We narrowed to 727 results for: cat.1
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TypeBlog Post...targeted expression. Surprisingly, <1% of synthetic promoters replicated the expression specificity of the...used four different design strategies: Strategy #1 (ProA): Create promoters with sequences upstream of...active in retinal cell types in mice. Figure 1: The four strategies used to design synthetic promoters...channelrhodopsin, fused to a fluorescent GFP marker (CatCH-GFP). The lab deposited AAV plasmids containing ...reproducibly labeled retinal cells can be found here. Applications for synthetic promoter AAVs Besides restricting...synthetic promoters have a few other potential applications: Using promoter combinations for targeted expression... promoters expressed in. The lab tested this application using one promoter to drive expression of Cre-mCherry...
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Progress Towards a PAM-Free CRISPR
TypeBlog Post...nucleotides are represented equally, that’s only a 1/16 chance of having a PAM at a given site. While it... NYN/NRN NYN is less effective than NRN Table 1 - Summary of PAM-flexible Cas enzymes Are we truly...editable with CRISPR technology. Fig. 1: SpCas9 has sparse PAM coverage in the human genome...flexibility in the location of the cut and subsequent edit. In these applications, location takes priority...make a choice about what is your top priority: location or efficiency. If you are just trying to shred...still leave you choosing between efficiency and location. Nearly PAM-less editing The Kleinstiver lab...in double stranded cleavage and base editing applications, with high editing capacity in both contexts... -
Genome-wide Screening Using CRISPR
TypeBlog Post..., check out Addgene's CRISPR Guide. Figure 1: Like this jar of jellybeans, a pooled CRISPR library... selecting a CRISPR library for your experiments. 1. What species are your cells derived from? Currently...a different gene. Libraries may be available in a 1-plasmid system, in which Cas9 is included on the gRNA-containing... unique compared to the rest of the genome and located immediately 5’ to a protospacer adjacent motif ...coli, and T. gondii genes. 2) What genetic modification are you trying to make? Addgene carries CRISPR...next-generation sequencing to check the quality of your amplification. If you've obtained a ready-to-use lentiviral... As such, sequencing CRISPR libraries after amplification and after a screen requires the use of next-... -
Corralling and Cornering the Goldilocks Antibody
TypeBlog Post...unlimited supply of identical antibodies (See Fig 1.). rAbs are a relatively new technology that takes...conveniently modified and engineered. Fig. 1: Antibody production methods NeuroMab and others... the signal. If the exposure time is long (e.g. > 1/7s) then the signal is weak and vice versa for a strong...the best, or even which one will work for your application? Like many scientists, I have spent hours sifting...produced from a new set of animals), and wrong application (different experiments/conditions can change ...differently over time), compatible with the desired applications (such as immunohistochemistry (IHC) or western...colleagues! Dr. Wu and his lab members (like me!) are dedicated to creating a public and accessible database for... -
Plan Your Experiment
TypeGuide...sequences containing a G nucleotide at position 20 (1 bp upstream of the PAM) may be more efficacious than...population. Some cells may be wild type due to either (1) a lack of gRNA and/or Cas9 expression or (2) a lack... in vitro and in vivo. Nature Biotechnology . 33 (1), 73–80. PMID: 25357182...Manipulation Select Expression System Design gRNA Publications Get Started CRISPR is a powerful system that...may not be a perfect plasmid for your specific application, and in such cases, it may be necessary to customize...reagent to suit your needs. Genetic Manipulation Application Cas9 gRNA Additional Considerations Knockout ...method Expression System Components of System Application Mammalian expression vector Cas enzyme promoter... -
Management for Scientists: Seeking Feedback
TypeBlog Post...-public settings. Ask over coffee. Have regular 1:1 meetings with team members (don’t become known for...Scientists series will focus on an aspect of communication especially important for a manager – getting... Creating a culture of excellent, effective communication between all members of a team. As described ... opinions in meetings, via email, at formal communications events or at informal gatherings, like at lunch... -
