Cloning Blunt-Ended DNA Fragments is Hard: pGEM®-T Vectors Can Make It Easier.

PCR amplification with a proofreading polymerase, like Pfu DNA polymerase, will leave you with a blunt end. However, another thermostable DNA polymerase, like Taq DNA Polymerase, adds a single nucleotide base to the 3’ end of the DNA fragment, usually an adenine, creating an “A” overhang. This “A” overhang can create difficulties when cloning the […]

How should I evaluate DNA isolated from FFPE samples to ensure success?

Part two of three. You can read part 1 here. Formalin-Fixed Paraffin embedded (FFPE) samples are being used in increasing numbers of molecular assays. In my last blog I discussed some of the pre-analytical variables that can affect results obtained when using FFPE samples. Laboratories can increase the quality of downstream results by controlling variables […]

It Takes a Village: Automating Plasmid Purification for iGEM

Today’s blog is guest-written by Wihan Adi, a Master’s student majoring in physics at Justus-Liebig-University in Giessen and team member of iGEM Marburg. Although his background is in nuclear and particle physics, his research interests shifted toward affordable biosensors for point-of-care cancer detection, which is how he ended up doing microbiology for iGEM. Back in […]

Cloning Modified Blunt-ended DNA Fragments into T-Vectors

Tailing blunt-ended DNA fragments with TaqDNA Polymerase allows efficient cloning of these fragments into T-Vectors such as the pGEM®-T Vectors. This method also eliminates some of the requirements of conventional blunt-end cloning — Fewer steps, who can argue with that?

Fished to the Edge: How DNA Identification Can Help Fight the Illegal Trade of Threatened Shark Species

Whether your first encounter was peering through the thick glass of an aquarium tank or peeking through your fingers in a darkened theater, there is something about sharks that captures our imagination. These fierce, and sometimes fearsome, creatures have existed in our oceans for over 400 million years, and  survived multiple mass extinction events, including […]

Beneath the Writing: Non-Invasive DNA Sampling from Modern and Historic Writing Surfaces

We can learn a lot about the past and its people from the written records of the time. What people write and how they write it can gives us glimpses into historical events, interpersonal relationships, social standing and even social and cultural norms. From paper to papyrus to clay tablets, the surface that holds the […]

High-Throughput Purification with Experts Included

Implementing automated nucleic acid purification or making changes to your high-throughput (HT) workflow can be complicated and time-consuming. There are also many barriers to success such as challenging samples types and maintaining desirable downstream results that can add to the stress, not to mention actually getting the robotic instrumentation to do what you want it […]

Six (and a Half) Reasons to Quantitate Your DNA

Knowing how much DNA you have is fundamental to successful experiments. Without a firm number in which you are confident, the DNA input for subsequent experiments can lead you astray. Below are six reasons why you should quantitate your DNA. 6. Saving time by knowing what you have rather than repeating experiments. If you don’t […]

The Making of a Promega Product: Teamwork = Success for the Maxwell RSC® ccfDNA Plasma Kit

Ever think about the kinds of challenges R&D scientists run up against in the course of developing a new product? The development of the Maxwell® RSC ccfDNA (circulating cell-free DNA) Plasma Kit is a particularly interesting example. Its path to commercialization was characterized by a number of unexpected technical hurdles, yet each was overcome through […]

Purification of biotinylated proteins

Biotinylation is an attractive approach for protein complex purification due to the very high affinity (Kd = 10–15 M) of avidin/streptavidin for biotinylated templates. With typical avidin or streptavidin, the biotin-binding affinity is so great that purification with these traditional media require denaturing conditions for elution,such as 8 M Guanidine•HCl at pH 1.5 or boiling […]