Some bats display remarkable longevity and don’t get cancer – but up until now no one knew how this was possible.
An international team headed by researchers at University College Dublin has identified a key genetic difference in bats that helps them counter the effects of ageing.
The researchers predict their work may ultimately help to unlock the secrets of slowing down the ageing process and extending “health-span” in humans, ie how long a person stays healthy.
The biologists studied wild populations of bats as they aged and focused on one known ageing process: the shortening of the protective caps at the end of chromosomes, known as telomeres. This occurs with age in nearly every animal studied, including humans. Chromosomes carry genes that determine the traits of a species.
"When our telomeres get too short, our cells become old, stop replicating, and this drives our ageing process," explained Prof Emma Teeling of UCD School of Biology and Environmental Science who directed the research. Their findings were published in the journal Science Advances on Wednesday.
Comparing the genomes of the "longest-lived bats" (a particular category also known as Myotis) to other mammals suggests they have evolved better mechanisms to prevent and repair age-induced cellular damage.
“Potentially they may have evolved a unique process to lengthen their chromosomes without inducing cancer, which may keep them young,” she said. “These results will help us design better intervention methods to slow down the ageing process and ultimately extend human health-spans.”
Longest-lived bats live an average of 37 years, which is extraordinarily long given their size, Prof Teeling said – it’s the human equivalent of 234 years. “In the longest-lived species of bats telomeres don’t shorten with age. Whereas in other bats species, humans and other animals they do, causing the age-related breakdown of cells that over the course of a lifetime can drive tissue deterioration and ultimately death.”
To conduct the study, they took small wing biopsies from some 500 wild bats from across four species that they captured, marked and released. The samples were flash frozen in liquid nitrogen or dried using silica beads. This enabled their DNA to be extracted, and the change in telomere length to be assessed.
"Our results show that telomeres shorten with age in two of the bat species . . . [which is] typical of most mammals," said zoologist Dr Nicole Foley of UCD, the study's lead author. "But in the longest-lived species of bats (Myotis), we did not detect any evidence that their telomeres shorten with age, contrary to all expectations."
To uncover how the long-lived species of bats can maintain their telomeres over time, they compared their genomes (complete set of genes) with those of 52 other mammals, focusing on 225 genes associated with the maintenance of telomeres.
“Our results suggest that long-lived bats have evolved better mechanisms to prevent and repair age-induced cellular damage. In particular, two genes – known as ATM and SETX – may drive this,” added Prof Teeling, senior author of the paper, which is the culmination of her 20 years of research on bats.
The bats may have evolved a unique process to lengthen their chromosomes without inducing cancer. “These are exciting new results that we need to further explore to uncover how bats can remain healthy as time passes,” she said.
The results mark a first step in helping to understand the molecular mechanisms bats have evolved, that underlie their unusual and long life-spans. “Studying wild bats in an ageing context may provide exciting new solutions to slow down the ageing process and ultimately extend human health-spans.”
“Understanding ageing is a grand challenge in biology,” Prof Teeling said, and while “supercentenarians” were now living to 115 years old and some scientists were striving to ensure humans lived for ever, her priority was to improve health-span to keep people healthy for a long as possible.
The bat study was funded by the European Research Council and involved 10 research and conservation institutes including bat biologists from France, Portugal, Germany and the UK.