Genome editing in plants is a powerful strategy that can substantially advance functional genomics research,facilitating the discovery,enhancement,and development of novel traits with significant agricultural implicat...Genome editing in plants is a powerful strategy that can substantially advance functional genomics research,facilitating the discovery,enhancement,and development of novel traits with significant agricultural implications.Various methodologies,such as zinc finger nucleases(ZFNs),transcription activator-like effector nucleases(TALENs),and CRISPR/Cas systems,have been developed for this purpose.展开更多
CRISPR homing gene drives have considerable potential for managing populations of medically and agriculturally significant insects.They operate by Cas9 cleavage followed by homology-directed repair,copying the drive a...CRISPR homing gene drives have considerable potential for managing populations of medically and agriculturally significant insects.They operate by Cas9 cleavage followed by homology-directed repair,copying the drive allele to the wild-type chromosome and thus increasing in frequency and spreading throughout a population.However,resistance alleles formed by end-joining repair pose a significant obstacle.To address this,we create a homing drive targeting the essential hairy gene in Drosophila melanogaster.Nonfunctional resistance alleles are recessive lethal,while drive carriers have a recoded“rescue”version of hairy.The drive inheritance rate is moderate,and multigenerational cage studies show drive spread to 96%–97%of the population.However,the drive does not reach 100%due to the formation of functional resistance alleles despite using four gRNAs.These alleles have a large deletion but likely utilize an alternate start codon.Thus,revised designs targeting more essential regions of a gene may be necessary to avoid such functional resistance.Replacement of the rescue element’s native 3'UTR with a homolog from another species increases drive inheritance by 13%–24%.This was possibly because of reduced homology between the rescue element and surrounding genomic DNA,which could also be an important design consideration for rescue gene drives.展开更多
目的探讨体外筛选效率较高的引导核糖核酸(guide ribonucleic acid,gRNA)的方法。方法以家兔扭转蛋白2A(torsin family 2 member A,TOR2A)基因的gRNA设计和筛选为例,介绍gRNA简单的体外筛选方法。首先根据TOR2A基因的外显子序列在线设计...目的探讨体外筛选效率较高的引导核糖核酸(guide ribonucleic acid,gRNA)的方法。方法以家兔扭转蛋白2A(torsin family 2 member A,TOR2A)基因的gRNA设计和筛选为例,介绍gRNA简单的体外筛选方法。首先根据TOR2A基因的外显子序列在线设计gRNA,选择3条gRNA序列(也可更多),将其分别插入到T7启动子之后,体外转录gRNA并纯化备用。设计包含gRNA打靶序列的一对引物,以基因组DNA为模板进行PCR扩增并胶回收PCR产物。将gRNA,PCR产物和Cas9内切酶组成的体系进行酶切实验,琼脂糖电泳判定gRNA引导的酶切效率。结果琼脂糖凝胶电泳结果显示第1条gRNA未能引导Cas9内切酶对含打靶位点的PCR产物进行DNA酶切,第2条gRNA(GCTTGTCCATCTCGTCGAAG)和第3条gRNA(TCTCTTCCTCTTCGACGAGA)引导Cas9进行了比较彻底的酶切,第2、3条gRNA可用于后续研究。结论此体外筛选方法是一种简单、可行和实用的gRNA的体外筛选策略。展开更多
The CRISPR/Cas9 mediates efficient gene editing but has off-target effects inconducive to animal breeding. In this study, the efficacy of CRISPR/Cas9 vectors containing different lengths of g RNA in reduction of the o...The CRISPR/Cas9 mediates efficient gene editing but has off-target effects inconducive to animal breeding. In this study, the efficacy of CRISPR/Cas9 vectors containing different lengths of g RNA in reduction of the off-target phenomenon in the bovine MSTN gene knockout fibroblast cell lines was assessed, providing insight into improved methods for livestock breeding. A 20-bp g RNA was designed for the second exon of the bovine MSTN gene, and CRISPR/Cas9-B was constructed to guide the Cas9 protein to the AGAACCAGGAGAAGATGGACTGG site. The alternative CRISPR/Cas9-19, CRISPR/Cas9-18, CRISPR/Cas9-17 and CRISPR/Cas9-15 vectors were constructed using g RNAs truncated by 1, 2, 3 and 5 bp, respectively. These vectors were then introduced into bovine fetal fibroblasts by the electroporation method, and single cells were obtained by flow cytometry sorting. PCR was performed for each off-target site. All samples were sequenced and analyzed, and finally the efficiency of each vector in target and off-target sites was compared. The CRISPR/Cas9-B vector successfully knocked out the MSTN gene, but the off-target phenomenon was observed. The efficiencies of CRISPR/Cas-B, CRISPR/Cas9-19, CRISPR/Cas9-18, CRISPR/Cas9-17 and CRISPR/Cas9-15 in triggering gene mutations at MSTN targeting sites were 62.16, 17.39, 7.69, 74.29 and 3.85%, respectively;rates of each at the Off-MSTN-1 locus were 52.86, 0, 0, 8.82 and 0%, respectively;all were 0% at the Off-MSTN-2 locus;rates at the Off-MSTN-3 site were 44.87, 51.72, 86.36, 0 and 50%, respectively. The efficiency of the CRISPR/Cas9-17 plasmid in the MSTN site was higher than that in the CRISPR/Cas9-B plasmid, and the effect at the three off-target sites was significantly lower. This study demonstrated that the CRISPR/Cas9-17 plasmid constructed by truncating 3 bp g RNA can effectively reduce the off-target effect without reducing the efficiency of bovine MSTN gene targeting. This finding will provide more effective gene editing strategy for use of CRISPR/Cas9 technology.展开更多
基金supported by the Agricultural Gongguan Project of Xinjiang Production and Construction Corps,China(NYHXGG,2023AA102)the Innovation Program of Chinese Academy of Agricultural Sciences(CAAS-CSIAF-202402)+1 种基金the Outstanding Youth Foundation of Henan Scientific Committee,China(222300420097)the China Agriculture Research System of MOF and MARA(CARS-15-02).
