Age-defying bats could help us live longer

Bats are the longest-lived mammals relative to their body size, using more energy and living for longer than other mammals of a similar size. 

By studying bats, the European Research Council-funded AGELESS project, which runs until 2017, aims to understand more about the mechanisms that lead to ageing, and potentially uncover the cellular processes that can be modified to halt, lessen and even reverse the process in people.

Dr Emma Teeling, a geneticist at University College Dublin, and principal investigator of AGELESS, believes that one of their greatest evolutionary feats may lie in an ability to subvert nature’s standard ageing process.

‘Among most mammals, there is a correlation between life expectancy and body mass,’ she said. ‘Smaller creatures with higher metabolic rates tend to age faster than larger ones. But, while mice and rats survive only a year or two in the wild, some bats can make it past their forties,’ said Dr Teeling. 

Dr Teeling is using genetic sequencing to look at any chemicals that change in bat blood over their lifespan.

‘The objective is to compare not only the DNA sequence, but also which genes get activated or deactivated as the organism grows older,’ said Dr Teeling. ‘In humans, the expression of genes becomes chaotic over the years. We want to see if this is any different in bats.’

“

‘In humans, the expression of genes becomes chaotic over the years. We want to see if this is any different in bats.’

Sorting through the muddle of genetic material that contains this information would previously have taken decades. But today, next-generation sequencing runs simultaneously through hundreds of thousands of base-pairs, reading out the sequence in just a few hours.

Dr Teeling is looking at some of the possible genetic factors which influence how bats age. She believes the answer could lie in their DNA repair mechanisms.

Since they split away from the ancestor that they shared with humans some 90 million years ago, bats may have evolved more effective DNA repair mechanisms because of their unusual ability for sustained flight.

Bats are the only mammals capable of sustained flight - some bats can fly up to 1 000 kilometres in a single night. However, flying generates toxic by-products. That is why they may have developed unique mechanisms such as more effective telomeres, which are parts of the chromosome which can protect the DNA sequence from deterioration when cells replicate.

Tracking bats

One challenge in tracking the effects of ageing is to find suitable test subjects for the study, which began in 2013. Dr Teeling needs to follow each specimen over a substantial portion of its life, but raising the bats in captivity tends to reduce their lifespan.

The solution came from Dr Sébastien Puechmaille, a zoologist at the Ernst Moritz Arndt University in Greifswald who prepared his PhD with Dr Teeling. ‘I contacted a nature conservation group called Bretagne Vivante,’ he said. ‘They had been studying wild bat colonies for years and were happy to take part in the project.’

The collaboration is now following five colonies of greater mouse-eared bats living in Brittany, in the north-west of France.

The team has implanted electronic transponders into 300 bats to identify them and track their movements across the seasons. Each year, they return to the field to weigh the specimens, measure their wingspan, take a blood sample for genetic sequencing, and then release them back into the wild.

The reward may prove to be worth the effort. Dr Teeling describes ageing as the most familiar but least well understood aspect of all biology. If its key lies within the blood samples being sent back to Dublin, this partnership will have contributed to our understanding of what it takes to live a longer life.