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Showing: 101 - 120 of 581 results
  1. Quantifying DNA? Here are Five DNA Quantification Methods to Consider

    Type
    Blog Post
    ...you only need 1-2 ul of sample and the run time is just a few minutes per sample. During the run, DNA fragments...absorbance. Then you measure the absorbance of the DNA sample.  These absorbance measures give you an idea of...especially when you expect low concentrations in your samples and are often used to quantify DNA for next generation...fluorescence-based methods require a standard curve, a set of samples with a known DNA quantity and their corresponding...That way, you can compare the fluorescence of your sample against this curve to quantify your DNA prep. Though...yourself as many fluorometers will calculate your sample concentration for you. Agarose gel electrophoresis...concentration of each band in the ladder. You then run samples of your DNA at different dilutions and quantify...
  2. Flow Cytometry Readouts: Yes, No, and Everything in Between

    Type
    Blog Post
    ...105 signal intensity. If your samples and controls were processed the same way, the GFP- population should... control (left) or with the sample (right). Negative and positive samples are clearly distinguishable ...designed your first flow panel, you’ll load your samples into the cytometer and see one of two results for...Created with biorender.com. Pro tip! If your samples and control underwent different treatment processes...peak overlaps with the baseline suggesting this sample has a comparable expression to the baseline/negative...marker would be a good statistic to compare between samples. In cases where there is no clear distinction between...histogram plot and MFI values to characterize your samples may allow for better interpretation. Priyamvada...
  3. Recombinase-based State Machines Enable Order-dependent Logic in vivo

    Type
    Blog Post
    ...states in a sample; instead, it will suggest the predominant state of registers in a sample based on a ... use the same recognition site array on the register, and all three-input GRSMs use the same recognition...implement the same gene regulation program. We recommend testing multiple register designs for the same gene regulation...If an attB-attP pair is aligned (sites facing the same direction) on a register, then the result of their...amplify in some states but not others. Because samples of many registers will likely not be homogenous...infer the predominant state of registers within a sample using a metric that we describe in the Materials...alternative. The qPCR method can be performed on a sample of multiple registers. However, it is only semi-quantitative...
  4. Plasmids 101: Dimers and Multimers

    Type
    Blog Post
    ...plasmid monomer from a plasmid sample, or if no monomers exist in your sample, you could try linearizing ... recombination between two or more copies of the same plasmid (Bedbrook & Ausubel, 1976). This recombination...restriction digest of multimers will produce the same fragment sizes and banding patterns on an agarose...Bedbrook & Ausubel, 1976). In fact, if your plasmid sample has a mix of different-sized multimers, you may...corresponding to each type of multimer present in your sample. In these instances, please note that the supercoiled...agarose gel). If the presence of a multimer in your sample remains unclear after visualizing it on a gel, ...perform whole plasmid sequencing of our plasmid samples during our quality control process. Since MiSeq...
  5. Addgene's Tips for Plasmid Quality Control

    Type
    Blog Post
    ... that consistently receives around 200 new DNA samples every week. Here we will provide an inside look...own plasmids. Staying organized With hundreds of samples coming through our doors, the first step to ensuring...our deposit process, and then we carefully track samples through our lab using barcoded tubes and plates...process. Always sequence verify Once the physical sample and its associated information are at Addgene, ... will catch any errors made during the cloning, sample handling, or sequence assembly steps. All of our...This means that we are sequencing from the exact same stock that we store and distribute from. Of course...for the efficient handling of large numbers of samples. When we grow overnight cultures for glycerol ...
  6. Antibodies 101: Stripping and Reprobing Western Blots

    Type
    Blog Post
    ...membrane will remove some of your sample —and harsher stripping means more sample loss. If you are still optimizing...you want to detect more than one protein in your sample? Or what if something weird happened during your..., almost like new. This approach preserves your sample and saves you from having to run a whole new gel...stripping solution (see below) to minimize loss of your sample from the membrane. Next, plan out the order of ... the weaker binding ones first to preserve your sample. Pro tip! Because some protein is lost each time...antibodies on it if you plan to reprobe! Just as your sample protein is retained better, antibodies will stick...even if round two is just another attempt at the same target!). In the stripping step, you’ll remove the...
  7. Antibodies 101: Conventional vs Spectral Flow Cytometry

