molecular biology

Promega qPCR Grant Series #2: Molecular Biologist, Laura Leighton

Posted on by Anna Bennett

Our second installment of the Promega qPCR Grant Recipient blog series highlights Dr. Laura Leighton, a trained molecular biologist and postdoctoral researcher at the Australian Institute for Bioengineering and Nanotechnology. Leighton’s scientific journey features a passion for molecular biology and problem-solving. Her path has been illuminated by mentorship, relationships with fellow scientists and a commitment to creativity in overcoming challenges. Here, we explore her scientific journey, reflect on research lessons and foreshadow her plans for the Promega qPCR grant funds.

Dr. Laura Leighton grew up in a rural area in Far North Queensland, Australia, where she spent her early life exploring critters on the family farm. Her upbringing was infused with a deep connection to the environment, from raising tadpoles in wading pools to observing wildlife and witnessing food grow firsthand. Observing the biology around her ultimately piqued her interest in science from a young age. She then began her academic journey in 2011 at the University of Queensland, Australia. She studied biology while participating in a program for future researchers, which led her to undergraduate research work in several research labs.  She dabbled in many research avenues in order to narrow in on her scientific interests all while adding different research tools to her repertoire.

After serving as a research assistant in Dr. Timothy Bredy’s lab, she decided to continue work in this lab and pursue a PhD in molecular biology. During her PhD, Leighton worked on several projects from cephalopod mRNA interference to neurological wiring in mice. The common thread in these projects is Leighton’s passion for the puzzles of molecular biology:

“I also love molecular engineering and the modularity of molecular parts. There’s something really special about stringing together sequence in a DNA editor, then seeing it come to life in a cell,” she says.

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An Ambitious Endeavor: The Human Proteoform Project

Posted on by Riley Bell

On November 15, 2021, Science Advances announced the launch of The Human Proteoform Project. The ambitious project, led by the Consortium for Top-Down Proteomics, aims to address a critical next step in disease research. This means developing new technologies to outline a complete set of protein forms based on the ~20,000 genes in the human genome.

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Tips for Successful Dual-Reporter Assays

Posted on by Ben Schmidt

Updated 02/12/2021

Previously, we described some of the advantages of using dual-reporter assays (such as the Dual-Luciferase®, Dual-Glo® Luciferase and the Nano-Glo® Dual-Luciferase® Systems). Another post describes how to choose the best dual-reporter assay for your experiments. For an overview of luciferase-based reporter gene assays, see this short video:

These assays are relatively easy to understand in principle. Use a primary and secondary reporter vector transiently transfected into your favorite mammalian cell line. The primary reporter is commonly used as a marker for a gene, promoter, or response element of interest. The secondary reporter drives a steady level of expression of a different marker. We can use that second marker to normalize the changes in expression of the primary under the assumption that the secondary marker is unaffected by what is being experimentally manipulated.

While there are many advantages to dual-reporter assays, they require careful planning to avoid common pitfalls. Here’s what you can do to avoid repeating some of the common mistakes we see with new users:

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A Quick Method for A Tailing PCR Products

Posted on by Isobel Maciver
PCR experiment and products, pipette tip, tube in researcher's hand.
PCR is a common technique used in research labs to amplify DNA.

Some thermostable DNA polymerases, including Taq, add a single nucleotide base extension to the 3′ end of amplified DNA fragments. These polymerases usually add an adenine, leaving an “A” overhang. There are several approaches to overcome the cloning difficulties presented by the presence of A overhangs on PCR products. One method involves treating the product with Klenow to create a blunt-ended fragment for subcloning. Another choice is to add restriction sites to the ends of your PCR fragments. You can do this by incorporating the desired restriction sites into the PCR primers. After amplification, the PCR product is digested and subcloned into the cloning vector. Take care when using this method, as not all restriction enzymes efficiently cleave at the ends of DNA fragments, and you may not be able to use every restriction enzyme you desire. There is some useful information about cutting with restriction sites close to the end of linear fragments in the Restriction Enzyme Resource Guide. Also, some restriction enzymes require extra bases outside the recognition site, adding further expense to the PCR primers as well as risk of priming to unrelated sequences in the genome.

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Why You Don’t Need to Select a Wavelength for a Luciferase Assay

Posted on by Ben Schmidt
Promega kit depicted; test involves wavelength for a luciferase assay.

It’s a question I’m asked probably once a week. “What wavelength do I select on my luminometer when performing a luciferase assay?” The question is a good and not altogether unexpected one, especially for those new to bioluminescent assays. The answer is that in most cases, you don’t and in fact shouldn’t select a wavelength (the exception to this rule is if you’re measuring light emitted in two simultaneous luciferase reactions). To understand why requires a bit of an explanation of absorbance, fluorescence, and luminescence assays, and the differences among them.

Absorbance, fluorescence, and luminescence assays are all means to quantify something of interest, be that a genetic reporter, cell viability, cytotoxicity, apoptosis, or other markers. In principle, they are all similar. For example, a genetic reporter assay is an indicator of gene expression. The promoter of a gene of interest can be cloned upstream of a reporter such as β-galactosidase, GFP, or firefly luciferase. The amount of each of these reporters that is transcribed into mRNA and translated into protein by the cell is indicative of the endogenous expression of the gene of interest.