Adeno Associated Virus (AAV) for Cell and Gene Therapy
TypeBlog Post...about HIV cure research and science communication. References 1. Gaspar, H. B., S. Howe, and A. J. ...reconstitution with a normally functioning T cell repertoire (1). In this example, it was possible to transduce the...significant improvements in vision over a period of 1 to 3 years – the treatment appears to be both safe...affinity-purified receptor-targeted viral vectors." Nature communications 6 (2015): ncomms7246. PubMed PMID: 25665714...our AAV Production Protocol Check out our AAV Purification Protocol ... -
Antibodies 101: Validation
TypeBlog Post...depend on your intended application and available resources. Figure 1: Table summarizing the... a good option for applications like immunohistochemistry on human tissues, when (1) other strategies ...expected in another. You’ll need to validate that points 1 and 2 hold true under your specific experimental conditions...validation: A view from the mountains. New Biotechnol 45:1–8. https://doi.org/10.1016/j.nbt.2018.08.002 Uhlen...intended application - Remember, just because your antibody performs as expected in one application does ...strategies for antibody validation in different applications. Here, I want to highlight the general suggestions...intentionally generalizable and not specific to certain applications or antibody targets. That said, not every strategy... -
Editor's Choice, September 2016
TypeBlog Post...School Advice Part 1: Picking a Lab and a Project That’s it for now. As I indicated in the opening paragraph... products). I picked this post for a few reasons: 1) I think phage are super cool and have considered ...Plasmids at a Low Price: Kits from Addgene Savvy Advocates Needed to Navigate a Scientific Enterprise in ... -
Plasmids 101: Repressible Promoters
TypeBlog Post...Bacillus. Appl Microbiol Biotechnol. 2019 Jan;103(1):303-313. doi: 10.1007/s00253-018-9485-4. Epub 2018...and clonal analysis in Drosophila.” Nat Methods 9(1) (2011): 47-55. PubMed PMID: 22205518. PubMed Central...Methods Mol Biol. 2016;1478:53-78. doi: 10.1007/978-1-4939-6371-3_3. PMID: 27730575; PMCID: PMC5270762. ... and lac promoters.” Proc Natl Acad Sci U S A. 80(1) (1983): 21-5. PubMed PMID: 6337371. PubMed Central... also been developed which don’t fit in either category, but those are a subject for a future post! ... GAL80 under different promoters and create sophisticated patterns of UAS-driven gene expression. To further... PMCID: PMC2942869. Find plasmids from this publication at Addgene. del Valle Rodriguez, Alberto, Dominic... -
Plasmids 101: Terminators and PolyA signals
TypeBlog Post...initiating cleavage of the transcript. Figure 1: A predicted conserved secondary structure and sequence...prokaryotic terminators and deposited several with Addgene (1). Prokaryotic polyadenylation Although mostly thought...constitutive RNA transport element lead to enhanced HIV-1 Gag expression in a context-dependent manner. Nucleic...type are generally broken down into two broad categories, prokaryotic or eukaryotic, based on the functional...termination mechanisms fall under two general categories: rho-dependent and rho-independent. Rho factor... -
PITChing MMEJ as an Alternative Route for Gene Editing
TypeBlog Post...” Nat Protoc. 11(1): 118-33. PMID: 26678082. Find the plasmids from this publication at Addgene. 2. ...homologies. Abbreviated protocol for PITCh Step 1: Generate microhomologies in the PITCh vector ~20...editing possibilities MMEJ can enable. References 1. Sakuma, Tatsushi, et al. (2016). “MMEJ-assisted gene...another method for making targeted modifications. A recent publication by Zhang et al. shows just that -...about a month and a half, without the need for complicated cloning of homology arms. MMEJ: An Introduction...required by MMEJ can easily be added via PCR amplification. Given the inefficiency of HDR for knock-ins... and 3’ junctions, respectively. These results indicate that PITCh is a robust method for genomic insertion... -
22 Hot Plasmid Technologies from 2014
