AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of to...AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of tobacco （Nicotiana tabacum cv. SR1）, to investigate the transgene expression and pE2 accumulation in plastids, and to evaluate the antigenic effect of the plastid-derived pE2 in mice. METHODS： Plastid-targeting vector pRB94-E2 containing the E2 fragment driven by rice psbA promoter was constructed. Upon delivery into tobacco plastids, this construct could initiate homologous recombination in psaB-trnfM and trnG-psbC fragments in plastid genome, and result in transgene inserted between the two fragments. The pRB94-E2 was delivered with a biolistic particle bombardment method, and the plastid-transformed plants were obtained following the regeneration of the bombarded leaf tissues on a spectinomycin-supplemented medium. Transplastomic status of the regenerated plants was confirmed by PCR and Southern blot analysis, transgene expression was investigated by Northern blot analysis, and accumulation of pE2 was measured by ELISA. Furthermore, protein extracts were used to immunize mice, and the presence of the pE2-reactive antibodies in serum samples of the immunized mice was studied by ELISA. RESULTS： Transplastomic lines confirmed by PCR and Southern blot analysis could actively transcribe the E2 mRNA. The pE2 polypeptide was accumulated to a level as high as 13.27 μg/g fresh leaves. The pE2 could stimulate the immunized mice to generate pE2-specific antibodies. CONCLUSION： HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.展开更多
The shortage of tissues and organs for transplantation is an urgent clinical concern.In situ 3D printing is an advanced 3D printing technique aimed at printing the new tissue or organ directly in the patient.The ink f...The shortage of tissues and organs for transplantation is an urgent clinical concern.In situ 3D printing is an advanced 3D printing technique aimed at printing the new tissue or organ directly in the patient.The ink for this process is central to the outcomes,and must meet specific requirements such as rapid gelation,shape integrity,stability over time,and adhesion to surrounding healthy tissues.Among natural materials,silk fibroin exhibits fascinating properties that have made it widely studied in tissue engineering and regenerative medicine.However,further improvements in silk fibroin inks are needed to match the requirements for in situ 3D printing.In the present study,silk fibroin-based inks were developed for in situ applications by exploiting covalent crosslinking process consisting of a pre-photo-crosslinking prior to printing and in situ enzymatic crosslinking.Two different silk fibroin molecular weights were characterized and the synergistic effect of the covalent bonds with shear forces enhanced the shift in silk secondary structure towardβ-sheets,thus,rapid stabilization.These hydrogels exhibited good mechanical properties,stability over time,and resistance to enzymatic degradation over 14 days,with no significant changes over time in their secondary structure and swelling behavior.Additionally,adhesion to tissues in vitro was demonstrated.展开更多
Guard cells are specialized cells forming stomatal pores at the leaf surface for gas exchanges between the plant and the atmosphere. Stomata have been shown to playan important role in plant defense as a part of the i...Guard cells are specialized cells forming stomatal pores at the leaf surface for gas exchanges between the plant and the atmosphere. Stomata have been shown to playan important role in plant defense as a part of the innate immune response. Plants actively close their stomata upon contact with microbes, thereby preventing pathogen entry into the leaves and the subsequent colonization of host tissues. In this review, we present current knowledge of molecular mechanisms and signaling pathways implicated in stomatal defenses, with particular emphasis on plant-bacteria interactions. Stomatal defense responses begin from the perception of pathogen-associated molecular patterns （PAMPs） and activate a signaling cascade involving the production of secondary messengers such as reactive oxygen species, nitric oxide, and calcium for the regulation of plasma membrane ion channels. The analyses on downstream molecular mechanisms implicated in PAMP-triggered stomatal closure have revealed extensive interplays among the components regulating hormonal signaling pathways. We also discuss the strategies deployed by pathogenic bacteria to counteract stomatal immunity through the example of the phytotoxin coronatine.展开更多
