In this paper a new idea, based on discussing the essence of flutter, to investigate flutter problems is proposed that we only study a few modes of an aeroelastic system instead of studying the whole. In the light of ...In this paper a new idea, based on discussing the essence of flutter, to investigate flutter problems is proposed that we only study a few modes of an aeroelastic system instead of studying the whole. In the light of this, an approach to analysing flutter characteristics which combines the merit of graphic and analytic methods, is presented. Also an optimal cost function with clear physical meaning which can overcome some inherent drawbacks of linear quadratic technique, is developed. The paper has shown a numerical example of an elastic wing, in which some comparisons between the approach and 'V-G' method for calculating the critical point (Vf,wf ) are carried out as well.展开更多
Synthetic gene activators consisting of nucleasedead Cas9(dCas9)for single-guide RNA(sgRNA)-directed promoter binding and a transcriptional activation domain(TAD)represent new tools for gene activation from endogenous...Synthetic gene activators consisting of nucleasedead Cas9(dCas9)for single-guide RNA(sgRNA)-directed promoter binding and a transcriptional activation domain(TAD)represent new tools for gene activation from endogenous genomic locus in basic and applied plant research.However,multiplex gene coactivation by d Cas9-TADs has not been demonstrated in whole plants.There is also room to optimize the performance of these tools.Here,we report that our previously developed gene activator,dCas9-TV,could simultaneously upregulate OsGW7 and OsER1 in rice by up to 3,738 fold,with one sg RNA targeting to each promoter.The gene coactivation could persist to at least the fourth generation.Astonishingly,thepolycistronictRNA-sgRNAexpression under the maize ubiquitin promoter,a Pol II promoter,could cause enormous activation of these genes by up to>40,000-fold in rice.Moreover,the yeast GCN4 coiled coil-mediated dCas9-TV dimerization appeared to be promising for enhancing gene activation.Finally,we successfully introduced a self-amplification loop for dCas9-TV expression in Arabidopsis to promote the transcriptional upregulation of AtFLS2,a previously characterized dCas9-TV-refractory gene with considerable basal expression.Collectively,this work illustrates the robustness of dCas9-TV in multigene coactivation and provides broadly useful strategies for boosting transcriptional activation efficacy of dCas9-TADs in plants.展开更多
文摘In this paper a new idea, based on discussing the essence of flutter, to investigate flutter problems is proposed that we only study a few modes of an aeroelastic system instead of studying the whole. In the light of this, an approach to analysing flutter characteristics which combines the merit of graphic and analytic methods, is presented. Also an optimal cost function with clear physical meaning which can overcome some inherent drawbacks of linear quadratic technique, is developed. The paper has shown a numerical example of an elastic wing, in which some comparisons between the approach and 'V-G' method for calculating the critical point (Vf,wf ) are carried out as well.
基金supported by a grant from the National Transgenic Science and Technology Major Program of China(2019ZX08010003-001-009)。
文摘Synthetic gene activators consisting of nucleasedead Cas9(dCas9)for single-guide RNA(sgRNA)-directed promoter binding and a transcriptional activation domain(TAD)represent new tools for gene activation from endogenous genomic locus in basic and applied plant research.However,multiplex gene coactivation by d Cas9-TADs has not been demonstrated in whole plants.There is also room to optimize the performance of these tools.Here,we report that our previously developed gene activator,dCas9-TV,could simultaneously upregulate OsGW7 and OsER1 in rice by up to 3,738 fold,with one sg RNA targeting to each promoter.The gene coactivation could persist to at least the fourth generation.Astonishingly,thepolycistronictRNA-sgRNAexpression under the maize ubiquitin promoter,a Pol II promoter,could cause enormous activation of these genes by up to>40,000-fold in rice.Moreover,the yeast GCN4 coiled coil-mediated dCas9-TV dimerization appeared to be promising for enhancing gene activation.Finally,we successfully introduced a self-amplification loop for dCas9-TV expression in Arabidopsis to promote the transcriptional upregulation of AtFLS2,a previously characterized dCas9-TV-refractory gene with considerable basal expression.Collectively,this work illustrates the robustness of dCas9-TV in multigene coactivation and provides broadly useful strategies for boosting transcriptional activation efficacy of dCas9-TADs in plants.
