Viruses: Manufacturing Tycoons?

Pseudomonas chlororaphis

A computer image shows a bacterial cell invaded by a virus. The virus uses the cell to copy itself many times. It has built a protein compartment (red, rough circle surrounding the center) to house its DNA. Viral heads (blue, smaller pentagonal shapes spread through out) and tails (pink, rod shaped near the edges) are essential parts of a finished viral particle. The small, light blue particles are the bacterium’s own protein-making ribosomes. Credit: Vorrapon Chaikeeratisak, Kanika Khanna, Axel Brilot and Katrina Nguyen.

As inventors and factory owners learned during the Industrial Revolution, the best way to manufacture a lot of products is with an assembly line that follows a set of precisely organized steps employing many copies of identical and interchangeable parts. Some viruses are among life’s original mass producers: They use sophisticated organization principles to turn bacterial cells into virus particle factories.

Scientists at the University of California, San Diego, and the University of California, San Francisco, used cutting-edge techniques to watch a bacteria-infecting virus (bacteriophage) set up its particle-making factory inside a host cell.

The image above shows this happening inside a Pseudomonas chlororaphis, a soil-borne bacterium that protects plants against fungal pathogens. The virus builds a compartment (red, rough circle surrounding the center) that helps organize an assembly line for making copies of itself. The compartment looks like a cell nucleus, which bacteria do not have, and it functions like a nucleus by keeping activities that directly involve DNA separate from other cellular functions. Continue reading

Chasing Fireflies—and Better Cellular Imaging Techniques

firefly
Firefly. Credit: Stock photo.

The yellow-green glow from this summer’s fireflies teased my kids across the yard. Max and Stella zigzagged the grass, occasionally jumping into the air to cup a firefly in their hands and then proudly shouting, “I got one!”

Chasing fireflies on a summer night is a childhood rite of passage for many, including Nathan Shaner who grew up in New Jersey. “It was one of my favorite things about summer,” he recalls. “I’d catch them with my hands—I’d never jar them.”

Today, Shaner studies the science of bioluminescence, which gives fireflies and many other organisms the natural ability to emit light. His goal is to make bright bioluminescent tags that he and other scientists can use to study living cells in greater detail. “There’s this very beautiful thing that evolved in nature, and we can use it to enable new discoveries,” he says.

Thousands of organisms glow as a way to communicate, spook predators, lure prey or attract mates. There are a few terrestial examples, such as fireflies, glowworm insect larvae and foxfire fungi, and many more acquatic ones, including types of marine plankton, fish, jellyfish, shrimp, squid and sea urchins. One research team estimated nearly three quarters of sea life have bioluminescent capabilities.

Bioluminescence is common across the tree of life (left to right): Panellus Stipticus (foxfire fungi); Lampryis noctiluca (glowworm insect); Aurelia Aurita (moon jellyfish). Credit: Wikimedia Commons, Ylem; Wikimedia Commons, Wofl; stock photo.

Every studied case of bioluminescence involves oxygen, a light-emitting pigment called luciferin and a protein called luciferase. Luciferase encourages the pigment’s reaction with oxygen, releasing energy in the form of light. Although many bioluminescent creatures have their own form of luciferase, they share just a handful of luciferins. For example, the luciferin called coelenterazine is found in many aquatic organisms. Continue reading

Interview With a Scientist: Namandjé Bumpus, Drug Metabolism Maven

Medications are designed to treat diseases and make us healthier. But our bodies don’t know that. To them, medications are merely foreign molecules that need to be removed.

Before our bodies can get rid of these drug molecules, enzymes in the liver do the chemical work of preparing the molecules for removal. There are hundreds of different versions of these drug-processing enzymes. Some versions work quickly, others work slowly. In some cases, the versions you have determine how well a medication works for you, and whether you experience side effects from it.

Namandjé Bumpus Exit icon, a researcher at Johns Hopkins University School of Medicine, is interested in how human bodies respond to HIV medications. She studies the enzymes that process these drugs. Her research team discovered that a genetic variant of a liver enzyme impacts the way some people handle a particular HIV drug. This variant is found in around 80 percent of people of European descent. She describes her work in this video.

Bumpus recently presented her research to a more scientifically advanced audience at an Early Career Investigator Lecture at the National Institutes of Health. Watch her talk titled Drug Metabolism, Pharmacogenetics and the Quest to Personalize HIV Treatment and Prevention.

Dr. Bumpus’ work is supported in part by NIGMS grant R01GM103853.