To inject or not inject?

GloMax® Discover Multimode Reader with injectors.

GloMax® Discover Multimode Reader with injectors.

Luciferase assays are useful tools for studying a wide range of biological questions. They can be performed easily by adding a reagent that provides components necessary to generate a luminescent signal directly to cells or a cell lysate. However, once this reagent has been added, how long you wait to measure the signal becomes a key consideration in generating consistent data. Dependent on which luciferase assay you use, you may need a luminometer that can use injectors to deliver the assay reagents. The reason for this is simple, but can be confusing to new users.

Let’s start by discussing two types of luciferase assays: “flash” vs. “glow”. Continue reading

DNA Reveals the Identity of Jack the Ripper?

A wanted poster for Jack the Ripper, who was also known as Leather Apron.  Image courtesy of the British Museum

A wanted poster for Jack the Ripper, who was also known as Leather Apron.
Image courtesy of the British Museum


In the late 1800s, Victorian England was mesmerized and horrified by a series of brutal killings in the crowded and impoverished Whitechapel district. The serial killer, who became known as “Jack the Ripper”, had murdered and mutilated at least five women, many of whom worked as prostitutes in the slums around London. None of these murders were ever solved, and Jack the Ripper was never identified, although investigators interviewed more than 2,000 people and named more than 100 suspects. Now, 126 years after the murders, a British author, who coincidentally has just published a book on the subject, is claiming that DNA analysis has revealed the identity of the notorious killer. DNA is often thought to be the “gold standard” of human identification techniques, so why is there so much skepticism surrounding this identification?
Continue reading

Fold It Up and Discover a Whole New World

FIGURE 1: Foldscope design, components and usage. (A) CAD layout of Foldscope paper components on an A4 sheet. (B) Schematic of an assembled Foldscope illustrating panning, and (C) cross-sectional view illustrating flexure-based focusing. (D) Foldscope components and tools used in the assembly, including Foldscope paper components, ball lens, button-cell battery, surface-mounted LED, switch, copper tape and polymeric filters. (E) Different modalities assembled from colored paper stock. (F) Novice users demonstrating the technique for using the Foldscope. (G) Demonstration of the field-rugged design, such as stomping under foot.

FIGURE 1: Foldscope design, components and usage.
(A) CAD layout of Foldscope paper components on an A4 sheet. (B) Schematic of an assembled Foldscope illustrating panning, and (C) cross-sectional view illustrating flexure-based focusing. (D) Foldscope components and tools used in the assembly, including Foldscope paper components, ball lens, button-cell battery, surface-mounted LED, switch, copper tape and polymeric filters. (E) Different modalities assembled from colored paper stock. (F) Novice users demonstrating the technique for using the Foldscope. (G) Demonstration of the field-rugged design, such as stomping under foot.

Scientific inquiry —looking at the world and asking questions about what we observe—is a natural human behavior. Why is the sky blue? What would happen if I did this Mom? Ask any grade school teacher. Kids do science naturally. They are not afraid of questions. They are not afraid of nature. They are not afraid of experiments and data collection.

One other things kids do really well is: fold paper. I never cease to be amazed at the elaborate fortune tellers, hoppers, boats, hats and other creations that my daughter and her friends make at a moment’s notice out of virtually any scrap of paper they can find.

Recently members of the Prakash Lab at Standford University announced the Foldscope: an optical microscope that is printed and folded from a single flat sheet of paper. These microscopes, which can provide magnification of up to 2000X, can be produced for less than $1.00/each. Furthermore these scopes weigh less than 10g (a couple of coins), require no external power source, can be dropped from 3-stories without damage, and can even be stepped on.

These characteristics make the Foldscope ideal for field work, particularly in remote locations where access to power and other resources is difficult. Prakash and colleagues have published their work in a PLOS One paper and have demonstrated many uses for these Foldscopes including high-resolution brightfield microscopy, fluorescence microscopy, and darkfield microscopy. Continue reading

How to use Cell Viability and Cytotoxicity Assays Together to Get Real-Time Answers about Cell Death

Real-time measurement of cytotoxicity

CellTox™ Green Dye Binds DNA Released By Dying Cells

If you have ever wondered about the differences between the various cell viability and cytotoxicity assays available, why you would choose one over another or how they can be used together, tune in to the webinar “A Real-Time Cytotoxicity Assay That Delivers More Relevant Data” (Tuesday, Sept 10). In this webinar, Promega Scientist Drew Niles explains how various metabolism and biomarker-based viability and cytotoxicity assays work, and describes how they can be used most effectively to give maximum information about mechanism and timing of cell death.

