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Disruption of G0/G1 switch gene 2 ( G0S2) reduced abdominal fat deposition and altered fatty acid composition in chicken.
Chicken as a food source is one of the most widespread domestic animals, and it has been used extensively as a research model. The clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) system is the most efficient and reliable tool for precise genome-targeted modification and has generated considerable excitement for industrial applications, as well as biologic science. Unlike in mammals, germline-transmittable primordial germ cells (PGCs) in chicken were used as an alternative strategy for the production of genetically altered chickens. Here, by combining the CRISPR-Cas9 platform and germ cell-mediated germline transmission, we generated G0/G1 switch gene 2 ( G0S2) knockout (KO) chickens, and G0S2 null KO chickens showed a dramatic reduction of abdominal fat deposition without affecting other economic traits. Additionally, G0S2 null KO chickens had altered fatty acid compositions in their blood and abdominal fat compared with wild-type chickens under normal dietary conditions. The global mRNA sequencing data showed that G0S2 disruption in chickens would activate the adipose tissue-specific peroxisomal oxidation pathway, and enoyl-coenzyme A (CoA), hydratase/3-hydroxyacyl CoA dehydrogenase might be a target molecule in metabolic homeostasis in the chicken adipose tissue. Our results demonstrate that the CRISPR-Cas9 system with chicken PGCs can facilitate the production of specific genome-edited chickens for practical applications, as well as basic research.-Park, T. S., Park, J., Lee, J. H., Park, J.-W., Park, B.-C. Disruption of G0/G1 switch gene 2 ( G0S2) reduced abdominal fat deposition and altered fatty acid composition in chicken.
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Advances and Perspectives in Tissue Culture and Genetic Engineering of Cannabis.
For a long time, Cannabis sativa has been used for therapeutic and industrial purposes. Due to its increasing demand in medicine, recreation, and industry, there is a dire need to apply new biotechnological tools to introduce new genotypes with desirable traits and enhanced secondary metabolite production. Micropropagation, conservation, cell suspension culture, hairy root culture, polyploidy manipulation, and Agrobacterium-mediated gene transformation have been studied and used in cannabis. However, some obstacles such as the low rate of transgenic plant regeneration and low efficiency of secondary metabolite production in hairy root culture and cell suspension culture have restricted the application of these approaches in cannabis. In the current review, in vitro culture and genetic engineering methods in cannabis along with other promising techniques such as morphogenic genes, new computational approaches, clustered regularly interspaced short palindromic repeats (CRISPR), CRISPR/Cas9-equipped Agrobacterium-mediated genome editing, and hairy root culture, that can help improve gene transformation and plant regeneration, as well as enhance secondary metabolite production, have been highlighted and discussed.
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First Report of CRISPR/Cas9 Mediated DNA-Free Editing of 4CL and RVE7 Genes in Chickpea Protoplasts.
The current genome editing system Clustered Regularly Interspaced Short Palindromic Repeats Cas9 (CRISPR/Cas9) has already confirmed its proficiency, adaptability, and simplicity in several plant-based applications. Together with the availability of a vast amount of genome data and transcriptome data, CRISPR/Cas9 presents a massive opportunity for plant breeders and researchers. The successful delivery of ribonucleoproteins (RNPs), which are composed of Cas9 enzyme and a synthetically designed single guide RNA (sgRNA) and are used in combination with various transformation methods or lately available novel nanoparticle-based delivery approaches, allows targeted mutagenesis in plants species. Even though this editing technique is limitless, it has still not been employed in many plant species to date. Chickpea is the second most crucial winter grain crop cultivated worldwide; there are currently no reports on CRISPR/Cas9 gene editing in chickpea. Here, we selected the 4-coumarate ligase (4CL) and Reveille 7 (RVE7) genes, both associated with drought tolerance for CRISPR/Cas9 editing in chickpea protoplast. The 4CL represents a key enzyme involved in phenylpropanoid metabolism in the lignin biosynthesis pathway. It regulates the accumulation of lignin under stress conditions in several plants. The RVE7 is a MYB transcription factor which is part of regulating circadian rhythm in plants. The knockout of these selected genes in the chickpea protoplast using DNA-free CRISPR/Cas9 editing represents a novel approach for achieving targeted mutagenesis in chickpea. Results showed high-efficiency editing was achieved for RVE7 gene in vivo compared to the 4CL gene. This study will help unravel the role of these genes under drought stress and understand the complex drought stress mechanism pathways. This is the first study in chickpea protoplast utilizing CRISPR/Cas9 DNA free gene editing of drought tolerance associated genes.