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Cloning Modified Blunt-ended DNA Fragments into T-Vectors

Posted on by Kelly Grooms

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?

Blue/White colony screening helps you pick only the colonies that have your insert.
Blue/White colony screening helps you pick only the colonies that have your insert.

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Nano, Nano: Tiny Lipid Particles with Big Therapeutic Potential

Posted on by Ken Doyle
cell-transfection-viafect-luciferase-assay

Getting DNA or RNA into cells can be a tricky business, and a variety of transfection reagents have been developed over the years to make the process easier. Lipid-based reagents are especially popular because they combine efficient transfection with relatively low toxicity.

When it comes to transfection, it pays to think small. Human cells range in volume from 20–40 µm3 (sperm cells) to as large as 4 million µm3 (mature egg cells, or oocytes). For several decades, transfection reagents have targeted this size range. However, breakthrough research involves leaving the “micro” realm and entering a world that was once the domain only of science fiction: nanotechnology.

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The Pan-Cancer Atlas: “The End of the Beginning”

Posted on by Isobel Maciver

In April 2018, a series of 27 papers representing the most comprehensive genomic analysis of human cancers to date was published in Cell Press journals.

The collection constitutes the final outputs from the Cancer Genome Atlas (TCGA) project, a collaboration between the National Cancer Institute (NCI) and the National Human Genome Research Institute (NHGRI) involving analysis of over 11,000 tumors representing 33 different cancers. The many research teams involved analyzed tumor DNA, mRNA, miRNA and chromatin, comparing them to matched normal cellular genomes to perform a complete molecular characterization of cancer-specific changes. The results have been presented with much hope that open access to this type of comprehensive analysis will build on recent advances in understanding tumor biology and spur further progress in developing new approaches to treatment. (See this news item for more detail).

The Pan-Cancer Atlas results are collected on a cell.com portal, where they are presented in three collections grouped by topic: Cell of Origin, Oncogenic Processes and Signaling Pathways. Each collection is accompanied by a “Flagship” paper introducing the topic and summarizing the findings. It seems fitting that these findings have been published in #HumanGenomeMonth. This comprehensive analysis of the genomic and metagenomic profiles of tumors illustrates one powerful application of the type of genomic analysis pioneered by the original Human Genome Project, and shows just how much has been made possible since the initial publication of the human genome fifteen years ago.

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From Napkin Sketch to “Custom Kit”: CloneWeaver® Workflow Builder Gets Your Cloning Organized

Posted on by Michele Arduengo

20161018_150403Let’s face it, most lab techs and purchasing agents aren’t all that happy when you send them an Instagram picture of your latest lunchroom-napkin cloning strategy as your order form for your next big cloning experiment. So we have created the CloneWeaver® Workflow Builder. You can transfer your brilliance easily from that lunchroom napkin to an orderly email or print out of every vector, enzyme, purification kit, and transfection reagent your next big molecular cloning experiment requires. You can even save your one-of-a-kind “cloning kit” for future endeavors.

The CloneWeaver® tool will walk you through every step of the molecular cloning process from selecting a vector to finding a transfection reagent for mammalian cells. So if you are starting a new project, we are with you every step of the way. We will help you find restriction enzymes and even remind you about markers and biochemicals that you may want to have on hand for your experiment. Within the tool we have links to additional resources like our RE Tool and catalog pages if you need more help.

clone_weaverAlready have a favorite vector and a freezer full of restriction enzymes? No problem, skip those steps and move on to getting the perfectly sized nucleic acid markers or the particular polymerase your experiment requires.

Are you teaching a molecular genetics course? CloneWeaver® workflow builder is perfect for creating the list of laboratory reagents you are going to need for your students—and you will have this same list as a starting point for other lab experiments or classes later on because you can save the lists that you build. You can even pass them along to other professors.

So, if molecular cloning is in your future, let us help you get organized. Try the CloneWeaver® Workflow Builder.

Welcome to Your Biotechnology Field Trip at the BTC Institute!

Posted on by Karin Borgh

BTCI provides our students an opportunity that they could never get in the classroom.
—Jim Geoffrey, Biology Teacher, Kaukauna High School

Kaukauna High School students arrive at the BTC for a biotechnology fieldtrip.
Kaukauna High School students arrive at the BTC for a biotechnology fieldtrip.

Your bus has arrived and parked in the circular driveway at the front of the BioPharmaceutical Technology Center on the Promega Corporation campus in Fitchburg, WI. Your BTC Institute hosts – and instructors – for your field trip are Barbara Bielec (K-12 Program Director) and Ryan Olson (Biotechnology Instructor). They’ll greet you in the Atrium and direct you to a conference room where you can leave coats and backpacks, and then to the lab you’ll be working in during your visit.

Here’s a taste of what happened next for students from Random Lake High School and Wonewoc High School on December 3rd, and from Kaukauna High School on December 4th.

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