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We narrowed to 956 results for: REP

Showing: 261 - 280 of 956 results

  1. Stabilized Bacterial Promoters: Constant Gene Expression at any Copy Number

    Type
    Blog Post
    ...trans-acting RepA protein under the control of IPTG. Because RepA is a plasmid replication initiator protein...genes closer to the origin of replication will be overrepresented compared to those further away. As a...increases, the amount of repressor protein also increases thereby intensifying repression of the gene of interest...problems. Rapidly dividing cells initiate genome replication more than once per cell division and thus, genes...regulation by using a promoter that is responsive to a repressor protein, the increase in expression due to copy...Segall-Shapiro et al., they chose a TALE protein as the repressor because TALEs can be programmed to bind tightly...sequences and have been shown to achieve ~100 fold repression in E. coli. In addition, TALEs bind non-cooperatively...

  2. CRISPR 101: Cytosine Transversion Editors

    Type
    Blog Post
    ...taking advantage of repair pathways within the cell — in some cases, the same repair pathways that were...an —NH2 (amine) group from the target base and replaced it with a double-bonded oxygen. This simple enzymatic...calling it the “edited strand.” Uracil excision repair leads to the first base transversion editor The...most CBEs include an inhibitor of base excision repair (BER), the cellular process that catches mutated...creating an “abasic,” or empty, DNA site, and then replacing the incorrect base with a G. Pro tip! Abasic sites...even better cytosine transversion editors. New DNA repair proteins fused to CGBEs Instead of using UNG, the...fusions of a CBE with other BER components: the DNA repair protein rXRCC1, or the DNA binding and lyase domain...

  3. Lambda Red: A Homologous Recombination-based Technique for Genetic Engineering

    Type
    Blog Post
    ...mismatch repair (MMR) system. MMR’s job is to correct DNA mismatches that occur during DNA replication. There... and repressor CI. For recombineering purposes, a temperature sensitive version of the repressor gene,...lowering the temperature allows the repressor to re-nature and again repress expression of exo, beta and gam...Overview of using Lambda Red recombineering system to replace a gene of interest with an antibiotic resistance...as non-selectable DNA fragments, such as gene replacements and tags.  The typical frequency of recombinants...targeted, it’s best to determine the direction of replication through your region of interest and design an...it’s easier to not determine the direction of replication and instead design oligos that target both strands...

  4. Plasmids 101: NGS Quality Control for Pooled Libraries

    Type
    Blog Post
    ...DNA, they grow and replicate, and then their DNA is harvested, much like one would prep an individual plasmid...things: underrepresented plasmids (plasmids that were lost or “dropped out”) and overrepresented plasmids...of 0.5 representing perfect uniformity (see Figure 3A). Addgene finds that this representation is most...for screening experiments, so the scale of the DNA prep is larger. And since the library contains many plasmids...library amplification and sequencing. Maintain representation of the library during transformation First,... to ensure all components of the library are represented. Typically, Addgene uses electrocompetent Stbl4...off the plates and pelleted for DNA extraction. Prepare library product for next-generation sequencing ...

  5. Optimizing Donor DNA for Enhanced CRISPR Genome Editing

    Type
    Blog Post
    ...causes the breaks) and host cell DNA repair factors (which repair those breaks) makes Cas9 extremely effective...inactivating genes), while breaks repaired by homology directed repair (HDR) pathways can modify the sequence...which sequence replacement holds some kind of fitness advantage but error-prone repair of the gene would...causes two types of editing outcomes: Cas9 breaks repaired by the non-homologous end-joining (NHEJ) pathway...low. Understanding the biological cause of this repair bias is a fascinating (and yet unanswered) question...approach to improve the efficiency of sequence replacement by HDR. Understanding Cas9 biophysics enhances...studies) to boost the efficiency of sequence replacement in vivo. We discovered that single stranded donor...

