Hyunjung (Anna) Kim, a graduate student in integrative biology, spends a lot of her time in the basement of the Beckman Institute, performing electron microscopy (EM) in Beckman’s Microscopy Suite, where some of the most advanced research in EM takes place every day.
Like many graduate students at the Microscopy Suite, Kim was trained by the microscopy experts who manage the facility, and she quickly mastered the two main modes of electron microscopy: scanning electron microscopy (SEM) and transmission electron microscopy (TEM). She became the go-to EM expert for her lab, directed by Dr. Steven Blanke, professor of microbiology. Kim is involved in several research projects with the lab’s grad students, aiding in the visualization of their samples.
“The Microscopy Suite at Beckman makes it easy to learn new techniques, from knowing who to contact about each instrument, to getting trained and helped,” said Kim. “With the help of [lab manager] Scott Robinson, I learned EM quickly, and thought it was so cool. With the magnification capabilities of EM—up to 2 nanometers for the SEM and 2 angstroms for the TEM—you can see subcellular details unmatched by conventional microscopy.”
Blanke’s lab looks at how common pathogens, through their production of toxins and spores, interact with host cells; the lab’s ultimate goal is developing countermeasures against those pathogens. Blanke’s group is involved in projects that focus on three different bacterial toxins/spores: vacuolating cytotoxin (VacA), a toxin secreted by Helicobacter pylori, which 50 percent of the world population is infected with and is the only bacteria known to cause cancer; cytolethal distending toxin (CDT), a toxin capable of damaging DNA within cells; and spores formed by Bacillus anthracis, the bacteria that causes anthrax, an infectious and fatal disease of the lungs, gastrointestinal tract, and skin.
The Microscopy Suite is one of my homes ... It’s an enormous advantage to have [it] as a resource for our lab. - Anna Kim
Kim’s original project was to visualize the process of VacA binding to the surfaces of epithelial cells. She and Blanke realized that imaging with high-resolution microscopes and having access to the Microscopy Suite 24 hours a day/seven days a week could prove beneficial to many students in the lab, as they too were trying to visualize host–pathogen interactions at various levels. Kim started working with other students in the lab, helping them image their samples.
“It became really useful, and I started working with four or five grad students at a time, listening to what they wanted and helping them get the best image of whatever they’re looking for, whether it’s the cell-binding process, the effects of toxins on organelles such as mitochondria, or finding the exact location of toxins in a cell,” Kim said.
Kim uses SEM and TEM for different types of samples. For SEM, Kim prepares and then coats the samples with gold–palladium. The microscope beams high-energy primary electrons at a cell, for example, and the secondary electron signal ejected from its gold–palladium coating provides faithful high-resolution images of that cell’s surface. In TEM, she slices the sample into 60- to 90-nanometer-thin sections, and electrons project through those sections, interacting with the heavy metal-stained specimen to form an image of what’s happening inside the cell.
“SEM is good to observe extracellular host–pathogen interactions, and TEM is good for intracellular host–pathogen interactions,” said Kim. “The best part of the job is when I can get a really good image for the grad students, or if I find something and show it to my advisor, and he just says, ‘Whoa!’ ”
Because she works with so many graduate students, Kim has her hands full, working between 10 and 20 hours a week in the Microscopy Suite, along with her classes and a T.A. position in the College of Veterinary Medicine. Some recent samples she has worked on include H.pylori-infected rat stomach tissues, B.anthracis spore-containing vesicles in macrophages, and immunogold labeling CDT in colorectal epithelial cells. All of these projects are aimed at developing a way to target and fight these pathogenic bacteria.
“I’m happy to be involved with all three of the groups examining these various samples. It allows me to expand the scope of my research,” Kim said.
Kim intends to continue as the lab’s EM expert, as she is planning on pursuing her doctorate in microbiology.
“The Microscopy Suite is one of my homes, and I even call some of the machines ‘my’ machines because I use them so much,” Kim said, with a laugh. “It’s an enormous advantage to have the Microscopy Suite as a resource for our lab.”