Specimens of zebrafish (Danio rerio)
A study revealed that fish embryos actively control the timing of their hatching through a specific neurohormone, which triggers the release of enzymes that dissolve the egg wall.
A study by researchers at the Hebrew University of Jerusalem in Israel reveals the chemical and biological processes that allow this to happen, showing how individual embryos program their emergence with optimal environmental factors.
The discovery has relevant implications for expanding knowledge in neurobiology, survival strategies and environmental adaptation in vertebrates.
The investigation describes am neural mechanism, until now unknownwhich governs a critical vital transition for fish, demonstrating that embryos are not passive, but actively control their own hatching processessential for its survival.
Scientists studied zebrafish eggs (Denmark rerio) and discovered that the release of thyrotropin-releasing hormone (TRH) by the embryo was crucial for the production of enzymes that dissolve the egg wall.
According to , this behavior was also observed in medaka specimens (Oryzias latipes), a species of tropical fish with characteristics unlike those of zebrafish.
The evolutionary paths of medaka and zebrafish separated about 200 million years ago, but the same hatching process triggered by TRH was identified in both speciesdespite their differences in terms of hatching glands, types of enzymes and embryonic periods.
“Hatching is a critical event in the history of life of oviparous species”, write the researchers in the article that presents the conclusions of the , published this Thursday in the magazine Science.
“Leaving too early or waiting too long it can mean certain death for a newborn animal, which is not prepared to face the challenges of the outside world, from breathing to escaping predators. Survival depends on perfect time for hatching“, detail the researchers
“And, surprisingly, It is the embryo itself that dictates this momentalthough until now the underlying mechanism was unknown,” they added.
According to the study authors, HRT travels through the bloodstream to a specialized gland and triggers the release of enzymes which dissolve the wall of the egg, allowing the embryo to be released.
This neural circuit critical for hatching forms shortly before the event and disappears soon after. And if it doesn’t work, the embryos can’t release the enzymes, causing them to die inside the egg.
This is how fish ‘decide’ when they will be born. This allows them, in practice, to choose their sign… which may not be Pisces.