  6. Plasmids 101: Inducible Promoters

    Type
    Blog Post
    ...a bound repressor protein actively prevents transcription. Once an inducer binds the repressor protein...protein, the repressor protein is removed from the DNA. With the repressor protein absent, transcription is...promoter to induce transcription of the phage repressor cI. Repressor cI inhibits transcription from phage promoter...expression of a reporter gene. When light is present, YFI is inactive, preventing repressor cI synthesis ...with this post, check out our follow up post on repressible promoters. How are inducible promoters regulated...promoter. This promoter requires removal of the lac repressor (lacI protein) for transcription to be activated...presence of lactose or lactose analog IPTG, the lac repressor undergoes a conformational change that removes...

  7. New and Upcoming Viral Vectors - May 2020

    Type
    Blog Post
    ...AAV and lentiviral preps we have released in the last few months: Lentiviral preps for expressing SARS-CoV...lentiviral preps to speed up COVID-19 research even further. The following lentiviral preps are now available...2-N-2xStrep-IRES-Puro: Expression of the SARS-CoV-2 N protein  pLVX-EF1alpha-SARS-CoV-2-M-2xStrep-IRES-Puro...pLVX-EF1alpha-SARS-CoV-2-orf3a-2xStrep-IRES-Puro: Expression of the SARS-CoV-2 ORF3a Lentiviral preps for expressing ...pLVX-EF1alpha-SARS-CoV-2-E-2xStrep-IRES-Puro) and NSP2 (pLVX-EF1alpha-SARS-CoV-2-nsp2-2xStrep-IRES-Puro) are also...dependent Cre and FLPo And more!  New lentiviral preps SARS-CoV-2 protein expression The Krogan lab quickly... pooled library is now available as a lentiviral prep. It's a human CRISPR inhibition library that inhibits...

  8. Human Germline Editing Using CRISPR

    Type
    Blog Post
    ...phase oocytes, thus allowing repair to take place before DNA replication. Indeed, they observed that 41... were able to distinguish between repair from the template vs repair from the maternal MYBPC3 allele. ...indicating that repair proceeded through NHEJ rather than HDR. Figure 1: Homology-directed repair in targeted...Note: After this blog was published, a bioRxiv preprint that questions the conclusion of inter-homologue...Nature gives us even more to talk about, as it represents another step towards CRISPR germline editing ...different gRNAs, and electroporated them with an ssODN repair template in induced pluripotent stem cells made... efficiency of only 27.9% and homology-directed repair (HDR) taking place in 41.2% of edited cells. The...

  9. With Our New Viral Service, We're Taking CRISPR Further!

    Type
    Blog Post
    ...and providing lentiviral preps of select lentiviral vectors from the repository for you. We perform test... gRNA representation, produce high titer lentivirus from the library, ensure gRNA representation in the...particular organism available at Addgene. Percentages represent the fraction of that total with the indicated ...excited to provide ready-to-use CRISPR lentiviral preps to researchers across the globe. Why provide CRISPR...in science, getting a high titer Cas9 lentivirus prep takes a bit of time and effort that, for many groups... protocol only to find that the low titer of her prep makes it unuseable. With the large size of the SpCas9...test infections with all of our viral preps and host our expression data (western blots or fluorescent ...

  10. Addgene is Expanding Our Viral Vector Service!

    Type
    Blog Post
    ...have added the prep to your cart and checked out.  Prices for Packaged on Request viral preps will be available...Request prep and run the same quality control assays we run with all of our in-stock viral preps: ddPCR...on Request prep 6–9 weeks after placing your order.  Can I order Packaged on Request preps through a distributor...AAV composed of an AAV plasmid in the Addgene repository and their choice of five different serotypes.... and ordering a Packaged on Request viral vector prep.    Excited? So are we! This expansion will ...ordering high-quality materials from the Addgene repository. Read on to learn more.  What will be available...available?  Over 3000 AAV plasmids in the Addgene repository will be available for Packaged on Request service...

