A unique gene found in sloths might hold the key to ageing well, a pioneering study has suggested.
In a scientific first, researchers have sequenced and analysed the genome of the tree-dwelling animal to reveal what might cause their low metabolic rate.
It was found that for millions of years, sloths have conserved "jumping genes” – DNA sequences that can leap around the genome.
One academic said the discovery around the sloth cell lines could inform further research into ageing, metabolic disease and even long-duration space travel.
The research was carried out by experts from Wellcome Sanger Institute, the Leibniz Institute for Zoo and Wildlife Research (IZW), the Hospital Sirio Libanes and their colleagues.
After taking samples from a captive sloth, the team extracted DNA from the tissues which was subsequently sequenced at the Max-Planck Institute for Molecular Cell Biology & Genetics in Germany.
Using a technique called comparative genomics, the team then analysed the sloth genome and compared the sequence to other mammal genomes.
This included an anteater and an armadillo which, alongside sloths, are also members of Xenarthra – the only clade of placental mammals originating from South America.
The scientists compared the genomes to understand what makes sloths unique.
They uncovered that the sloth genome had several copies of active transposable elements called "transposons” or "jumping genes”.
These are short DNA sequences that leap from one location in the genome to another.
Conserved genes
While some transposons are still seen in the human genome, they are usually old and inactive.
By using genomics to look back through the evolution of the unique animal, they found that these transposons arose in the last common ancestor of all sloth species – about 30 million years ago.
According to the researchers, these genes have been conserved over time and are now ingrained genetic sequences that are unique to sloths.
The team uncovered that many of these genes are connected to mitochondria, which are responsible for generating energy and metabolic pathways.
The researchers believe that these jumping genes are related to their unusual adaptations to the environment and evolution of their metabolism - which is the lowest among mammals.
Dr Pedro Galante, co-lead author at the Hospital Sirio Libanes in Sao Paulo, Brazil, said: "Many human conditions – including diabetes, ageing-related disorders, neurodegeneration, and muscle wasting – involve problems with energy production and mitochondrial function.
"While further research is needed, sloth cell lines may offer a natural model for understanding how organisms cope with low-energy states, and what goes wrong in disease.
"In the long term, this could inform research into tissue preservation, critical care medicine, ageing, metabolic disease, and even long-duration space travel.”
Dr Marcela Uliano-Silva, senior bioinformatician and co-lead author at the Wellcome Sanger Institute, said: "Evolution has already run billions of experiments. By studying unusual animals like sloths, we sometimes uncover biological solutions that humans never evolved.
"Using genomics to look back through time, we found jumping genes that sloths have conserved over millions of years.
"These sloth-specific genes are linked to mitochondria and metabolic pathways, suggesting they might be related to the evolution of their extremely slow metabolism.”
Dr Camila Mazzoni, co-lead author and head of evolutionary and conservation genomics at the IZW in Berlin, said: "Sloths have the slowest metabolism of any mammal, yet they remain healthy.
"Understanding how they achieve this may reveal new insights into how cells manage energy efficiently.
"Our findings suggest that sloths might have evolved genetic back-up systems that help compensate for their relaxed mitochondria and support their unique lifestyle.” – dpa
Pullout quote: Our findings suggest that sloths might have evolved genetic back-up systems that help compensate for their relaxed mitochondria and support their unique lifestyle. – Dr Camila Mazzoni,
