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  1. Fluorescent Proteins 101: When GFP lets you down

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    Blog Post
    ...are numerous GFP variants. Here I use the name ‘GFP’, which refers to mEGFP. This variant was made by introducing... generate the strictly monomeric EGFP variant, mEGFP (Zacharias et al., 2002). GFP needs oxygen Chromophore...jellyfish GFP (AvGFP) to create enhanced GFP (EGFP), a variant with improved brightness (Tsien, 1998). Another...Cranfill et al., 2016 and FPbase.org). A number of variants remain fluorescent under acidic conditions, with...although it still is worthwhile to generate several variants and check the functionality of the fusion (Mastop...on twitter: @joachimgoedhart.   References 1. Zacharias, David A., et al. "Partitioning of lipid-modified...
  2. Deep Dive: qPCR

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    Blog Post
    ...should be 60-65°C For qPCR, the important primer variable is the annealing temperature, not the melting ...reference genes have shown to have as much as sixfold variation in expression levels reported (Biassoni, 2014)...negative error on the other will introduce unwanted variation into your data. Try different types of pipettes... within each set of triplicates to understand variation due to technical error.  Plate readouts can be...type or tubes, sealing method, and other small variations in consumables. Track and record these details...Reference Dyes Whatever your pipetting method, some variation will occur. A passive reference dye, such as ROX...they are, however, affected by bubbles in wells, variations in volume, or machine surge errors and allow ...
  3. Progress Towards a PAM-Free CRISPR

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    Blog Post
    ...that don’t utilize NGG   There are plenty of Cas9 variants which utilize alternative PAMs. These alternative...rounds of engineering, they developed the SpRY Cas9 variant (Walton, et. al, 2020). SpRY uses NRN PAMs and ...efficiency and less reliability. Notably, the SpRY variant didn’t display higher off-target effects than SpCas9...experiments. Between SpRY and several of the other Cas variants described, nearly all genomic landscapes should...targeting with near-PAMless engineered CRISPR-Cas9 variants. Science 368,290-296(2020). DOI:10.1126/science.aba8853...PAM compatibility and editing activities of Cas9 variants. Nucleic Acids Res. 2021 Sep 7;49(15):8785-8795...Expanding Beyond Cas9 xCas9: Engineering a CRISPR Variant with PAM Flexibility History of CRISPR Cas – A ...
  4. Beyond the Blood Brain Barrier: PHP.B Enters the Central Nervous System Via the LY6A Receptor

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    Blog Post
    ...reach all regions of the CNS. PHP.B, a neurotropic variant of AAV9, is better than AAV9 at gaining access ...PHP.B viruses. Creating PHP.B, a neurotropic AAV9 variant PHP.B’s specificity for C57BL/6J mice is likely...screened in vivo in C57BL/6J mice strains to identify variants that reached the CNS following IV injection. Compared...efficiency, but at a log lower dose than PHP.B.  A Ly6a variant is linked to PHP.B CNS permissiveness Both the ...permissiveness. The Wilson Lab also looked for the gene variant responsible for the PHP.B permissive phenotype ...how the method used to select novel AAV capsid variants could unintentionally limit the utility of candidate...E., et al. "Cre-dependent selection yields AAV variants for widespread gene transfer to the adult brain...
  5. New and Upcoming Viral Vectors - September 2019

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    Blog Post
    ...-AAV-syn-jGCaMP7c variant 1513-WPRE (105321-AAV1) pGP-AAV-syn-FLEX-jGCaMP7c variant 1513-WPRE (105322-...vectors to more serotypes. We currently package four variants of these biosensors, which are optimized for specific...relative to baseline fluorescence, as the GCaMP7f variant, and is approximately 5-fold brighter than GCaMP6s...GCaMP6s. jGCaMP7f is the fastest responding variant. jGCaMP7b exhibits the brightest resting fluorescence...fluorescence from inactive neurons is reduced. This variant has an approximately 12-fold increase in brightness...
  6. Choosing a CRISPR Nuclease: Site Accessibility, Specificity, and Sensitivity

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    Blog Post
    ...the most recent advances and how some of these variants may be appropriate for your specific research ...isolated from different organisms and engineered Cas9 variants that were able to target different PAM sites (... be targeted (Hu et al., 2018).  These altered variants can allow for targeting of your genomic loci of...off-site activity of Sniper-Cas9 to different Cas9 variants using gRNAs of different lengths (Lee et al., ...genome, there are more and more Cas enzymes and variants to choose from. While no enzyme is perfect for...References Hu, Johnny H., et al. "Evolved Cas9 variants with broad PAM compatibility and high DNA specificity...
  7. Typing CRISPR Systems

