The secret of Lonesome George

International study published in Nature, Ecology and Evolution

Giant tortoises live a very long life and are an excellent model to study the characteristics of longevity, but the information on the evolution of their genome are scarce. An international team has decoded the DNA of a very special specimen.

Solitary and extremely old, Lonesome George, last specimen of the giant tortoises of Pinta Island in the Galapagos archipelago, has left, in his genetic code, clues to decode the secret of longevity, as revealed in a study published in Nature Ecology & Evolution. An international team that includes Claudio Ciofi, a professor of Ecology at the department of Biology, has studied the genome of the giant turtles in search of the distinctive traits of longevity and age-related diseases.

The researchers — led by Carlos López-Otín, of the University of Oviedo in Spain, and Adalgisa Caccone of Yale University — have sequenced the entire genomes of Lonesome George (who died in 2012 at an age of over 100 years, according to scientists’ estimates ) and a giant Aldabra tortoise, the only living species in the Indian Ocean, to identify genes potentially associated with the development of body size and longevity of these animals, as well as a lower risk of contracting tumors.

“Comparing them with genomes of related species — explains Ciofi — we found a mechanism of positive selection and expansion of families of genes associated with the regulation of metabolism and immune responses, probably related to the exceptional size of these tortoises.”

The team has identified gene variants that are involved in the life span of giant tortoises, thus opening up new potential lines of research on the phenomenon of aging organisms. Furthermore, the researchers found that in the genome of the tortoises there are specific alterations of some tumor suppressors, in particular of two genes whose overexpression is known as the cause of the onset of tumors.