Human beings are related to lampreys, discovered a new study conducted by scientists at the Stowers Institute for Medical Research and published in the journal The nature of communication. The researchers identified Remarkable similarities in brain development between humans and sea lampreys, creatures that fit perfectly into what it means to be a deep sea monster and all They are 500 million years old. (The lamprey is a fish known for its prominent suction cup mouth with sharp teeth.)
A new study shows that sea monsters are our cousins
Similarities in the brain
There are three basic units of the vertebrate brain: midbrain, forebrain and hindbrain. This last part includes the upper part of the spinal cord, the brainstem and the cerebellum. It controls some vital functions that are necessary for our survival, including blood pressure, heart rate, breathing rate, motor activity, sleep and wakefulness. Like other vertebrates, lampreys have a spine and a skeleton, but they lack a very important feature of the head: the jaw. The study focused specifically on the hindbrain, a region that has been evolutionarily conserved or virtually unchanged throughout the process of evolution.
“Our study of the hindbrain, the part of the brain that controls vital functions such as blood pressure and heart rate, is essentially a window into the distant past and serves as a model for understanding the evolution of complexity,” says researcher Hugo Parker. at the Stowers Institute for Medical Research.
According to scientists, both humans and sea lampreys build this vital part of the brain using a strikingly similar set of genetic and molecular tools. In a new study, the authors identified a common molecular signal, although it is known to control head-to-tail patterning in a wide variety of animals as part of the genetic circuit that controls hindbrain patterning in sea lampreys.
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“About 500 million years ago there was a split in the origin of vertebrates between jawless and jawed,” said Alice Bedois of the same institution. “We wanted to understand how the vertebrate brain evolved and whether there was something unique to jawed vertebrates that was missing from their jawless relatives.”
Meaning of retinoic acid
The research focused on a key molecular signal, retinoic acid, previously believed to control genetic circuitry in hindbrain development in complex species. Although scientists knew that retinoic acid signals the genetic circuit that builds the hindbrain in complex species, it is not thought to be involved in simpler animals like sea lampreys.
In terms of a very specific genetic function, humans are a little more related to the sea lamprey than scientists previously thought.
“We found that not only the same genes but also the same signal are involved in the development of the hindbrain of the sea lamprey. suggesting that this process is ancestral to all vertebrates”, explained Bedois. “This signal is called retinoic acid, commonly known as vitamin A.”
The discovery challenges previous assumptions about the development of the sea lamprey’s brain. This not only concludes the investigation evolutionary gap between humans and sea lampreys (it was not known that the genetic circuit that builds the hindbrain was also involved in that of more primitive species), but also highlights the role of retinoic acid as a key signaling molecule in vertebrate development. It also opens up new avenues for understanding the incredible diversity among vertebrates, suggests that other mechanisms contribute to the great diversity that exists in the animal kingdom.
The hindbrain is an older region that has been evolutionarily preserved or virtually unchanged throughout the entire process of evolution.
“We all come from a common ancestor,” Bedois said. “The sea lampreys provided another clue. “Now we have to look even further back in evolutionary time to find out when the genetic circuit that controls the formation of the hindbrain first evolved.”
Understanding how signals provided by retinoic acid are used to create normal head and face structures in vertebrates is essential to understanding how this process can fail.
With their eel-like bodies and circular rows of teeth, sea lampreys may look like creatures from a sci-fi movie, but these jawless fish are part of our natural history.
Sea lampreys are fish native to the Atlantic Ocean and the Great Lakes.
It belongs to an ancient line of jawless fish known as Agatha. Unlike many of his contemporaries in the seas Devonian Lampreys have managed to survive to this day, making them one of the oldest vertebrate lineages in existence. They witnessed the rise and fall of the dinosaurs, the splitting of the continents, and the transformation of Earth’s climate and ecosystems.
Reference:
Alice MH Bedois, Hugo J. Parker, Andrew J. Price, Jason A. Morrison, Marianne E. Bronner, Robb Krumlauf. Sea lamprey elucidates the origin of the coupling of retinoic acid signaling to vertebrate hindbrain segmentation. Nature Communications, 2024; 15 (1) DOI: 10.1038/s41467-024-45911-x
