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A newly discovered Bordetella species carries a transcriptionally active CRISPR-Cas with a small Cas9 endonuclease.
BACKGROUND: Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated genes (cas) are widely distributed among bacteria. These systems provide adaptive immunity against mobile genetic elements specified by the spacer sequences stored within the CRISPR. METHODS: The CRISPR-Cas system has been identified using Basic Local Alignment Search Tool (BLAST) against other sequenced and annotated genomes and confirmed via CRISPRfinder program. Using Polymerase Chain Reactions (PCR) and Sanger DNA sequencing, we discovered CRISPRs in additional bacterial isolates of the same species of Bordetella. Transcriptional activity and processing of the CRISPR have been assessed via RT-PCR. RESULTS: Here we describe a novel Type II-C CRISPR and its associated genes-cas1, cas2, and cas9-in several isolates of a newly discovered Bordetella species. The CRISPR-cas locus, which is absent in all other Bordetella species, has a significantly lower GC-content than the genome-wide average, suggesting acquisition of this locus via horizontal gene transfer from a currently unknown source. The CRISPR array is transcribed and processed into mature CRISPR RNAs (crRNA), some of which have homology to prophages found in closely related species B. hinzii. CONCLUSIONS: Expression of the CRISPR-Cas system and processing of crRNAs with perfect homology to prophages present in closely related species, but absent in that containing this CRISPR-Cas system, suggest it provides protection against phage predation. The 3,117-bp cas9 endonuclease gene from this novel CRISPR-Cas system is 990 bp smaller than that of Streptococcus pyogenes, the 4,017-bp allele currently used for genome editing, and which may make it a useful tool in various CRISPR-Cas technologies.
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The advancements, challenges, and future implications of the CRISPR/Cas9 system in swine research.
Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) genome editing technology has dramatically influenced swine research by enabling the production of high-quality disease-resistant pig breeds, thus improving yields. In addition, CRISPR/Cas9 has been used extensively in pigs as one of the tools in biomedical research. In this review, we present the advancements of the CRISPR/Cas9 system in swine research, such as animal breeding, vaccine development, xenotransplantation, and disease modeling. We also highlight the current challenges and some potential applications of the CRISPR/Cas9 technologies.
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Multigene editing via CRISPR/Cas9 guided by a single-sgRNA seed in Arabidopsis.
We report that a solo single-guide RNA (sgRNA) seed is capable of guiding Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR -associated 9 (CRISRP/Cas9) to simultaneously edit multiple genes AtRPL10A, AtRPL10B and AtRPL10C in Arabidopsis. Our results also demonstrate that it is possible to use CRISPR/Cas9 technology to create AtRPL10 triple mutants which otherwise cannot be generated by conventional genetic crossing. Compared to other conventional multiplex CRISPR/Cas systems, a single sgRNA seed has the advantage of reducing off-target gene-editing. Such a gene editing system might be also applicable to modify other homologous genes, or even less-homologous sequences for multiple gene-editing in plants and other organisms.
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CRISPR genome editing in food and feed crops: intellectual property challenges, global accessibility, and the Indian perspective.
The ever-increasing global demand for food and feed, coupled with population growth and climate change, necessitates the development of high-yielding and stress-resilient crops. CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology has emerged as a transformative genome-editing tool due to its efficiency, precision, and ability to generate targeted genetic modifications. This review highlights recent advances in CRISPR genome editing, including base editing, prime editing, and novel Cas variants, together with emerging approaches such as epigenome editing, mitochondrial genome editing, and hypercompact Cas systems, and their applications in improving crop productivity, stress tolerance, and nutritional quality. In food and feed crops, these applications also include crop-specific priorities such as grain and nutritional quality in food crops and digestibility, forage quality, and mineral bioavailability in feed and forage crops. Particular emphasis is placed on the complex intellectual property (IP) landscape surrounding CRISPR technologies, including patents on editing systems, delivery platforms, and proprietary vectors. These intellectual property barriers can restrict research access, technology transfer, and commercialization, particularly in developing countries. The review further discusses patent limitations, licensing frameworks, and strategies to enhance equitable global access through collaborative approaches such as non-exclusive licensing, humanitarian licensing, indigenous technology development, and international partnerships. Overall, the review underscores the need to balance innovation, intellectual property protection, and global accessibility to ensure that CRISPR-based technologies contribute effectively to worldwide food and feed security and sustainable agriculture.
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[Seamless genome editing in Drosophila by combining CRISPR/Cas9 and piggyBac technologies].
The type2 CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR- associated protein 9) is an efficient RNA-guided genome-editing technique. Guided by sgRNA, the Cas9 endonuclease generates site-specific double-stranded breaks (DSB) at specific site, which is amenable to repair by homology-directed repair (HDR) to generate a designed knock-out or knock-in transgene. In combination with CRISPR/Cas9 and Cre/loxP or FLP/FRT system, efficient gene targeting can be achieved, and meanwhile screening markers introduced can be readily removed except a 34-base pair residual fragment. Thus, difficulties remain in accurate editing of the genome without introducing any extraneous sequences. In human induced pluripotent stem cells (iPSCs), a two-step strategy has been developed using CRISPR/Cas9 and the piggyBac system to establish a seamless genomic editing, in which CRISPR/Cas9 is initially used to introduce mutations along with screening markers by HDR, then the markers are precisely excised by piggyBac transposase. Using this strategy, we have successfully transformed the tyrosine to cysteine at position 21 within the 18th exon of the CG4894 gene in the Drosophila genome without introducing any extraneous sequence. Hence, this strategy provides more options for precise and seamless editing of the Drosophila genome.
