Ramer à Angers

Loisirs

How stripes are formed in zebrafish

The great evolutionary meaning of any animal body coloration is that it makes it possible to live longer and produce more offspring. Natural selection constantly weeds out those who are less adapted to their environment and less well camouflaged. And while this is quite understandable in the macroevolutionary context, the question of the cellular and molecular mechanisms of the formation of stripes, spots and dots still remains.

Theoretically, there are several different mechanisms for the formation of body coloration. One thing is clear - that they are all determined by pigments and are genetically embedded. There are, of course, variations, however, the mechanism that produces the coloring of some cells in a certain color, and their neighbors in another, remains not fully understood. There are probably several mechanisms for the formation of body coloration at the cellular and tissue levels. One of them, in fact, is the appearance of stripes in the small tropical fish Zebrafish.

Danio's charisma is betrayed by his electric blue stripes. The mechanism of occurrence of these bands has remained a mystery for a very long time.

Scientists have tested the Zebrafish's skin in detail and found that it consists of three types of cells pigmented in black, silver and yellow. The combination of these three types of cells forms the color of the fish. Yellow and silver cells combine to form light golden stripes on the body, and yellow, black and silver cells form dark electric blue stripes. Alas, moreover, yellow and silver cells can change their shape, depending on their location in the skin: in light stripes, both yellow and silver cells have a classic shape, whereas in black stripes they have a finely branched stellate.

However, it turned out that all three types of cells arise independently from each other in different parts of the body of the fish embryo, and only then, during metamorphosis, migrate into the skin, forming stripes. That is, their pigmentation is not a consequence of the synthesis or blockade of pigment production in the same cells, as postulated by classical Mendelian genetics. In order to uncover this mechanism, the researchers carried out a series of careful experiments, and showed how stripes appear in Zebrafish.

In the laboratory, scientists injected a special pigment into the cells of zebrafish embryos, which glows under certain conditions. Thus, labeled cells can be easily tracked under a microscope. It turned out that yellow cells are the first to completely cover the skin of fish larvae, while black and silver cells appear later. During the time of embryo formation, yellow cells develop from a group of stem cells that are located on the back of the embryo. Separating, they begin to migrate from there all over the skin.

In contrast to yellow cells, black and silver cells arise from small groups of stem cells that are located in nerve nodes near the spinal cord in each of the segments of the embryo's body. But the ways of their penetration into the skin are completely different from each other. Actually, the black cells, dividing, migrate along the nerve fibers in each of the segments. This way they reach the place of future dark streaks. At the same time, silvery cells migrate along the gaps between the muscle segments, also entering the skin. At the same time, by contacting each other, all cell types differentiate even more - changing their shape and forming contrasting light and dark stripes.

It is not known for sure whether this mechanism is inherent in all fish or only Zebrafish and its close relatives, but scientists have managed to uncover another mystery of nature, which is full of the world around us. Imaginez démarrer votre parcours sur une plateforme de paris avec un avantage financier immédiat. Melbet rend cela possible grâce à une interface intuitive et des options de paiement variées adaptées à tous les pays francophones. Des cotes compétitives sur les ligues majeures aux machines à sous populaires, tout est conçu pour plaire. Au centre de cette proposition irrésistible figure le code promo de melbet qui offre un bonus de bienvenue jusqu’à 130 € sur votre premier dépôt. Ce code active également des tours gratuits au casino. Profitez d’une sécurité optimale, de paris en direct fluides et de retraits rapides.