Everything that lives also dies. This is the cycle of life as we know it. Or maybe as we have known it until a scientific discovery changed everything!
Completely by accident, in 1980s was discovered a species of jellyfish known as “the immortal jellyfish”. The extraordinary fact about it is that when it gets attacked, sick or old, it can completely revert to a sexually immature polyp stage and “begin: its life again. This process can go on indefinitely, thus making the jellyfish biologically immortal.
In the 1980s, a German student, Christian Sommer collected a hydrozoan thought to be Turritopsis nutricula. Sommer kept his hydrozoans in petri dishes and observed their reproduction habits. After several days he noticed that his Turritopsis dohrnii was behaving in a very peculiar manner, for which he could hypothesize no earthly explanation. Plainly speaking, it refused to die. It appeared to age in reverse, growing younger and younger until it reached its earliest stage of development, at which point it began its life cycle anew. This finding appeared to debunk the most fundamental law of the natural world — you are born, and then you die.
From 1980s to today, the discovery still amazes scientists. This specific jellyfish is very popular in all oceans of the world. However, with the engagement of so many researchers, some progress has been made in understanding the life cycle of the “immortal jellyfish”. We now know that the rejuvenation of Turritopsis dohrnii and some other members of the genus is caused by environmental stress or physical assault. We know that, during rejuvenation, it undergoes cellular transdifferentiation, an unusual process by which one type of cell is converted into another — a skin cell into a nerve cell, for instance.
By this point, you are probably wondering how can we use this knowledge to find the so wanted “elixir of immortality”! That question still remains unanswered. The life cycle of the “immortal jellyfish” is of a more technical nature. While in its habitat, the process of aging backward comes very naturally for this specific species, as it turns out, it is extraordinarily difficult to culture in a laboratory. It requires close attention and an enormous amount of repetitive, tedious labor; even then, it is under only certain favorable conditions, most of which are still unknown to biologists, that a Turritopsis will produce offspring.
But we know that every cell contains all the information necessary to build a new whole organism, but only part of this information is actually used once a cell becomes differentiated. The genome of Turritopsis dohrnii is still being investigated and decoding it will be the first step towards the search for an ‘immortality switch’.
Leaving the discovery aside for a moment, one might think if the “immortality switch” is something which will be concrete for the humans in the future? And if so, will the idea ever work in an overpopulated Earth with limited resources?
Still, the discovery is pretty exciting and we cannot wait to know more about it!
Sources: The biologist, New York Times
