scholarly journals Precise and broad scope genome editing based on high-specificity Cas9 nickases

2021 ◽  
Author(s):  
Qian Wang ◽  
Jin Liu ◽  
Josephine M Janssen ◽  
Marie Le Bouteiller ◽  
Richard L Frock ◽  
...  
Keyword(s):  
Genome Editing ◽  
High Throughput Sequencing ◽  
High Specificity ◽  
Multiple Copy ◽  
Genetic Manipulations ◽  
Genome Wide ◽  
Single Base Pair ◽  
Gene Knockouts ◽  
Chromosomal Sequences ◽  
Eukaryotic Genomes

Abstract RNA-guided nucleases (RGNs) based on CRISPR systems permit installing short and large edits within eukaryotic genomes. However, precise genome editing is often hindered due to nuclease off-target activities and the multiple-copy character of the vast majority of chromosomal sequences. Dual nicking RGNs and high-specificity RGNs both exhibit low off-target activities. Here, we report that high-specificity Cas9 nucleases are convertible into nicking Cas9D10A variants whose precision is superior to that of the commonly used Cas9D10A nickase. Dual nicking RGNs based on a selected group of these Cas9D10A variants can yield gene knockouts and gene knock-ins at frequencies similar to or higher than those achieved by their conventional counterparts. Moreover, high-specificity dual nicking RGNs are capable of distinguishing highly similar sequences by ‘tiptoeing’ over pre-existing single base-pair polymorphisms. Finally, high-specificity RNA-guided nicking complexes generally preserve genomic integrity, as demonstrated by unbiased genome-wide high-throughput sequencing assays. Thus, in addition to substantially enlarging the Cas9 nickase toolkit, we demonstrate the feasibility in expanding the range and precision of DNA knockout and knock-in procedures. The herein introduced tools and multi-tier high-specificity genome editing strategies might be particularly beneficial whenever predictability and/or safety of genetic manipulations are paramount.

scholarly journals CRISPR/Cas9 gene editing to make conditional mutants of the human malaria parasite Plasmodium falciparum

2018 ◽  
Author(s):  
Heather M. Kudyba ◽  
David W. Cobb ◽  
Anat Florentin ◽  
Michelle Krakowiak ◽  
Vasant Muralidharan
Keyword(s):  
Genome Editing ◽  
Malaria Parasite ◽  
Gene Editing ◽  
Genetic Manipulation ◽  
Human Malaria Parasite ◽  
Genetic Manipulations ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Gene Knockouts ◽  
Protein Tagging

ABSTRACTMalaria is a significant cause of morbidity and mortality worldwide. This disease, which primarily affects those living in tropical and subtropical regions, is caused by infection with Plasmodium parasites. The development of better drugs to combat malaria can be accelerated by improving our understanding of the biology of this complex parasite. Genetic manipulation of these parasites is key to understanding their biology, but historically, the genome of P. falciparum has been difficult to manipulate. Recently, CRISPR/Cas9 genome editing has been utilized in malaria parasites, allowing for easier protein tagging, generation of conditional protein knockdowns, and deletion of genes. CRISPR/Cas9 genome editing has proven to be a powerful tool for advancing the field of malaria research. Here, we describe a CRISPR/Cas9 method for generating glmS-based conditional knockdown mutants in P. falciparum. The method is highly adaptable to other types of genetic manipulations, including protein tagging and gene knockouts.

scholarly journals The new genomic editing system (CRISPR)

2019 ◽  
Author(s):  
Mehrdad Talebi ◽  
Mohammad Yahya Vahidi Mehrjardi
Keyword(s):  
Genetic Engineering ◽  
Genome Editing ◽  
High Specificity ◽  
Repair System ◽  
End Joining ◽  
Genetic Manipulations ◽  
Dna And Rna ◽  
A Cell ◽  
Non Homologous End Joining ◽  
Genomic Editing

Over the past decades, progression in genetic element manipulation, and consequently, the treatment of diseases has been remarkable. It is worth noting that these genetic manipulations perform at different levels, including DNA and RNA. The earlier genomic editing techniques, including MN, ZFN , TALEN , performing their functions by creating double-stranded breaks (DSBs), and after breakage, the cell tries to repair the breakage through two systems, homologous recombination and non-homologous end joining. CRISPR/Cas technology has been discovered recently, and has become the most widely used genome-editing tool, mainly due to its capabilities and those added to this through the genetic engineering. In this study, we aimed to introduce a variety of CRISPR classes in the elementary parts, and then the modified CRISPR systems developed to increase the efficiency and specificity of the system and provide acceptable results will be introduced. In this study, for three months in the fall and winter, Pubmed and Web of science sites searched for keywords such as CRISPR, Types of CRISPR, gRNA, Cas9, and CRISPR-Cas9 nickase that eventually resulted in about four hundred Sixty-one articles, and some of these articles after closer study, reviewed in this article. Genetic engineering techniques have successfully transformed this system into the most efficient genome editing tool in recent years. Researchers are working on a system to treat various diseases by resolving problems such as high specificity, cutting off non-target sites, how to move to a cell, and setting up a proper repair system.

