Native American scientist discovers ancient stress hormone

University of British Columbia Professor David Close has discovered a steroid hormone in the Pacific lamprey that may help in the conservation of this eel-like fish, which dates back 500 million years and is culturally important to the tribes of the Columbia River.

The identification of the stress hormone also provides insight to evolutionary science about the development of stress hormones.

“This corticosteroid hormone is a clinical indicator of stress and is important for monitoring environmental impacts causing stress on the lamprey,” said Close, who is director of the Aboriginal Fisheries Research Unit at UBC’s Fisheries Centre.

“If the Pacific lamprey are stressed because they are going down the river in barges or because they are trying to negotiate fish ladders designed salmonid, we can now monitor that stress using this finding.”

UBC’s Aboriginal Fisheries Research Unit is dedicated to training Indigenous students to conduct cutting-edge research that is of importance to Indigenous communities in North America. The unit currently has two Aboriginal students from Canada, and is seeking to recruit more First Nations and Native American students from Canada and the U.S.

Close published the finding of his research, supported by the Confederated Tribes of Umatilla and the Bonneville Power Administration, in the Proceedings of National Academy of Sciences Early Edition in July.

The research is receiving international attention because it provides evidence of the origin and evolution of stress hormones in vertebrates.

The implications of the findings are significant to the study of the evolution of stress hormones and their receptors. The lamprey, as one of the oldest living vertebrates, has a single corticosteroid and a single receptor for that hormone, while more modern vertebrates, including humans, have two corticosteroids and receptors which function to balance ions and the stress response.

“Through evolution, eventually these ancestral functions for responding to stress and ion balance diverged after a genome duplication event that produced two corticosteroid receptors,” Close said.

“That’s how we think complexity in organisms has increased through time. When these functions diverged it allowed vertebrates to exploit more diverse habitats. It is about the co-evolution of steroids and receptors and eventual divergence of ancestral functions.”

Close also intends for the findings to have a practical application in the efforts to save the Pacific lamprey in the Columbia River, where the clinical monitoring of stress hormones in salmonids has aided conservation efforts for decades.

He began his career in the fisheries program at the Confederated Tribes of Umatilla Indian Reservation in Northeastern Oregon. A Cayuse enrolled in the Umatilla Tribes, he published oral histories of tribal Elders, who helped him to understand the biology of the Pacific lamprey, and they charted its decline starting in the 1970s.

Like other lamprey, the Pacific lamprey has been historically viewed as a pest rather than a culturally important subsistence and medicinal fish to the Umatilla and other tribes on the Columbia River.

The Pacific lamprey is native to the Pacific Coast from Baja California, Mexico, to the Pacific Northwest of the U.S., and to Japan. Like salmon, it is born in the freshwater, travels to the ocean for its adult life, and then returns to the upper reaches of rivers where it forgoes food for a year before spawning.

Before construction of the dams, the Pacific lamprey were abundant, and tribal peoples fished for them in the falls along the Columbia and its tributaries. But now there are only an estimated 11,000 Pacific lampreys left in the Columbia River, Close said.

The Umatilla have been at the forefront of calling for restoration of the Pacific lamprey, but have not been able to get the fish, which has no commercial fishery, targeted for conservation, as are many salmonid populations listed as endangered or threatened under the Endangered Species Act.

The lack of information about the Pacific lamprey, which Close calls “living fossils,” has contributed to the lack of U.S. federal and state efforts to protect them. It would take the Pacific lamprey’s cousin, the sea lamprey, to make Close’s research possible.

“We needed to get a lot of blood to isolate the steroids, and we couldn’t use the Pacific lamprey because we didn’t want to kill this delicate population,” Close said. “We used the sea lamprey which is very abundant in the Great lakes, as a model for Pacific lamprey which are located on the West Coast.”

The findings are important not only for the conservation of the Pacific lamprey, but also for the control of the sea lamprey. An exotic fish in the Great Lakes, it is blamed for decimating the fish population.

For Close, the findings also indicate the importance of Indigenous knowledge to science. He considers traditional knowledge to be just as important as Western science to the management of tribal resources.

“By getting more Native peoples into the sciences with masters’ degrees and doctorates, we can work through the political tool of self-determination to protect our tribal resources,” Close said. “Most of the time we have been hiring people to come in and do this science for us. They can miss important insights into natural processes that are known to our cultures, because of their cultural biases.”