Using fish to understand our immune systems
We share 70 percent of our genes with fish, and advances in genetic engineering allow us to test how these genes contribute to everything from behavior to disease. While several fish species are already used as model systems, all contain a duplicated genome. This genome duplication is a major problem that makes relating genetic mechanisms between humans and fish especially difficult. Consequently, this raises the challenge of identifying species that bridge the genetic gap between model fish and humans. Fortunately, two species of fish that reside in the waters of North America may well be the missing link – gar and bowfin.
Longnose gar being measured prior to release by the NC Wildlife Resource Commission during a sportfish survey we assisted on last year. These ancient fishes are very common in all the major rivers of North Carolina
Referred to by Darwin as living fossils, both gar and bowfin are ancient fish lineages that do not possess a duplicated genome. Instead they contain a mix of genes that sometimes more closely resemble those in humans rather than fish. Over the past year we have teamed up with Jeff Yoder at the NC State Veterinary School and Michael Fisk of the North Carolina Wildlife Resources Commission on several projects funded by the Triangle Center for Evolutionary Medicine (TriCEM) that investigate genes relevant to human immune function also shared by these species, with the goal of effectively translating genetic research in model fish to human health and disease.
Gar and bowfin housed at the NCSU College of Veterinary Sciences. These fishes were referred to as “living fossils” by Charles Darwin. Our research aims to link immune genes in these fishes to similar genes in mammals
This week, we went out with Jeff and Michael to collect some additional blood samples from a gar and bowfin on the Cape Fear River to further advance our studies this fall.
View from the front of the boat as we travelled up the Cape Fear River
We were also joined by Kent Passingham who was simultaneously collecting critical baseline data with which to conduct a health assessment of these fishes. Despite the promise of these fishes for medical research, no data exists on what healthy blood values look like. Without this information, any future blood based health assessments are impossible.
Electrodes on the boat. We use a sampling technique that sends a small amount of electricity into the water and temporarily stuns fish, bringing them to the surface. The fish are stunned for a few seconds, just long enough to net and place into the livewell. This is a very effective and non-destructive sampling technique routinely used by agencies to monitor fish populations
It was suprisingly difficult to find either gar or bowfin on this stretch of the Cape Fear. After nearly 4 hours we had only found a single gar despite virtually nonstop effort. Furtunately, our luck was about to change. By midafternoon we were able to catch a decent sample size of both gar and bowfin from which we could assess vital blood based health statistics. These values represent the first bloodwork values in either species and will form the foundation for a more intensive health assessment in different habitats.
A snapshot of a bowfin about to be released after health data was collected
In addition to catching gar and bowfin, an NC Wildlife Resource Commission photographer was on the scene photographing other sportfish we encountered for an updated pamphlet on game fishes. We brought in several bass, catfish, and sunfish for her to photograph and release.
Stay tuned for more updates as we continue our journey to link fish models to human health and monitor the health of these species in our waterways.