNA)targeting essential or virulence-related pathogen genes are exogenously applied to plants and postharvest products to trigger RNA interference(RNAi)of the targeted genes,inhibiting fungal growth and disease.However,SIGS is limited by the unstable nature of RNA under environmental conditions.The use of layered double hydroxide or clay particles as carriers to deliver biologically active dsRNA,a formulation termed BioClay^(TM),can enhance RNA durability on plants,prolonging its activity against pathogens.Here,we demonstrate that dsRNA delivered as BioClay can prolong protection against Botrytis cinerea,a major plant fungal pathogen,on tomato leaves and fruit and on mature chickpea plants.BioClay increased the protection window from 1 to 3 weeks on tomato leaves and from 5 to 10 days on tomato fruits,when compared with naked dsRNA.In flowering chickpea plants,BioClay provided prolonged protection for up to 4 weeks,covering the critical period of poding,whereas naked dsRNA provided limited protection.This research represents a major step forward for the adoption of SIGS as an eco-friendly alternative to traditional fungicides.展开更多
After decades of research, functional dyspepsia (FD) remains one of the most elusive gastrointestinal disorders. Endoscopic appearance of mild inflammation of the gastric mucosa without ulceration and microscopic evid...After decades of research, functional dyspepsia (FD) remains one of the most elusive gastrointestinal disorders. Endoscopic appearance of mild inflammation of the gastric mucosa without ulceration and microscopic evidence of mild chronic inflammation are often considered as normal findings since no etiology could be found other than H. Pylori. Enteroviruses infect the gastrointestinal tract and have been shown to persist in the stomach of symptomatic patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). In this study, we evaluated FD patients with and without the diagnosis of ME/CFS, and were able to support the viral protein staining with finding of double-stranded RNA in 63% of the same stomach biopsies by immunoperoxidase staining. Furthermore, we clarified the possible cross-reaction with creatine kinase brain subtype (CKB), present in parietal cells, using antibody competition experiments and western blot analysis of stomach proteins. Viral protein+ and dsRNA+ biopsies were infectious in SCID mice. More research is needed to elucidate the mechanism of enterovirus infection of the stomach associated with FD and chronic gastritis.展开更多
Hepatitis A virus (HAV) is very persistent in the environment and is especially difficult to detect in the seafoods. In recent years, molecular cloning of the genome of HAV has led to sensitive polymerase chain reacti...Hepatitis A virus (HAV) is very persistent in the environment and is especially difficult to detect in the seafoods. In recent years, molecular cloning of the genome of HAV has led to sensitive polymerase chain reaction (PCR) method for the detection of HAV RNA. Here we describe a new and simple procedure to extract RNA from contaminated clams and the PCR method for detection of HAV in environmental samples. The specificity and efficiency of PCR amplification were studied using cDNA and RNA of HAV. Three primer couples gave satisfactory results. Some basic parameters of the PCR were modified to perform a highly specific and sensitive test.展开更多
Dear Editor,Chikungunya virus(CHIKV),a single-stranded RNA virus that belongs to the genus Alphavirus,family Togaviridae,is transmitted by mosquitoes of the genus Aedes(Diptera:Culicidae),predominantly Aedes aegypti a...Dear Editor,Chikungunya virus(CHIKV),a single-stranded RNA virus that belongs to the genus Alphavirus,family Togaviridae,is transmitted by mosquitoes of the genus Aedes(Diptera:Culicidae),predominantly Aedes aegypti and A.albopictus(Staples et al.,2014).CHIKV infection is most often characterized by fever,headache,展开更多
Dolphin Morbillivirus (DMV) is one of the most frequently detected pathogens in stranded cetacean specimens worldwide as well as in Italy. Due to the persistence of DMV in the Mediterranean Sea and to the lack of info...Dolphin Morbillivirus (DMV) is one of the most frequently detected pathogens in stranded cetacean specimens worldwide as well as in Italy. Due to the persistence of DMV in the Mediterranean Sea and to the lack of information about the efficiency of the available diagnostic techniques, the Italian National Reference Centre for diagnostic activities on dead stranded marine mammals (C.Re.Di.Ma) performed the first inter-laboratory ring trial with the aim to standardize a diagnostic biomolecular approach for DMV in Italy. Viral isolation is usually considered the “gold standard” for the definitive diagnosis of most pathogens, but it is not often