We recently worked with YouTuber, Tom McFadden, to create a Plasmid Rap and introduce newcomers to the world of plasmids. As part of this process, we sent Tom a primer on plasmids and some of the ways that they can be used. We present this primer to you now with the hope that you can use it to introduce plasmids to any novice molecular biologist. You can find much more information about plasmids and their uses in our Plasmids 101 series. Happy reading!
When facing a cloning project, scientists are no longer limited to traditional restriction enzyme cloning. Instead, you can choose a molecular cloning technique that will work well with a given set of resources, time, and experimental needs. Since its invention in the late 1990s, Gateway cloning technology has become very popular as a rapid and highly efficient way to move DNA sequences into multiple vector systems. With the appropriate entry and destination vectors, one can use Gateway to clone a gene of interest into a variety of expression systems. Keep reading to learn more about the Gateway cloning method and its advantages.
If you’re into cloning, you’re probably aware that there are several methodologies currently available for approaching it. These include the traditional restriction enzyme/ligase-mediated method, the more recently developed Gibson Assembly Cloning and Gateway® cloning technologies, as well as several others. Each method is unique and relies on specific components that are key to the cloning reaction. Understanding the specific components is essential for choosing the correct cloning method for your own experiments, and here we will focus on a unique gene that makes the popular GatewayTM method possible: ccdB. But what is ccdB, what role does it play in modern cloning, and why should you learn more about it? Read on to find out how ccdB can make your cloning experiments a little easier.
One of the most powerful strategies to investigate a gene's function is to inactivate, or "knockout", the gene by replacing it or disrupting it with an piece of DNA designed in the lab. Specially constructed plasmids can be used to replace genes in yeast, mice, or Drosophila through homologous recombination. The concept is simple: deliver a template with a modified version of the targeted sequence to the cell which will recombine the template with the endogenous gene. Here, we'll describe the techniques and the plasmids used to inactivate specific genes in mammalian cells. Despite the popularity of CRISPR-based knockout/knock-in systems, these systems remain valuable, especially in cases where CRISPR cannot be used (e.g. there are no suitable PAM sequences nearby or your gene of interest is difficult to target specifically with a gRNA). Be sure to keep these techniques in mind when choosing a knockout strategy!
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.