Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditiona...Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.展开更多
The accessibility provided by the transportation system plays an essential role in driving urban growth and urban functional land use changes.Conventional studies on land use simulation usually simplified the accessib...The accessibility provided by the transportation system plays an essential role in driving urban growth and urban functional land use changes.Conventional studies on land use simulation usually simplified the accessibility as proximities and adopted the grid-based simulation strategy,leading to the insufficiencies of characterizing spatial geometry of land parcels and simulating subtle land use changes among urban functional types.To overcome these limita-tions,an Accessibility-interacted Vector-based Cellular Automata(A-VCA)model was proposed for the better simulation of realistic land use change among different urban functional types.The accessibility at both local and zonal scales derived from actual travel time data was considered as a key driver of fine-scale urban land use changes and was integrated into the vector-based CA simulation process.The proposed A-VCA model was tested through the simulation of urban land use changes in the City of Toronto,Canada,during 2012-2016.A vector-based CA without considering the driving factor of accessibility(VCA)and a popular grid-based CA model(Future Land Use Simulation,FLUS)were also implemented for compar-isons.The simulation results reveal that the proposed A-VCA model is capable of simulating fine-scale urban land use changes with satisfactory accuracy and good morphological feature(kappa=0.907,figure of merit=0.283,and cumulative producer’s accuracy=72.83%±1.535%).The comparison also shows significant outperformance of the A-VCA model against the VCA and FLUS models,suggesting the effectiveness of the accessibility-interactive mechanism and vector-based simulation strategy.The proposed model provides new tools for a better simula-tion of fine-scale land use changes and can be used in assisting the formulation of urban and transportation planning.展开更多
A vector-based RNAi expression system was developed using the Xenopus tropicalis U6 promoter, which transcribes small RNA genes by RNA polymerase Ⅲ. The system was first validated in a Xenopus laevis cell line, desig...A vector-based RNAi expression system was developed using the Xenopus tropicalis U6 promoter, which transcribes small RNA genes by RNA polymerase Ⅲ. The system was first validated in a Xenopus laevis cell line, designing a short hairpin DNA specific for the GFP gene. Co-transfection of the vector-based RNAi and the GFP gene into Xenopus XR1 cells significantly decreased the number of GFP-expressing cells and overall GFP fluorescence. Vector-based RNAi was subsequently validated in GFP transgenic Xenopus embryos. Sperm nuclei from GFP transgenic males and RNAi construct-incubated-sperm nuclei were used for fertilization, respectively. GFP mRNA and protein were reduced by -60% by RNAi in these transgenic embryos compared with the control. This transgene-driven RNAi is specific and stable in inhibiting GFP expression in the Xenopus laevis transgenic line. Gene silencing by vector-based RNAi and Xenopus transgenesis may provide an alternative for ＇repression of gene function＇ studies in vertebrate model systems.展开更多
AIM:To evaluate the effect of RNA interference (RNAi) mediated silence of signal transduction and activation of transcription (STAT)3 on the growth of human pancreatic cancer cells both in vitro and in vivo.METHODS:ST...AIM:To evaluate the effect of RNA interference (RNAi) mediated silence of signal transduction and activation of transcription (STAT)3 on the growth of human pancreatic cancer cells both in vitro and in vivo.METHODS:STAT3 specific shRNA was used to silence the expression of STAT3 in pancreatic cancer cell line SW1990.The anti-growth effects of RNAi against STAT3 were studied in vitro and in experimental cancer xenografts in nude mice.The potential pathways involved in STAT3 signaling were detected using reverse transcription polymerase chain reaction and western blotting.RESULTS:The expression of the STAT3 was inhibited using RNAi in SW1990 cells.RNAi against STAT3 inhibited cell proliferation,induced cell apoptosis and significantly reduced the levels of CyclinD1 and Bcl-xL when compared with parental and control vector-transfected cells.In vivo experiments showed that RNAi against STAT3 inhibited the tumorigenicity of SW1990 cells and significantly suppressed tumor growth when it was directly injected into tumors.CONCLUSION:STAT3 signaling pathway plays an important role in the progression of pancreatic cancer,and silence of STAT3 gene using RNAi technique may be a novel therapeutic option for treatment of pancreatic cancer.展开更多
RNA interference(RNAi)has been used for agricultural insect pest control based on silencing of targeted insect genes.However,the effectiveness of RNAi and its applications in insect pest control remain challenging.Her...RNA interference(RNAi)has been used for agricultural insect pest control based on silencing of targeted insect genes.However,the effectiveness of RNAi and its applications in insect pest control remain challenging.Here we review factors that may affect the effectiveness of RNAi application,including the variability in RNAi efficacy among different insect species,a limited understanding of double-stranded RNA(dsRNA)uptake and systemic RNAi mechanisms,and the effective delivery of dsRNA in field conditions.Furthermore,we summarize recent progress in RNAi strategies for crop protection,discuss the advantages and disadvantages of RNAi-based insect control,and propose potential strategies to increase the effectiveness of RNAi in insect control.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41101349)Surveying and Mapping Scientific Research Projects of Jiangsu Province(No.JSCHKY201304)+1 种基金Program of Natural Science Research of Jiangsu Higher Education Institutions of China(No.13KJB420003)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.