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Gene editing in plants: assessing the variables through a simplified case study.
Multiple variables that control the relative levels of successful heritable plant genome editing were addressed using simple case studies in Arabidopsis thaliana. The recent advent of genome editing technologies (especially CRISPR, Clustered Regularly Interspaced Short Palindromic Repeats) has revolutionized various fields of scientific research. The process is much more specific than previous mutagenic processes and allows for targeting of nearly any gene of interest for the creation of loss-of-function mutations and many other types of editing, including gene-replacement and gene activation. However, not all CRISPR construct designs are successful, due to several factors, including differences in the strength and cell- or tissue-type specificity of the regulatory elements used to express the Cas9 (CRISPR Associated protein 9) DNA nuclease and single guide RNA components, and differences in the relative editing efficiency at different target areas within a given gene. Here we compare the levels of editing created in Arabidopsis thaliana by CRISPR constructs containing either different promoters, or altered target sites with varied levels of guanine-cytosine base content. Additionally, nuclease activity at sites targeted by imperfectly matched single guide RNAs was observed, suggesting that while the primary goal of most CRISPR construct designs is to achieve rapid, robust, heritable gene editing, the formation of unintended mutations at other genomic loci must be carefully monitored.
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Homology-integrated CRISPR-Cas (HI-CRISPR) system for one-step multigene disruption in Saccharomyces cerevisiae.
One-step multiple gene disruption in the model organism Saccharomyces cerevisiae is a highly useful tool for both basic and applied research, but it remains a challenge. Here, we report a rapid, efficient, and potentially scalable strategy based on the type II Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR associated proteins (Cas) system to generate multiple gene disruptions simultaneously in S. cerevisiae. A 100 bp dsDNA mutagenizing homologous recombination donor is inserted between two direct repeats for each target gene in a CRISPR array consisting of multiple donor and guide sequence pairs. An ultrahigh copy number plasmid carrying iCas9, a variant of wild-type Cas9, trans-encoded RNA (tracrRNA), and a homology-integrated crRNA cassette is designed to greatly increase the gene disruption efficiency. As proof of concept, three genes, CAN1, ADE2, and LYP1, were simultaneously disrupted in 4 days with an efficiency ranging from 27 to 87%. Another three genes involved in an artificial hydrocortisone biosynthetic pathway, ATF2, GCY1, and YPR1, were simultaneously disrupted in 6 days with 100% efficiency. This homology-integrated CRISPR (HI-CRISPR) strategy represents a powerful tool for creating yeast strains with multiple gene knockouts.
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What is CRISPR/Cas9?
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CRISPR/Cas9 for cancer treatment: technology, clinical applications and challenges.
Clustered regularly interspaced short palindromic repeats (CRISPR) is described as RNA mediated adaptive immune system defense, which is naturally found in bacteria and archaea. CRISPR-Cas9 has shown great promise for cancer treatment in cancer immunotherapy, manipulation of cancer genome and epigenome and elimination or inactivation of carcinogenic viral infections. However, many challenges remain to be addressed to increase its efficacy, including off-target effects, editing efficiency, fitness of edited cells, immune response and delivery methods. Here, we explain CRISPR-Cas classification and its general function mechanism for gene editing. Then, we summarize these preclinical CRISPR-Cas9-based therapeutic strategies against cancer. Moreover, the challenges and improvements of CRISPR-Cas9 clinical applications will be discussed.
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Genome Editing Enhanced Abiotic Stress ToleranceIn Cereal Crops.
Cereals are crucial sources of food for human and animal populations worldwide. Their grain and fodder primarily serve as sources of energy and nutrition. Cereal production is hampered because of the prevalent abiotic stress worldwide. Abiotic stresses such as drought, salinity, extreme temperatures, and heavy metal toxicity significantly reduce global cereal crop production. Previously, traditional breeding and transgenic technology have been promising and potent approaches used to mitigate unfavourable abiotic stresses, enhancing crop production to some extent. The recent advent of more potent genome-editing technologies, particularly Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), has revolutionized the pace of crop improvement programs. Genome-editing technology using engineered nucleases offers significant opportunities for crop improvement. Genome editing tools include Meganucleases, Zinc Finger Nucleases (ZFN), Transcription activator-like effector nucleases (TALENs), and CRISPR/CRISPR-associated protein (Cas). Among all genome-editing tools, CRISPR/Cas9 has been widely used to improve crop cultivars due to its specificity, simplicity, robustness, and flexibility. Recent progress in genome-editing technology have improved various plant traits in cereals. Among these traits, cereal genotypes have shown substantial advances in the last decade, particularly in enhanced tolerance to abiotic stress, enabled by genome-editing tools. This review summarizes the recently developed cereal cultivars for abiotic stress tolerance that employ different genome-editing technologies, including the most recent additions, prime editing and base editing. These improved cereal cultivars perform better and maintain higher yields under adverse abiotic stresses.
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