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Showing: 41 - 60 of 421 results
  1. CrispyCrunch: High-throughput Design and Analysis of CRISPR+HDR Experiments

    Type
    Blog Post
    Published
    Feb. 7, 2019, 2:16 p.m.
    ...CrispyCrunch is how it mutates guide sequences to prevent re-cutting of the sequence inserted by HDR. Although this...algorithm then compares the guide sequence to every possible 23bp sequence (protospacer + PAM) in the target... often because the HDR inserted sequence splits up the guide sequence.) If neither of the above are options...codons in the guide sequence, one by one, from the PAM outwards so that the DNA sequence is altered but the...needed to design guide RNAs, donor templates and sequencing primers for quality control. At such a scale,...requires the additional step of mutating guide sequences in a way that prevents re-cutting but does not...not be enough to prevent re-binding. Lastly, the sequence inserted by HDR may inadvertently re-create a ...
  2. Optimizing Donor DNA for Enhanced CRISPR Genome Editing

    Type
    Blog Post
    Published
    March 24, 2016, 2:30 p.m.
    ...end-joining (NHEJ) pathway disrupt target gene sequences (thus inactivating genes), while breaks repaired... directed repair (HDR) pathways can modify the sequence of a gene (thus altering its function). HDR is...rational approach to improve the efficiency of sequence replacement by HDR. Understanding Cas9 biophysics...from in vitro studies) to boost the efficiency of sequence replacement in vivo. We discovered that single...from Richardson et al., 2016.   dCas9 enables sequence replacement without cutting Our in vitro results... thus wondered if such a structure could drive sequence replacement in cells. Targeting three dCas9 molecules...molecules to a precisely spaced region allowed sequence replacement rates of approximately 1%. This is...
  3. Progress Towards a PAM-Free CRISPR

    Type
    Blog Post
    Published
    March 7, 2024, 2:39 p.m.
    ...sneaky little bit of sequence that you hope is present next to the "perfect" guide sequence for your genome... a Protospacer Adjacent Motif (PAM) sequence. If the gRNA sequence is suitable, but there is no PAM next...typically selected by the ‘quality’ of the gRNA sequence, including propensity for off-targets, secondary...To add insult to injury, the most utilized PAM sequence, that of SpCas9, is NGG. Assuming all nucleotides...Cas enzyme or evolve one that uses a PAM with no sequence constraints, or at least has looser or different...such as Cpf1/Cas12a, which recognizes the PAM sequences of TTTV. While all of these enzymes certainly ...equal; just because an enzyme recognizes a PAM sequence in your site doesn’t mean it’s suitable for your...
  4. How to Deposit Your Plasmids with Addgene

    Type
    Blog Post
    Published
    Feb. 27, 2024, 2:15 p.m.
    ...   Step 1: Sequences, Maps, and Files Please provide any full or partial plasmid sequences and any vector...The more sequence data available, the better. We highly encourage you to upload full sequence data whenever...files, etc). We can accept sequence files in any format. Figure 6: Add sequence, maps, and files. Step 2...addgene.org along with your GenBank files, plasmid sequences, and/or maps. Add plasmids to your article After...plasmid with one or more genes, protein coding sequences, or other elements inserted into it. You will ...shRNA A plasmid with one or more gRNA or shRNA sequences cloned into it. gRNAs are used for directing CRISPR...expression of mRNAs with complementarity to the shRNA sequence. Empty backbone A plasmid designed for cloning...
  5. Anatomy of a Plasmid Page at Addgene

    Type
    Blog Post
    Published
    Feb. 4, 2016, 3:30 p.m.
    ... from Addgene’s sequencing reactions (‘Addgene Sequences’).  These sequences are provided in FASTA format... your research! Sequence information: Depositors may provide full or partial sequence information for ...be made available as ‘Depositor Sequences’. Additional partial sequence information is also available from...auto-generate a plasmid map based off of the plasmid sequence and feature information given by our depositors...example) and can be analyzed using Addgene’s Analyze Sequence tool. Excellent, how can I check if the plasmid... own lab.  If depositors have provided primer sequences for use, these are listed.  We also provide a ...a link to our list of common primers used for sequencing. Growth in Bacteria: This section describes how...
  6. Plasmids 101: Methylation and Restriction Enzymes

