Insect dormancy discovery offers clues to flipping the hibernation switch

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UF/IFAS

GAINESVILLE — It’s a scientific question straight out of a science fiction novel: Can the biological impulse that prompts a dormancy period in some living beings be activated in other organisms, including humans?

This question is among several that University of Florida researchers are pondering after their new study modeled what regulates metabolism in an insect called the flesh fly during its dormant, or diapause, phase. The flies enter into a state of massive “metabolic depression” that is regularly punctuated with “periodic metabolic arousal,” following a pattern shared by some mammalian hibernators.

Dan Hahn, a UF/IFAS entomology professor who co-authored the study along with assistant research scientist Chao Chen, said that he and Ohio State’s David Denlinger, also on the research team, thought up the study some 15 years prior. To get the needed expertise in cellular metabolism, the physiological entomologists recruited the help of Matt Merritt, an associate professor of biochemistry and molecular biology in the UF College of Medicine, and his postdoctoral researcher Rohit Mahar.

“This study gives us greater fundamental understanding of how dormancy is regulated,” Hahn said. “Nobody exactly knows what regulates these periodic wakings and entering back into metabolic depression in mammalian hibernators. One of the things that’s special about our study is that we’ve identified one of the regulatory mechanisms for the switch between metabolic depression and periodic arousal in the flesh fly. We want to understand what regulates dormancy and arousal from dormancy for all of the possible downstream applications.”

For the field of entomology, Hahn offers an example of what could be possible if dormancy could be induced or broken in insects whenever needed.

“If you could produce biocontrol insects, such as parasitoid wasps, at a steady rate and store them in dormancy until you need them, it could be a major economic benefit and a major advance for biological control,” said Hahn, who along with Denlinger is also part of a United Nations international working group that seeks to improve insects’ use in biological control.

A species that may be key to investigating these ideas is Drosophila melanogaster, the common fruit fly.

“One of our larger goals is to test whether we could induce deep dormancy in different stages of the fruit fly lifecycle as a proof of concept for what we learned about pupal diapause in the flesh fly. These two species are more than 90 million years diverged from one another,” Hahn explained, before contemplating further: “So if we can make it work there, how could it be translated to vertebrate cells?”

Hahn says known mammal hibernator species like the ground squirrel may share the same triggers as flesh flies to enter periods of dormancy and periodic arousal, but further research is needed.

“I encourage my colleagues who study mammalian hibernators to explore whether periodic arousal could be regulated the same way in their systems,” he said. “The reason we think mammals could regulate their dormancy-periodic arousal cycles similarly is that all the pieces that are being regulated in these insect cells are regulated in everybody’s cells, if you look at the fundamental cellular biochemistry.”

While applications for this work are still far off, in Hahn’s view this line of basic research could lead to the possibility of inducing and breaking dormancy at will in a wide range of organisms, from improving breeding programs for endangered butterflies to inducing dormancy in human organs to extend the time for transplant, or amputated limbs being kept viable long enough for reattachment.

“These are the things that I dream about – how can we improve society somehow with this science,” Hahn said. “The building blocks that we’re putting forward today could lead to those sorts of advancements.”

The study, “ROS and hypoxia signaling regulate periodic metabolic arousal during insect dormancy to coordinate glucose, amino acid, and lipid metabolism,” is published in the journal PNAS: pnas.org/content/118/1/e2017603118.

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