Caddisflies are among nature’s master underwater builders, capable of spinning sticky silk that they use to form protective cases and webs in freshwater streams.

Russell Stewart in his lab in the U’s Biomedical Polymers Research Building beside a photo of a caddisfly larva.
Russell Stewart in his lab in the U’s Biomedical Polymers Research Building beside a photo of a caddisfly larva. Credit: Brian Maffly.

Scientists like the University of Utah’s Russell Stewart have long studied this bioadhesive material in the hopes of using it as a chemical model for creating a synthetic version for use in the human body in medical applications. Now the genetics of caddisflies’ evolutionary superpower is coming into focus, providing science with new clues for developing bioadhesives.

In his most recent study, Stewart worked with Brigham Young University biologists to zero in on a net-spinning species native to Utah called Arctopsyche grandis. The scientists focused on H-fibroin, a gene that produces the main protein in caddisfly silk with an eye toward determining how much this silk gene varies among individuals living in two nearby, but separate wild populations found in streams near BYU’s Provo campus.

“It’s an incredibly detailed look at how nature does polymer chemistry. We looked at the main silk protein from 18 individual caddisflies from the same species in two populations very close together. The heterogeneity in those genes was remarkable,” said Stewart, an emeritus professor of biomedical engineering who has also conducted pioneering research into the natural glues created by marine sandcastle worms.

The results are reported in the journal Molecular Biology and Evolution.

Looking to nature for bio-inspired materials

Adhesives that work underwater would be incredibly useful, but such substances are notoriously hard to manufacture. Thanks to natural selection, however, many critters figured out millions of years ago how to produce substances to make stuff stick together.

These aquatic organisms are remarkable because their adhesives adhere underwater—something human-made adhesives and fibers struggle to do. Understanding how evolution naturally modifies caddisfly silk while preserving performance could lead to the development of new bio-inspired materials for medicine, engineering or underwater technologies.

Paul Paul Frandsen, an associate professor of plant and wildlife sciences at BYU, collects samples of freshwater macroinvertebrates in Utah’s Wasatch Mountains
Paul Paul Frandsen, an associate professor of plant and wildlife sciences at BYU, collects samples of freshwater macroinvertebrates in Utah’s Wasatch Mountains. Photo credit: Brigham Young University.

“We started to look into the genes involved in silk production because of emerging techniques, especially now with genetic engineering, to make prototypes for bio-inspired materials,” said co-author Paul Frandsen, a BYU evolutionary biologist. “The first step is to try to understand gene function. Russell’s early work was really foundational to understanding exactly how the protein was folding and how it was adapted to life underwater.”

Now an associate professor in BYU’s Department of Plant & Wildlife Sciences, Frandsen came across Stewart’s research—which was covered by The New York Times in 2010—while a graduate student and has since become a research collaborator.

In the years since, a University of Utah startup Stewart co-founded, Fluidx Medical Technology, has developed an embolic agent based on a synthetic version of sandcastle worm glue. That product, which forms targeted embolisms to cut off blood flow to a specific spot in the patient, has cleared clinical trials and is seeking approvals from the Food and Drug Administration.

Continue reading Brian Maffly’s “Caddisfly silk gene evolves quickly without losing adhesive power” on @theU.