feasible in DMV diagnosis, due to the poor preservation of virus-targeted tissues in stranded cetacean carcasses, as well as to the lack of appropriate sensitivity of cell lines towards DMV variability. Therefore direct viral detection on tissues by means of reverse transcription-PCR (RT-PCR) represents a valuable option for DMV infection’s diagnosis. For detecting DMV in cetacean die-offs occurred in the Mediterranean basin since 2013, C.Re.Di.Ma developed an RT-PCR based method targeting to a 287 bp fragment of DMV nucleoprotein (N) gene. With the purpose to evaluate its performances in terms of accuracy (Se = sensitivity and Sp = specificity) and precision (reproducibility), it was submitted to a ring trial. So, 12 Public Laboratories belonging to the Italian dead stranded marine mammals diagnostic network were asked to analyze a panel of 40 samples (positive and negative for DMV, using different dilutions of a viral suspension obtained from a cell culture supernatant of a DMV strain) with the aforementioned technique. Furthermore, we also aimed at comparing the accuracy of other 7 molecular methods routinely applied for DMV detection in Italy. For this purpose, the second panel of identical 40 DMV +ve and -ve samples was provided to Laboratories that routinely used DMV detection methods other than those developed by C.Re.Di.Ma, in order to be analyzed simultaneously展开更多
In 1990, Bai et al.first directly observed an unusual triple-stranded braid-likeconformation of denatured λ-DNA Hind Ⅲ in vitro with scanning tunneling microscopy(STM). The triple-stranded braid-like conformation pr...In 1990, Bai et al.first directly observed an unusual triple-stranded braid-likeconformation of denatured λ-DNA Hind Ⅲ in vitro with scanning tunneling microscopy(STM). The triple-stranded braid-like conformation presented in this work was dif-ferent from the model of the right-handed triple helix DNA proposed by otherauthors.In the triple helix model, the third strand winds round the major groove ofthe double helix DNA. Several studies indicated that the triple-stranded DNA, whichwas prepared by the reaction of homopurine and homopyrimidine or single-strandedDNA and doube-stranded DNA, had a low melting temperatue (T_m), a highabsorbance at 280 run in the unwinding process and was resistant to DNase展开更多
The double-stranded DNA (dsDNA) probe contains two different protein binding sites. One is for DNA- binding proteins to be detected and the other is for a DNA restriction enzyme. The two sites were arranged together w...The double-stranded DNA (dsDNA) probe contains two different protein binding sites. One is for DNA- binding proteins to be detected and the other is for a DNA restriction enzyme. The two sites were arranged together with no base interval. The working principle of the capturing dsDNA probe is described as follows: the capturing probe can be cut with the DNA restriction enzyme (such as EcoR I) to cause a sticky terminal, if the probe is not bound with a target protein, and the sticky terminal can be extended and labeled with Cy3-dUTP by DNA polymerase. When the probe is bound with a target protein, the probe is not capable to be cut by the restriction enzyme because of space obstruction. The amount of the target DNA binding proteins can be measured according to the variations of fluorescent signals of the corresponding probes.展开更多
Due to the nucleosides and nucleotides located in different positions of nucleic acids, there will be different Cotton effects; therefore, the determination of the circular dichroism is one of the most sensitive metho...Due to the nucleosides and nucleotides located in different positions of nucleic acids, there will be different Cotton effects; therefore, the determination of the circular dichroism is one of the most sensitive methods to study the structure of polynucleotides. The triple stranded DNA (triplex DNA or braid-like DNA), as a specific DNA structure, will be dif-展开更多
Dear Editor,Hepaciviruses,members of the family Flaviviridae,are enveloped viruses containing a single-stranded positive-sense RNA genome of approximately 8.9-10.5 kb in size(Simmonds et al.,2017).To date,15species(He...Dear Editor,Hepaciviruses,members of the family Flaviviridae,are enveloped viruses containing a single-stranded positive-sense RNA genome of approximately 8.9-10.5 kb in size(Simmonds et al.,2017).To date,15species(Hepacivirus A-N,and P)have been documented within the Hepacivirus genus that show distinct host ranges,including primates,bats,horses,donkeys,cows,and various rodents(Hartlage et al.,2016).展开更多
