Coral, a door to understand human aging

© Jonathan Lancelot / Fondation Tara Océan

Coral definitely has many qualities. By forming beautiful, colorful limestone structures, it shelters a large number of marine species, provides food security for millions of people, protects coastlines, and shows promising applications in human health. Another reason draws the attention of scientists: its incredible resistance to aging.

Coral: an animal that doesn’t age

This aspect of coral could tell us more about the processes that control aging in humans. But what exactly is the link between the aging of coral and that of humans? What makes this animal so interesting for the study of aging? First, a coral is a colonial animal. A limestone structure formed by a colony of coral, as impressive as it may be, begins initially from a single egg cell. Given their considerable age, the number of cell divisions necessary is gigantic.

When a human cell divides, the chromosomal DNA is progressively “nibbled” at its tips, causing a loss of genetic information contained at the extremities of the chromosomes. This genetic loss causes the cell to age: it can no longer divide and enters into senescence. This process is at the root of aging in vertebrates. Coral, in spite of all its cellular divisions, seems not to undergo any alteration, as if it were not aging. What mechanisms make these cells much more resistant? Are they able to protect the DNA at the ends of their chromosomes? Scientists have trouble giving a specific age to corals, but some of them are certainly several hundred years old.

Another reason that makes coral interesting to study is the proximity of its genome to that of humans. These famous sequences at the ends of the DNA molecule that are damaged, division after division in humans, are the same in coral.

L’équipe scientifique en charge de l’étude des récifs coralliens travaille en binôme durant les plongées.© Pete West / Tara Expéditions Fondation

Understanding coral resistance thanks to the data collected byTara

Initiated by the Tara Foundation, the Tara Pacific expedition (which ended with the schooner’s return to Lorient last October) will help to advance some unprecedented, large-scale research on coral. In particular, on the mechanisms that enable coral to fight against aging, thanks to the research conducted by IRCAN, directed by Eric Gilson at the Université Côte d’Azur. Until now little research had been done on the subject and it was not exhaustive. The samples and data collected aboard Tara are so numerous that scientists are sure to be able to answer certain questions concerning the aging process of coral.

Throughout the expedition, the Tara Pacific team harvested three species of coral. Researchers will be able to determine if some species are more resistant than others to aging, and if they use specific mechanisms. On the contrary, perhaps all types of corals use the same process to protect and maintain their cells in good condition over long periods of time, despite their large number of cell divisions.

Another very important variable which scientists in this research group (partner of the Tara Foundation) will be able to examine — the environments in which the corals live. Do they live longer in certain types of environments, or are their living conditions ultimately of little consequence? It is quite possible that certain particularly stressful conditions for the coral cause faster aging. Microorganisms that live in symbiosis with coral and are essential to its functioning may also play a role. It has already been shown that two organisms living in symbiosis can influence each other at this level.

Once scientists understand how the coral is so well maintained over time, and if it turns out that these mechanisms are encoded in its genome, this discovery could lead to treatment paths for humans. More research would be needed to achieve this, but it would be an important first step.

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