scholarly journals Whole-genome sequencing reveals rare off-target mutations in CRISPR/Cas9-edited grapevine

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xianhang Wang ◽  
Mingxing Tu ◽  
Ya Wang ◽  
Wuchen Yin ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Whole Genome Sequencing ◽  
Genome Editing ◽  
Genome Sequencing ◽  
Plant Biotechnology ◽  
High Specificity ◽  
Fruit Trees ◽  
Whole Genome ◽  
Nucleotide Polymorphisms ◽  
Indel Mutation ◽  
Target Sites

AbstractThe CRISPR (clustered regularly interspaced short palindromic repeats)-associated protein 9 (Cas9) system is a powerful tool for targeted genome editing, with applications that include plant biotechnology and functional genomics research. However, the specificity of Cas9 targeting is poorly investigated in many plant species, including fruit trees. To assess the off-target mutation rate in grapevine (Vitis vinifera), we performed whole-genome sequencing (WGS) of seven Cas9-edited grapevine plants in which one of two genes was targeted by CRISPR/Cas9 and three wild-type (WT) plants. In total, we identified between 202,008 and 272,397 single nucleotide polymorphisms (SNPs) and between 26,391 and 55,414 insertions/deletions (indels) in the seven Cas9-edited grapevine plants compared with the three WT plants. Subsequently, 3272 potential off-target sites were selected for further analysis. Only one off-target indel mutation was identified from the WGS data and validated by Sanger sequencing. In addition, we found 243 newly generated off-target sites caused by genetic variants between the Thompson Seedless cultivar and the grape reference genome (PN40024) but no true off-target mutations. In conclusion, we observed high specificity of CRISPR/Cas9 for genome editing of grapevine.

scholarly journals Editing GWAS: experimental approaches to dissect and exploit disease-associated genetic variation

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Shuquan Rao ◽  
Yao Yao ◽  
Daniel E. Bauer
Keyword(s):  
Genome Editing ◽  
Genetic Variants ◽  
Association Studies ◽  
Genome Wide Association ◽  
Genome Wide Association Studies ◽  
Functional Studies ◽  
Functional Genetics ◽  
Genome Wide ◽  
Causal Variants ◽  
Experimental Approaches

AbstractGenome-wide association studies (GWAS) have uncovered thousands of genetic variants that influence risk for human diseases and traits. Yet understanding the mechanisms by which these genetic variants, mainly noncoding, have an impact on associated diseases and traits remains a significant hurdle. In this review, we discuss emerging experimental approaches that are being applied for functional studies of causal variants and translational advances from GWAS findings to disease prevention and treatment. We highlight the use of genome editing technologies in GWAS functional studies to modify genomic sequences, with proof-of-principle examples. We discuss the challenges in interrogating causal variants, points for consideration in experimental design and interpretation of GWAS locus mechanisms, and the potential for novel therapeutic opportunities. With the accumulation of knowledge of functional genetics, therapeutic genome editing based on GWAS discoveries will become increasingly feasible.

scholarly journals Genome-wide Analysis of Alternative Pre-mRNA Splicing

2007 ◽  
Vol 283 (3) ◽  
pp. 1229-1233 ◽  
Author(s):  
Claudia Ben-Dov ◽  
Britta Hartmann ◽  
Josefin Lundgren ◽  
Juan Valcárcel
Keyword(s):  
Alternative Splicing ◽  
Large Scale ◽  
Mrna Splicing ◽  
Diagnostic Tools ◽  
Primary Transcript ◽  
Genome Wide ◽  
Human Genes ◽  
Multicellular Organisms ◽  
Eukaryotic Genomes ◽  
Key Questions

Alternative splicing of mRNA precursors allows the synthesis of multiple mRNAs from a single primary transcript, significantly expanding the information content and regulatory possibilities of higher eukaryotic genomes. High-throughput enabling technologies, particularly large-scale sequencing and splicing-sensitive microarrays, are providing unprecedented opportunities to address key questions in this field. The picture emerging from these pioneering studies is that alternative splicing affects most human genes and a significant fraction of the genes in other multicellular organisms, with the potential to greatly influence the evolution of complex genomes. A combinatorial code of regulatory signals and factors can deploy physiologically coherent programs of alternative splicing that are distinct from those regulated at other steps of gene expression. Pre-mRNA splicing and its regulation play important roles in human pathologies, and genome-wide analyses in this area are paving the way for improved diagnostic tools and for the identification of novel and more specific pharmaceutical targets.

scholarly journals An Efficient, Rapid, and Recyclable System for CRISPR-Mediated Genome Editing in Candida albicans

mSphere ◽  
2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Namkha Nguyen ◽  
Morgan M. F. Quail ◽  
Aaron D. Hernday
Keyword(s):  
Candida Albicans ◽  
Genome Editing ◽  
Fungal Pathogen ◽  
Gene Knockout ◽  
Strain Engineering ◽  
Molecular Genetic Analysis ◽  
Content Type ◽  
Highly Efficient ◽  
Discovery Research ◽  
Gene Knockouts