Dear Editor,Parainfluenza virus 5(PIV5),known as canine parainfluenza virus in the veterinary field,is a negative-sense,nonsegmented,single-stranded RNA virus belonging to the Paramyxoviridae family(Chen 2018).The vir...Dear Editor,Parainfluenza virus 5(PIV5),known as canine parainfluenza virus in the veterinary field,is a negative-sense,nonsegmented,single-stranded RNA virus belonging to the Paramyxoviridae family(Chen 2018).The virus was first reported in primary monkey kidney cells in 1954(Hsiung 1972),then it has been frequently discovered in various hosts,including humans,dogs,pigs,cats,rodents,calves,and lesser pandas(Chatziandreou et a i 2004;Lee and Lee 2013;Liu et al.2015;Zhai et al.2017;Jiang et al.2018).So far,PIV5 has not been reported in horse.In this study,using metagenomics analysis we have identified a novel equine PIV5.展开更多
基金supported by National Natural Science Foundation for Distinguished Young Scholar of China (Grant No. 50925518)National Natural Science Foundation of China (Grant No. 50775226)+1 种基金Key Project of Ministry of Education of China(Grant No. 109129)Chongqing Municipal Key Scientific and Technological Project of China (Grant No. CSTC2009AC3049)
文摘A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375508,51375517)the Key Technologies R&D Program of China(Grant No.2012BAF12B09)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT1196)
文摘The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identification methods usually relies either solely nonlinear iterative algorithms or manually trial and error. Therefore, the identification process can be rather time consuming and effort taking. As a result, these methods are not ideal for engineering applications. To come up with a more practical method, a three-stage identification method is proposed. Periodic loading and identification simulations are carried out to verify the effectiveness of the proposed method. Noises are added to the simulated data to test the performance of the proposed method when dealing with noise contaminated data. The simulation results indicate that the proposed method is able to give satisfying results when the noise levels are set to be 0.01, 0.03, 0.05 and 0.07. In addition, the proposed method is also applied to experimental data and compared with an existing method. The experimental data is acquired through a periodic loading test. The experiment results suggest that the proposed method features better accuracy compared with the existing method. An effective approach is proposed for identifying the model parameters of the stranded wire helical spring.
基金supported by the National Transgenic Breeding Program of China (2016ZX08006001)the Doctor’s Fund of Southwest University, China (SWU 118082)
文摘CRISPR/Cpf1 has emerged recently as an effective tool for genome editing in many organisms,but its use in pigs to generate precise genetic modifications has seldom been described.Myostatin(MSTN)is a well-characterized negative regulator of muscle development,and natural mutations in this gene cause a double-muscled phenotype in many species.However,to the best of our knowledge,no naturally occurring mutation in MSTN has been found in pigs.In addition,no living pig models with sophisticated modifications orthologous to natural mutations in MSTN have yet been reported.In this study,we exploited the CRISPR/Cpf1 system to introduce a predefined modification orthologous to the natural MSTN mutation found in Belgian Blue cattle(thus known as the Belgian Blue mutation).Our research demonstrated that the cutting efficiency of CRISPR/Cpf1 was 12.3%in mixed porcine fetal fibroblasts in drug free medium,and 41.7%in clonal colonies obtained using G418 selection.Then,the Cpf1-sgRNA vector,ssODN template,and a self-excision cassette were co-transfected into porcine fetal fibroblasts.After G418 selection,8 clonal colonies were examined and 5 with genetic modification were found.Of these 5,2 harbored the precise 11-bp deletion.Using 1 heterozygous clonal colony,2 cloned Duroc piglets were successfully generated,which was heterozygous for the Belgian Blue mutation.In summary,our results demonstrate that CRISPR/Cpf1 system can be used efficiently to generate double-stranded breaks,and also to mediate homologous recombination to introduce precise genomic modifications in pigs.
文摘A large portion of world＇s natural gas reserves are ＂stranded＂ resources, the drive to monetize these resources leads to the development of gas-to-liquids （GTL） and liquefied natural gas （LNG） technologies. LNG has the advantage of having been developed for the past 40 years and having an excellent safety record. GTL on the other hand is another option with substantial benefits, but its development stage and commercial viability are far behind LNG. This paper presents a techno-economic comparison of GTL with LNG, including technical development, plant efficiency, market potential for the products, and capital cost for the infrastructure. The aim is to give an overall view on both LNG and GTL and provide a perspective on the profitability of these two technologies.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘Dear Editor,Torque Teno virus(TTV)is a nonenveloped human DNA virus that was isolated from the serum of a patient with transfusion-transmitted hepatitis with unknown etiology in 1997(Nishizawa et al.,1997).TTV is the first human virus with a single-stranded circular DNA genome to be identified,and is recently classified as the Alphatorquevirus genus of the Anelloviridae family by the International Committee on Taxonomy of Viruses(ICTV)(King et al.,2011).TTV shows very high genetic
