Toposiomerase based cloning (TOPO cloning) is a DNA cloning method that does not use restriction enzymes or ligase, and requires no post-PCR procedures. Sounds easy right? The technique relies on the basic ability of complementary basepairs adenine (A) and thymine (T) to hybridize and form hydrogen bonds. This post focuses on "sticky end" TOPO (also called TOPO-TA) cloning; however, the TOPO cloning technique has also be adapted for blunt end cloning.
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 process all of the plasmids we distribute for quality control purposes in order to confirm the integrity of the DNA.
Read on to learn more about our two recommended methods for plasmid DNA verification: sequencing and diagnosic restriction digest.
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.
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.