Both double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) targets can activate the trans-cleaving activity (also known as collateral cleavage) of Cas12a, similar to Cas12b. However, the efficiency differs: ssDNA targets activate Cas12b trans-cleaving activity more efficiently than dsDNA targets, while dsDNA targets activate Cas12a trans-cleaving activity more efficiently than ssDNA targets.

CRISPR detection reagents:
1.The RPA isothermal amplification kit can be stored at -20°C for long-term storage.
2.Target plasmids can be stored at -20°C for long-term use.
3.Cas proteins are sensitive to repeated freeze-thaw cycles; it is recommended to aliquot into multiple tubes and store at -80°C, retrieving them as needed for experiments. For short-term use, they can be stored at -20°C.
4.crRNA is prone to degradation and should be stored at -80°C if not used in the short term.
5. Probes, being double-stranded DNA, are relatively stable and can be stored at -20°C.

1.Design an efficient crRNA sequence. Proper design and structure prediction using online resources can help select suitable crRNA to achieve good trans-cleavage activity of the Cas enzyme.
2.Choose an appropriate signal reporter substrate. Research indicates that using a 15 nt single-stranded DNA (ssDNA) as a reporter substrate maximizes the cleavage reaction rate of Cas12a, significantly enhancing the reaction rate compared to the commonly used 5-nt ssDNA.
3.Optimize reaction conditions and buffers. Adjusting the CRISPR reaction parameters, such as the ratio of Cas enzyme to crRNA, the concentration of the Cas enzyme, and the reaction temperature, can improve detection performance to some extent.

1.The design process can follow these steps:
1.Identify the target gene sequence.
2.Specify the Cas protein being used. Different Cas proteins require corresponding PAM (Protospacer Adjacent Motif) sequences; for instance, Cas12a needs the "TTTV" PAM sequence for target recognition.
3.Select the crRNA targeting region. Choose a 20 nt nucleotide sequence on the target gene that is adjacent to the PAM site and pairs with the complementary strand of the crRNA.
4.Combine the selected 20 nt target sequence (variable part) with the scaffold sequence (fixed part) to design the crRNA sequence.
5.Use online tools such as CRISPR design tools (e.g., CRISPOR, Benchling, etc.) to assist in designing crRNA. These tools can predict the efficiency and specificity of the sgRNA, helping to avoid potential off-target effects.
6.After completing the design, the synthetic crRNA sequence can be ordered from a synthetic biology company.

During vector amplification, Escherichia coli (E. coli) strains are typically used. The commonly used strain for most non-recombinant vectors is DH5α, which is suitable for most applications. For recombinant vectors, such as lentiviral vectors and transposon vectors, the Stbl3 strain can be used for amplification. Stbl3 is a specialized E. coli strain derived from HB101, which has a mutation in the recombinase gene recA13, effectively suppressing recombination of long fragment terminal repeat regions and reducing the likelihood of erroneous recombination.

When selecting a vector, consider the purpose of the experiment and the type of host cells. For example, plasmid vectors are commonly used for gene expression or amplification in bacteria, while viral vectors are more suitable for gene transfer in mammalian cells. Additionally, the vector's promoter, replicon, and antibiotic selection markers should be chosen based on specific requirements.

During vector amplification, Escherichia coli (E. coli) strains are typically used. The commonly used strain for most non-recombinant vectors is DH5α, which is suitable for most applications. For recombinant vectors, such as lentiviral vectors and transposon vectors, the Stbl3 strain can be used for amplification. Stbl3 is a specialized E. coli strain derived from HB101, which has a mutation in the recombinase gene recA13, effectively suppressing recombination of long fragment terminal repeat regions and reducing the likelihood of erroneous recombination.

During vector amplification, Escherichia coli (E. coli) strains are typically used. The commonly used strain for most non-recombinant vectors is DH5α, which is suitable for most applications. For recombinant vectors, such as lentiviral vectors and transposon vectors, the Stbl3 strain can be used for amplification. Stbl3 is a specialized E. coli strain derived from HB101, which has a mutation in the recombinase gene recA13, effectively suppressing recombination of long fragment terminal repeat regions and reducing the likelihood of erroneous recombination.

Lentivirus is a gene delivery tool that introduces exogenous genes into cells. By using tool cells such as 293T, lentiviral vectors carrying target DNA fragments are packaged into lentiviral particles with cell-infectious activity. This packaging process includes constructing lentiviral vectors, preparing packaging plasmids, culturing tool cells, transfecting plasmids, collecting viral particles, purifying and concentrating viral particles, and titration.

Lentiviruses have high transduction efficiency and the ability to maintain stable gene expression over the long term, making them particularly suitable for cell types that are difficult to transfect. Furthermore, lentiviruses can integrate exogenous genes into the host genome, ensuring prolonged gene expression.

4.Poor cell condition after lentiviral infection may be caused by various factors. Here are some possible reasons and corresponding solutions: 1.High viral titer: High titers of lentivirus may cause cytotoxicity, preventing normal cell growth. Solution: Lower the viral titer and conduct a series of dilution experiments to find a titer that effectively transduces without adversely affecting cell growth. 2.Poor cell condition: The health status of cells before infection can affect growth after infection. Solution: Ensure cells are in optimal condition for infection, for example, by changing to fresh culture medium 24 hours before infection and ensuring appropriate cell density. 3.Toxicity of gene expression mediated by the virus: The gene carried by the lentiviral vector may be toxic to the cells, affecting their growth. Solution: If possible, use a control vector to determine if the problem is related to gene expression, and select appropriate vectors or genes for research. 4.Excessive antibiotic selection pressure: If antibiotics are used to select transfected cells, excessive concentrations of antibiotics may inhibit cell growth. Solution: Optimize the antibiotic concentration and use gradient experiments to determine the optimal concentration.

Prime Editing is a novel gene editing technology that enables precise gene editing without introducing double-strand DNA breaks. It has two core components: pegRNA and the PEmax gene-editing enzyme (Cas9n-RT). PegRNA not only targets the desired sequence but also contains the base modification information. In the editing system, pegRNA guides PEmax to the designated edit site, nicks the DNA single strand, and reverse transcribes the sequence within the pegRNA to modify, inserting it into the target genome location, thereby achieving precise single-base substitutions or small insertions and deletions

EDITGENE’s newly upgraded seventh-generation Bingo™ Prime Editing (PE7) platform optimizes editing protein and RNA editing activity. Compared to the fifth-generation PE technology, point mutation success rates and gene editing efficiency have significantly improved, with one-on-one support from PhDs from globally renowned institutions.

EDITGENE’s Bingo™ Prime Editing 7 (PE7) platform is built upon over ten years of gene editing experience, with optimization and advancements derived from thousands of gene editing CRO projects, achieving significantly higher success rates than traditional site-specific mutation systems. The Bingo™ Prime platform utilizes highly efficient reverse transcriptase and precise guide RNA design, ensuring each point mutation reaches the desired outcome.

Not all genes are suitable for knockout. Some gene knockouts may result in cell death or severe dysfunction, particularly for essential genes. In such cases, conditional knockouts or gene knockdowns (e.g., RNAi) may be used instead.