基金supported by the Shaanxi Agriculture Science and Technology Research Projects (2014K02-06-01)
文摘Dear Editor,Rabbit hemorrhagic disease(RHD)is a highly contagious disease of both wild and domesticated rabbits(Oryctolagus cuniculus).The causative agent of the disease is the rabbit hemorrhagic disease virus(RHDV),belongs to the genus Lagovirus within the family Caliciviridae(Granzow et al.,1996;Ohlinger et al.,1990).It is a small and non-enveloped virus with a 7.5 kb single stranded positive sense RNA genome(Meyers et al.,1991;Meyers et al.,2000).Based on an analysis of VP60
基金partially supported by the Australian Research Council Research Hub for Sustainable Crop Protection(IH190100022)funded by the Australian GovernmentNational Institute of Health(R35GM136379)+5 种基金National Science Foundation(IOS 2020731)United State Department of Agriculture(2021-67013-34258)the CIFAR‘Fungal Kingdom’fellowship to H.J.supported by MINECO(PID2019-110459RB-I00)MICINN(PLEC2021-008076)supported by an Advance Queensland Industry Research Fellowship。
文摘One of the most promising tools for the control of fungal plant diseases is spray-induced gene silencing(SIGS).In SIGS,small interfering RNA(siRNA)or double-stranded RNA(dsRNA)targeting essential or virulence-related pathogen genes are exogenously applied to plants and postharvest products to trigger RNA interference(RNAi)of the targeted genes,inhibiting fungal growth and disease.However,SIGS is limited by the unstable nature of RNA under environmental conditions.The use of layered double hydroxide or clay particles as carriers to deliver biologically active dsRNA,a formulation termed BioClay^(TM),can enhance RNA durability on plants,prolonging its activity against pathogens.Here,we demonstrate that dsRNA delivered as BioClay can prolong protection against Botrytis cinerea,a major plant fungal pathogen,on tomato leaves and fruit and on mature chickpea plants.BioClay increased the protection window from 1 to 3 weeks on tomato leaves and from 5 to 10 days on tomato fruits,when compared with naked dsRNA.In flowering chickpea plants,BioClay provided prolonged protection for up to 4 weeks,covering the critical period of poding,whereas naked dsRNA provided limited protection.This research represents a major step forward for the adoption of SIGS as an eco-friendly alternative to traditional fungicides.
文摘After decades of research, functional dyspepsia (FD) remains one of the most elusive gastrointestinal disorders. Endoscopic appearance of mild inflammation of the gastric mucosa without ulceration and microscopic evidence of mild chronic inflammation are often considered as normal findings since no etiology could be found other than H. Pylori. Enteroviruses infect the gastrointestinal tract and have been shown to persist in the stomach of symptomatic patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). In this study, we evaluated FD patients with and without the diagnosis of ME/CFS, and were able to support the viral protein staining with finding of double-stranded RNA in 63% of the same stomach biopsies by immunoperoxidase staining. Furthermore, we clarified the possible cross-reaction with creatine kinase brain subtype (CKB), present in parietal cells, using antibody competition experiments and western blot analysis of stomach proteins. Viral protein+ and dsRNA+ biopsies were infectious in SCID mice. More research is needed to elucidate the mechanism of enterovirus infection of the stomach associated with FD and chronic gastritis.
文摘Hepatitis A virus (HAV) is very persistent in the environment and is especially difficult to detect in the seafoods. In recent years, molecular cloning of the genome of HAV has led to sensitive polymerase chain reaction (PCR) method for the detection of HAV RNA. Here we describe a new and simple procedure to extract RNA from contaminated clams and the PCR method for detection of HAV in environmental samples. The specificity and efficiency of PCR amplification were studied using cDNA and RNA of HAV. Three primer couples gave satisfactory results. Some basic parameters of the PCR were modified to perform a highly specific and sensitive test.
