Immortality, ‘Where’ Art Thou?
By Dr Zafar M. Iqbal
TCCI, Chicago, IL
Imagine a life that, defying all odds, does not end. What a heretic surprise after we have been, for ages, passionately pursuing eternal youth and immortality, but have not come close to the real elixir or ‘aab-e-hayath’. Not even a drop… yet!
Other than the fabled Khizer, no one lives forever, or is supposed to -- unless we think of emulating an unlikely example, not the strongest but a tiny, fragile form of marine life – some jellyfish, notably of genus, Turritopsis (a member of Oceanidae, Anthomedusae, Hydrozoa, Cnidaria). On its two species, T. nutricula and T. dohrnii, considerable scientific evidence has accumulated on ‘reverse aging’, ‘reincarnation’ or the so-called ‘immortality.”
Essentially focusing on the latter species, a 6,500-word article by Nathaniel Rich (“Can a Jellyfish Unlock the Secret of Immortality?”) in the New York Times stirred a few weeks ago our deep-seated personal and scientific interest in this area. In spite of this, this jellyfish is as fragile as any other life-form, an easy prey to any marine predator and susceptible to disease.
The story stems from research by a German marine biologist, Christian Sommer, who in his early twenties, spent a summer on the Italian Riviera, collecting hydrozoan marine life for his research. Essentially native to Caribbean, this jellyfish has spread in other waters around the world “hitchhiking” on ships using seawater for the ballast. It has been found proliferating in the Mediterranean and off the coast of Japan, Florida, Spain, Panama, and world’s every ocean, from temperate to tropical regions, in what a noted marine biologist, Maria Pia Miglietta, described as “a silent invasion,” worldwide.
Like most hydrozoa, this jellyfish is predatory and essentially has two stages of life: first, the polyp that lives on the ocean floor before maturing into medusa, a shorter phase, free-living in the plankton. The large bright red blob visible under the gelatinous dome is the stomach. A polyp is like a floating “sprig of dill” with hair-like stalks/tentacles that branch out, and terminate in buds. These buds swell and break off to become medusae.
In most hydrozoa, the medusa die after spawning, but Turritopsis medusa, after spawning, sinks to the ocean floor and folds on itself, absorbing the tentacles into the bell and turning itself into a gelatinous blob that eventually develops an outer shell, before growing root-like hairy stolons that lengthen, and become a polyp that again give rise to new medusa and the jellyfish life begins anew, after a cell trans-differentiation phase. A medusa is bell-shaped transparent-to-translucent gelatinous dome, 4-5 mm wide and nearly as tall, with 80-90 hair-like stinging tentacles, which on maturity produce equivalents of sperms and eggs that when fertilized sink to the ocean floor to produce larvae (planulae) which then develop into polyps. Sommer noticed that T. dohrnii that he was then growing in a Petri dish could, instead of growing old and dying, transform itself, at any stage of its life, back into its earliest developmental stage, polyp, and re-live its life again
For its potential ‘immortality’ this jellyfish has also been named a ‘Benjamin Button’, after a 2008 Hollywood movie character that ages in reverse, loosely based on a 1922 short story, bearing the same name, by F. Scott Fitzgerald. An interesting coincidence: this research was being conducted in the same Italian Riviera town, Rapallo, where a century after Nietzsche reportedly conceived of “Thus Spake Zarathustra, ” with such memorable lines as “…. Eternally rolls the wheel of being. Everything dies, everything blossoms again…”
Years after Sommer’s observation, a paper appeared on a related species (T. nutricula), the only other metazoan jelllyfish besides T. dohrnii which undergoes cellular transdifferentiation , that is, an unusual process in which one cell-type is converted into another — similar to what occurs in stem cells, e.g., a skin cell becoming a nerve, muscle or other cell. After it reaches maturity (medusa stage), this jellyfish goes back to its initial stage (polyp). It escapes death, the paper concludes, “potentially achieving immortality” (Piraino et al. Reversing the life cycle: Medusae transforming into polyps and cell-transdifferentiation…….. Biol. Bull.190; 302-312, 1996). Although the findings were considered to be “unparalleled in the animal kingdom,” this research was buried in scientific literature, with no follow-up commercial biotech interest in exploiting it, despite our age-old interest in immortality.
Cell trans-differentiation, which amounts to rejuvenation, can also be induced in this jellyfish by physical trauma, stress and starvation. The NYT correspondent Nathaniel Rich saw it himself in the crammed labs of Shin Kubota, a marine biologist in Shirahama, a picturesque town four hours south Kyoto, Japan. When Kubota deliberately tried to destroy the gelatinous tissue (mesoglea) that makes the medusa’s bell, the NYT correspondent saw the severely damaged jellyfish convulse and ‘die’ in a Petri dish. Over the next 4 days, a series of dynamic cellular transdifferentiative changes occur: After a day, the depleted gelatinous material settles down and attaches itself to the bottom of Petri dish, tentacles collapse and disappear, and it looks more like an amoeba than a medusa, and then stolons emerge and it grows again as a polyp. Although this rejuvenation has always been observed “in 100% of the specimens” in laboratory studies, it has yet to be confirmed in natural circumstances.
Shirahama, Japan, is well-known for its white beaches (thanks to the imported Australian sand) and for its rejuvenating salt water sulfur hot springs, onsens. A simple onsen popular with Kubota and the local old citizens is Muronoyu that traces its history back well over a thousand years. In his spare time, Kubota with his grossly under-financed research, is also a karaoke-enthusiast, a prolific song writer on jellyfish and a TV personality, “Mr. Immortal Jellyfish Man.” This jellyfish is not just difficult to grow in the lab, but the experts in the field are unfortunately restricted to the highly dedicated Kubota and just a few other researchers around the world. Besides, we have, as reported, more scientists interested in crabs than the jellyfish.
To understand this rejuvenation, we have to study the jellyfish genetics. Kevin J. Peterson , a molecular paleobiologist at Dartmouth, who has contributed in this area, was surprised at the similarity in jellyfish and human genomes, and found that the jellyfish genome to be far more complex than previously imagined. He believes that important clues may lie in the jellyfish micro-RNA (MiRNA), small pieces of RNA, also found in stem cells, which act as “on-off” switch, regulating gene expression. When the switch is “off,” the cell remains in its primitive or undifferentiated state, but when turned “on,” the cell gets differentiated or matures normally as a skin, nerve or various other cells.
Another hydroid researcher, Daniel Martínez at Pomona College working on an NIH grant on another metazoan, hydra, believes that this species resembles a polyp but never yields medusas and it is almost entirely composed of stem cells that allow it to regenerate itself continuously, or is thus “truly immortal.”
Surprisingly, or perhaps not so in this age of popularized science, biology has also gotten into architecture. In ‘Tower of Eternity’ of Dubai, some pillars are turned into aquarium, and some of these aquaria are filled with T. nutricula jellyfish displaying beautifully colorful, floating gelatinous and multi- tentacled umbrellas. Perhaps a tacit but unmistakable tribute across cultural geography to the biologically recognized immortality of this tiny, fragile marine life!