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Showing: 161 - 180 of 934 results
  1. Plasmids 101: Methylation and Restriction Enzymes

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    Blog Post
    ...there, although other restriction sites (including other XbaI sites not preceded by GA or followed by ...occurring restriction modification systems that prokaryotes use to protect themselves from foreign DNA. The...digesting DNA. Why? Well, even though Dam methylation sites are not specifically associated with any restriction...systems, their sequences may overlap with restriction sites, inhibiting enzymes such as ClaI or XbaI, or, conversely...as DpnI require methylation at their recognition sites in order to efficiently cleave DNA. DpnI is often...mutation into your plasmid of interest by PCR generates mutated plasmids with no methylation (there are...commonly used in the lab do not have recognition sites that could overlap with a methylation site. The ...
  2. Golden Gate Assembly Upgrades: More Fragments, Faster Assembly, and Higher Fidelity

    Type
    Blog Post
    ...prefers ligation of Watson-Crick base pair substrates, it demonstrates significant activity on some mismatch-containing...experimentally-derived DNA Ligase fidelity data. Our work demonstrates that it is now possible to achieve 20+ fragment...amplicon form (shown above) are flanked by BsaI sites in an orientation that results in 5’ four base overhangs...pre-determined manner. If the original insert religates into its original vector, it will subsequently...target construct. Development of Golden Gate Assembly test systems Our research focused on three different ...phenotype upon growth on LB/Cam/X-gal/IPTG agar plates, indicating successful reconstruction of the coding...A final validation of the 5-, 12- or 24-fragment test systems was performed by setting up assembly reactions...
  3. A Control for All Seasons

    Type
    Blog Post
    ...results.  Replicates Replicates are another critical control in biological experiments. Replicates can be...of biological replicates such as multiple mice in each group and C, technical replicates or repeated measurements...specificity is to test the primary antibody against wild-type and knockout samples. In this test, wild-type ... control, you will be able to confirm that the testing protocols elicited the expected response and have...statistical power of an experiment. Technical replicates are repeated measurements of the same sample ...difficult to obtain meaningful results.  Biological replicates are distinct samples that are treated identically...mice, for example, it would be better to treat and test multiple mice with the drug rather than rely on ...
  4. Viral Vectors 101: AAV Variables That Matter

    Type
    Blog Post
    ...serotypes and promoters to test in your AAV system and b) steps for testing and optimizing your serotypes...Transactivator Correlates with Long-Term Doxycycline-Regulated Transgene Expression in Nonhuman Primates after ...you know that, you’re ready to start selecting, testing, and optimizing three key variables of an AAV vector...titer, and promoter. Note that several steps in testing are effected by multiple AAV variables.    ...transduce your cells. In fact, we usually recommend testing more than one.  Most AAV serotypes have broad tropism...translate to in vivo efficacy. You’ll therefore need to test potential AAV vectors in your specific experimental...harm, your experimental goals when designing and testing your AAV.  Figure 2: Comparison of AAV ...
  5. Starter Guide to induced Pluripotent Stem Cells (iPSCs) Part 2:  Reprogramming and Transdifferentiation

    Type
    Blog Post
    ...13]:  Germ cells [14] Hepatocytes [15] Pancreatic β-cells [16] Intestinal tissue [17] Lung epithelial...22] Cardiomyocytes [23, 24] Smooth muscle cells [25] Skeletal myogenic cells [26] Chondrocytes [27...27]         Adipocytes [28] Keratinocytes [29] Photoreceptors [30] Otic hair cells [31] Neurons [32...reverts back to a pluripotent state, which then proliferates and is redifferentiated to a different cell ... from donors. Apart from fibroblasts, human keratinocytes from hair pluck, peripheral blood cells, and...transdifferentiation. Multiple cell types such as fibroblasts, hepatocytes, and pancreatic exocrine cells have been successfully...of induced pluripotent stem cells from human keratinocytes. Nat Biotechnol, 2008. 26(11): p. 1276-84. PubMed...
  6. Lambda Red: A Homologous Recombination-based Technique for Genetic Engineering

    Type
    Blog Post
    ...recombineering substrates to avoid errors introduced during PCR. ssDNA Substrate ssDNA substrates can be generated...).  Shifting bacteria to 42˚C for 15 minutes quickly inactivates the repressor and allows for expression...Pro Tip: ssDNA substrates have a much higher rate of recombination than dsDNA substrates, so you should...modifications can only be made at restriction enzyme cut sites. The lambda red system is an alternative method ...within E. coli and is independent of restriction sites. The lambda red system is derived from the lambda...enzyme cloning where the genetic changes occur in a test tube. The donor DNA substrate only requires ~50 ...Beta: Beta protects the ssDNA created by Exo and promotes its annealing to a complementary ssDNA target ...
  7. The Many Reasons for Irreproducible Research- and a Vaccine to Eradicate It