  11. Hot Plasmids: Spring 2025

    Type
    Blog Post
    ...the new plasmids, antibodies, and viral preps in the repository through our Hot Plasmids articles. Here's...protein labeling with TurboCas Enhancer-AAV viral preps targeting interneurons Glutamate indicators with... intensity-based Glutamate-Sensing Fluorescent Reporter (iGluSnFR) designed and improved by the Loren ...DNA vector that contains everything needed to replicate inside a host cell but with space to insert your... a GPI-anchor. Image courtesy of IPI.   Repurposing retrotransposons for DNA editing By Emily P. ... genome. The team established that they could reprogram the genomic target by swapping the homology arms...formation than methods relying on homology-directed repair (HDR), and insertion is scarless, unlike previous...

  12. Technologies Enabled by NanoLuc® Luciferase

    Type
    Blog Post
    ...has dubbed these fusions LumiFluor Reporters. The LumiFluor reporter constructs were designed to be packaged... The researchers took a FRET reporter and adapted it into a BRET reporter by using NanoLuc® Luciferase...and NanoLuc® Luciferase are available from the repository. We encourage people to go to Addgene to get ...couples NLuc to fluorescent proteins to make better reporters and the second couples NLuc to fluorescent proteins...host cells. The fluorescent moiety of the BRET reporter was used to sort successfully infected/expressing...NanoLuc luciferase. Both GpNLuc and OgNLuc BRET reporters produced bright signals without exogenous excitation...near 600 nm – a clear demonstration of why a BRET reporter can improve deep tissue imaging. The constructs...

  13. CRISPR 101: Which Cas9 Do I Choose for My CRISPR Experiment?

    Type
    Blog Post
    ...activators and repressors to target genes. Repressing target genes using dCas9-based repressors Early experiments...sufficient to repress transcription by blocking its initiation. In mammalian cells, robust repression requires...transcriptional repressors to the promoter region of the gene of interest. dCas9-based repressors are useful...researchers to knock out, knock in, base edit, activate, repress, and even image your favorite gene. With so many...array of Cas9s (many available through Addgene’s repository) and make it easy to find your perfect match..... Image from David Liu.   Activation and repression using Cas9 Don’t want to permanently modify the...particular gene isn’t feasible. For example, temporary repression or knockdown allow you to study essential genes...

  14. Finding nucleic acids with SHERLOCK and DETECTR

    Type
    Blog Post
    ... to cleave and activate a reporter. The detectable signal from this reporter can be measured and quantified...and a Csm6 specific reporter (in the same fluorescent channel as the Cas13 reporter), they could significantly...method termed Specific High Sensitivity Enzymatic Reporter UnLOCKING (SHERLOCK and SHERLOCKv2) (Gootenberg... termed DNA Endonuclease Targeted CRISPR Trans Reporter (DETECTR) (Chen et al., 2018). Both SHERLOCK and... SHERLOCK- Specific High Sensitivity Enzymatic Reporter UnLOCKING Cas13 (C2c2) was first identified in...molecules. In SHERLOCK a quenched fluorescent ssRNA reporter is added to the reaction. Cleavage of the quenchable...amplification step in combination with the ssRNA reporter enables SHERLOCK to detect DNA or RNA with atomolar...

  15. Plasmids 101: Yeast Vectors

    Type
    Blog Post
    ...recombination. Yeast Replicating plasmids (YRp):  These vectors contain an Autonomously Replicating Sequence (ARS...mammalian vectors, will catch you up on the core replication and resistance features of yeast vectors and ...includes but is not limited to: rapid growth, ease of replica plating and mutant isolation, a well-defined genetic...homologous recombination to facilitate simple gene replacement/mutation. Yeast expression plasmids used in the...vectors must contain a yeast-specific origin of replication (ORI) and a means of selection in yeast cells...antibiotic selection markers.  The yeast origin of replication (Please note: This first section primarily pertains...ve also noted some features required for the replication of fission yeast, Schizosaccharomyces pombe, ...

