The Ugliest Catch

Hagfish. That’s probably not the first marine species that comes to mind when thinking about deep-sea creatures, but Susan L. Edwards finds the bottom-dwelling fish fascinating, and uses their mysteries to excite students about science.

Edwards is assistant chairman of the College of Arts and Sciences’ Department of Biology at Appalachian State University and an associate professor of comparative physiology.

She has received a two-year $347,808 National Science Foundation grant to continue her research on how the hagfish eliminates waste, research that may show how similar genes evolved and work in humans.

“They are quite disgusting looking little creatures,” she said of the species that has been around nearly 500 million years. “They have no eyes, no jaws and live at the bottom of the ocean where their job essentially is to clean dead and decaying flesh.”

It’s how these ocean-floor vacuum cleaners have survived for millions of years, often at times experiencing periods in a toxic environment, that intrigues Edwards and other researchers.

“They often are found eating their way from the inside out of a dead carcass, and they very efficiently excrete a waste product known as ammonia,” Edwards said. “Ammonia is a waste product that results from the breakdown of proteins. It is highly toxic if allowed to accumulate in the body, so many aquatic organisms have developed mechanisms to rid their bodies of ammonia as soon as it is produced. It is our hypothesis that the gene in the hagfish that is responsible for the excretion of the ammonia waste product is a member of the Rhesus glycoprotein family.”

Most key physiological processes in vertebrates are based on the functions of the membrane proteins such as those in the focus of Edwards’ research. Since those proteins may have evolved in a unique way in the basal vertebrates, such as hagfish, in comparison to higher vertebrates, like humans, Edwards’ project has the potential to answer fundamental questions on the evolution of different modes of ammonia transport.

Unraveling that mystery could lead researchers to better understand how humans excrete waste products, she said.

Fish have been used for a long time as model organisms to study human mechanism. For example, the rectal gland of the shark is the main model for studies examining the gene that causes cystic fibrosis — CFTR.

“A lot of our knowledge about water and salt balance in human kidneys has come from studying salt-water fishes. This is because the fish gill works in a similar fashion as the mammalian kidney,” Edwards said.

Edwards’ base of operation in the summer is the Mount Desert Island Biological Laboratory in Maine. This summer, she will be joined by undergraduate and graduate research assistants from Appalachian who will work with her to collect hagfish tissue samples for research in Edwards’ campus lab.

“I am very passionate about the organisms I work on and I love the fact I can hook students in to what I do,” she said. “They don’t always have to want to be scientists. The awarding of research grants is great, but at the same time, the buzz I get every day from working with students is equally great. If I can just switch one student on in a class, if I can change how one person thinks, then they can go out and change another person, so all of a sudden overall we become more aware of the importance of organisms that aren’t cute and cuddly and in the national spotlight.”