Celebrating the 100th Cartoon with a Few Words from the Promega Cartoonist

Heading into 2020, we realized that our Cartoon Lab was reaching a milestone: the 100th cartoon! We asked the “official” Promega Cartoonist Ed Himelblau to list his Top Five Cartoons and what inspired them. See what he has chosen in his own words:

This was the first of my cartoons that Promega published and it’s still one of my favorites. The file on my computer is dated February, 1999. I have been an undergraduate in a lab. I’ve mentored undergraduates in lab. Today I have lots of undergraduates working in my plant genetics lab at Cal Poly in San Luis Obispo. For the record, I enjoy having undergraduates in the lab and I never make them dress like robots. In this cartoon, I particularly like the centrifuge and stir plate on the right. I’ve always tried to put something in each cartoon (a tube rack, an enzyme shipping box, a desiccator) that make molecular biologists say, “I know that!”

Continue reading “Celebrating the 100th Cartoon with a Few Words from the Promega Cartoonist”

NanoLuc® Luciferase Powers More than Reporter Assays

Bright NanoLuc® Luciferase

What can you do with a small, super bright luciferase? Amazing things. We’ve highlighted many of the papers and new applications that NanoLuc® luciferase has enabled on this blog. While NanoLuc® luciferase was first introduced as a reporter enzyme to assess promoter activity, its capabilities have expanded far beyond a genetic reporter, creating bioluminescent tools used to study endogeneous protein dynamics, target engagement, protein degradation, immunodetection and more. So where did the NanoLuc luciferase come from and how does one enzyme power so many research capabilities? Read further for a primer on the various technologies and applications developed from this enzyme over the last 10 years.

Continue reading “NanoLuc® Luciferase Powers More than Reporter Assays”

Working in the Lab to Save Animals in the Wild

Asian elephants with babies in Planckendael zoo, Muizen near Mechelen, Flanders, Belgium. Image copyright: Ad Meskens [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)] via Wikimedia Commons

Wildlife conservation is a major focus around the world. With habitat loss and climate change, Asian elephant populations are under severe pressure. Add in an infectious disease that is fatal to the young and you have a recipe for disaster. Even with efforts to breed the endangered Asian elephants in zoos to build the population, elephant endotheliotropic herpesvirus (EEHV) thwarts conservation efforts. EEHV causes hemorrhagic disease in Asian elephants younger than 10 years old, a disease with rapid onset and high mortality. In fact, some numbers indicate EEHV is the cause of death for at least 25% of Asian elephants born in zoos and the wild globally.

Continue reading “Working in the Lab to Save Animals in the Wild”

Choosing a Tag for Your Protein

You have identified and cloned your protein of interest, but you want to explore its function. A protein fusion tag might help with your investigation. However, choosing a tag for your protein depends on what experiments you are planning. Do you want to purify the protein? Would you like to identify interacting proteins by performing pull-down assays? Are you interested in examining the endogenous biology of the protein? Here we cover the advantages and disadvantages of some protein tags to help you select the one that best suits your needs.

Immunofluorescent detection of HiBiT-tagged proteins in CRISPR-edited cell pools and clones using the Anti-HiBiT Monoclonal Antibody.
CRISPR-Cas9 editing knocked-in HiBiT at the endogenous locus of proteins with varying subcellular localization. Fixed CRISPR-modified clones or pools of cells were imaged by immunofluorescent staining using the Anti-HiBiT Monoclonal Antibody (red) and Hoechst dye (blue). Panel A. VCL-HiBiT pool. Panel B. SMARCA4-HiBiT clone. Panel C. HDAC2-HiBiT clone. Panel D. HSP90B1-HiBiT pool.

Affinity Tags

The most commonly used protein tags fall under the category of affinity tags. This means that the tag binds to another molecule or metal ion, making it easy to purify or pull down your protein of interest. In all cases, the tag will be fused to your protein of interest at either the amino (N) or carboxy (C) terminus by cloning into an expression vector. This protein fusion can then be expressed in cells or cell-free systems, depending on the promoter the vector contains.

Continue reading “Choosing a Tag for Your Protein”

All You Need is a Tether: Improving Repair Efficiency for CRISPR-Cas9 Gene Editing

Ribonucleoprotein complex with Cas9, guide RNA and donor ssDNA. Copyright Promega Corporation.

With the advent of genome editing using CRISPR-Cas9, researchers have been excited by the possibilities of precisely placed edits in cellular DNA. Any double-stranded break in DNA, like that induced by CRISPR-Cas9, is repaired by one of two pathways: Non-homologous end joining (NHEJ) or homology-directed repair (HDR). Using the NHEJ pathway results in short insertions or deletions (indels) at the break site, so the HDR pathway is preferred. However, the low efficiency of HDR recombination to insert exogenous sequences into the genome hampers its use. There have been many attempts at boosting HDR frequency, but the methods compromise cell growth and behave differently when used with various cell types and gene targets. The strategy employed by the authors of an article in Communications Biology tethered the DNA donor template to Cas9 complexed with the ribonucleoprotein and guide RNA, increasing the local concentration of the donor template at the break site and enhancing homology-directed repair. Continue reading “All You Need is a Tether: Improving Repair Efficiency for CRISPR-Cas9 Gene Editing”

Delving into the Diversity of The Plague of Justinian

Wayson stain of Yersinia pestis showing the characteristic
Yersinia pestis. U.S. Center for Disease Control [Public domain], via Wikimedia Commons.
Human teeth play a key role in our understanding of how organisms evolve. Whenever a possible new member of the hominid family is uncovered, the shape and number of teeth are used to place that individual in the family tree. Teeth also harbor information about pathogens that have plagued humans for millennia. Because bacteria use our bloodstream as a transport system, protected places that can preserve DNA—like the pulp of teeth—are a rich medium for uncovering information about humans and the microbes that infected them.