    Type
    Blog Post
    Published
    June 30, 2016, 2:30 p.m.
    ...specific DNA sequences and companion endonucleases that recognizes and cleave the same DNA sequence if not ...methyltransferases, methylate DNA at particular sequences to prevent them from being degraded by restriction...with any restriction modification systems, their sequences may overlap with restriction sites, inhibiting...therefore have methylated adenines in any GATC sequences found in the plasmid. When the PCR products are...plasmids which can later be verified by Sanger sequencing. How can I tell if my enzyme will cut? Whether...enzyme is affected by methylation, knowing the sequence of the DNA surrounding your restriction site(s...methylation), the figure below illustrates how sequence visualization software (we used Snapgene here)...
  7. A Needle in a Base-Stack: Cas9 Structural Biology

    Type
    Blog Post
    Published
    June 4, 2024, 1:15 p.m.
    ...the DNA and test for sequence complementarity with its guide RNA. If the sequence is recognized, Cas9 ...bases, or why it’s so important to choose a target sequence with a nearby protospacer-adjacent motif (PAM)...recognize PAMs, so it associates with random DNA sequences (Sternberg et al., 2014). The nuclease lobes are...editing requires three major steps: RNA loading, DNA sequence recognition, and DNA cleavage. RNA loading Once... (left) and transparent (right). The RNA guide sequence is extended as a single unpaired strand in the...anti-repeat duplex of the guide RNA, confirming its sequence. This region of the protein varies between Cas9... RNA loading: the structure to interrogate the sequence isn’t in place yet.     Figure 4: S. pyogenes...
  8. 3 Tips to Improve HDR Efficiency for CRISPR Editing in Human Cells

    Type
    Blog Post
    Published
    Sept. 5, 2017, 1:58 p.m.
    ...introduction of specific sequence changes. To generate a specific sequence change the cell must undergo...CRISPR/Cas9 extensively for the purpose of making sequence-specific changes in human induced pluripotent ...oligodeoxynucleotide (ssODN), which contains the intended sequence changes to be incorporated into the edited genome...our excitement turned into frustration when we sequenced our cells and found how inefficiently our edits... – but avoid NAG) or guide RNA target (“seed”) sequence. The idea was that these “blocking mutations” ...mutations prevent CRISPR from re-cutting the target sequence once the desired edit has been introduced. We ...So if the locus does not allow blocking the PAM sequence (e.g. if it would lead to a missense or nonsense...
  9. Plasmids 101: Sequence and Ligation Independent Cloning (SLIC)

    Type
    Blog Post
    Published
    Sept. 26, 2024, 1:15 p.m.
    ...issue is sequence similarity. If fragments in a multicomponent assembly have 5′ or 3′ sequence homology...If cloning methods had personalities, SLIC (sequence- and ligation-independent cloning) would be a true...reliable cloning method, but it is limited by its sequence constraints. The long overhangs must not contain... often limited to specially designed plasmids. Sequence- and ligation-independent cloning: A SLIC makeover...depositor Stephen Elledge. His new method, named sequence- and ligation-independent cloning (SLIC), eliminated...and linearized vectors must have homologous DNA sequences (20–60 bp) on either end and single-stranded 5...multicomponent assembly, as fragments with overlapping sequence homology can be assembled in a unique order with...
  10. Plasmids 101: Cre-lox

    Type
    Blog Post
    Published
    Jan. 13, 2015, 3:47 p.m.
    ... long asymmetric core spacer sequence. The asymmetry in the core sequence gives the loxP site directionality...the canonical loxP sequence is ATAACTTCGTATA-GCATACAT-TATACGAAGTTAT. The loxP sequence does not occur naturally...in P1) sites are 34-base-pair long recognition sequences consisting of two 13-bp long palindromic repeats...inserting loxP sites at deliberate locations in a DNA sequence allows for very specific manipulations as discussed...or on separate pieces of DNA. Both 13bp repeat sequences on a single loxP site are recognized and bound...: If the sites face in the same direction, the sequence between the loxP sites is excised as a circular...indicates which bases may vary from the canonical sequence. Among these are loxN (GtATACcT), lox2272 (GgATACtT...
  11. Plasmids 101: Using Transposons in the Lab

