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Originally published Jan. 14, 2014.

Any newcomer who joins a molecular biology lab will undoubtedly be asked to design, modify, or construct a plasmid. A plasmid is a small circular piece of DNA found in bacterial cells, and someone new to plasmids may need some extra guidance to understand the specific components that make up a plasmid and why each is important.

Our “Plasmids 101” series designed to educate all levels of scientists and plasmid lovers - serves as an introduction to plasmids. Plasmids 101 will provide you with an overview of general molecular biology knowledge and techniques, and empower you with a firm understanding of the fundamentals. Our mission is to curate a one-stop reference guide for plasmids, so that you can spend less time researching the basics and spend more time developing cleverly designed experiments and innovative solutions necessary for advancing the field.

Plasmid incompatibility is defined as the inability of different plasmids to be maintained in one bacterial cell. In this Plasmids 101 post, we’ll cover why this happens, how it might affect your work, and how understanding it can be used for good. 

First, why are plasmids incompatible? Plasmid incompatibility occurs when multiple plasmids within one cell have the same replicon and/or partitioning system. Let’s start with the replicon- the part of the plasmid that contains the origin of replication and the replication control machinery (Need a refresher on the Origin of Replication? See our Plasmids 101: Origin of Replication blog). 

As with DNA isolation, scientists commonly rely on RNA isolation kits to make their life easier. Recently, we published a blog on DNA purification without a kit that outlined several reasons why doing something without a kit has advantages: less plastic waste, less expense, and less of being left with a bunch of random solutions when all the spin columns run out. In this article, we cover the basics of isolating RNA without a kit.

Are you a grad student, postdoc, or bench scientist who began working remotely recently? Most of us at Addgene began working from home last week to flatten the curve, but working remotely can be more difficult if your work is based in the lab.

If you’re unsure what to do during this period, check out these tips and resources collated by Addgenies to help you keep calm and science on.

David Liu’s lab created the first base editor in 2016 (Komor et al., 2016) and since then has been trying to expand their precision editing capabilities. Base editors make specific DNA base changes and consist of a catalytically impaired Cas protein (dCas or Cas nickase) fused to a DNA-modifying enzyme, in this case a deaminase. Base changes from C•G-to-T•A are mediated by cytosine base editors (CBEs) and base changes from A•T-to-G•C are mediated by adenine base editors (ABEs). How does this work? Through molecular biology teamwork. The guide RNA (gRNA) specifies the editing target site on the DNA, the Cas domain directs the modifying enzyme to the target site, and the deaminase induces the DNA base change without a DNA double-strand break. But base editors aren’t perfect. They may be slow, can only target certain sites, or make only a subset of base substitutions.