A study from the University College Dublin found that two species of long-lived bats have evolved unique tricks to prevent their telomeres from shortening with age.
“Only 19 species of mammal are longer-lived than humans given their body size, and 18 of these species are bats," the authors wrote in Science Advances.
"Bats are the longest-lived mammals relative to their body size, with the oldest bat recaptured (Myotis brandtii) being >41 years old…Living ~9.8 times longer than predicted for its size.”
Every time a cell replicates, it must unzip the double-stranded DNA bundled in the chromosomes and make a copy of each half. A short section at the end of the chromosome is lost during each iteration because the enzymes that string together new copies of the DNA template cannot reach all the way down.
To protect the important genes encoded on the strand from being lost during this process, complex organisms evolved to have extra sections of nonessential DNA at the end of each chromosome. The repeated sequences of filler nucleotides constitute the telomere.
As we age, the telomeres in the majority of our cells become shorter and shorter. The consequences of this are not yet fully understood, but evidence suggests that our potential lifespan and several signs of aging (including gray hair and poor wound healing) may be influenced by the integrity of our telomeres
Earlier studies implied that bats have long telomeres compared to other species, so the UCD group led by Dr Nicole Foley decided to dig deeper.
After examining wing tissue cells collected from nearly 500 wild-captured bats of four species, they established that two non-Myotis bat species experience normal telomere shortening with age.
"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,” said Dr Foley in a statement.
Their laboratory investigation also revealed that Myotis bats do not express telomerase (an enzyme that maintains telomeres) in their blood, just like humans, meaning that other factors must be responsible for preventing telomere shortening in these creatures
Analysis of over 225 genes known to be associated with telomere maintenance and DNA repair showed that the Myotis bats express five genes differently than all other mammals examined (using a large database), including the similarly long-lived naked mole rat. Moreover, two of these genes, ATM and SETX, appear to have changed from the versions shared by all other mammals, suggesting beneficial variations have been recently acquired.
The discovery could aid research into anti-aging medicine for humans, as currently boosting telomerase levels in our bodies could result in cancer.
"Our results suggest that long-lived bats have evolved better mechanisms to prevent and repair age-induced cellular damage," said Dr Teeling. “These are exciting new results that we need to further explore to uncover how bats can remain healthy as time passes."