Just a little fishy

A deeper look into the science of water

By Natalie Eastwood

Even her computer knows she’s been spending too much time with mucus.

Grammarly, a proofreading app, told Wren Wakeman ’19, “Mucus: word used too much, try using slime instead.”

Wakeman, a double major in biology and psychology, wrote her senior capstone on the research she’s been conducting with Assistant Professor Anna Jozwick. Together, they have been identifying beneficial bacteria found in zebrafish skin mucus. If these zebrafish sound familiar, it’s because of Assistant Professor Jenny Lenkowski, who is researching regenerative processes of zebrafish retina. (The biology professors are very good at sharing their research materials.)

Jozwick’s research is twofold, and Wakeman is helping with one part of the whole, the “mucusy” part. After collecting the mucus by rubbing Q-tips and filter paper across the fish’s bodies, Wakeman and Jozwick extracted the DNA and sent it to a company that will tell them what is there.

“Then we do research, a lot of research on our campus databases, and try to find the role of what’s present and see if those same bacteria are present in other fish,” Wakeman said.

The reason their research is important, Wakeman said, is multi-faceted. For one, they don’t know what, or rather who, is living in fish mucus. Scientists think that stress changes the composition of the mucus, and this knowledge of how it changes could help keep fish on fish farms healthy, Wakeman said. Additionally, zebrafish are a model organism for humans, which means that they are widely studied, and any additional information will only help scientists study human characteristics.

“Everyone has bacteria in you and on you—everyone,” Jozwick said. “These bacteria on your skin fight off pathogens. That’s the same for fish, but we don’t know who’s there or what they’re doing on fish skin.”

The other part of Jozwick’s research is looking at the bad bacteria living in the water on fish farms, specifically the pathogen Yersinia ruckeri, which scientists have been studying since the 1950s, Jozwick said. There has been extensive research on the disease, but not the bacteria that causes it. Bacteria, apparently, are quite chatty, and Jozwick has been listening. Jozwick is studying how the bacteria “talk to each other.” Bacteria release chemicals, in the form of molecules, and when there is a high density of these molecules, the bacteria can sense that there a lot of them present.

Jozwick explained it this way: “If you were to put a small amount of Crystal Light in a bucket, you wouldn’t taste it, right? But if you add a lot of Crystal Light you would taste it. Bacteria are the same way. If a lot of the chemicals are produced, they can sense that they’re at a high population size and then they turn on or off different genes. So, they talk to each other and they change what they do.”

The bacteria don’t turn on the virulence genes that make organisms sick until they are at a high density (strength in numbers). If scientists can figure out how to keep the virulence genes from turning on, they could prevent organisms from getting sick in the first place, Jozwick said. The research Jozwick and her students are completing is relevant to fish farms, where the solution to get rid of the bacteria is to kill all the fish on the farm, she said.

Although Jozwick’s research is important for the future of fish, it has also resulted in some positive spin-off for her students.

Wakeman, for example, did not expect to enjoy research. She wanted to be able to say that she participated in research and add it to her resume.

What happened was much more than a resume builder. Wakeman will go into the research lab for two hours of planned work, and then she’ll look at the clock and realize she’s been there for five. She then thinks, “‘Wow, time went by really fast, and I’m really okay with the fact that I spent five hours in the lab.’”

The reason, Wakeman said, is that she loves not knowing the answers. It also helps that she’s working with a professor like Jozwick, who is there as a supportive backboard to answer questions but lets her experiment and make the research hers.

“We’re problem-solving, and I’m really starting to fall in love with the question and the mystery that research brings, and hopefully we’ll be able to discover something really cool,” Wakeman said. “When you’re in a lab setting for a class, you have a set of protocol that you have to follow and have expected results. We have hypotheses, but we have no idea what our results will be. The mystery is fun.”