“Is a cell treatment toxic?” and “Why are the cells dying?” are questions that can be difficult to answer simply. The answer depends on dosage, treatment time, mechanism of action of the test compound, and the cell type used—and may sometimes be limited by features of the assay itself. For example, many viability and cytotoxicity assays measure biomarkers that are themselves subject to degradation over the course of longer experiments, complicating the interpretation of results. Drew provides an explanation of these issues and illustrates the critical role of timing in deciding on the assay to use and in interpreting results. Continue reading

Reflections on Summer 2014 Courses

Group Photo from the 2014 Core Techniques in Protein and Genetic Engineering Course Held at the BTC Institute July 14-18. Photo credit: BTCI

Group Photo from the 2014 Core Techniques in Protein and Genetic Engineering Course Held at the BTC Institute July 14-18. Photo credit: BTCI

One of the things that I encourage all of the students I interact with in BTC Institute courses to do in order to boost retention and make meaning out of the activities that we do in class is to reflect on their experiences. Reflection is one way to connect new knowledge to past experience and get it to really stick in the brain, among other things.

Taking my own advice to heart, I use this space to ponder some interesting aspects of these experiences from my own perspective. This summer, I worked with 65 students and over 25 instructors to deliver four weeks of intensive instruction in molecular biology applied to a wide range of research areas. Continue reading

Pop Quiz: What Scientific Job is Right for You?

Word Quiz on yellow backgroundI used to love taking magazine quizzes to learn more about myself. I thought it would be fun to create a quiz to help you find out what scientific career path may be the best fit for you. Be open-minded while taking the quiz and remember that this is just for fun!

1. My greatest strength is:

a)      My artistry
b)      My perseverance
c)       My attention to detail
d)      My problem solving skills
e)      My personality- I get along with everyone

Continue reading

Protein Kinase Inhibitors Show Promise in Malaria Study

Life cycle of the Malaria parasite.

Life cycle of the Malaria parasite.

A paper published in on August 8 in ChemBioChem has identified a number of small molecule kinase inhibitors that may have potential as antimalarial drugs. The authors, Derbyshire et al from Duke University, used a panel of human kinase inhibitors to screen for activity against malaria parasites. Using a high-throughput screening approach, they were able to identify several potential drug targets among the kinases of Plasmodium sp.,—most of which were effective against the parasite during both it’s blood-borne and liver-based life cycle stages.

Liver and blood-stage malaria parasites have different gene expression profiles and infect different host cells. The authors exploited these differences to try to specifically identify compounds that were active against the parasite while it was still in the liver, the idea being that any drug-based prevention strategy needs to be effective against the parasites in the liver in order to eradicate infection.

The authors screened a library of over 1300 kinase inhibitors that included several compounds already being used in clinical trials for anti-cancer activity. Initial screening was performed in human liver-derived HepG2 cells infected with Plasmodium berghei expressing a luciferase reporter. Compounds that decreased parasite load by more than 95% were further characterized in dose-response experiments, and promising hits were tested in using luminescent and fluorescent cell based assays to identify compounds that were not toxic to liver cells. Continue reading

Promising Treatment for Marburg Virus Hemorrhagic Fever

This negative stained transmission electron micrograph depicts a number of filamentous Marburg virions. Note the virus’s characteristic “Shepherd’s Crook” shape; Magnified approximately 100,000x. Content Providers(s): CDC/ Dr. Erskine Palmer, Russell Regnery, Ph.D., via Wikimedia Commons

I admit to some trepidation about the diseases that may be harbored in my backyard. For example, do the mice in my yard and, despite my and my cats’ efforts, in my house carry deer ticks that harbor the bacterium Borrelia burgdorferi, which causes Lyme disease? Should I be keeping an eye on the vitality of the birds around my property and density of my local mosquito population for potential risk of West Nile Virus transmission? As troublesome as these infections can be, mortality is low for infected humans. Contrast that with the mortality rate of up to 90% for the filoviruses Ebola and Marburg. I find it easy to dismiss these viruses because the reservoir (asymptomatic host) is not in the Upper Midwest but rather Africa, but the tragedy of the Ebola outbreak in the West African countries of Liberia, Sierra Leone and Guinea demonstrates the number of lives lost in an epidemic. Currently, there is no therapy or vaccine to treat these deadly viruses other than transferring antibodies from survivors to those infected. Therefore, the article in Science Translational Medicine about an antiviral treatment that protected macaques injected with a lethal dose of Marburg virus was welcome news. Continue reading

Chikungunya Virus and the Promise of a Virus-Like Particle Vaccine

My family and I just returned from a week-long camping trip along the North Shore of Lake Superior in Minnesota. It is beautiful country, filled with lakes, rivers, ponds—and mosquitoes, lots and lots of mosquitoes. We went prepared for the worse. We had a screen tent, head nets and tubes and tubes of insect repellent because in this area of the world, mosquitoes are a flying, buzzing, picnic-ruining, itch-inducing pest. In the US, though, a pest is really all they are. In other areas of the world they are a flying, buzzing, disease-carrying, deadly menace.

Image courtesy of James Gathany and the CDC

Image courtesy of James Gathany and the CDC

Mosquitos act as vectors for many diseases including malaria, Dengue fever, Yellow fever, encephalitis, West Nile Virus and chikungunya virus. Many of these diseases are deadly; in fact, mosquitoes are responsible for more human deaths than any other animal (~725,000 deaths annually). Although most of these diseases have a long and infamous history, two of them, West Nile virus (first identified in 1932) and chikungunya virus (first identified in 1950), are relative new comers on the world health stage. Continue reading