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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

Your Lentiviral Plasmid FAQs Answered

Posted by Kendall Morgan on Apr 23, 2014 9:08:00 AM

Lentiviruses are useful and efficient tools to introduce your gene of interest into cells. Unlike gamma-retroviruses that can only infect dividing cells, lentiviruses can infect dividing and non-dividing cells. 

Addgene has an extensive collection of lentiviral plasmids created for a variety of applications including cDNA expression, shRNA-mediated knockdown, Tet and Cre-regulated expression, CRISPR genome editing, and more. Not surprisingly, we receive many questions from scientists all over the world looking for some additional information or clarification on these vectors. Read on to find the answers to our most frequently asked lentiviral questions.

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Topics: Plasmid How To, Plasmid Elements, Lab Tips, Viral Vectors

Plasmids 101: Mammalian Vectors

Posted by Marcy Patrick on Mar 25, 2014 11:15:00 AM

Although plasmids do not naturally exist in mammals, scientists can still reap the benefits of plasmid-based research using synthetic vectors and cultured mammalian cells. Of course, these mammalian vectors must be compatible with the cell type they are tranfected into – a bacterial origin of replication (ORI) will not allow for plasmid replication in mammalian cells, for example, and a toxin that kills bacteria may not have any discernable effect on mammalian cells. In this blog post we will discuss how mammalian plasmids differ from their bacterial counterparts, including how replication occurs and whether selection is necessary for transfected cells.

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Topics: Plasmid How To, Plasmid Technology, Plasmids 101

Plasmids 101: Yeast Vectors

Posted by Marcy Patrick on Feb 25, 2014 2:11:00 PM

In our first few Plasmids 101 posts, we focused mainly on the elements required for plasmid maintenence within an E. coli cell, but vectors can be widely utilized across many different cell types and each one requires different elements for vector propogation. This post, along with a future companion post on mammalian vectors, will catch you up on the core replication and resistance features of yeast vectors and explain how they differ from the bacterial elements previously described.

Why Do Scientists Use Yeast Vectors?

Yeast are eukaryotes and thus contain complex internal cell structures similar to those of plants and animals. Unlike bacteria, yeast can post-translationally modify proteins yet they still share many of the same technical advantages that come with working with prokaryotes. This includes but is not limited to: rapid growth, ease of replica plating and mutant isolation, a well-defined genetic system, and a highly versatile DNA transformation system.

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Topics: Plasmid How To, Plasmid Elements, Lab Tips, Plasmids 101

Plasmids 101: How to Name Your Plasmid in 3 Easy Steps

Posted by Matthew Ferenc on Feb 13, 2014 8:00:00 AM

There are no universal rules for naming plasmids but here are some good guidelines to follow in order to ensure that people can quickly and easily identify what your plasmid contains and other important information.

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Topics: Plasmid How To, Lab Tips, Plasmids 101

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