TypeBlog Post...expression. Brown et al., Genesis 2014 Jan;52(1):39-48. APEX2 for proteomic mapping and electron...engineering cells that lack release factor one (RF-1; Bacterial strain EcAR7) and minimizing the set of... of human mitogen-activated ERK activating kinase 1 (MEK1) with either one or two phosphoserine residues...comprised of three sets of cloning vectors (Level 0, 1, or 2) which can be utilized in three successive assembly... vectors are directionally assembled into a Level 1 vector creating a single transcriptional unit (Ex:...coding region, and terminator). Next, up to six Level 1 modules can be similarly assembled into a Level 2 ...vectors to allow for additional iterations of Level 1 assembly if necessary. Combining multiple Level 2 ... -
5 Tips for Troubleshooting Viral Transductions
TypeBlog Post...some technical obstacles when working with virus: 1. Viral vectors undergo DNA rearrangements. Depending...approximately 20–50% of the packaging cells after 1–3 days of selection. A lower percentage of surviving...up-to-date tips for your virus experiments. References 1. Anthony, Simon J., et al. "A strategy to estimate...experiment and they don't do anything. Viruses are complicated and they perform complex biological tasks, both...vector may undergo genomic rearrangements during replication. To avoid genomic rearrangements, try amplifying...membranes (Davis et al., 2002). Polybrene is one such cationic reagent that is commonly used and has been shown... during transfection, and does not necessarily indicate the production of virus. Alternatively, if the... -
Fluorescent Proteins 101: Visualizing Subcellular Structures & Organelles
TypeBlog Post...cell with the images from the Allen Cell Explorer (1). When studying the function of a protein or its role...various subcellular structures. Please see Figure 1 for commonly used markers for major mammalian organelles...Subcellular Localization Poster here! References 1. Allen Institute Plasmid Pages 2. Cooper GM. 2000....functionality can be gained by understanding the location and transport of the protein within a living cell...to observe membrane trafficking events in vivo. Locate your protein and see who it is hanging out with...potential overlap, it is possible to determine the location of proteins within complex structures. In order...way it is important to choose the appropriate quantification methods and tools. It is usually not enough... -
Mobile-CRISPRi: Bringing CRISPRi to Diverse Bacteria
TypeBlog Post...active for greater than 50 generations. Figure 1: Mobile-CRISPRi's modular components. Image from Peters...on a non-selective plate. Most bacteria tested had 1 transfer in every ~100 to 1,000 colonies, but some...including E. faecalis and P. mirabilis, had only ~1 transfer per 1,000,000 colonies. Higher transfer rates...The vast majority of bacteria are undomesticated which limits the tools scientists can use to study them...the genome and is propagated during normal DNA replication and cell division. Mobile-CRISPRi does not disrupt...single-gene knockdown experiments. Mobile-CRISPRi applications Mobile-CRISPRi expands CRISPRi to non-model ...Elizabeth A., and Pamela A. Silver. "Harnessing undomesticated life." Nature microbiology 4.2 (2019): 212.... -
What's the Best Way to Elute and Store Your Plasmid DNA?
TypeBlog Post.... pH and DNases affect DNA stability Figure 1: So many choices! What to do? The main factors ...your downstream experiment. TE (10 mM Tris-HCl,1 mM EDTA, pH 8.0) buffer is the best buffer for preserving...If you use a kit for DNA purification or if you use a DIY purification protocol, you might have noticed... mutations in single stranded DNA undergoing replication. DNase on the other hand can digest and degrade...degradation during plasmid DNA extraction and purification from E. coli is the presence of the protein ...most common E. coli strains used for plasmid amplification are endA negative, meaning the gene has been...chelating agents that can be introduced in the purification protocol to remove endonucleases activity. For... -
Cloning Mammalian Cells with the Agarose Method
TypeBlog Post... spread out onto the plate. We test the (capped) 1:1 agarose/DMEM solution against a part of the body ...a 60 mm dish ready for picking is shown in figure 1. Find Additional Useful Protocols on Addgene's Protocol...to rapidly punch out cell clones with sterile truncated pipet tips. Indeed, an experienced operator can...wiped down with 70% ethanol, and a box of sterile truncated pipet tips (USA Scientific #1011-8410) is also..., and making sure we always maintain a backup replicates of each clone in case of contamination. We do... -
Which Fluorescent Protein Should I Use?