    Type
    Blog Post
    ...stained samples. If you are using conjugated dyes, it is critical that your controls and your sample antibodies...unmixing if your sample is stained with a PE/Cy7 antibody from a batch that is not the same as your single...fluorophore from another within a fully stained sample. Figure 2 is an example of the emission spectra...allows the user to use the autofluorescence in a sample as a fluorescent marker. Given that the level of... varies, it is critical to include an unstained sample for each tissue type you are running in your panel...control(s) Compensation or “reference” controls are samples stained with a single fluorophore. They’re required...antibodies are from the same batch, to avoid unmixing issues from batch-to-batch variation. Tandem dyes ...
  8. Deep Dive: qPCR

    Type
    Blog Post
    ...individual values match across the board. If the samples or sample conditions change, the multiplexed protocol...validation data, be aware that different machines, samples, and treatments may affect the assay. It’s unusual...everything should be denaturing or annealing at the same temperatures. If there are multiple amplicons, or... here, here, or here).  If you’re working with samples that have not been documented in the literature...reaction should be compared to an individually run sample when developing the protocol and optimized until...setting it up for larger or frequently analyzed sample types and sets.   🔥Hot Tip🔥 The ABI machines...an RQ value representing the fold change of each sample compared to your control. But as we said previously...
  9. Antibodies 101: Polyclonal Antibodies

    Type
    Blog Post
    ...recognize the same region, or epitope, of the target protein. These antibodies are also all the same isotype...heterogeneous mixture of many antibodies that recognize the same protein. In the immune system, antibodies are produced...peptide sequence derived from this protein. At the same time, an adjuvant such as KLH or Freund’s adjuvant...clones will still recognize your protein. For the same reason, they’re also useful in experiments where...experiment, you should either order several vials of the same lot of polyclonal antibody, or select a monoclonal...your polyclonal antibody, you’ll want to use the same positive control across experiments to be aware ... include a negative control using serum from the same species your polyclonal antibody was generated in...
  10. Antibodies 101: Secondary Antibodies

    Type
    Blog Post
    ...approach is as follows: Prepare the sample. Incubate the sample with the primary (unconjugated) antibody...if all the primary antibodies are the same isotype from the same species, only one secondary antibody ...remove any unbound or excess antibody. Incubate the sample again with a conjugated secondary antibody, which...will need to be developed and optimized for the samples, antibodies, activation, and assay readout used...primary antibodies indiscriminately, giving them the same output signal. In these cases, it is best to use...not allow for absolute quantitative analysis of a sample. Instead, relative quantification can be done using...
  11. AAV Vector Quality Control: Going the Extra Mile with NGS

    Type
    Blog Post
    ... mean the sample is contaminated? No - what really matters is the number of hits to the same sequence ... DNA and processed the mixed sample in our pipeline (see Figure 2, sample 2). When we blindly analyzed...these known impurities, as was the case for clean sample AAV-44362. In addition to these expected hits, ...sequence (gene). In a clean sample, there are typically fewer than 10 hits to a given sequence, and we believe... the contaminant we mixed into the original AAV sample at 5%. Detecting 5% contamination is a good start...low we could go. We prepared a range of spiked samples from 0.1-20% and discovered that, with a high enough...
  12. Plasmids 101: Control Plasmids

    Type
    Blog Post
    ...were derived from the same source and were incubated on the same plate at the same time. Although the replicate...separate wells (within the same plate) with purified plasmid from the same aliquot/preparation. The replicate...provide the baseline/standard against which other samples can be compared. The Empty Vector Control (mentioned...control in this experiment could be an shRNA—in the same backbone as Plasmid A—that does not target any mammalian...". Biological replicates are what makes up your sample size (aka your n value)" and should come from multiple...
  13. Evolution of Lab Techniques

    Type
    Blog Post
    ...searching for), then the probe will bind to the sample thereby labeling it. The label can then be visualized...strength of the signal in comparison to a control sample. Southern blotting applications range from confirming... MstII and southern blotting are conducted on a sample from an individual without sickle cell anemia, ... largely replaced by real-time PCR to answer the same experimental questions. Real-time PCR detects and...DNA sequences to see which is more abundant in a sample. Whereas Southern blotting is labor intensive and...different restriction enzyme digests. Incubating a DNA sample of unknown sequence with restriction enzymes and...transcriptomes (RNAseq) require sequencing of many samples at once for later comparison. These next-generation...
  14. Multicolor Animals: Using Fluorescent Proteins to Understand Single Cell Behavior

