The axolotl, this eternal child, regenerates infinitely
Here is a strange amphibian, with its long tadpole body, sometimes gray, sometimes pink, its head flattened like a pebble and its gills springing from it like bouquets of flowers. This Mexican salamander can remain a "child" as long as it wants and regenerate endlessly! Transcription of an episode of the family-friendly Bêtes de Science podcast , it is aimed at young and old alike. Whether you want to read the story or listen to it, check out the episode below.
There are adorable faces, funny faces, strange faces and then there is the axolotl's face, which combines all of these things at the same time. With its large smiling mouth, its tiny eyes resembling two black dots, its six gills that spring from each side of its head like so many leafy antennae, and the membranous crest that runs along its entire tadpole-like body of four-legged fish, in short, with its panoply of quirks, the axolotl looks like Pokémon on the run. He also inspired one, named… Axoloto. Yes, it is original!
However, far from Charizard and other Pikachu, the axolotl is a salamander native to Mexico; an amphibian belonging to the order of urodeles and responding to the sweet Latin name of Ambystoma mexicanum. Its common name, axolotl means "water monster" in Nahuatl, a Mexican language already spoken by the Aztecs in their time. I let you judge if you find it monstrous or not, but in any case, it is an aquatic animal: the axolotl evolves in the high perched lakes of Mexico like a fish in the water. It feeds on small fish, crustaceans and even insects. And takes it easy, during the 10 to 15 years that his life lasts. In its natural environment, the axolotl is most often dark grey, almost black. Albino axolotls, a pretty pale pink color with often candy pink gills, only exist in captivity. Aquarists, humans who like to take care of aquatic plants and animals, love it. But unfortunately, aquarium life is far from ideal for our little beast, which sees its life expectancy reduced to five short years, as soon as it evolves in captivity.
Its chewable face is not entirely due to chance. Unlike other amphibians, which metamorphose, that is, go from a larval form, like a tadpole, to an adult form, like a frog, to leave the waters and live the high life on dry land. , the axolotl remains a kind of big baby for life. This phenomenon is called neoteny: the axolotl becomes an adult, but its body does not transform into an adult body, it remains at a stage of its development that is called larval. Under certain specific conditions (if it suddenly finds itself out of the water, facing sharply rising temperatures or in contact with certain chemicals), the axolotl can then metamorphose. His gills atrophy, his lungs expand... and he suddenly loses his superpowers. But I won't tell you more because we will come back to it later. This eternal youth of the axolotl is of great interest to scientists. It is so studied that it has become what is called a model in biology: it is an organism that we know well and which serves as a reference for all kinds of studies.
Despite the interest it arouses, the axolotl is in danger. He, who swarmed in the Aztec era, saw his habitat shrink due to the extension of cities and pollution due to human activities. Today there are about a thousand left in the wild, making it a critically endangered species. However, under its air of aquatic dragon, the axolotl has extraordinary powers that fascinate the entire scientific community. To discover them, we are going to meet Ashley Maynard, on the side of the University of Zurich. She's about to guide us through uncharted territory... Don't forget your compass, we're off to explore the intricacies of the axolotl's brain.
So here we are at the Swiss Federal Institute of Technology in Zurich, a city in northern Switzerland, from where you can admire the snow-capped peaks of the Alps while taking a short walk near the beautiful Lake Zurich. Ashley Maynard works here and studies the biological development of organisms. So the axolotl and its superpowers are for her, as for many scientists in her field, an absolutely fascinating subject of study! As you already know, the axolotl remains "young" throughout its life, and could therefore teach us a lot about a natural biological mechanism that we all know: aging. But there is something else. By studying the axolotl, scientists discovered that it was able to regenerate. Yes, yes, the axolotl can regrow a leg, an eye, its lungs or its heart! A bit like having your arm cut off and after a month, a brand new arm had grown back instead! Handy, isn't it? To tell the truth, we humans are also endowed with regenerative abilities. We regularly regenerate the cells of our skin, or those of our blood for example. These cells are the basic components of all living things. We humans are multicellular: our organism is made up of trillions – that is to say trillions – of cells, invisible to the naked eye, which have different roles and which we can therefore regenerate when it is necessary. is necessary. I am sure that you have already cut yourself, for example, to see a scab form on the surface of your wound before this scab disappears to reveal brand new skin. This is a fine example of regeneration!
Le cerveau de l'axolotl
Mais tu l’auras compris, à ce petit jeu l’axolotl nous bat à plate couture. Ne t’en fais pas, Ashley Maynard est là pour nous livrer tous ses secrets. Elle et ses collègues ont en effet coupé une partie du cerveau d’un axolotl, puis… ils ont attendu. Attendu, que le cerveau de l’axolotl se mette à fabriquer de nouvelles cellules, parmi lesquelles des cellules dont tu as certainement déjà entendu parler : des neurones, ces cellules qui te permettent de penser, de voir, de parler ou encore de bouger ! Pour suivre l’évolution de la situation, les chercheurs ont utilisé des marqueurs qui permettaient de colorer les cellules du cerveau de l’axolotl en fonction du rôle qu’elles jouaient et au fur et à mesure qu’elles se développaient ! Les images qu’ils ont obtenues ressemblaient alors à des constellations de points colorés, verts, rouges, bleus, agglutinés entre eux. Et là, surprise : l’axolotl ne se contente pas uniquement de faire repousser la partie de son cerveau endommagée. Il recrée toutes sortes de cellules différentes qui jouent chacune un rôle bien précis. Et il ne s’arrête pas là : les chercheurs ont également découvert qu’il est capable de recréer les ponts qui permettent à chaque partie du cerveau de communiquer entre elles. Bref, son cerveau ne se contente pas de former une cicatrice ; il redevient comme neuf ! Cette étude a permis de découvrir quels moyens biologiques permettent à l’axolotl de régénérer ses cellules mais également de mieux comprendre la naissance et les étapes de croissance et d’évolution des cellules qui constituent nos cerveaux ! Bien que nous soyons très différents, l’axolotl nous en apprend donc un peu plus sur nous-mêmes. Incroyable, n’est-ce pas ?
Source: websites