    Type
    Blog Post
    ...and how each hypothesis will be tested with a specific statistical test.  Preregistration makes clear the...distinction between hypothesis testing work, in which a-priori hypotheses are tested with a new experiment; and...where reported methods may not include how many tests were conducted on how the results were analyzed....more credible than they actually are. Throwing out plates that don’t respond as expected, use of representative...encouraged to present that work using hypothesis testing statistical tools that generate a p-value.  As ...As an example, if you hypothesize that growth rates will be higher in treatment versus control, and you...rate, you report the results of all four of those tests and not just the subset of those that return a particular...
  8. Antibodies 101: Flow Cytometry

    Type
    Blog Post
    ...contain a mix of cells including granulocytes, lymphocytes, and monocytes. Due to differences in size and...separate into distinct populations of monocytes, lymphocytes and granulocytes in a plot of forward scatter (FSC...and fluorescent light sources. Visible light illuminates each cell as it passes through and scatters in...intensity of events. Since intensity positively correlates with expression, the further the shift of a cell...staining is quicker than indirect staining and eliminates potential non-specific staining that may arise...through the cell membrane. Formaldehyde fixation creates cross-links between lysine residues thus preserving...subset of cells. During FACS, the sample stream oscillates to generate droplets that are charged as they...
  9. Enhancing CRISPR Targeting Specificity with eSpCas9, SpCas9-HF1, & HypaCas9

    Type
    Blog Post
    ... or decreased off-target activity across the sites tested when compared to eSpCas9(1.1) and SpCas9-HF1...editing can result in unwanted changes at non-target sites. Means to decrease these so-called “off-target effects...activity of the Cas9 nuclease itself. Design and testing of eSpCas9 Looking at the structure of the Cas9...However, this is not always enough to keep off-target sites from being cut. Slaymaker et al reasoned that, if...separation afforded by gRNA binding at non-target sites would theoretically decrease off-target cutting....throughout the groove in 32 separate Cas9 mutants. When tested for their ability to cut the EMX1 locus in human...went on to combine the best of these mutations and tested the combination mutants for their on-target and...
  10. Mouse Modeling, Part 1: Genetically Engineered Mice

    Type
    Blog Post
    ... DNA sequences located between two loxP sites. The loxP sites are present at both ends of a gene in the...include Swiss Webster and Harlan (Hsd) National Institutes of Health (NIH) Swiss. Genetically engineered...embryonic stem cells. Non-homologous recombination incorporates this DNA randomly into the mouse genome. In ...also included to select for successfully modified zygotes or embryonic stem cells. Modified embryonic stem...vector containing homologous ends to the breakpoint promotes homologous recombination of the targeting vector...undergone genetic modification that alters or eliminates the expression of a particular gene. Targeting...because non-homologous repair is a random process, zygotes edited using the same nuclease may not result in...
  11. Mobile-CRISPRi: Bringing CRISPRi to Diverse Bacteria

    Type
    Blog Post
    ... (green) integrates downstream of the glmS gene in the recipient's genome. Antibiotic plates lacking DAP...bacteria. Once transferred, Mobile-CRISPRi stably integrates into the genome and is propagated during normal... a tri-parental mating scheme. Mobile-CRISPRi integrates downstream of the highly conserved glutamine-...is transferred to recipient bacteria where it integrates into the trnS-leu2 locus.   Figure 2: ...recipient bacteria by bi-parental mating. The ICE integrates into the trnS-leu2 locus. Antibiotics select ...of transfer was variable. They measured transfer rates by comparing the number of colonies that grew on...that grew on a non-selective plate. Most bacteria tested had 1 transfer in every ~100 to 1,000 colonies,...
  12. Plasmids 101: Protein tags

    Type
    Blog Post
    ...Protease recognition sites commonly used with tags Protease Recognition site Notes TEV ENLYFQS Cleaves...make something the cell doesn’t need to make. Eukaryotes and some bacteria deploy proteosomes to degrade...proteolysis. That’s one form of instability. Prokaryotes can also have a hard time folding eukaryotic ...correctly, there’s no point in crystallizing it or testing its function. Small ubiquitin-related modifier ...protein tags Tag Epitope Mass (kDa) Function Notes CBP KRRWKKNFIAVSAANRFKKISSSGAL 4 Affinity and ...solulibility and folding of eukaryotic proteins in prokaryotes; single step purification with amylose, but wicked...amino acid protein  12 Stability At N-terminus, promotes folding and structural integrity; cleavable. Not...
  13. Bioinformatics at Addgene

    Type
    Blog Post
    ...96-well microplates, and thanks to our dedicated product and development teams, frequent updates allowed...have evolved over the years to keep up with the latest tools. In Addgene’s early days, we would ‘spot-...eventually outpaced our software, even with continuous updates. The generous donation of a Illumina MiSeq sequencer...and optimize our pipeline. After reviewing and testing several platforms for engineering pipelines, we...other programs running on a computer, so it safely operates in isolation, and can be easily shared with others...others without any complicated setup. We created, tested, and debugged each of our pipeline steps within...resources. Now, we could iterate our development and testing cycle faster due to the ease of jumping back and...
  14. New and Upcoming Viral Vectors - September 2019