In 2012,a novel coronavirus,initially named as human coronavirus EMC(HCoV-EMC) but recently renamed as Middle East respiratory syndrome human coronavirus(MERS-CoV),was identified in patients who suffered severe acute ...In 2012,a novel coronavirus,initially named as human coronavirus EMC(HCoV-EMC) but recently renamed as Middle East respiratory syndrome human coronavirus(MERS-CoV),was identified in patients who suffered severe acute respiratory infection and subsequent renal failure that resulted in death.Ongoing epidemiological investigations together with retrospective studies have found 61 laboratory-confirmed cases of infection with this novel coronavirus,including 34 deaths to date.This novel coronavirus is culturable and two complete genome sequences are now available.Furthermore,molecular detection and indirect immunofluorescence assay have been developed.The present paper summarises the limited recent advances of this novel human coronavirus,including its discovery,genomic characterisation and detection.展开更多
The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world.Even though several COVID-19 vaccines are currently in distribution worldwide,with others in the pipeline,treatment m...The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world.Even though several COVID-19 vaccines are currently in distribution worldwide,with others in the pipeline,treatment modalities lag behind.Accordingly,researchers have been working hard to understand the nature of the virus,its mutant strains,and the pathogenesis of the disease in order to uncover possible drug targets and effective therapeutic agents.As the research continues,we now know the genome structure,epidemiological and clinical features,and pathogenic mechanism of SARS-CoV-2.Here,we summarized the potential therapeutic targets involved in the life cycle of the virus.On the basis of these targets,small-molecule prophylactic and therapeutic agents have been or are being developed for prevention and treatment of SARS-CoV-2 infection.展开更多
Hepatitis B is an infectious disease with serious health im-plications caused by hepatitis B virus. With blood, iatro-genic, sexual and mother-to-fetus transmission as its main transmission routes, hepatitis B virus c...Hepatitis B is an infectious disease with serious health im-plications caused by hepatitis B virus. With blood, iatro-genic, sexual and mother-to-fetus transmission as its main transmission routes, hepatitis B virus causes diseases in-cluding acute or chronic hepatitis, liver cirrhosis and liver cancer. Most adults infected with hepatitis B virus can be healed, while infected infants may typically live with a chronic and persistent infection. According to the national survey of hepatitis B epidemics conducted in 1979, among all surveyed people, the mean carrier rate of hepatitis B surface antigen （HBsAg） was 9.76% and that children may reach or approximate the peak value when they are only four years old.展开更多
Vascular cambium produces the phloem and xylem,vascular tissues that transport resources and provide mechanical support,making it an ideal target for crop improvement.However,much remains unknown about how vascular ca...Vascular cambium produces the phloem and xylem,vascular tissues that transport resources and provide mechanical support,making it an ideal target for crop improvement.However,much remains unknown about how vascular cambium proliferates.In this study,through pharmaceutical and genetic manipulation of reactive oxygen species(ROS)maxima,we demonstrate a direct link between levels of ROS and activity of LATERAL ORGAN BOUNDARIES DOMAIN 11(LBD11)in maintaining vascular cambium activity.LBD11 activates the transcriptionof several keyROS metabolic genes,including PEROXIDASE71and RESPIRATORY BURST OXIDASE HOMOLOGS D and F,to generate local ROS maxima in cambium,which in turn enhance the proliferation of cambial cells.In a negative feedback mechanism,higher Ros levels then repress LBD11 expression and maintain the balance of cambial cell proliferation.Our findings thus reveal the role of a novel LBD11/ROS-dependent feedback regulatory system in maintaining vascular cambiumspecific redox homeostasis and radial growth inplants.展开更多
Sorghum （Sorghum bicolor） has high levels of starch, sugar, and fiber and is one of the most important energy crops in the world. Insect damage is one of the challenges that impacts sorghum biomass production. There...Sorghum （Sorghum bicolor） has high levels of starch, sugar, and fiber and is one of the most important energy crops in the world. Insect damage is one of the challenges that impacts sorghum biomass production. There are at least 150 insect species that can infest sorghum varieties worldwide. These insects can complete several generations within a growing season, they target various parts of sorghum plants at devel- opmental stages, and they cause significant biomass losses. Genetic research has revealed the existence of resistant genetics in sorghum and insect tolerant sorghum varieties have been identified. Various control methods have been developed, yet more effective management is needed for increasing sorghum biomass production. Although there are no transgenic sorghum products on the market yet, biotechnology has been recognized as an important tool for controlling insect pests and increasing sorghum production.展开更多
