In the DNA of Lone George and other giant turtles, genes have been found that are associated with suppression of the growth of cancer cells and increased immunity.
An international team of geneticists from five countries led by Carlos López-Otín of the Spanish University of Oviedo analyzed the genomes of giant tortoises. They have identified those genes that, in their opinion, allow these animals to live up to 200 years. The work was published in the journal Nature Ecology & Evolution.
Lonely George is a male subspecies of the Abingdon elephant turtles (Chelonoidis abingdonii), which lived in the Galapagos Islands before they were exterminated 150 years ago. In the 19th century, whalers and fur traders used these turtles as food, because they could go for a long time without food and water in the hold. Due to this treatment, the population of the subspecies constantly declined until only Lone George survived. Researchers found it in 1972 on Pinta Island. He was transported to the Charles Darwin Research Station in the Galapagos Islands and tried to get offspring from him, but to no avail. In 2012, Lonely George died, leaving only genetic material to scientists.
In addition to the Abingdon elephant turtles, there are other subspecies, such as the Seychelles giant tortoise (Aldabrachelys gigantea). Its representatives live on the island of Aldabra in the Indian Ocean, their number is estimated at 150 thousand individuals. The authors of the work sequenced the genome of both subspecies and compared them with the genetic material of reptiles, fish, mice and humans to determine the DNA regions that play a key role in the longevity of turtles.
Scientists first found that the common ancestor of the Abingdonian elephant and Seychelles giant tortoises lived about 40 million years ago. With humans, the connection of this species was divided 312 million years ago. According to the researchers, such long periods of time only help in finding common patterns among genes of different subspecies.
Comparison of species and isolation of genes responsible for DNA repair / © Nature Ecology & Evolution
In total, the authors found 43 genes that can influence long life expectancy. Among them are those related to the immune system and protection against viruses, parasites and infections. Also, in giant turtles, additional copies of genes were found that are responsible for suppressing the growth of malignant tumors. However, the most interesting finding turned out to be those genes that are involved in repairing chemical damage and breaks in DNA molecules. In particular, they noticed a change in the XRCC6 gene, which is involved in the joining of double-stranded DNA breaks. The only animal with a similar mutation is the naked mole rat, which is known to be able to stop individual development at the neonatal stage (neoteny).
Scientists plan to find out why Lonely George could not leave offspring when mating with representatives of other subspecies.
You can learn more about giant turtles and the phenomenon of their longevity from our video, which tells about the most amazing cases. For example, about the male Seychelles giant tortoises - Jonathan, who is now 186 years old.