    Type
    Blog Post
    ...samples of AAV for testing purposes. To address this, we recently released our serotype testing AAV, which are...GCaMP6s. jGCaMP7f is the fastest responding variant. jGCaMP7b exhibits the brightest resting fluorescence ...AAVs include: EGFP-expressing AAV for serotype testing Calcium sensors and GABA sensors Optogenetics Recombinases...are distributed individually. See our Serotype Testing AAV inventory for the entire collection! We are... promoters and fluorophores for validating and testing purposes. We will continue to add more controls...calcium sensors and GABA sensors) Calcium sensors The latest calcium sensors from Janelia (jGCaMP7) continue...be used for imaging small neuronal processes (dendrites and axons). jGCaMP7c exhibits high contrast between...
  15. Retrovirus Guide

    Type
    Guide
    ... packaging cell line. This system provides the greatest flexibility to pseudotype γ-retrovirus using different...because once in the host cell cytoplasm, the viral componentes are small enough to enter the nucleus through...post‐transcriptional regulatory element; sequence that stimulates the expression of transgenes via increased nuclear...U5 and the rest of the provirus. 3' LTR in cis Terminates transcription started by 5' LTR by the addition...
  16. Plasmids 101: Restriction Cloning

    Type
    Blog Post
    ...contain a variety of restriction enzyme cut sites (restriction sites) downstream of the promoter as part of...these stains see the Bitesize Bio Blog and their associated manufacturers websites. These stains require...and insert - these both must have compatible cut sites for restriction enzymes that allow your insert to... a multiple cloning site (MCS). Having multiple sites allows you to easily orient your gene insert with...promoter (blue arrow) followed by the restriction sites EcoRI, XhoI, and HindIII. To place your gene in ...flanked on both sides by that enzyme’s restriction sites, but the insert can then anneal to the backbone ...digest large amounts of DNA in as little as 10 minutes, but check with your enzyme’s manufacturer to ensure...
  17. Finding Your Perfect Job After University

    Type
    Blog Post
    ... 20’s, new graduates often ask me for advice on careers available to new science graduates and the pro...better. I worked in a Microbiology testing facility, where I tested materials for bacterial contamination... in Spanish or French, and so they were ideal candidates for these positions.  I had to reassess what ...Standard Operating Procedures (SOP’s) and every item I tested was constantly tracked with barcodes and spreadsheets...the constant fear of failure because I knew the tests worked and would produce a reliable result. This...quickly; as soon as I learned how to do the different tests and became efficient, I then started to become bored...Molecular Genetics to give me an edge over other graduates during the recession. As each advertised job received...
  18. Antibody Validation for Flow Cytometry

    Type
    Blog Post
    ...reasons, it is essential to test the selectivity of your antibody. But testing is not one size fits all....important to test for the protocol you intend to use in your experiment. An antibody that demonstrates selectivity...best to determine this by testing them. For intracellular targets, we usually test 3 different fix/perms ... Correctly interpreting your data therefore necessitates careful design of RNAi sequences, confirmation...like a blood sample containing many different leukocytes. Where data is available from antibody-independent...quite useful. HCDM, among other things, works to test flow cytometry antibodies through their HLDA workshops... labeling patterns on different primary blood leukocytes. The file shared also contains information about...
  19. Advice on Career Paths and the Green Card Process for International Researchers and Entrepreneurs

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    Blog Post
    ...important for candidates during a job search and it is even more critical for international candidates. Being...international candidates that they should join their relevant associations/groups. These candidates should also...looking to continue their careers in the United States. There has been a growing shift away from employers...with filing a permanent residence case with United States Citizenship and Immigration Services (USCIS). If...years to work (up to 40 years for recent Ph.D. graduates). Therefore, it is imperative to plan for and ...following paths to maintaining a status in the United States including green cards that are well-tailored to...startups and firms with a non-international focus. Candidates in need of an industry H-1B need to be aware ...
  20. An “elegans” Approach to Better CRISPR/Cas9 Editing Efficiency

    Type
    Blog Post
    ...following a report that one can use linear repair templates (ie. PCR-derived dsDNA) with 30-60 basepair homology...ribonucleoprotein complex with linear DNA as repair templates which reduces time to generate edits to only four...rescued F1 animals (gel image under worm). Image courtesy of Jordan Ward, UCSF. In 2015 (Ward, 2015)...optimize a range of editing parameters: oligo repair templates with homology arms of 35-80 bp, and DNA double-strand...guidelines for designing single-stranded repair templates (Farboud et al., 2019).   The Mello lab also reported...of oligos used to generate linear dsDNA repair templates by PCR boosted efficiency (Ghanta et al., 2018...that melting and rapidly cooling dsDNA repair templates dramatically boosted editing efficiency (Ghanta...
Showing: 161 - 180 of 934 results