＂I have the greatest respect for Dr. Chu, who upheld great standards of science during very difficult times in China. His contributions to the genetic characterisation of influenza viruses were extraordinary.＂
The detyrosination/retyrosination cycle is the most common post-translational modification of α-tubulin.Removal of the conserved C-terminal tyrosine of α-tubulin by a still elusive tubulin tyrosine carboxypeptidase,...The detyrosination/retyrosination cycle is the most common post-translational modification of α-tubulin.Removal of the conserved C-terminal tyrosine of α-tubulin by a still elusive tubulin tyrosine carboxypeptidase, and religation of this tyrosine by a tubulin tyrosine ligase(TTL), are probably common to all eukaryotes. Interestingly, for plants, the only candidates qualifying as potential TTL homologs are the tubulin tyrosine ligase-like 12 proteins. To get insight into the biological functions of these potential TTL homologs, we cloned the rice TTL-like 12 protein(Os TTLL12)andgeneratedoverexpression Os TTLL12-RFP lines in both rice and tobacco BY-2 cells. We found, unexpectedly, that overexpression of this Os TTLL12-RFP increased the relative abundance of detyrosinated α-tubulin in both coleoptile and seminal root, correlated with more stable microtubules. This was independent of the respective orientation of cortical microtubule, and followed by correspondingly changing growth of coleoptiles and seminal roots. A perturbed organization of phragmoplast microtubules and disoriented cell walls were further characteristics of this phenotype. Thus, the elevated tubulin detyrosination in consequence of Os TTLL12 overexpression affects structural and dynamic features of microtubules, followed by changes in the axiality of cell plate deposition and, consequently, plant growth.展开更多
The principle of scanning probe microscopes (SPM) was lust described by J. A. O’Keefe in the 1960s. In 1982, the scanning tunnelling microscope (STM), the first supreme example of SPM family, was developed; for which...The principle of scanning probe microscopes (SPM) was lust described by J. A. O’Keefe in the 1960s. In 1982, the scanning tunnelling microscope (STM), the first supreme example of SPM family, was developed; for which Binnig and Rohrer received the 1986 Nobel Prize in Physics. Shortly after that, in 1986 Binnig together with Quate and Gerber introduced the first atomic force microscope (AFM). Unlike the STM, the AFM展开更多
基金Supported by a grant from the Hong Kong Research Grant Council, No. 7342/03M to YX Zhou and E Lam
文摘AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of tobacco （Nicotiana tabacum cv. SR1）, to investigate the transgene expression and pE2 accumulation in plastids, and to evaluate the antigenic effect of the plastid-derived pE2 in mice. METHODS： Plastid-targeting vector pRB94-E2 containing the E2 fragment driven by rice psbA promoter was constructed. Upon delivery into tobacco plastids, this construct could initiate homologous recombination in psaB-trnfM and trnG-psbC fragments in plastid genome, and result in transgene inserted between the two fragments. The pRB94-E2 was delivered with a biolistic particle bombardment method, and the plastid-transformed plants were obtained following the regeneration of the bombarded leaf tissues on a spectinomycin-supplemented medium. Transplastomic status of the regenerated plants was confirmed by PCR and Southern blot analysis, transgene expression was investigated by Northern blot analysis, and accumulation of pE2 was measured by ELISA. Furthermore, protein extracts were used to immunize mice, and the presence of the pE2-reactive antibodies in serum samples of the immunized mice was studied by ELISA. RESULTS： Transplastomic lines confirmed by PCR and Southern blot analysis could actively transcribe the E2 mRNA. The pE2 polypeptide was accumulated to a level as high as 13.27 μg/g fresh leaves. The pE2 could stimulate the immunized mice to generate pE2-specific antibodies. CONCLUSION： HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.
基金funding from the Italian Ministry for Education,University,and Research(MIUR)within the program“Departments of Excellence”2018-2022(DII-UNITN)from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no.101008041.the NIH(P41EB027062)for support of this work.
