The most common bat in the United States, the big brown bat, has an exceptionally long lifespan of up to 19 year. A new study by researchers at the University of Maryland identifies one of the techniques of the exceptional longevity of this bat: hibernation.
“Hibernation has allowed bats, and presumably other animals, to stay in northern or far southern regions where there is no food in winter,” said the study’s lead author, UMD biology professor Gerald Wilkinson. “Hibernators tend to live much longer than migrants. We knew this, but we didn’t know if we would detect epigenetic age changes due to hibernation.”
Researchers have determined that hibernation during a winter prolongs the epigenetic clock of a big brown bat – a biological marker of aging – by three quarters of a year. The study, published in the journal Proceedings of the Royal Modern society Bon on 10 August 2022, also included scientists from McMaster University and the University of Waterloo, both in Ontario, Canada.
They analyzed small tissue samples taken from the wings of 20 big brown bats (Eptesicus fuscus) during two periods: in winter when they were hibernating and in summer when they were active. The bats, kept in a research colony at McMaster University, were between less than a year old and just over years old.
After the samples were taken, the researchers measured changes in DNA methylation – a biological process associated with gene regulation – between samples taken from the same animal during the periods active and hibernation. They found that changes in DNA methylation occurred at certain sites in the bat genome, and these sites appeared to affect metabolism during hibernation.
“It’s pretty clear that the web pages that decrease methylation in winter are the ones that seem to have an active effect,” Wilkinson said. “Many of the genes closest to them are known to be involved in regulating metabolism, so they presumably keep metabolism low.”
Some of these genes are the same than those that Wilkinson and his fellow researchers identified as “longevity genes” in a previous study. Wilkinson said that there is significant overlap between hibernation genes and longevity genes, further emphasizing the link between hibernation and longer lifespan.
The previous study also established the first epigenetic clock for bats, capable of accurately predicting the age of n’ any bat in mother nature. This clock was applied to this latest study, allowing the researchers to demonstrate that hibernation reduces the epigenetic age of a bat compared to a non-hibernating animal of the same age.
Studies like this help explain why bats have longer lifespans than expected for a small, mouse-sized mammal. However, they also raise new questions.
“We still don’t fully understand why some bats can live very long and others don’t,” Wilkinson said. “We have shown that those who live very long all share the ability to hibernate, or enter torpor frequently. It seems like a corollary, but it’s not enough because hibernating rodents don’t live for 20 years.”
Wilkinson said he is planning a follow-up study to compare the epigenetic aging of big brown bats in Canada, where they hibernate, with the same species in Florida, where they do not hibernate. In doing so, Wilkinson hopes to get an even clearer impression of the role hibernation plays in extending lifespan.