基金the National Key R&D Program of China[Grant Number 2019YFA0607203]the National Natural Science Foundation of China[Grant Number 42001326 and 42171410]the Natural Science Foundation of Guangdong Province of China[Grant Number 2021A1515011192].
文摘The accessibility provided by the transportation system plays an essential role in driving urban growth and urban functional land use changes.Conventional studies on land use simulation usually simplified the accessibility as proximities and adopted the grid-based simulation strategy,leading to the insufficiencies of characterizing spatial geometry of land parcels and simulating subtle land use changes among urban functional types.To overcome these limita-tions,an Accessibility-interacted Vector-based Cellular Automata(A-VCA)model was proposed for the better simulation of realistic land use change among different urban functional types.The accessibility at both local and zonal scales derived from actual travel time data was considered as a key driver of fine-scale urban land use changes and was integrated into the vector-based CA simulation process.The proposed A-VCA model was tested through the simulation of urban land use changes in the City of Toronto,Canada,during 2012-2016.A vector-based CA without considering the driving factor of accessibility(VCA)and a popular grid-based CA model(Future Land Use Simulation,FLUS)were also implemented for compar-isons.The simulation results reveal that the proposed A-VCA model is capable of simulating fine-scale urban land use changes with satisfactory accuracy and good morphological feature(kappa=0.907,figure of merit=0.283,and cumulative producer’s accuracy=72.83%±1.535%).The comparison also shows significant outperformance of the A-VCA model against the VCA and FLUS models,suggesting the effectiveness of the accessibility-interactive mechanism and vector-based simulation strategy.The proposed model provides new tools for a better simula-tion of fine-scale land use changes and can be used in assisting the formulation of urban and transportation planning.
文摘A vector-based RNAi expression system was developed using the Xenopus tropicalis U6 promoter, which transcribes small RNA genes by RNA polymerase Ⅲ. The system was first validated in a Xenopus laevis cell line, designing a short hairpin DNA specific for the GFP gene. Co-transfection of the vector-based RNAi and the GFP gene into Xenopus XR1 cells significantly decreased the number of GFP-expressing cells and overall GFP fluorescence. Vector-based RNAi was subsequently validated in GFP transgenic Xenopus embryos. Sperm nuclei from GFP transgenic males and RNAi construct-incubated-sperm nuclei were used for fertilization, respectively. GFP mRNA and protein were reduced by -60% by RNAi in these transgenic embryos compared with the control. This transgene-driven RNAi is specific and stable in inhibiting GFP expression in the Xenopus laevis transgenic line. Gene silencing by vector-based RNAi and Xenopus transgenesis may provide an alternative for ＇repression of gene function＇ studies in vertebrate model systems.
基金Supported by A Grant from the Science and Technology Commission of Shanghai Municipality,No. 09QA1404600a grant from the Affiliated First People’s Hospital of ShanghaiJiao Tong University,No. 0801
文摘AIM:To evaluate the effect of RNA interference (RNAi) mediated silence of signal transduction and activation of transcription (STAT)3 on the growth of human pancreatic cancer cells both in vitro and in vivo.METHODS:STAT3 specific shRNA was used to silence the expression of STAT3 in pancreatic cancer cell line SW1990.The anti-growth effects of RNAi against STAT3 were studied in vitro and in experimental cancer xenografts in nude mice.The potential pathways involved in STAT3 signaling were detected using reverse transcription polymerase chain reaction and western blotting.RESULTS:The expression of the STAT3 was inhibited using RNAi in SW1990 cells.RNAi against STAT3 inhibited cell proliferation,induced cell apoptosis and significantly reduced the levels of CyclinD1 and Bcl-xL when compared with parental and control vector-transfected cells.In vivo experiments showed that RNAi against STAT3 inhibited the tumorigenicity of SW1990 cells and significantly suppressed tumor growth when it was directly injected into tumors.CONCLUSION:STAT3 signaling pathway plays an important role in the progression of pancreatic cancer,and silence of STAT3 gene using RNAi technique may be a novel therapeutic option for treatment of pancreatic cancer.
基金funded by the National Natural Science Foundation of China(32188102 to Lanqin Xia)Natural Science Foundation for Distinguished Young Scholars of Jiangxi province(20212ACB215001 to Xiudao Yu)+1 种基金supported by the China Scholarship Council(202303250062)the GSCAAS-ULg Joint PhD Program。
文摘RNA interference(RNAi)has been used for agricultural insect pest control based on silencing of targeted insect genes.However,the effectiveness of RNAi and its applications in insect pest control remain challenging.Here we review factors that may affect the effectiveness of RNAi application,including the variability in RNAi efficacy among different insect species,a limited understanding of double-stranded RNA(dsRNA)uptake and systemic RNAi mechanisms,and the effective delivery of dsRNA in field conditions.Furthermore,we summarize recent progress in RNAi strategies for crop protection,discuss the advantages and disadvantages of RNAi-based insect control,and propose potential strategies to increase the effectiveness of RNAi in insect control.