文摘The shortage of tissues and organs for transplantation is an urgent clinical concern.In situ 3D printing is an advanced 3D printing technique aimed at printing the new tissue or organ directly in the patient.The ink for this process is central to the outcomes,and must meet specific requirements such as rapid gelation,shape integrity,stability over time,and adhesion to surrounding healthy tissues.Among natural materials,silk fibroin exhibits fascinating properties that have made it widely studied in tissue engineering and regenerative medicine.However,further improvements in silk fibroin inks are needed to match the requirements for in situ 3D printing.In the present study,silk fibroin-based inks were developed for in situ applications by exploiting covalent crosslinking process consisting of a pre-photo-crosslinking prior to printing and in situ enzymatic crosslinking.Two different silk fibroin molecular weights were characterized and the synergistic effect of the covalent bonds with shear forces enhanced the shift in silk secondary structure towardβ-sheets,thus,rapid stabilization.These hydrogels exhibited good mechanical properties,stability over time,and resistance to enzymatic degradation over 14 days,with no significant changes over time in their secondary structure and swelling behavior.Additionally,adhesion to tissues in vitro was demonstrated.
文摘Guard cells are specialized cells forming stomatal pores at the leaf surface for gas exchanges between the plant and the atmosphere. Stomata have been shown to playan important role in plant defense as a part of the innate immune response. Plants actively close their stomata upon contact with microbes, thereby preventing pathogen entry into the leaves and the subsequent colonization of host tissues. In this review, we present current knowledge of molecular mechanisms and signaling pathways implicated in stomatal defenses, with particular emphasis on plant-bacteria interactions. Stomatal defense responses begin from the perception of pathogen-associated molecular patterns （PAMPs） and activate a signaling cascade involving the production of secondary messengers such as reactive oxygen species, nitric oxide, and calcium for the regulation of plasma membrane ion channels. The analyses on downstream molecular mechanisms implicated in PAMP-triggered stomatal closure have revealed extensive interplays among the components regulating hormonal signaling pathways. We also discuss the strategies deployed by pathogenic bacteria to counteract stomatal immunity through the example of the phytotoxin coronatine.
基金supported by grants from the National Basic Research Program of China (2011CB504704)the State Megaproject for Infectious Disease Research of China (2011ZX10004-001)
文摘In 2012,a novel coronavirus,initially named as human coronavirus EMC(HCoV-EMC) but recently renamed as Middle East respiratory syndrome human coronavirus(MERS-CoV),was identified in patients who suffered severe acute respiratory infection and subsequent renal failure that resulted in death.Ongoing epidemiological investigations together with retrospective studies have found 61 laboratory-confirmed cases of infection with this novel coronavirus,including 34 deaths to date.This novel coronavirus is culturable and two complete genome sequences are now available.Furthermore,molecular detection and indirect immunofluorescence assay have been developed.The present paper summarises the limited recent advances of this novel human coronavirus,including its discovery,genomic characterisation and detection.
基金This work was supported by grants from the National Natural Science Foundation of China(81974302 and 82041025)the Program for“333 Talents Project”of Hebei Province(A202002003,China)Science and Technology Project of Hebei Education Department(QN2021071,China).
文摘The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world.Even though several COVID-19 vaccines are currently in distribution worldwide,with others in the pipeline,treatment modalities lag behind.Accordingly,researchers have been working hard to understand the nature of the virus,its mutant strains,and the pathogenesis of the disease in order to uncover possible drug targets and effective therapeutic agents.As the research continues,we now know the genome structure,epidemiological and clinical features,and pathogenic mechanism of SARS-CoV-2.Here,we summarized the potential therapeutic targets involved in the life cycle of the virus.On the basis of these targets,small-molecule prophylactic and therapeutic agents have been or are being developed for prevention and treatment of SARS-CoV-2 infection.
文摘Hepatitis B is an infectious disease with serious health im-plications caused by hepatitis B virus. With blood, iatro-genic, sexual and mother-to-fetus transmission as its main transmission routes, hepatitis B virus causes diseases in-cluding acute or chronic hepatitis, liver cirrhosis and liver cancer. Most adults infected with hepatitis B virus can be healed, while infected infants may typically live with a chronic and persistent infection. According to the national survey of hepatitis B epidemics conducted in 1979, among all surveyed people, the mean carrier rate of hepatitis B surface antigen （HBsAg） was 9.76% and that children may reach or approximate the peak value when they are only four years old.
