The hindbrain of both sea lampreys and humans is built using an extraordinarily similar molecular and genetic toolkit, according to new research led by the Stowers Institute for Medical Research.
“Our study on the hindbrain — the part of the brain controlling vital functions like blood pressure and heart rate — is essentially a window into the distant past and serves as a model for understanding the evolution of complexity,” said Dr. Hugo Parker, a researcher at the Stowers Institute for Medical Research.
Like other vertebrate animals, sea lampreys have a backbone and skeleton, but they are noticeably missing a feature of their heads — a jaw.
Because most vertebrates, including humans, have jaws, this striking difference in sea lampreys makes them valuable models for understanding the evolution of vertebrate traits.
“There was a split at the origin of vertebrates between jawless and jawed around 500 million years ago,” said Dr. Alice Bedois, also from the Stowers Institute for Medical Research.
“We wanted to understand how the vertebrate brain evolved and if there was something unique to jawed vertebrates that was lacking in their jawless relatives.”
Previous work had identified that the genes structuring and subdividing the sea lamprey hindbrain are identical to those in jawed vertebrates including humans.
However, these genes are part of an interconnected network or circuit that needs to be initiated and directed to build the hindbrain correctly.
In the new study, the authors identified a common molecular cue, while known to direct head-to-tail patterning in a wide variety of animals, as part of the gene circuitry guiding hindbrain patterning in sea lampreys.
“We found that not only are the same genes but also the same cue is involved in sea lamprey hindbrain development, suggesting this process is ancestral to all vertebrates,” Dr. Bedois said.
“This cue is called retinoic acid, commonly known as vitamin A.”
While the researchers…
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