MADRID – The vast majority of all living things go through a predictable life cycle, with cells and tissue ageing to such an extent that death is a logical consequence. Yet there is a jellyfish creature that seems to ignore all ‘ageing rules’.
A fertilised jellyfish egg usually settles on the seabed and grows into a polyp: a kind of stalk with tentacles with which it catches plankton. When the time is right, the upper part of the polyp detaches and the familiar free-swimming jellyfish or medusae forms. The jellyfish soon become sexually mature and usually die after they have produced offspring. T. Dhornii not, the Benjamin Button of the jellyfish may under certain circumstances choose to revert from free-swimming jellyfish to the initial phase of ‘polyp’.
A Spanish team of scientists at the University of Oviedo has mapped the genome (the complete genetic makeup) of T. Dhornii. This finally led to the key factors explaining the “biological immortality” of the slippery creature.
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These scientific developments offer perspective and may provide answers to questions about age-related diseases in humans. According to Carlos López-Otrín, research leader and professor of molecular biology, “the study is certainly not a quest for human immortality, but rather for understanding ‘cell plasticity: the ability of cells to take on characteristics of other cells.” López-Otrín adds that this research may help us learn more about ageing diseases in humans.
The research, which was funded by several leading Spanish institutes, among others, has now also been published in the American scientific journal Proceedings of the National Academy of Sciences.
Comparative research between T. Dhornii and humans
By unravelling the jellyfish’s DNA code, the researchers mapped out the genes that characterise T. Dhornii’s immortality. These are genes associated with the repair and replication of DNA and the protection of chromosomes. These genes influence processes related to longevity and healthy ageing in humans. For T. Dhornii, a complicated genetic process called transdifferentiation enables the jellyfish to change its composition and function in its cells. This allows it to cyclically rejuvenate and transform from a free-swimming jellyfish to a polyp.
A complex interplay
According to Maria Pascual-Torner, a postdoctoral researcher in the Department of Molecular Biology, there is not so much one reason that explains the jellyfish’s rejuvenation success. “It is a combination of factors, a synergistic interplay that enables the jellyfish to make this remarkable transformation.”