基金grants to I.H.from the New Breeding Technologies Development Program funded by the Rural Development Administration,Republic of Korea(project no.PJ016538)from the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science and ICT,Republic of Korea(project no.2020R1A2C3012750)+1 种基金Brain Pool Program through the NRF funded by the Ministry of Science and ICT(grant no.2017H1D3A1A03055171)Basic Science Research Program through the NRF funded by the Ministry of Education(grant no.2019R1/1A1A01055449).
文摘Vascular cambium produces the phloem and xylem,vascular tissues that transport resources and provide mechanical support,making it an ideal target for crop improvement.However,much remains unknown about how vascular cambium proliferates.In this study,through pharmaceutical and genetic manipulation of reactive oxygen species(ROS)maxima,we demonstrate a direct link between levels of ROS and activity of LATERAL ORGAN BOUNDARIES DOMAIN 11(LBD11)in maintaining vascular cambium activity.LBD11 activates the transcriptionof several keyROS metabolic genes,including PEROXIDASE71and RESPIRATORY BURST OXIDASE HOMOLOGS D and F,to generate local ROS maxima in cambium,which in turn enhance the proliferation of cambial cells.In a negative feedback mechanism,higher Ros levels then repress LBD11 expression and maintain the balance of cambial cell proliferation.Our findings thus reveal the role of a novel LBD11/ROS-dependent feedback regulatory system in maintaining vascular cambiumspecific redox homeostasis and radial growth inplants.
基金supported by Pioneer Hi-Bred International Inc.,A DuPont Company
文摘Sorghum （Sorghum bicolor） has high levels of starch, sugar, and fiber and is one of the most important energy crops in the world. Insect damage is one of the challenges that impacts sorghum biomass production. There are at least 150 insect species that can infest sorghum varieties worldwide. These insects can complete several generations within a growing season, they target various parts of sorghum plants at devel- opmental stages, and they cause significant biomass losses. Genetic research has revealed the existence of resistant genetics in sorghum and insect tolerant sorghum varieties have been identified. Various control methods have been developed, yet more effective management is needed for increasing sorghum biomass production. Although there are no transgenic sorghum products on the market yet, biotechnology has been recognized as an important tool for controlling insect pests and increasing sorghum production.
文摘＂I have the greatest respect for Dr. Chu, who upheld great standards of science during very difficult times in China. His contributions to the genetic characterisation of influenza viruses were extraordinary.＂
基金This work was supported by a fellowship from the the Chinese Scholarship Council to Kunxi ZhangOpen access funding enabled and organized by Projekt DEAL。
文摘The detyrosination/retyrosination cycle is the most common post-translational modification of α-tubulin.Removal of the conserved C-terminal tyrosine of α-tubulin by a still elusive tubulin tyrosine carboxypeptidase, and religation of this tyrosine by a tubulin tyrosine ligase(TTL), are probably common to all eukaryotes. Interestingly, for plants, the only candidates qualifying as potential TTL homologs are the tubulin tyrosine ligase-like 12 proteins. To get insight into the biological functions of these potential TTL homologs, we cloned the rice TTL-like 12 protein(Os TTLL12)andgeneratedoverexpression Os TTLL12-RFP lines in both rice and tobacco BY-2 cells. We found, unexpectedly, that overexpression of this Os TTLL12-RFP increased the relative abundance of detyrosinated α-tubulin in both coleoptile and seminal root, correlated with more stable microtubules. This was independent of the respective orientation of cortical microtubule, and followed by correspondingly changing growth of coleoptiles and seminal roots. A perturbed organization of phragmoplast microtubules and disoriented cell walls were further characteristics of this phenotype. Thus, the elevated tubulin detyrosination in consequence of Os TTLL12 overexpression affects structural and dynamic features of microtubules, followed by changes in the axiality of cell plate deposition and, consequently, plant growth.
文摘The principle of scanning probe microscopes (SPM) was lust described by J. A. O’Keefe in the 1960s. In 1982, the scanning tunnelling microscope (STM), the first supreme example of SPM family, was developed; for which Binnig and Rohrer received the 1986 Nobel Prize in Physics. Shortly after that, in 1986 Binnig together with Quate and Gerber introduced the first atomic force microscope (AFM). Unlike the STM, the AFM