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    Blog Post
    ... simple hierarchy: class to type to subtype to variant. Despite the seemingly complicated steps to arrive...on main function and composition; subtypes and variants are typically based on species of origin. There...currently two classes, six types, 33 subtypes, and 17 variants. Figure 1: Overview of the CRISPR classification...hierarchy flows from Class to type to subtype to variant (shown in italics). Created with BioRender.com....others have become more notable in recent years. A variant of V-U, paradoxically called V-K, is a CRISPR-associated...that can insert large fragments of DNA. The V-F variants, which are among the smallest Cas enzymes (400...CRISPR–Cas systems: a burst of class 2 and derived variants. Nature Reviews Microbiology, 18(2), 67–83. https...
  8. Fluorescent Proteins 101: Photoactivatable Fluorescent Proteins

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    Blog Post
    ...designed 2 variants of EosFP that can withstand these conditions- mEos4a and mEos4b (12). Both variants are ... random mutagenesis screening for enhanced RFP variants. PA-mCherry (E26V / A58T / K69N / L84F / N99K ...respectively. When illuminated with violet light, both variants are photoconverted to forms that emit brighter...PA-FPs. Several other irreversible PA-FP spectral variants have been discovered such as Kaede and PS-CFP2...available to the scientific community, and new variants are still being engineered. By combining PA-FPS...PubMed Central PMCID:PMC1635685. 12.Paez-Segala, Maria G., et al. "Fixation-resistant photoactivatable ...
  9. Antibodies 101: Fab Fragments

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    Blog Post
    ...light chains) each with a constant region and a variable region. The chains are covalently linked to one...the Y and comprise the entire light chain and a variable and constant region of the heavy chain. As the...structure with important features labeled. V = Variable domain. L = Light chain. C = Constant domain. ... Fv - These fragments are composed of just the variable domains of the heavy and light chains of an antibody...resulting in a product called a single-chain Fragment Variable (scFv). Size: ~25 kDa.   Figure 2: Comparison...Introduction to AntibodiesSingle Chain Fragment Variables (scFvs)Avoiding the Mouse on Mouse Mess in IHC...
  10. Uncovering Ancestral Bias in CRISPR Research

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    Blog Post
    ...the effects of ancestry and germline sequence variation in cancer cell lines took them down unexpected... screens based on the cells’ germline genetic variations. They then wanted to identify cancer-associated...correct, either. However, when they analyzed the variations in gene expression, they found that for approximately...genome does not represent the diversity of genetic variation across the human population. Rather, it primarily...designed that target regions with high genomic variability.   Moving forward It took a five-team response...Resources and references References Germline variation contributes to false negatives in CRISPR-based...
  11. CRISPR 101: Which Cas9 Do I Choose for My CRISPR Experiment?

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    ...your experimental target, SpCas9 and its enhanced variants, eSpCas9 and HypaCas9, are great choices. Check...regions of the genome and consider using a Cas9 variant with higher specificity (eSpCas9 and HypaCas9) ...added bonus of low off-target effects. The SpG variant, discovered by the Kleinstiver group has a PAM ...Further, this group also characterized a second Cas9 variant, SpRY, which cuts at NRN PAMs with high efficiency...targeting with near-PAMless engineered CRISPR-Cas9 variants. Science (80-. ). 368, 290–296 (2020). More resources...Learn about the PAM Requirements of Different Cas9 variants Learn about CRISPR Pooled Library Experiments ...
  12. Hot Plasmids: Summer 2024

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    Blog Post
    ...recombinase variants to optimize PASSIGE efficiency (Pandey et al., 2024). The best-performing variant yielded...TALEs), with fifteen total variants deposited with Addgene. These variants, including a “miniCRISPR” version... linkers and spacers could enable many future variations using nanobodies or scFvs for other targets or...allowing the team to develop self-silencing CHARM variants that stop their own expression after silencing...
  13. Evolution of Brainbow: Using Cre-lox for Multicolor Labeling of Neurons

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    ...levels.   Overview of Variations Between Brainbow Systems   Brainbow variants and applications beyond...expression; these deletions are defined using 2 loxP variants (only identical loxP sites can mediate recombination...either deletion removes one of the other loxP site variants, preventing further recombination. Brainbow-1.1...with recombination events specified by three loxP variants, but the principles remain the same. The first...Brainbow to be used in a variety of species. More variants have been created by other labs, including R26R-Confetti...
  14. 22 Hot Plasmid Technologies from 2014