TypeBlog Post...biological questions. The two most common uses are: 1) to test the expression level in a specific system...brightness is compared to that of EGFP which is set as 1. Some proteins are very dim (e.g. TagRFP657, which...Photostability can be as short as 100ms (EBFP) or as long as 1 hour (mAmetrine1.2). However, for most FPs it is a... to be considered when choosing an FP: Unique categories of fluorescent proteins Photoactivatable / Photoconvertible... used are GECIs - genetically encoded calcium indicators (e.g. GCaMP). Others include: pHluorin & pHTomato.... al. (2010) “Fluorescent proteins and their applications in imaging living cells and tissues” Physiol... -
Using Ultrasound to Image Bacteria in vivo: Acoustic Reporter Genes
TypeBlog Post...optimized for expression in E. coli: acoustic gene 1 (arg1) and acoustic gene 2 (arg2). The key difference... plasmids are available from Addgene! References 1 Bourdeau, R.W., Lee-Gosselin, A., Lakshmanan, A., ...Knowing where bacteria are located within their host is often key to understanding their role in both...reporters are not as well suited for imaging organs located deep in the body, like the gastrointestinal tract...lab recently discovered that gas vesicles also scatter sound waves and therefore produce signals in ultrasound... experiment to demonstrate the most exciting application for ARG’s: in vivo imaging. Specifically, arg1... -
Sharing Your Lab Protocols: Using Apps to Save Time & Track Your Experiments
TypeBlog Post...Recently I learned that Addgene’s pLKO.1 cloning protocol is viewed around 3,000 times each month. I ...on the Addgene website in December 2006, the pLKO.1-TRC cloning vector (deposited by David Root of the...would the thousands of other scientists using pLKO.1 variants learn about those updates? This is a problem...manuscript to get reviewed and edited prior to publication, and this will delay the dissemination of your...deposited by George Church’s lab). Addgene has also cataloged a variety of useful molecular cloning protocols...bacterial transformation. And more plasmid-related educational resources can be found in our Plasmids 101 blog...bring your phone into the lab? Maybe having a dedicated lab-use tablet? The software also makes it easy... -
Avoiding the Dark Side of Fluorescent Protein Fusions with mOX FPs
TypeBlog Post...focuses on the replication machinery of Kaposi’s sarcoma-associated herpesvirus. References 1. Snapp, ...experiments or even negatively impact cells (see Figure 1). When behaving properly, FPs enable researchers ... disulfide bonds in the secretory pathway (Figure 1) [4,6–8]. Additionally, FPs that encode N-glycosylation...compartments undergo significant post-translational modifications including glycosylation, disulfide bond formation...are equally susceptible to these non-native modifications, which can all potentially affect function [...N-glycans [9]. Both of these posttranslational modifications can disrupt FP folding rendering the protein... non-optimized parental proteins. Our recent publication illustrated the quantitative increase in fluorescent... -
Production of Virus in Insect Versus Mammalian Cells
TypeBlog Post...(lenti) Centrifugation Titration time ~1 day (AAV); ~1 week (lenti) 2–10 days Initial titers Higher...will help you decide which is right for you. Table 1: Mammalian versus insect cells for viral production...so most labs opt to purchase adenoviruses from dedicated adenoviral production labs or companies. Production...something you may have to optimize for your specific application. With mammalian systems, it is standard to do...more cells, while AAV can be titrated following purification using qPCR or digital droplet PCR. Insect cells...to collect your viral supernatant. Baculovirus replicates inside insect cells, and its lifecycle ends in...titer the virus, or go straight into your viral application, like protein production. Titration of baculovirus... -
Science communication: 9 Strategies to Get Your Foot in the Door
TypeBlog Post... Posts from Addgene 1) Twitter – Get your voice out there Here’s one thing you can do today: Sign up for...science communication are as varied as the field itself. Among other things, science communication comprises...certain aspects of art and education. If you suspect that science communication might be for you, don’t ... science education Do you aim to reach young people? Try networking with your local education community... Training – Get a formal education Some people get into science communication by taking a media or journalism...project. Science communication opens doors Getting involved in science communication has been the most...career researcher looking to break into science communication? Everybody goes about this in their own way.... -
Savvy Advocates Needed to Navigate a Scientific Enterprise in Flux
