194-year-old tortoise has exceptional DNA repair systems that fight off ageing — SkimNews
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- Jonathan's genome, the first ever sequenced for the world's oldest known land animal, contains 287 gene changes unique to him, with 41 deemed functionally significant and a dozen overlapping with ageing databases of other long-lived species.
- Mitochondrial-function genes in Jonathan are as efficient as those of a 5-year-old Aldabra tortoise, giving his DNA repair systems more energy to counteract the effects of ageing, lead researcher Stephen Clark of the Kallel Foundation said.
- Researchers had to assemble Jonathan's genome from saliva and cheek swabs because St Helena authorities refused blood draws over infection risk, forcing them to fill gaps using DNA from another Aldabra tortoise — a method prone to bacterial contamination.
- Some of Jonathan's genetic changes resemble those found in human supercentenarians, supporting the view that ageing mechanisms are conserved across species, according to Clark.
- Kousuke Hashimoto at the University of Osaka called the work "fascinating" but cautioned the comparison was made against only a few other tortoises, which may themselves carry unique genetic changes.
- Aldabra giant tortoises average around 80 years but can live much longer; Jonathan arrived on St Helena around 1882 as a fully grown adult thought to already be about 50, making him Napoleon's famous contemporary on the remote British territory.
Why it matters: The mitochondrial-efficiency finding echoes Manel Esteller's prior study of a 117-year-old woman, giving longevity researchers a cross-species signal — youthful mitochondria in both the world's oldest tortoise and a human supercentenarian. But the source flags a real caveat from Osaka's Hashimoto: the genome was pieced together from saliva and benchmarked against only a handful of tortoises, any of which could carry their own unique changes.
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