Achieving immortality is something that has guided human beings throughout their history. Many particular legends and fables have been told about the search for the elixirs of life. Medieval alchemists worked tirelessly to find the formula for the philosopher’s stone, which conferred rejuvenating powers. Another well-known story is that of the travels of Juan Ponce de León, who, while conquering the New World, searched for the mysterious Fountain of Youth.
But to this day, no one has succeeded in discovering the keys to eternal life. There is, however, an exception – a creature not exceeding four millimeters in size Turritopsis dohrniialso known as “the immortal jellyfish”.
Biological immortality, within reach of a jellyfish
Unlike most living organisms, Turritopsis dohrnii is capable of biological rejuvenation and immortality. It challenges our perception of aging, but how does it do it?
Let’s start by understanding the generic life cycle of a “deadly jellyfish”. It reproduces sexually: the sperm of the male fertilizes the eggs of the female and the zygote is formed. The zygote develops as a larva and drifts until it attaches to the seabed. Once settled, it turns into a polyp, and when ready, it reproduces asexually. To do this, it releases tiny jellyfish from its own body, which then grow to adulthood and reproduce, before dying.
The immortal jellyfish, Turritopsis dohrnii, also follows this cycle, but after having reproduced, it does not always die: it can choose an alternative path and reverse its life cycle. Along the way, her jellyfish body shrinks into something like a sphere, called a “cysto”. This drifts until it sticks to the bottom, then generates a new polyp, which in turn gives rise to new jellyfish, thus entering the cycle again.
This process can happen endlessly and allows the jellyfish to escape death.
Turritopsis dohrnii life cycle with the alternative pathway of rejuvenation. Image credit: provided by the author
Deciphering the genome of the immortal jellyfish
The keys to immortality Turritopsis dohrnii are inscribed in its DNA, but discovering them was no small feat.
Our research team led by Carlos López Otín from the University of Oviedo has helped decipher the genome of this immortal jellyfish. The results were published in the journal PNAS. This was done by reading letter by letter and writing gene by gene all of his DNA as if it were a huge instruction book.
This enormous book contains all the information necessary for cells to carry out their vital functions. As a result, several genomic clues have been defined that contribute to understanding the extraordinary longevity of the immortal jellyfish.
Using various bioinformatics tools and comparative genomics (comparing the gene book between species), it was discovered that Turritopsis dohrnii has a number of genetic variations that contribute to its biological plasticity and longevity.
The genes found are associated with different keys to aging such as DNA repair and replication, renewal of the stem cell population, cell-to-cell communication and reduction of the oxidative cellular environment that damages cells, as well as the maintenance of telomeres (chromosome ends).
All of these processes are associated with longevity and healthy aging in humans.
Moreover, by studying in detail each step of their rejuvenation, a series of changes in gene expression have been identified, necessary for the transformation of cells, through a process called dedifferentiation. This allows the Turritopsis dohrnii effectively resetting one’s own biological clock.
All of these mechanisms act synergistically as a whole, thus orchestrating the process to ensure successful rejuvenation of the immortal jellyfish.
The real secret of immortality
If Juan Ponce de León had known the secrets kept by Turritopsis dohrnii during his search for the fountain of youth, he was said to have dried out. And the alchemists would not have found the much-desired philosopher’s stone. This is because, unfortunately, it would not be possible for a human body to replicate what the jellyfish does. Perhaps the only way to find such a fountain or stone is to realize that there is no life without death. That any system, like humanity or our own body, needs the death of some of its parts to stay in balance and survive.
Fascinating feats of Turritopsis dohrnii we have learned the keys and limits of cellular plasticity, and through this knowledge we hope to find better answers to the many age-related diseases that trouble us today.
Nevertheless, the dream of biological immortality for man remains just that: a dream. Humans have at least discovered another way to be immortal – by contributing to history through art and knowledge.
Daniel Maeso Miguel, Doctor of Biomedicine and Molecular Oncology, University of Oviedo and Maria Pascual Torner, postdoctoral researcher, University of Oviedo
This article is republished from The Conversation under a Creative Commons license. Read the original article.