TypeBlog Post.... Follow David on Twitter @driglar. References: 1. Alberts, Bruce, et al. "Rescuing US biomedical research...Riglar Advocating for Science Symposium and Workshop 2016 – Sept 16-17 MIT, Boston The Advocating for Science...futureofresearch.org/advocating-for-science-boston-2016/. Sign Up For the Advocating for Science Symposium...Director of Media Communications, Harvard University Ray Howell -Founder of Howell Communications Philip Brenner...union dues. Time will tell the extent of the implications of this ruling and whether graduate students...labor laws, rather than as trainees in a special category, as has been the ‘labor-of-love’ philosophy of...tight lab budgets and even simply being able to categorize all postdocs at institutions, will be challenging... -
Don’t FRET: Bimolecular Fluorescence Complementation Makes Visualizing Protein-Protein Interactions Easy
TypeBlog Post...tethered to bring them into close proximity (Figure 1). Formation of the complete FP results in a fluorescent...detected by fluorescence microscopy. Figure 1: How BiFC works. A split FP (e.g., yellow fluorescent... protein interactions in living cells. Nat Protoc 1:1278–1286. https://doi.org/10.1038/nprot.2006.201 ...PIPs, resulting in a fluorescent readout. Applications for bimolecular fluorescence complementation...resulting from the assayed PPI. This high-throughput application is much more straightforward to carry out because...protein construction, cellular expression, and quantification (Kerppola, 2006, 2013). These are described... supraphysiological expression levels. BiFC quantification This is where BiFC outshines FRET — BiFC experiments... -
Better Dyeing Through Chemistry & Small Molecule Fluorophores
TypeBlog Post...environments such as live cells and tissues (Figure 1). These flexible strategies give you the best of both...majority of in-cell labeling strategies have two parts: (1) a genetically encoded “tag” expressed as a fusion...Follow him on twitter @rhodamine110. References 1. Liu, Zhe, Luke D. Lavis, and Eric Betzig. "Imaging...Subsequent advances in fluorescent proteins have replicated many of the properties once exclusive to small-molecules...phosphopantetheinyltransferase) – These enzymes catalyze the covalent attachment of a fluorophore ligand...labels for fixed-cell imaging, not for live-cell applications. Thus, these fluorophores are often bulky and...the Addgene Blog Learn About Other Protein Tags Catch Up on Your Fluorescent Protein Background Which ... -
Tips for Screening with Yeast Two Hybrid Systems
TypeBlog Post... fusions that retain their individual activities (1). Researchers also discovered the modular format of...systems could be combined effectively (3). In Figure 1 for instance, the DBD of the fusion protein shown ...ubiquitin system has been devised (8). References 1. Casadaban M.J., Martinez-Arias A., Shapira S.K., ... can often be accounted for using appropriate replicates and controls (see Tips below), and by validating...two-hybrid screening Minimizing false positives: Run replicates of the experiment to reduce the likelihood of...expression and correct folding, post-translational modification, protein degradation, access to the nucleus ...co-expression of the enzyme responsible for the modification in the assay host strain can help. In order... -
27 Hot Plasmids from 2016
TypeBlog Post...a rate of up to 1 per 500-1000 bp. In comparison, the DNA replication error rate is 1 per 109 bp. Unlike...variety of biological applications. First, GMAP-compatible backbones for lentivirus LV 1-5 and retrovirus ...Transcriptional Output-TANGO (PRESTO-TANGO) to screen the NCC-1 library of approved drugs against the entire kit; ...generated 5 common 30bp overlap sequences (Sites #1-5). Each overlap site encodes a unique restriction...is multiplex automated genome engineering (MAGE) (1). MAGE uses recombineering (2) to simultaneously incorporate...of GFP (SEP) by a 9 amino-acid linker (see Figure 1). The key to the biosensor lies in pH: DsRed is relatively...inactivate SEP and leave only DsRed to fluoresce (1). With variants that can be targeted to specific cellular... -
Technologies Enabled by NanoLuc® Luciferase
TypeBlog Post...GpNLuc and OgNLuc are available through Addgene (Cat.# 70185 and 70186, respectively). Antares Chu, J...construct for Antares is available through Addgene (Cat. # 74279). Enhanced Nano-Lanterns Suzuki, K., et...furimazine by Promega’s Chemistry group is a good story (1). From a deep sea shrimp to a compact powerhouse of...cellular analysis products at Promega. References 1. Hall, M.P., et al. (2012) Engineered luciferase reporter...et al (2). In this post, I’ll cover two great applications of the NLuc technology. The first couples NLuc...fluorescence. The paper reports a wide variety of applications of the Enhanced Nano-Lanterns including monitoring...2017) Genetically encoded bioluminescent voltage indicator for multi-purpose use in wide range of bioimaging...