  16. Adeno-associated Viruses (AAVs) for Genome Editing

    Type
    Blog Post
    ...gRNA in one AAV and a repair template in second a second AAV to deliver their repair template to mouse zygotes...two halves of a repair template spread across two AAVs, it is possible sequentially repair a target site...deliver a repair template that would take up ~6.5 kB if delivered in a single AAV. They report roughly ...Russell and Hirata from the University of Washington reported a surprising finding - when delivered via AAV ... mutations through aberrant double strand break repair, it has proven more challenging to develop high... via homologous recombination with a homologous repair template. It is this application - the creation...appropriate for a CRISPR-based approach. Second, the AAV preps generally used for gene editing are low titre, and...

  17. What's New in CRISPR - March 2020

    Type
    Blog Post
    ... derived from Streptococcus pasteurianus  or the type II CRISPR3 module of Streptococcus thermophilus ...tools for your research! This time: Optogenetic repression in yeast Base editing CRISPRi in Caulobacter ... CRISPR-based DNA demethylation Optogenetic repressors of gene expression in yeast Megan McClean’s lab...generated an optogenetic toolkit that controls repression of gene expression in Saccharomyces cerevisiae...consists of dCas9, the mammalian transcriptional repressor Mxi1, and an optogenetic tool that controls nuclear...complex enters the nucleus where dCas9-Mxi1 can repress gene expression. In the dark, the NLS is inaccessible...Molecular Bioengineering Find the optogenetic repressor plasmids Cytosine base editors with minimized...

  18. Plasmids 101: In-house NGS Plasmid Quality Control Now at Addgene

    Type
    Blog Post
    ...other services that we provide, including viral preps and pooled libraries. As anyone who has ever worked... libraries. From start to finish the library preparation process only takes about one day, even for six...plasmids)! These libraries are then QC’d, pooled, and prepared for Illumina sequencing on our newly donated MiSeq... are “failed” and removed from the plate to be prepped again. These holes are then filled with other samples...VGS). QC is performed throughout the library preparation process and includes Picogreen quantification...often find a few mismatches in the origin of replication or other common backbone elements. Since we’ve...ve successfully grown the plasmid in culture to prepare it for sequencing, we feel confident that these...

  19. Viral Vectors 101: AAV Serotypes and Tissue Tropism

    Type
    Blog Post
    ...available as plasmids in the repository, as part of our in-stock viral prep service and can be selected...al., 2023). AAV1 capsids are available in the repository and can be selected as a serotype for Addgene...AAV1 tools are available through our in-stock viral prep service.  AAV2 Despite being isolated second, AAV2...AAV2 capsids are available as plasmids in the repository and can be selected as a serotype for Addgene...AAV2 tools are available through our in-stock viral prep service.  AAV5 AAV5 is the most genetically distinct... targeting astroglia. It has additionally been reported to have tropism for lung, liver, vascular endothelial...al., 2023). AAV5 capsids are available in the repository and can be selected as a serotype for Addgene...

  20. Three Tips for Preventing Viral Plasmid Recombination in Your Samples

    Type
    Blog Post
    ...involves viral vectors and plasmids with repeating sequences. Repeating sequences within a plasmid can undergo... (AmpR) and origins of replication (ori and f1 ori) which allow it to replicate.   How can I prevent...contain repeating elements. Knowing how to amplify recombination-prone plasmids and testing your prep can ...recombinases like RecA and RecBCD in bacteria. When two repeating elements love each other very much undergo recombination...recombination often occurs between the long-terminal repeats (LTRs). After recombination, one resulting plasmid...the bacterial selection marker and origin of replication. During bacterial culture, only the plasmid with...the antibiotic resistance gene and origin will replicate, and the transgene will be lost. Over time, bacteria...
Showing: 261 - 280 of 956 results