基金supported by the Department of International Affairs of the Institut Pasteur International Network(ACIP A12-2011)approved by the National Ethical Committee of Cameroon(permit number,255/CNE/SE/2011)
文摘Dear Editor,Chikungunya virus(CHIKV),a single-stranded RNA virus that belongs to the genus Alphavirus,family Togaviridae,is transmitted by mosquitoes of the genus Aedes(Diptera:Culicidae),predominantly Aedes aegypti and A.albopictus(Staples et al.,2014).CHIKV infection is most often characterized by fever,headache,
文摘Dolphin Morbillivirus (DMV) is one of the most frequently detected pathogens in stranded cetacean specimens worldwide as well as in Italy. Due to the persistence of DMV in the Mediterranean Sea and to the lack of information about the efficiency of the available diagnostic techniques, the Italian National Reference Centre for diagnostic activities on dead stranded marine mammals (C.Re.Di.Ma) performed the first inter-laboratory ring trial with the aim to standardize a diagnostic biomolecular approach for DMV in Italy. Viral isolation is usually considered the “gold standard” for the definitive diagnosis of most pathogens, but it is not often feasible in DMV diagnosis, due to the poor preservation of virus-targeted tissues in stranded cetacean carcasses, as well as to the lack of appropriate sensitivity of cell lines towards DMV variability. Therefore direct viral detection on tissues by means of reverse transcription-PCR (RT-PCR) represents a valuable option for DMV infection’s diagnosis. For detecting DMV in cetacean die-offs occurred in the Mediterranean basin since 2013, C.Re.Di.Ma developed an RT-PCR based method targeting to a 287 bp fragment of DMV nucleoprotein (N) gene. With the purpose to evaluate its performances in terms of accuracy (Se = sensitivity and Sp = specificity) and precision (reproducibility), it was submitted to a ring trial. So, 12 Public Laboratories belonging to the Italian dead stranded marine mammals diagnostic network were asked to analyze a panel of 40 samples (positive and negative for DMV, using different dilutions of a viral suspension obtained from a cell culture supernatant of a DMV strain) with the aforementioned technique. Furthermore, we also aimed at comparing the accuracy of other 7 molecular methods routinely applied for DMV detection in Italy. For this purpose, the second panel of identical 40 DMV +ve and -ve samples was provided to Laboratories that routinely used DMV detection methods other than those developed by C.Re.Di.Ma, in order to be analyzed simultaneously
文摘In 1990, Bai et al.first directly observed an unusual triple-stranded braid-likeconformation of denatured λ-DNA Hind Ⅲ in vitro with scanning tunneling microscopy(STM). The triple-stranded braid-like conformation presented in this work was dif-ferent from the model of the right-handed triple helix DNA proposed by otherauthors.In the triple helix model, the third strand winds round the major groove ofthe double helix DNA. Several studies indicated that the triple-stranded DNA, whichwas prepared by the reaction of homopurine and homopyrimidine or single-strandedDNA and doube-stranded DNA, had a low melting temperatue (T_m), a highabsorbance at 280 run in the unwinding process and was resistant to DNase
文摘The double-stranded DNA (dsDNA) probe contains two different protein binding sites. One is for DNA- binding proteins to be detected and the other is for a DNA restriction enzyme. The two sites were arranged together with no base interval. The working principle of the capturing dsDNA probe is described as follows: the capturing probe can be cut with the DNA restriction enzyme (such as EcoR I) to cause a sticky terminal, if the probe is not bound with a target protein, and the sticky terminal can be extended and labeled with Cy3-dUTP by DNA polymerase. When the probe is bound with a target protein, the probe is not capable to be cut by the restriction enzyme because of space obstruction. The amount of the target DNA binding proteins can be measured according to the variations of fluorescent signals of the corresponding probes.
基金Project supported by the "85" Key Project Grant of the Chinese Academy of Sciences
文摘Due to the nucleosides and nucleotides located in different positions of nucleic acids, there will be different Cotton effects; therefore, the determination of the circular dichroism is one of the most sensitive methods to study the structure of polynucleotides. The triple stranded DNA (triplex DNA or braid-like DNA), as a specific DNA structure, will be dif-
基金funded by the Academic Promotion Programme of Shandong First Medical University(2019QL006)the Open Research Fund Program of CAS Key Laboratory of Special Pathogens and Biosafety,Wuhan Institute of Virology(Grant No.2021SPCAS002)W.S.was supported by the Taishan Scholars program of Shandong Province。
文摘Dear Editor,Hepaciviruses,members of the family Flaviviridae,are enveloped viruses containing a single-stranded positive-sense RNA genome of approximately 8.9-10.5 kb in size(Simmonds et al.,2017).To date,15species(Hepacivirus A-N,and P)have been documented within the Hepacivirus genus that show distinct host ranges,including primates,bats,horses,donkeys,cows,and various rodents(Hartlage et al.,2016).
基金This study was supported by Natural Science Foundation of Xinjiang Uyghur Autonomous Region(2019D01A47)China Postdoctoral Science Foundation(2019M653901XB)Prior Period Project of Xinjiang Agricultural University(XJAU201721)。
文摘Dear Editor,Parainfluenza virus 5(PIV5),known as canine parainfluenza virus in the veterinary field,is a negative-sense,nonsegmented,single-stranded RNA virus belonging to the Paramyxoviridae family(Chen 2018).The virus was first reported in primary monkey kidney cells in 1954(Hsiung 1972),then it has been frequently discovered in various hosts,including humans,dogs,pigs,cats,rodents,calves,and lesser pandas(Chatziandreou et a i 2004;Lee and Lee 2013;Liu et al.2015;Zhai et al.2017;Jiang et al.2018).So far,PIV5 has not been reported in horse.In this study,using metagenomics analysis we have identified a novel equine PIV5.