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Genome Editing in Potato with CRISPR/Cas9.
Cultivated potato, Solanum tuberosum Group Tuberosum L. (2n = 4x = 48) is a heterozygous tetraploid crop that is clonally propagated, thereby resulting in identical genotypes. Due to the lack of sexual reproduction and its concomitant segregation of alleles, genetic engineering is an efficient way of introducing crop improvement traits in potato. In recent years, genome-editing via the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system for targeted genome modifications has emerged as the most powerful method due to the ease in designing and construction of gene-specific single guide RNA (sgRNA) vectors. These sgRNA vectors are easily reprogrammable to direct Streptococcus pyogenes Cas9 (SpCas9) to generate double stranded breaks (DSBs) in the target genomes that are then repaired by the cell via the error-prone non-homologous end-joining (NHEJ) pathway or by precise homologous recombination (HR) pathway. CRISPR/Cas9 technology has been successfully implemented in potato for targeted mutagenesis to generate knockout mutations (by means of NHEJ) as well as gene targeting to edit an endogenous gene (by HR). In this chapter, we describe procedures for designing sgRNAs, protocols to clone sgRNAs for CRISPR/Cas9 constructs to generate knockouts, design of donor repair templates and use geminivirus replicons (GVRs) to facilitate gene-editing by HR in potato. We also describe tissue culture procedures in potato for Agrobacterium-mediated transformation to generate gene-edited events along with their molecular characterization.
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Inducible CRISPRi enables efficient and high-fidelity genome editing in Streptomyces.
Streptomycetes are prolific producers of bioactive natural products, but many of the biosynthetic gene clusters (BGCs) are silent in the laboratory. Genetic manipulation is important to unlock their full potential. CRISPR-Cas-based genome editing has greatly advanced genetic engineering in Streptomyces. However, several challenges remain, including Cas nuclease toxicity, unintended genomic rearrangements, and elimination of the delivery plasmid. Here, we present a novel genome editing strategy that harnesses cumate-inducible CRISPR interference (CRISPRi) to transiently knockdown essential genes such as divIVA or dnaA as counterselectable marker. This enforces loss of the vector backbone, promotes homologous recombination, and yields markerless mutants by loss of the antibiotic resistance cassette during the final recombination step. We demonstrate the versatility of the ICE system (Inducible CRISPRi targeting an Essential gene) by (i) deleting four BGCs in Streptomyces coelicolor M145, (ii) inserting both a promoter and a large BGC, and (iii) introducing precise single-nucleotide substitutions. Furthermore, deletion of the prodigiosin BGC elicited expression of a poorly expressed BGC for prolinolexin lipopeptides in Streptomyces roseifaciens DSM 106196T. Considering that different essential genes may be targeted, we anticipate that inducible CRISPRi-based counterselection may be adaptable to genome editing strategies in a broad range of microbial systems.
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Exploring pigment-producing Streptomyces as an alternative source to synthetic pigments: diversity, biosynthesis, and biotechnological applications. A review.
The increasing health and environmental concerns associated with synthetic pigments have intensified the global search for natural, eco-friendly alternatives. Among microbial sources, Streptomyces, a genus within the class Actinomycetia, has emerged as a prolific source of bioactive pigments with wide-ranging industrial applications. The review provides a comprehensive synthesis of pigment-producing Streptomyces, focusing on their ecological diversity, biosynthetic pathways, and taxonomic relevance. This review has discussed key pigment classes, including melanin, prodiginine, quinone, and actinorhodin, with their bioactive properties, such as antioxidants, antimicrobials, and anticancer. The review further emphasizes recent advancements in synthetic biology, including clustered regularly interspaced short palindromic repeats/CRISPR-associated (CRISPR/Cas)-based gene editing, which has facilitated the activation of silent biosynthetic gene clusters (BGCs) that can enhance pigment yield. Additionally, this review discusses the optimization and fermentation protocols, industrial scalability, and the application of pigments in food, pharmaceutical, cosmetic, textile, and environmental sectors. Despite these advancements, critical research gaps persist, particularly in toxicological evaluation, pigment stability under industrial conditions, high-throughput screening of unexplored Streptomyces strains, and the integration of AI-based predictive tools for pathway optimization. Addressing these gaps is essential to unlocking the full potential of Streptomyces-derived pigments to replace harmful synthetic colorants.
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Comprehensive Analysis of CRISPR/Cas9-Mediated Mutagenesis in Arabidopsis thaliana by Genome-wide Sequencing.
