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Plasmids 101: How to Verify Your Plasmid

Posted by Lianna Swanson on Aug 28, 2014 11:34:00 AM

Congratulations, you have a plasmid expressing your gene of interest (YGOI) and are ready to dive into your functional experiments! Whether you’ve cloned the plasmid yourself or obtained it from a colleague down the hall, it is always a good idea to take some time to confirm that you are working with the correct construct, and verify that the plasmid you received matches the expected sequence. Here at Addgene, we use NGS-based quality control to confirm the sequence of all the plasmids we distribute. This method is time-intensive, so we recommend two other methods for quick plasmid verification: Sanger sequencing and diagnostic restriction digest.

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Topics: Plasmid How To, Lab Tips, Plasmids 101

Choosing Your Perfect Empty Backbone

Posted by Lianna Swanson on Aug 19, 2014 11:39:33 AM

Vectors (or empty backbones) are frequently used in molecular biology to isolate, multiply, or express the insert they carry in the target cell. These vectors allow you to test the function of Your Gene Of Interest (YGOI) in a controlled environment under various conditions. The first thing you'll need to decide when running your experiment, is which vector will best suit your needs?

At Addgene, we have a vast collection of empty backbones that have been designed, tested, and published by academic scientists. To help you find the vector that fits your experiments, I've described below some of the most frequently requested vectors in our repository and will discuss some of the features you may want to consider as you make your choice.

The first and most important thing you need to know is your expression system or environment. The host organism will determine the type of vector that you will need. You will also have to make sure that your plasmid has been incorporated into the host organism, usually achieved with the proper selection marker or antibiotic resistance.

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Topics: Plasmid How To, Plasmid Technology, Plasmid Elements

6 Tips for Analyzing and Troubleshooting Sanger Sequencing Results

Posted by Lianna Swanson on Jun 26, 2014 10:23:15 AM

This blog was originally published on BitesizeBio here.

As part of my job ensuring plasmid quality at Addgene, I analyze 50-100 sequencing reactions a week. So I have developed some good habits that I wanted to pass on to you to make sure you are getting the most out of the data you get back from your sequencing runs.

When you run a restriction digest on a gel you always include proper controls like uncut DNA and the proper ladder. These controls help you properly visualize your results.The most important of those is to always look closely at the trace file (or chromatogram) of the sequencing results you get back from your favorite sequencing facility.

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Topics: Plasmid How To, Inside Addgene, Lab Tips

Tips for Using BLAST to Verify Plasmids

Posted by Jason Niehaus on May 29, 2014 9:29:00 AM

This post was updated on Dec 4, 2017.

At Addgene, we continually use the Basic Local Alignment Search Tool (BLAST) provided by NCBI. BLAST helps us compare the sequencing results of the plasmids in our repository with known reference sequences, such as full plasmid sequences provided by the laboratories that deposit their plasmids with us or other entries in NCBI’s numerous databases.

As our repository has grown over the years (we now have over 60,000 plasmids!), the number of sequencing results we analyze as part of our quality control process has steadily grown. On a busy week, we may need to analyze more than 200 plasmids as part of our quality control process. Consequently our team has refined our use of the BLAST web browser interface to be as efficient as possible.

If you find yourself frequently on the BLAST website to verify plasmids or validating your new clones, try these tips to make the most of your time and sequence! You might also enjoy seeing how our quality control process has changed with the introduction of next generation sequencing! 

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Topics: Plasmid How To, Lab Tips

Which Fluorescent Protein Should I Use?

Posted by Guest Blogger on May 20, 2014 10:06:00 AM

This post was contributed by Gal Haimovich of greenfluorescentblog.

Be honest.  Do you really know how fluorescent proteins glow?  

Fluorescent Proteins (FPs) were first discovered over 50 years ago, with the discovery of the Green Fluorescent Protein (GFP), a protein from the jellyfish Aequorea Victoria. Since that discovery, the family of FPs just keeps getting larger with hundreds of variants available. Read on to familiarize yourself with the available FP emission colors and 10 points to keep in mind when choosing an FP (or two) for your upcoming experiments.

Fluorescence is the emission of light by a substance that has absorbed light. The emitted light is at a longer wavelength than the exciting wavelength. Thus, FPs are proteins with this unique capacity.

Many of these FPs are fluorescent when ectopically expressed in most organisms. Furthermore, fusing FPs to another protein usually does not affect its fluorescence. Therefore, FPs are used to study many biological questions. The two most common uses are: 1) to test the expression level in a specific system (by measuring the fluorescence intensity); and 2) to visualize the localization of the FP (fused to the protein of interest), thus tracking the localization of that biomolecule inside living cells.

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Topics: Plasmid How To, Plasmid Technology, Fluorescent Proteins

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