文摘Genome editing in plants is a powerful strategy that can substantially advance functional genomics research,facilitating the discovery,enhancement,and development of novel traits with significant agricultural implications.Various methodologies,such as zinc finger nucleases(ZFNs),transcription activator-like effector nucleases(TALENs),and CRISPR/Cas systems,have been developed for this purpose.
基金supported by laboratory startup funds from Peking University and the Center for Life Sciences,as well as the grants from the National Science Foundation of China(32302455 and 32270672)。
文摘CRISPR homing gene drives have considerable potential for managing populations of medically and agriculturally significant insects.They operate by Cas9 cleavage followed by homology-directed repair,copying the drive allele to the wild-type chromosome and thus increasing in frequency and spreading throughout a population.However,resistance alleles formed by end-joining repair pose a significant obstacle.To address this,we create a homing drive targeting the essential hairy gene in Drosophila melanogaster.Nonfunctional resistance alleles are recessive lethal,while drive carriers have a recoded“rescue”version of hairy.The drive inheritance rate is moderate,and multigenerational cage studies show drive spread to 96%–97%of the population.However,the drive does not reach 100%due to the formation of functional resistance alleles despite using four gRNAs.These alleles have a large deletion but likely utilize an alternate start codon.Thus,revised designs targeting more essential regions of a gene may be necessary to avoid such functional resistance.Replacement of the rescue element’s native 3'UTR with a homolog from another species increases drive inheritance by 13%–24%.This was possibly because of reduced homology between the rescue element and surrounding genomic DNA,which could also be an important design consideration for rescue gene drives.
文摘目的探讨体外筛选效率较高的引导核糖核酸(guide ribonucleic acid,gRNA)的方法。方法以家兔扭转蛋白2A(torsin family 2 member A,TOR2A)基因的gRNA设计和筛选为例,介绍gRNA简单的体外筛选方法。首先根据TOR2A基因的外显子序列在线设计gRNA,选择3条gRNA序列(也可更多),将其分别插入到T7启动子之后,体外转录gRNA并纯化备用。设计包含gRNA打靶序列的一对引物,以基因组DNA为模板进行PCR扩增并胶回收PCR产物。将gRNA,PCR产物和Cas9内切酶组成的体系进行酶切实验,琼脂糖电泳判定gRNA引导的酶切效率。结果琼脂糖凝胶电泳结果显示第1条gRNA未能引导Cas9内切酶对含打靶位点的PCR产物进行DNA酶切,第2条gRNA(GCTTGTCCATCTCGTCGAAG)和第3条gRNA(TCTCTTCCTCTTCGACGAGA)引导Cas9进行了比较彻底的酶切,第2、3条gRNA可用于后续研究。结论此体外筛选方法是一种简单、可行和实用的gRNA的体外筛选策略。
基金supported by the National Transgenic Project of China (2016ZX08010001-002 and 2016ZX08010005-001)the National Natural Science Foundation of China (81471001)the Inner Mongolia Science and Technology Program, China (201502073)
文摘The CRISPR/Cas9 mediates efficient gene editing but has off-target effects inconducive to animal breeding. In this study, the efficacy of CRISPR/Cas9 vectors containing different lengths of g RNA in reduction of the off-target phenomenon in the bovine MSTN gene knockout fibroblast cell lines was assessed, providing insight into improved methods for livestock breeding. A 20-bp g RNA was designed for the second exon of the bovine MSTN gene, and CRISPR/Cas9-B was constructed to guide the Cas9 protein to the AGAACCAGGAGAAGATGGACTGG site. The alternative CRISPR/Cas9-19, CRISPR/Cas9-18, CRISPR/Cas9-17 and CRISPR/Cas9-15 vectors were constructed using g RNAs truncated by 1, 2, 3 and 5 bp, respectively. These vectors were then introduced into bovine fetal fibroblasts by the electroporation method, and single cells were obtained by flow cytometry sorting. PCR was performed for each off-target site. All samples were sequenced and analyzed, and finally the efficiency of each vector in target and off-target sites was compared. The CRISPR/Cas9-B vector successfully knocked out the MSTN gene, but the off-target phenomenon was observed. The efficiencies of CRISPR/Cas-B, CRISPR/Cas9-19, CRISPR/Cas9-18, CRISPR/Cas9-17 and CRISPR/Cas9-15 in triggering gene mutations at MSTN targeting sites were 62.16, 17.39, 7.69, 74.29 and 3.85%, respectively;rates of each at the Off-MSTN-1 locus were 52.86, 0, 0, 8.82 and 0%, respectively;all were 0% at the Off-MSTN-2 locus;rates at the Off-MSTN-3 site were 44.87, 51.72, 86.36, 0 and 50%, respectively. The efficiency of the CRISPR/Cas9-17 plasmid in the MSTN site was higher than that in the CRISPR/Cas9-B plasmid, and the effect at the three off-target sites was significantly lower. This study demonstrated that the CRISPR/Cas9-17 plasmid constructed by truncating 3 bp g RNA can effectively reduce the off-target effect without reducing the efficiency of bovine MSTN gene targeting. This finding will provide more effective gene editing strategy for use of CRISPR/Cas9 technology.
