Jonathan’s genome offers clues to extreme longevity

Researchers who sequenced the genome of Jonathan, an Aldabra giant tortoise estimated to be about 194 years old, identified genetic variants and unusually youthful patterns in some DNA-related processes that may help explain his exceptional lifespan. The study, published Wednesday in Science Advances, does not establish that these features caused him to live so long. The team reported 287 gene variants found in Jonathan but not in the tortoises used for comparison. Researchers considered 41 of those variants potentially functionally significant. The variants occurred in genes associated with processes including DNA repair, mitochondrial function, insulin regulation and telomere maintenance, according to the researchers. The study also examined methylation, chemical markers that influence whether genes are switched on or off. Researchers found that methylation in some regions related to mitochondrial function resembled that of a five-year-old tortoise, while much of Jonathan’s methylation showed age-related change. Mitochondria help cells produce energy, which researchers said could be relevant to how cells maintain and repair themselves.