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    ...naturally-occurring variations in the TALE repeat, referred to as “non-RVD variations”, were found to improve...which is 45 nm more red-shifted compared to other variants. The group further optimized Chrimson through ...off-kinetics (15.8 ± 0.4ms from 21.4 ± 1.1 ms); this new variant was named ChrimsonR. Plasmids containing Chronos...lentiviral and AAV expression vectors for certain variants. Klapoetke et al., Nat Methods 2014 Mar 11;(...Addgene interview. Engineering TALENs containing variable-repeats using Platinum Gate system Interested ... which reduces the number of individual repeat-variable di-residue (RVD) module plasmids and simultaneously...the Platinum Gate system contains an identical variable repeat (VR) at the 4th and 32nd residues of the...
  15. 27 Hot Plasmids from 2016

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    Blog Post
    ... activity have remained challenging due to the variable availability of enhancer sequences in different...gene was chosen to represent the primary splice variant in 38 types of human cancer. Many of the transcripts... consists of DsRed connected to a pH-sensitive variant of GFP (SEP) by a 9 amino-acid linker (see Figure...SEP and leave only DsRed to fluoresce (1). With variants that can be targeted to specific cellular compartments...pcDNA3.1-GoldenGate, pcDNA3.1-GoldenGate-VP64 Maria-Elena Torres-Padilla pTALYM3, pTALYM4 Boris Greber...cause severe human and livestock diseases such as malaria and toxoplasmosis. Despite their importance to ...infection, and necessary for the asexual cycle of malaria parasites. Find Lourido CRISPR Plasmids. Sidik...
  16. Using AAV for Neuronal Tracing

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    Blog Post
    ... faint signals (Schwab et al., 1979; Buttry & Goshgarian, 2015). Nevertheless, the use of these tracers...visual, and auditory neuronal circuitry in vivo. A variant of RABV has been developed to only label a neuronal...proteins VP1, VP2, and VP3. To date several hundred variants, or serotypes, have been found naturally or have...Janelia Research Campus also developed a new AAV variant, rAAV2-retro, that migrates retrogradely at higher...toxicity, higher specificity and reduced technical variability compared to chemical tracers. rAAV2-retro also... Central PMCID: PMC3174680. Buttry, J.L., and Goshgarian, H.G. (2015). WGA-Alexa Transsynaptic Labeling...D.V., and Karpova, A.Y. (2016). A designer AAV variant permits efficient retrograde access to projection...
  17. Antibodies 101: Chimeric Antibodies

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    Blog Post
    ...and heavy chains made up of variable regions and constant regions. Variable regions are unique to each ...Figure 1: In the isotype conversion process the variable regions of a parental antibody (blue, rat) are...resulting chimeric antibody would have the original variable regions from the parental rat antibody but the... tools. In the case of isotype conversion, the variable regions of a specific antibody are cloned into...
  18. Bright Monomeric Fluorescent Proteins: mNeonGreen, mTFP1, and mWasabi

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    ...Hui-wang, et al. "Hue-shifted monomeric variants of Clavularia cyan fluorescent protein: identification...tetrameric cyan fluorescent protein from the coral Clavularia sp. protein CFP484. Hui-wang Ai and colleagues... coli with a gene library of approximately 484 variants, including some potential tetramer-breaking mutations... monomeric, bright and photostable version of Clavularia cyan fluorescent protein: structural characterization...
  19. Hot Plasmids: FRET-Based Biosensors

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    ...from muscle cells. They identified a toadfish TnC variant which had a high-affinity for calcium binding and...Methods, the FRET changes of these Twitch sensor variants were optimized by testing various linker configurations...large-scale functional screen in bacteria. Sensor variants were then refined by a secondary screen in rat...“trick” to the development of additional color variants. This resulted in the construction of redCALWY...redCALWY-1, a red-shifted FRET sensor for zinc using variants of mOrange2 and mCherry as donor and acceptor ...
  20. New and Upcoming Viral Vectors - June 2019

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    ...biosensor tools, we now offer the jGCaMP7c variant in AAV1. This variant exhibits high contrast between its resting...basal fluorescence of the sensor. This “contrast” variant provides improved detection for tracking large ...-WPRE 105322  AAV1 pGP-AAV-syn-FLEX-jGCaMP7c variant 1513-WPRE 111262  AAV1 pAAV-hSynapsin1-axon-GCaMP6s...Name 105322  AAV1  pGP-AAV-syn-FLEX-jGCaMP7c variant 1513-WPRE 105714  AAV8  pAAV-Ef1a-fDIO-GCaMP6s...
Showing: 61 - 80 of 381 results