    Type
    Blog Post
    Published
    July 6, 2021, 1:28 p.m.
    ...: The transposon is the DNA sequence that moves around. This DNA sequence encodes the proteins the transposon...the protein that’s required for the transposon sequence to move from one DNA site to another. This protein...Different transposons insert at different DNA sequences or target sites. Integration of most transposable...results in the duplication of this target site sequence at the site of insertion.  Types of transposons...behind the CAG DNA footprint from its terminal sequences at the excision site after cleavage by the transposase...transposons, it does not leave behind a DNA footprint sequence after excision. piggyBac can mobilize DNA over...Beauty and piggyBac, Tol2 has a weak consensus sequence for its preferred target integration site: TNA...
  12. Four Ways to Package Transgenes That Exceed the Size Limit of Adeno-associated Virus

    Type
    Blog Post
    Published
    Sept. 1, 2020, 1:15 p.m.
    ... site donor and acceptor sequences were tested and with the optimal sequences, the group achieved ~80%... non-endogenous sequences, such as a 77bp long highly recombinogenic homology sequence derived from the...trans-plicing, splice site donor and acceptor sequences are used to reconstitute the two pieces of the...step, but optimization of the exon-splitting site sequence can enhance the rate of trans-splicing (Lai et..., the 5’ half of the transgene, a splice donor sequence and the region of homology. The AAV encoding part...contains the region of homology, a splice acceptor sequence, the 3’ half of the transgene. The full length...mechanism. The splice site donor and acceptor sequences and the homologous region of the two vectors can...
  13. Visualizing Genomic Loci with CRISPR-Sirius

    Type
    Blog Post
    Published
    April 18, 2019, 12:53 p.m.
    ...localized to specific loci based on the guide RNA sequence. A year later, they developed CRISPRainbow (Ma...set of gRNA scaffolds that contain two hairpin sequences (either MS2, PP7, or boxB) that each recruits ... CRISPRainbow labeling. Two MS2, PP7, or boxB sequences inserted into the sgRNA generates blue, green,... labeling. A combination of MS2, PP7, or boxB sequences in the same sgRNA will generate additional colors...living cells. Broccoli aptamers are nucleic acid sequences that bind to the small molecule, DFHBI-1T to induce...of the success of the MS2 and PP7 RNA hairpin sequences in CRISPRainbow, they knew they could be good ...created another sgRNA containing the PP7 hairpin sequence (sgRNA-Sirius-8XPP7) to recruit GFP to the loci...
  14. CRISPR 101: Making a Knock-In Cell Line

    Type
    Blog Post
    Published
    Dec. 22, 2022, 2:15 p.m.
    ...homologous sequence to the right and/or left of the knock-in site. The length of that sequence and the makeup...Knock-in mutations typically require an exact DNA sequence to be incorporated at a precise genomic location...introduce the edit. Finally, you must stipulate what sequence to introduce, which is done through the design...to the targeted locus on either side of the new sequence. This homology will guide the cell to use the ...which will result in the incorporation of your sequence, a.k.a a knock-in! So how does the donor get used... can efficiently knock-in a few hundred bps of sequence. However, if you have a larger knock-in (200 bp...al., Nat Chem Biol). Mutate the PAM or sgRNA sequences Cas9 likely goes through multiple rounds of cleavage...
  15. Golden Gate Assembly Upgrades: More Fragments, Faster Assembly, and Higher Fidelity

