A team of researchers from the University of Oviedo in Spain mapped the genetic sequence of the jellyfish, revealing “key molecular mechanisms behind the rejuvenation of Turritopsis dohrnii.”
At first, gathering enough Turritopsis dohrnii to study was difficult. When it comes to living in a tank, “they are very picky,” said Maria Pascual Torner. “And they are very, very small, which also makes them difficult to identify and sample in the field.” To get enough specimens, they drove a specially equipped camper van to a coast in Italy and went diving to gather wild jellyfish. They then rushed them back to the lab.
To trigger rejuvenation, the researchers put the jellyfish under stress by letting them go hungry. As the medusae got smaller, changed into little balls called bud polyps, and began remaking their adult bodies, the scientists took pictures of what genes they were using in each phase of their development. They took some jellyfish in each phase, froze them, and crushed them into a thick mixture to extract their mRNA, creating a record of which genes were actively being used to make proteins.
They also compared Turritopsis dohrnii to Turritopsis rubra, a related jellyfish species that ages normally. Researchers found that, compared to its relative, the “immortal jellyfish” has double the amount of genes that repair and protect DNA. This allows Turritopsis dohrnii to produce more restorative proteins.
The authors found differences in several other genes, including those associated with reproduction and stem cell population. Normally, during the process of DNA copying and cell division, the protective end-caps on chromosomes, called telomeres, slowly get shorter and shorter, and when they are too short, a cell enters senescence and can no longer keep dividing. However, “immortal jellyfish” had mutations that preserved and maintained the telomeres. These differences may be key to the jellyfish’s immortality.
“The most interesting thing is that it’s not a single molecular pathway ... It is a combination of many of them,” said Jan Karlseder, a molecular biologist and director of the Glenn Center for Biology of Aging Research at the Salk Institute. “If we want to look for an extension of a healthy lifespan, we cannot just focus on one pathway. That will not be sufficient. We need to look at many of them and how they work together.”
Of course, Turritopsis dohrnii is not really immortal in the manner that Qin Shi Huang aspired to be; it can easily be killed by predators or die of disease. However, its ability to reverse the aging process by reprogramming its cells could help develop treatments for some of humanity’s most widespread diseases. And that would grant an undying legacy on this tiny sea creature.
After reading about how jellyfish seem to have achieved eternal life, you’re probably asking one major question: How can I get some of that? Unfortunately, while the immortal jellyfish can go full Benjamin Button at will, humans are a long way from mastering this level of rejuvenation.
“It seems that we’re far away from any kind of real-world application,” says Dr. Maria Pia Miglietta, associate professor and head of The Real Immortal Jellyfish research project.
“But we hope that studying what happens in these jellyfish can tell us how their genes change cells–and how these changed cells integrate with others. This is the base of understanding cellular regeneration and tissue regeneration. A lot of reasons why we age are still very mysterious. But by looking at this very simple animal with this very simple system, we can follow some genes and see how they behave.”