    Type
    Blog Post
    ...cell remains the same color for its entire lifetime and daughter cells retain the same color, allowing ...3.0 and using the same fluorescent markers, Brainbow 3.1 and 3.2 (described in the same publication) are...stage, meaning that neurons of the same lineage will express the same XFP transgene in an adult fly. As... that target these epitopes and fluoresce in the same color as the fused XFP can be used to amplify the...expressing YFP, CFP, and RFP are not present at the same frequencies. The small population size of CFP++ ...
  15. Antibodies 101: Epitope Availability

    Type
    Blog Post
    ...the researcher and ones that happen naturally.  Sample Denaturing  First, let’s think about induced conformation...frequently denature the proteins as part of the sample prep. This involves using heat and/or chemicals...that are available on the outside of the cell. The same protein may have different epitopes available if...help to visualize an abstract protein during your sample prep process, imagining how it starts and if any...has been validated for an assay that uses similar sample preparation - for instance, if you cannot find ...because they both typically use denatured protein samples. If, however, you are performing an immunohistochemistry...validate for recognizing the protein following your sample prep steps; ie, you may only need to validate on...
  16. Developing Lab Management Software for Biology

    Type
    Blog Post
    ...appropriate glycerol stock within our freezers Pick the sample into the appropriate stab culture Grow the stab...proper location To keep ourselves from mixing up samples and to ensure that everything is grown successfully...fail. Some step failures require re-attempting the same step, some require going back two steps, some require...’s time for our lab technicians to retrieve the sample and get it ready for shipping. In the first case...and do troubleshooting on their own. For a few samples this isn’t so bad, for thousands it’s monumentally...arise if a lab veteran who worked with a particular sample suddenly left and didn’t have a system through ...transfer her instructions for dealing with the samples to newer lab members. We can set ourselves up for...
  17. RNA Extraction Without A Kit

    Type
    Blog Post
    ...tissues, cells, plants, fungi, or bacteria, keep samples cold and work quickly to mitigate RNA degradation...180°C for at least 4 hours.   If your final RNA sample(s) are resuspended in water or TE buffer, store...requires a lot of time and depending on how many samples you may have, access to one or more large, expensive...thiocyanate-phenol-chloroform. In this method, samples are still homogenized and lysed in a guanidinium... above, working with RNA requires keeping your samples cold until homogenization and cell lysis. This ... market to choose from) on your resuspended RNA sample will help ensure DNA contamination is not an issue...issue.  References                 Allewell NM, Sama A (1974) The effect of ammonium sulfate on the activity...
  18. Polymerase Chain Reaction Overview and Applications

    Type
    Blog Post
    ...scientific applications. These PCR methods all use the same basic PCR set up and steps but differ in how the... the presence of an insert or piece of DNA in a sample such as in colony PCR, or for generating mutated...determine the amount of starting material in your sample.  qPCR can also be used to quantitate RNA levels...droplet technology that fractions the PCR reaction sample into approximately 20,000 droplets. Each droplet...concentration of the original template DNA in the sample.  Addgene currently uses ddPCR for AAV titrating...concentrations of multiple starting DNA templates in one sample. It is important to note however, that multiplex...Multiplex PCR Amplify multiple targets from one sample Disease or pathogen identification SNP genotyping...
  19. Plan Your Experiment

    Type
    Guide
    ...different activators exist, including the multi-plasmid SAM system. Select Expression System To use CRISPR, you...efficacious than gRNAs containing a C nucleotide at the same position in spite of being a perfect match for the...
  20. Antibodies 101: Introduction to Gating in Flow Cytometry

    Type
    Blog Post
    ...When using flow cytometry to analyze your samples, it is necessary to set up a sequence of gates to be...the area under the resulting curve. By default, a sample on the flow cytometer (before you set the first...Practical example: lymphocytes in a mouse tumor sample You made it! So much about the theoretical background...gated out my lymphocyte population from a tumor sample. Many cell types can be found in the tumor microenvironment...proportion between H and A (or W and A) within the same type of scatter. Here I employed an FSC-H / FSC-...pattern of positive vs. negative signal remains the same (Figure 5).   A.                                                                                                        ...displayed. As the separation pattern largely stays the same and does not impact my ability to draw a proper ...
Showing: 101 - 120 of 581 results