This study provides a comprehensive summary of the current development status of the potato industry in Liangshan Prefecture,and analyzes the primary factors that hinder the advancement of this industry,including a lo...This study provides a comprehensive summary of the current development status of the potato industry in Liangshan Prefecture,and analyzes the primary factors that hinder the advancement of this industry,including a low degree of scale,a limited popularization rate of high-quality seeds,insufficient mechanization,a low level of commercialization,inadequate technological support,minimal integration between the secondary and tertiary industries,and an ineffective mechanism for connecting and benefiting farmers.Furthermore,it presents a problem-oriented approach that is grounded in the current climatic,resource,water,and soil conditions of Liangshan Prefecture,and proposes several pathways to promote the high-quality development of the potato industry.The strategies include:expanding coverage and increasing production volume as foundational steps to ensure food security;enhancing quality and efficiency as key drivers to stimulate agricultural advancement through scientific and technological innovation;focusing on the integration of the three industries to achieve industrial revitalization;implementing risk management measures as a preventive strategy to ensure industrial stability;establishing incentive policies to foster production enthusiasm;and ultimately assisting farmers in increasing their income to achieve the overarching goal of improving the livelihoods of the population.展开更多
Many flaviviruses are significant human pathogens.The plus-strand RNA genome of a flavivirus contains a 5′terminal cap 1 structure(m7GpppAmG).The flavivirus encodes one methyltransferase(MTase),located at the Ntermin...Many flaviviruses are significant human pathogens.The plus-strand RNA genome of a flavivirus contains a 5′terminal cap 1 structure(m7GpppAmG).The flavivirus encodes one methyltransferase(MTase),located at the Nterminal portion of the NS5 RNA-dependent RNA polymerase(RdRp).Here we review recent advances in our understanding of flaviviral capping machinery and the implications for drug development.The NS5 MTase catalyzes both guanine N7 and ribose 2'-OH methylations during viral cap formation.Representative flavivirus MTases,from dengue,yellow fever,and West Nile virus(WNV),sequentially generate GpppA!m7GpppA!m7GpppAm.Despite the existence of two distinct methylation activities,the crystal structures of flavivirus MTases showed a single binding site for S-adenosyl-L-methionine(SAM),the methyl donor.This finding indicates that the substrate GpppA-RNA must be repositioned to accept the N7 and 2'-O methyl groups from SAM during the sequential reactions.Further studies demonstrated that distinct RNA elements are required for the methylations of guanine N7 on the cap and of ribose 2'-OH on the first transcribed nucleotide.Mutant enzymes with different methylation defects can trans complement one another in vitro,demonstrating that separate molecules of the enzyme can independently catalyze the two cap methylations in vitro.In the context of the infectious virus,defects in both methylations,or a defect in the N7 methylation alone,are lethal to WNV.However,viruses defective solely in 2'-O methylation are attenuated and can protect mice from later wild-typeWNV challenge.The results demonstrate that the N7 methylation activity is essential for the WNV life cycle and,thus,methyltransferase represents a novel and promising target for flavivirus therapy.展开更多
基金Supported by Special Fund for the Construction of China Agricultural Industry Research System(CARS-09-ES22).
文摘This study provides a comprehensive summary of the current development status of the potato industry in Liangshan Prefecture,and analyzes the primary factors that hinder the advancement of this industry,including a low degree of scale,a limited popularization rate of high-quality seeds,insufficient mechanization,a low level of commercialization,inadequate technological support,minimal integration between the secondary and tertiary industries,and an ineffective mechanism for connecting and benefiting farmers.Furthermore,it presents a problem-oriented approach that is grounded in the current climatic,resource,water,and soil conditions of Liangshan Prefecture,and proposes several pathways to promote the high-quality development of the potato industry.The strategies include:expanding coverage and increasing production volume as foundational steps to ensure food security;enhancing quality and efficiency as key drivers to stimulate agricultural advancement through scientific and technological innovation;focusing on the integration of the three industries to achieve industrial revitalization;implementing risk management measures as a preventive strategy to ensure industrial stability;establishing incentive policies to foster production enthusiasm;and ultimately assisting farmers in increasing their income to achieve the overarching goal of improving the livelihoods of the population.
基金This research was partially supported by grants from the National Institute of Health(NIH)(No.AI07079201A1)to H.L。
文摘Many flaviviruses are significant human pathogens.The plus-strand RNA genome of a flavivirus contains a 5′terminal cap 1 structure(m7GpppAmG).The flavivirus encodes one methyltransferase(MTase),located at the Nterminal portion of the NS5 RNA-dependent RNA polymerase(RdRp).Here we review recent advances in our understanding of flaviviral capping machinery and the implications for drug development.The NS5 MTase catalyzes both guanine N7 and ribose 2'-OH methylations during viral cap formation.Representative flavivirus MTases,from dengue,yellow fever,and West Nile virus(WNV),sequentially generate GpppA!m7GpppA!m7GpppAm.Despite the existence of two distinct methylation activities,the crystal structures of flavivirus MTases showed a single binding site for S-adenosyl-L-methionine(SAM),the methyl donor.This finding indicates that the substrate GpppA-RNA must be repositioned to accept the N7 and 2'-O methyl groups from SAM during the sequential reactions.Further studies demonstrated that distinct RNA elements are required for the methylations of guanine N7 on the cap and of ribose 2'-OH on the first transcribed nucleotide.Mutant enzymes with different methylation defects can trans complement one another in vitro,demonstrating that separate molecules of the enzyme can independently catalyze the two cap methylations in vitro.In the context of the infectious virus,defects in both methylations,or a defect in the N7 methylation alone,are lethal to WNV.However,viruses defective solely in 2'-O methylation are attenuated and can protect mice from later wild-typeWNV challenge.The results demonstrate that the N7 methylation activity is essential for the WNV life cycle and,thus,methyltransferase represents a novel and promising target for flavivirus therapy.
