Texas A&M Researchers Peer Into The Microcosmos With High-Resolution Microscope

Powerful cryogenic-electron microscope reveals interactions at the molecular scale

ASHLEY VARGO

TEXAS A&M UNIVERSITY

Here’s a movie trivia question for you: How did the scientists in “Jurassic Park” retrieve the DNA they used to clone the dinosaurs?

If you grew up with those movies, you might remember the zany description of how the cloning was made possible: “A hundred million years ago, there were mosquitoes, just like today. And, just like today, they fed on the blood of animals, even dinosaurs. Sometimes, after biting a dinosaur, the mosquito would land on the branch of a tree and get stuck in the sap…”

By extracting the blood from a mosquito trapped in amber, the scientists obtained the genetic blueprint to clone dinosaurs. And, while that idea is itself trapped within the realm of science fiction, Junjie Zhang, Ph.D., associate professor in the Department of Biochemistry and Biophysics, said it’s fairly similar to freezing a sample for observation with a cryogenic-electron microscope, or cryo-EM.

Within the Texas A&M College of Agriculture and Life Sciences, researchers are resolving some of the tiniest biological and chemical structures and viewing detailed molecular interactions by cryogenically freezing samples in place, capturing them like a mosquito in amber. Once the sample is frozen, the scientists can use the high-resolution electron microscope to observe what’s happening at the molecular scale.

“Instead of using amber, we use a special kind of ice called vitreous ice that doesn’t disrupt the proteins or nucleic acids very much,” Zhang said. “Similar to how the amber protects and preserves the mosquito, the ice preserves the molecules or cells so that we can image the structures and interactions.”

Unlike the “Jurassic Park” movies, these scientists won’t be bringing any huge man-eating animals back from extinction. But they are answering some questions that hold huge biological implications for the world on everything from infectious disease and structural biology to cancer.

Who’s using the cryo-EM at Texas A&M

Since the cryo-EM’s initial opening in November 2022, it’s already aided in several high-impact research projects. For instance, it was only with the use of the cryo-EM that Zhang and Lanying Zeng, Ph.D., also a professor in the Department of Biochemistry and Biophysics, were able to detail the mechanism of how a virus infects a bacterial cell by attaching to an appendage on the cell surface.

“We can use the cryo-EM to literally see interactions between a cell and bacteriophage,” Zhang said. “Other imaging techniques wouldn’t give a high enough resolution. They wouldn’t tell you which part of the virus is interacting with which part of the bacteria or show precise physical interactions.”

However, using the cryo-EM, Zhang said they can see the interface between a protein on a bacteriophage and another on a bacterium.

“And with that, it allows us to understand exactly how the phage recognizes its host and eventually destroys it,” he said.  ∆

ASHLEY VARGO: Texas A&M University