The Secrets of Scales

By Anna Carmichael ‘18

Kyle DeMarr
Kyle DeMarr ’16

Imagine that you walk into the American Museum of Natural History in New York City. You are immediately drawn to the exhibits of immortal jellyfish and trilobite fossils, so something that may slip your mind is the science that goes on behind the scenes, in labs tucked away on the floors above. Kyle DeMarr ’16 says that before he started working at museums, he didn’t think about it either.

“This internship allowed me to interact with the museum environment while doing hands-on research, and I’ve always wanted to work in a museum,” said DeMarr, who participated in the National Science Foundation-funded Biology Research Experience for Undergraduates Program.

Under the guidance of David Grimaldi Ph.D. ’86, a curator in the Division of Invertebrate Zoology, and postdoctoral fellow Steve Davis, the entomology major spent his summer studying the scales covering the bodies of weevils, a type of beetle that has a snout. During the course of his internship, he conducted research on the evolution of weevil traits.

Insect scales are small pieces of chitin—a polysaccharide that makes up an insect’s exoskeleton—which overlap each other to form a cover on the outside of an insect.  According to DeMarr, such scales are common on beetles, butterflies, and moths.

DeMarr at the microscope
DeMarr at the microscope injecting a larva for a gene expression experiment using RNAi.

“Traditionally, scientists have only studied scales from butterflies and moths in-depth, but my project looked at how an unrelated group of insects evolved such similar structures completely independently,” DeMarr said.

DeMarr first shaved the scales off a weevil and then used scanning and transmission electron microscopes, two high-powered microscopy techniques, to view the intricate details of the interior and exterior of these structures.

“I dealt with machinery not working, waiting for samples, and small initial setbacks,” DeMarr admitted. “But I learned to roll with the punches as well as the ebbs and flows of doing research.”

Close-up of a weevil larva
Close-up of a weevil larva (Sitophilus oryzae),  injected with RNAi and green food dye to track the injection.

To explore the genes involved in the development of weevil scales, DeMarr tinkered with the weevil’s larval development with a technique called RNA interference (RNAi). Using RNA molecules to alter a gene’s level of expression, he could see how the development of a larva was affected when a specific gene was turned off.

“It’s really cool to get the opportunity to work on my own project, to research what interests me, and to see how research in a museum works,” said DeMarr.