The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) system has been widely applied in functional genomics research and plant breeding. In contrast to the off-target studies of mammalian cells, there is little evidence for the common occurrence of off-target sites in plants and a great need exists for accurate detection of editing sites. Here, we summarized the precision of CRISPR/Cas9-mediated mutations for 281 targets and found that there is a preference for single nucleotide deletions/insertions and longer deletions starting from 40 nt upstream or ending at 30 nt downstream of the cleavage site, which suggested the candidate sequences for editing sites detection by whole-genome sequencing (WGS). We analyzed the on-/off-target sites of 6 CRISPR/Cas9-mediated Arabidopsis plants by the optimized method. The results showed that the on-target editing frequency ranged from 38.1% to 100%, and one off target at a frequency of 9.8%-97.3% cannot be prevented by increasing the specificity or reducing the expression level of the Cas9 enzyme. These results indicated that designing guide RNA with high specificity may be the preferred factor to avoid the off-target events, and it is necessary to predict or detect off-target sites by WGS-based methods for preventing off targets caused by genome differences in different individuals.
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Friend or Foe? Evidence Indicates Endogenous Exosomes Can Deliver Functional gRNA and Cas9 Protein.
The clustered regularly interspaced short palindromic repeats (CRISPR)/associated nuclease (Cas) system is an efficient gene editing tool. In this study, it is found that both single guide RNA (gRNA) and Cas9 protein could be exported from the CRISPR/Cas9-expressing cells by endogenous exosomes independently. Further experiments demonstrate that these naturally produced endogenous exosomes could be used as a vehicle to deliver the functional Cas9 and hepatitis B virus (HBV)-specific gRNA to cut HBV DNA transfected in HuH7 cells or human papilloma virus (HPV)-specific gRNA to cut the integrated HPV DNA in HeLa cells, respectively. In conclusion, this study indicates the potential of endogenous exosomes as a safe and effective delivery vehicle of the functional gRNA and Cas9 protein. Meanwhile, the endogenous exosomes-mediated delivery of gene editing activity to adjacent and distant cells or tissues may further complicate the off-target and safety concerns about the CRISPR/Cas9 system.
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Questions Answered and Unanswered by the First CRISPR Editing Study in a Canine Model of Duchenne Muscular Dystrophy.
Clustered regularly interspaced short palindromic repeats (CRISPR) editing is being considered as a potential gene repair therapy to treat Duchenne muscular dystrophy, a dystrophin-deficient lethal muscle disease affecting all muscles in the body. A recent preliminary study from the Olson laboratory (Amoasii et al. Science 2018;362:89-91) showed robust dystrophin restoration in a canine Duchenne muscular dystrophy model following intramuscular or intravenous delivery of the CRISPR editing machinery by adeno-associated virus serotype 9. Despite the limitation of the small sample size, short study duration, and the lack of muscle function data, the Olson lab findings have provided important proof of principle for scaling up CRISPR therapy from rodents to large mammals. Future large-scale, long-term, and comprehensive studies are warranted to establish the safety and efficacy of CRISPR editing therapy in large mammals.
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Evaluation of CRISPR/CasRx-Mediated VEGF mRNA Knockdown in Mouse Retina.
Neovascular eye diseases (NEDs) are a group of diseases caused by the abnormal overgrowth of blood vessels in the eye. Normal vasculature is maintained through a dynamic balance of the vascular endothelial growth factor (VEGF). In diseases such as advanced diabetic retinopathy (DR) and neovascular age-related macular degeneration (AMD), an overexpression of VEGF leads to the formation of structurally weak and leaky blood vessels, resulting in vision impairment and, without intervention, legal blindness. In the clinic, NEDs are presently managed through anti-VEGF agents that specifically bind and neutralize VEGF signaling. While effective, this approach requires invasive intravitreal injections monthly and places a heavy burden on patients and healthcare providers. A flexible, long-lasting therapeutic that can reduce or eliminate frequent anti-VEGF treatment will significantly advance NED management.RNA editing with clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) is an emerging strategy to achieve reversible gene editing. The CRISPR-Cas13 system exclusively targets single-stranded RNA and allows gene silencing in a safe manner through RNA knockdown, as the genome is left intact. In addition, the compact CasRx enzyme (930aa) allows RNA silencing to be achieved through the delivery of a single adeno-associated virus (AAV), ideal for gene therapy applications. Herein, we outline methods to target VEGFA mRNA using CRISPR/CasRx in a mammalian cell line and humanized VEGFA transgenic mice.
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