Teeth have been the choice for identifying the infectious agent behind the Plague of Justinian in the sixth century and the Black Plague in the 14th century. In fact, Yersinia pestis, the bacterium responsible for these plagues, has infected humans as far back as the Neolithic. But what can we learn about the pandemic strain or strains of Y. pestis described in historical records? A team of researchers from Europe and the US, many of whom have been delving into the history of Y. pestis for the last decade, wanted to further investigate the Plague of Justinian. They studied bacterial DNA extracted from human remains found in Western European communal graves that were dated to around 541–750, the period of the historically documented Plague of Justinian. Their investigation examined the bacteria’s diversity and how far it spread during this “First Pandemic” of plague. Continue reading “Delving into the Diversity of The Plague of Justinian”

PROTACs, PHOTACs and LYTACs: How to Target a Protein for Degradation

PROTACs for Targeted Protein Degradation
An illustration of PROTAC structure and the proteins it binds.

Targeting a single protein and making it disappear from the cell is quite the magic trick, and there are various molecular tools available for this task. You can use RNA interference, which prevents a protein from being made, inhibitors that bind the protein, rendering it unavailable for use or even gene editing tools like CRISPR that can remove it from the genome. But did you know that you can target an existing protein for destruction, using the cell’s own garbage disposal system to degrade the protein? All you need is a molecule that can connect your protein to one with a role in cellular protein degradation and your protein can be destroyed.

Continue reading “PROTACs, PHOTACs and LYTACs: How to Target a Protein for Degradation”

Cardboard Couture: From Conception to Runway Debut

The five-member team at the Read(y) To Wear event.

What do fashion, paperboard product packaging and literacy have in common? Answer: The Read(y) to Wear submission from a team of Promega employees for an event put on by the Madison Reading Project. With a challenge that stated teams need to make a garment mostly of paper, the resulting creations would be displayed on a runway as part of a charitable evening for an organization dedicated to bringing books to children.

Volunteering to be part of what became a five-person team to create a wearable garment from paper was the easy part. Our first few meetings we were experimenting with ideas and techniques using paper we could access on campus: Print catalogs, discarded books and our prototype product kit boxes. It was the kit boxes with the David Goodsell imagery that inspired our ideas to create a suit of armor. The paperboard boxes protect the products we ship to customers like a suit of armor protects warriors in battle. Continue reading “Cardboard Couture: From Conception to Runway Debut”

Expanding the Plague Family Tree: Yersinia pestis in the Neolithic

Yersinia pestis. See page for author [Public domain], via Wikimedia Commons

In recent years, scientists have been able to refine their molecular tools to resurrect ancient DNA from human graves and determine that yes, Yersinia pestis was the causative agent for the Black Death in the 14th century and the Plague of Justinian in the 6th century.  As more and more human graves have been uncovered, their DNA has revealed many secrets that scientists even ten years ago were unable to discover. With the ability to sequence entire genomes of bacteria that died with their hosts hundreds and even thousands of years ago, researchers are exploring the rise and possible spread of Y. pestis. Each new member sequence adds to the Y. pestis family tree, pinpointing the origin of this bacteria as it diverged from its ancestor Y. pseudotuberculosis. Peering into the past, scientists have been able to track down a strain of Y. pestis from individuals in a Swedish passage grave that is basal to known strains and that the authors of a Cell article suggest has interesting implications.

This pathogenic journey into history started by analyzing ancient DNA data sets from the teeth of individuals present in a communal passage grave in Gökhem parish, located in western Sweden, for any disease-causing microbial sequences that might be present. Y. pestis was flagged in one 20-year-old female dated 4,867–5,040 years ago. The bacterial sequences from this individual, named Gok2, were more closely aligned with Y. pestis than the Y. pseudotuberculosis reference genome.

Continue reading “Expanding the Plague Family Tree: Yersinia pestis in the Neolithic”

How Prostate Cancer Cells Survive Glucose Deprivation

Illustration of energy metablism in cell.

Glucose is an energy metabolite necessary for cellular survival and growth whether or not the cell is part of a tumor. Not only do cancer cells switch from oxidative phosphorylation to aerobic glycolysis (the Warburg effect) to gain more glucose, a hallmark of cancer, but they also increase the amount of glucose taken up from the surrounding extracellular space. However, the lack of glucose can have a negative effect on cells, causing them to become apoptotic in the absence of this metabolite. Cancer cells have methods to get around the requirement for glucose, including upregulating glucose transporters to improve access to the energy metabolite. In this Redox Biology article, researchers describe how activating androgen receptor in response to a lack of glucose affects the amount of GLUT1 expressed on prostate cancer cells, making the cells resistant to glucose deprivation.

To set the stage, two prostate cancer cell lines, LNCaP, an androgen-sensitive cell line, and LNCaP-R, an androgen-insensitive cell line, were deprived of glucose. Both cell lines showed signs of cell death, but LNCaP-R cells died in greater numbers. To probe how LNCaP cells died, several inhibitors (a pan-caspase inhibitor, two necroptosis inhibitors and a ferroptosis inhibitor) were added but did not change the way the cells died. However, an autophagy inhibitor enhanced cell death, suggesting the cells were necrotic not apoptotic. Teasing apart if the necrosis of LNCaP cells was due to glucose availability or merely disrupted glycolysis, the glucose analog 2DG was added to the medium with glucose. The cells survived when treated with 2DG, suggesting it was the absence of glucose that induced necrosis. When LNCaP cells were cultivated in medium that replaced glucose with mannose or fructose, the cells survived, another point in favor of sugar depletion causing cell death.

Continue reading “How Prostate Cancer Cells Survive Glucose Deprivation”