ABSTRACT Candida albicans is the most common fungal pathogen of humans. Historically, molecular genetic analysis of this important pathogen has been hampered by the lack of stable plasmids or meiotic cell division, limited selectable markers, and inefficient methods for generating gene knockouts. The recent development of clustered regularly interspaced short palindromic repeat(s) (CRISPR)-based tools for use with C. albicans has opened the door to more efficient genome editing; however, previously reported systems have specific limitations. We report the development of an optimized CRISPR-based genome editing system for use with C. albicans. Our system is highly efficient, does not require molecular cloning, does not leave permanent markers in the genome, and supports rapid, precise genome editing in C. albicans. We also demonstrate the utility of our system for generating two independent homozygous gene knockouts in a single transformation and present a method for generating homozygous wild-type gene addbacks at the native locus. Furthermore, each step of our protocol is compatible with high-throughput strain engineering approaches, thus opening the door to the generation of a complete C. albicans gene knockout library. IMPORTANCE Candida albicans is the major fungal pathogen of humans and is the subject of intense biomedical and discovery research. Until recently, the pace of research in this field has been hampered by the lack of efficient methods for genome editing. We report the development of a highly efficient and flexible genome editing system for use with C. albicans. This system improves upon previously published C. albicans CRISPR systems and enables rapid, precise genome editing without the use of permanent markers. This new tool kit promises to expedite the pace of research on this important fungal pathogen.

scholarly journals Agrobacterium tumefaciens Gene Transfer: How a Plant Pathogen Hacks the Nuclei of Plant and Nonplant Organisms

2015 ◽  
Vol 105 (10) ◽  
pp. 1288-1301 ◽  
Author(s):  
Salim Bourras ◽  
Thierry Rouxel ◽  
Michel Meyer
Keyword(s):  
Genetic Transformation ◽  
Host Cell ◽  
Dna Integration ◽  
Genome Wide ◽  
Genomic Tools ◽  
Genome Features ◽  
Integration Mechanisms ◽  
Dna Fragment ◽  
Eukaryotic Genomes

Agrobacterium species are soilborne gram-negative bacteria exhibiting predominantly a saprophytic lifestyle. Only a few of these species are capable of parasitic growth on plants, causing either hairy root or crown gall diseases. The core of the infection strategy of pathogenic Agrobacteria is a genetic transformation of the host cell, via stable integration into the host genome of a DNA fragment called T-DNA. This genetic transformation results in oncogenic reprogramming of the host to the benefit of the pathogen. This unique ability of interkingdom DNA transfer was largely used as a tool for genetic engineering. Thus, the artificial host range of Agrobacterium is continuously expanding and includes plant and nonplant organisms. The increasing availability of genomic tools encouraged genome-wide surveys of T-DNA tagged libraries, and the pattern of T-DNA integration in eukaryotic genomes was studied. Therefore, data have been collected in numerous laboratories to attain a better understanding of T-DNA integration mechanisms and potential biases. This review focuses on the intranuclear mechanisms necessary for proper targeting and stable expression of Agrobacterium oncogenic T-DNA in the host cell. More specifically, the role of genome features and the putative involvement of host’s transcriptional machinery in relation to the T-DNA integration and effects on gene expression are discussed. Also, the mechanisms underlying T-DNA integration into specific genome compartments is reviewed, and a theoretical model for T-DNA intranuclear targeting is presented.

scholarly journals Genome-wide miRNA analysis and integrated network for flavonoid biosynthesis in Osmanthus fragrans

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yong Shi ◽  
Heng Xia ◽  
Xiaoting Cheng ◽  
Libin Zhang
Keyword(s):  
Secondary Metabolites ◽  
High Throughput Sequencing ◽  
Target Genes ◽  
Expression Profiles ◽  
Flavonoid Biosynthesis ◽  
Integrated Network ◽  
Osmanthus Fragrans ◽  
Flavonoid Synthesis ◽  
Genome Wide

AbstractBackgroundOsmanthus fragransis an important economical plant containing multiple secondary metabolites including flavonoids and anthocyanins. During the past years, the roles of miRNAs in regulating the biosynthesis of secondary metabolites in plants have been widely investigated. However, few studies on miRNA expression profiles and the potential roles in regulating flavonoid biosynthesis have been reported inO. fragrans.ResultsIn this study, we used high-throughput sequencing technology to analyze the expression profiles of miRNAs in leaf and flower tissues ofO. fragrans. As a result, 106 conserved miRNAs distributed in 47 families and 88 novel miRNAs were identified. Further analysis showed there were 133 miRNAs differentially expressed in leaves and flowers. Additionally, the potential target genes of miRNAs as well as the related metabolic pathways were predicted. In the end, flavonoid content was measured in flower and leaf tissues and potential role of miR858 in regulating flavonoid synthesis was illustrated inO. fragrans.ConclusionsThis study not only provided the genome-wide miRNA profiles in the flower and leaf tissue ofO. fragrans, but also investigated the potential regulatory role of miR858a in flavonoid synthesis inO. fragrans. The results specifically indicated the connection of miRNAs to the regulation of secondary metabolite biosynthesis in non-model economical plant.

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