    Type
    Blog Post
    Published
    Oct. 11, 2018, 12:30 p.m.
    ...achieved by the sequencing of plasmids isolated from blue or white colonies. Sequencing of blue colonies...showed the expected complete sequence for the lacI/lacZ genes (1), while sequencing of white colonies showed...overhang sequences under standard reaction conditions. This data set allows quantitation of sequence-dependent...restriction enzymes and careful choice of junction sequences guided by experimentally-derived DNA Ligase fidelity...indicating successful reconstruction of the coding sequence for beta-galactosidase in the lacI/lacZ cassette... Gate assembly through application of ligation sequence-dependent fidelity and bias profiling." bioRxiv... Potapov, Vladimir, et al. "A single-molecule sequencing assay for the comprehensive profiling of T4 DNA...
  16. Viral Vectors 101: Gamma-Retroviral Packaging Systems

    Type
    Blog Post
    Published
    Aug. 6, 2024, 1:15 p.m.
    ...interest: The transgene sequence is flanked by long terminal repeat (LTR) sequences, which facilitate integration...the transfer plasmid sequences into the host genome. Typically, it is the sequences between and including...Leukemia Virus) or MSCV (Murine Stem Cell Virus) sequences. Packaging genes (viral Gag-Pol): Gag is a structural...virus post‐transcriptional regulatory element; sequence that stimulates the expression of transgenes via...the 5' and 3' ends of the provirus). Contains sequences necessary for activation of viral genomic RNA ...the addition of a poly A tract just after the R sequence. This post was written and updated by multiple...
  17. Plasmids 101: How to Verify Your Plasmid Using a Restriction Digest Analysis

    Type
    Blog Post
    Published
    Aug. 28, 2014, 3:34 p.m.
    ...expected sequence. Here at Addgene, we use NGS-based quality control to confirm the sequence of all the...cleaving sequences which are similar, but not identical, to their defined recognition sequence. Most enzyme...successfully even if you don't have the full plasmid sequence. Once you have purified plasmid DNA, this method...NCBI for YGOI to find the particular reference sequence if necessary. The example plasmid on the right... dna sequencing results...
  18. xCas9: Engineering a CRISPR Variant with PAM Flexibility

    Type
    Blog Post
    Published
    March 28, 2018, 6:52 p.m.
    ...CRISPR enzymes require a short PAM sequence adjacent to the targeted sequence at the locus of interest. SpCas9...engineered alternative Cas9s binding distinct PAM sequences. Now, Hu et al., working in David Liu’s lab, have...PAM-interacting domain. However, these alternative PAM sequences are longer and often more complex than NGG, resulting... for and interest in enzymes with shorter PAM sequences and/or broader PAM flexibility. Creating xCas9...plasmid library contained all 64 possible NNN PAM sequences adjacent to a protospacer. If ω-dCas9 could recognize...permitting phage propagation and keeping that dCas9 sequence in the pool. According to this logic, ω-dCas9 ...off-target effects across 5 gRNAs with NGG PAM sequences were actually lower for xCas9 3.6/3.7 than for...
  19. Advanced Uses of Cre-lox and Flp-FRT - A Neuroscientist’s View

    Type
    Blog Post
    Published
    Oct. 19, 2017, 1:54 p.m.
    ...adding a nuclear localization sequence (SV40 Large T nuclear localization sequence) and expressing it from ... of the DNA sequence of interest can lead to poor expression of genes within that sequence and should ...between target sites of the same sequence in FLEx vectors, the DNA sequence that should be inverted is flanked...differ in their sequence. Recombination between the two target sites with identical sequence leads to inversion...when it was discovered that it is not the exact sequence of the asymmetric target site core but its 8 bp...inversion of the flanked DNA sequence and the interior target sites. In a second step, the two compatible...
  20. Channelrhodopsins with improved light sensitivity for minimally-invasive optogenetics

    Type
    Blog Post
    Published
    Nov. 3, 2020, 2:15 p.m.
    ...recombinant channelrhodopsin sequences. The model first removed sequences from the library predicted to...reducing the library to 1,161 sequences. Thirty of these remaining sequences were selected for characterization...to have improved photocurrent properties: The sequence and structures that determine membrane expression...model was trained to predict if a channelrhodopsin sequence would result in a functional channelrhodopsin,...library of ~120,000 predicted channelrhodopsin sequences would have photocurrent properties best suited...for less-invasive optogenetics experiments. The sequences in this library were designed using structural...
Showing: 41 - 60 of 421 results