There sea nut (Menemiopsis leidyi) is a ctenophore native to the Atlantic which has also been permanently present in the Mediterranean Sea for several years. It is not particularly dangerous for people (even if it resembles jellyfish it is not stinging) but it is an invasive species in many seas, including the Black Sea but also our Adriatic and Tyrrhenian Seas. One of its most interesting features is the fact that this organism would be capable of “go back in time” and regress to an earlier life stage, as published in a recent study in the journal bioRxiv. An ability to regeneration similar to that of delle “immortal jellyfish” as Turritopsis dohrnii. But how does the sea walnut rejuvenate and how can the mechanism be useful to the species (as well as to us humans)?
What are sea nuts and the reversal of aging
Mnemiopsis leidyicommonly known as sea nutis a small marine invertebrate native to the eastern Atlantic Ocean. Although it is part of a phylogenetic group in itself (it is in fact one ctenophore), this animal being transparent and gelatinous it is often confused with jellyfish (belonging to the phylum Cnidaria). It is hermaphrodite, therefore it reproduces by self-fertilizing.
In addition to being studied in zoology, sea nuts have over time become a topic of debate in the ecological field due to their invasion of the Black Sea, Asia and most of the European seas. However, one of the most interesting aspects of this species has to do with a recent discovery: by analyzing its morphology, it was demonstrated how these small marine animals are capable of regress to a tentacled larval form, reversingif we want, the passage of time.
How sea nuts rejuvenate: the biological mechanism
In short, when things get tough they take over stressful conditions elevate active sea nut a regression mechanism reaching a more minute, rounded shape without tentacles. The results of the experiments demonstrate that sea nuts they get smaller until it becomes small blobs of a few millimetres, but without dying. At that point, re-establishing a suitable environment and by feeding the animals, many of the specimens were able to develop again, in some cases even reforming the tentacles typical of the larval phase, hunting and reproducing as if nothing had happened.
Basically sea nuts they become young again under stress and become adults when environmental conditions are favourable. These data were obtained by taking the animals to limit: Researchers have studied how M. leidyi responds in the absence of food and to the export of some body parts (in particular the gelatinous lobes).
The ecological implications of the discovery on the rejuvenation of sea walnut
Regression might explain how M. leidyi was able to overcome ecological barriers and stress factors (food and heat) surviving transoceanic journeys transported by ballast water. This organism (as well as many others) due to its size, high transparency and not being able to completely counteract the force of the water, is easily collected together with ballast water (ballast water in English) which are used to keep the vessel in trim and safe during navigation.
Although the law imposes the obligation of water treatment to ensure the environmental safety (avoiding exchanges of potentially harmful liquids from a chemical, physical and biological point of view), many organisms are embarkedtransported and released at a great distance from the point of origin. This action can have a very impactful effect on an ecological level, promoting dispersion of potentially invasive organisms which tolerate little oxygenation, temperature changes and the absence of food well.
And that’s exactly what is supposed to have happened with the sea walnut: the significant increase in the ecological area of the species it might have been favorite precisely from a phenomenon of “rejuvenation” or rather, from adult regression to the larval phase which would have increased its ability to plasticity and resilience.
Implications of the study
Specific pluripotent stem cells in sea walnut have not yet been identified and further data are needed to support the hypothesis. The scientific community is not yet fully in agreement on the concept of “individual”on the functioning of thecellular biological clock and on what in some cases appears to be an imperfect rejuvenation but, while waiting for confirmation, the analysis of the processes of senescence continues also thanks to these new and interesting assumptions.
The study of aging is, in fact, in the eye of the storm both in the zoological and medical fields: any data can be a small but important achievement for understanding even better how they work not only i development processes but also theecology el’evolution of speciesthe molecular and genetic mechanisms involved in cellular trans-differentiation, the action of telomeres as well as the DNA regulation and repair.
The results they raise important questions on the anatomy and life cycles of many animals, hopefully leading to innovative ideas for application in regenerative medicine and in therapies against human aging.
