Living things have to contend with aging - except for a few unusual creatures, like Turritopsis dohrnii, which has an extraordinary ability to survive. It starts out as a fertilized egg that develops into a larva, which eventually settles onto the seafloor and generates a colony that can spawn free-swimming medusae, or jellyfish. These jellyfish become adults within a matter of weeks, and can reproduce asexually when conditions are favorable.
When these tiny jellyfish, which are only about the size of a pinky nail, come under threat from events like starvation or tissue damage, they can revert to their polyp stage. In that form, the polyp colony can release more jellyfish when the time is right, and the new spawns are genetically identical to the original adult. Thus, these animals have a kind of immortality, and have been given the nickname the immortal jellyfish, though the term is a bit misleading when compared with their actual abilities.
Scientists have now investigated the genetics of T. dohrnii. The findings have been reported in the Proceedings of the National Academy of Sciences.
While there are other jellyfish that can reverse the aging process and go back to a larval stage, most lose that ability after reaching sexual maturity; T. dohrnii. is different.
In this study, the researchers compared the genomics of T. dohrnii to a close jellyfish relative called Turritopsis rubra, which cannot revert to the polyp stage after it reaches sexual maturity. This comparison showed that there are some variants in the T. dohrnii genome that may give it special powers of DNA repair or replication; the jellyfish has about twice as many genes involved in gene protection and repair when compared to T. rubra. The immortal jellyfish can also maintain the length of their telomeres better than other animals can. Previous research has shown that telomeres get shorter as organisms age, and other work has linked genomic instability with aging.
T. dohrnii can also alter the transcription of certain genes as it reverts to a polyp.
While this work won't be leading to the delveopment of any new anti-aging treatments or creams, it may help scientists learn more about how humans age, and how to prevent some of the genetic or cellular damage that builds up as we age and causes disease. It may one day be possible not to cheat death, but to live a healthier life as we get older.
Sources: AMNH, Proceedings of the National Academy of Sciences
