The starfish also has a “head”: it is not located in a specific area of the organism, but is distributed partly in the central disc and partly within each of the five arms. This was discovered by researchers from the Universities of Stanford and Southampton, thanks to advanced genetic and molecular techniques that made it possible to create a three-dimensional atlas of the genes expressed in different parts of the body of these strange animals. The study was conducted with support from NASA, the National Science Foundation, and the Chan Zuckerberg BioHub published In the journal Nature.
The study’s first author, Laurent Formieri, says her finding is “more complex than we imagined.” “It’s as if the starfish is missing a proboscis entirely. It would be better to describe it simply as a head crawling on the sea floor. This is not at all what scientists have assumed about these animals.”
Starfish anatomy has always been a puzzle to zoologists, because it does not have bilateral symmetry like most animals (including humans), but rather a five-radial symmetry that does not allow us at first glance to determine the location of the head, torso or animal. a line. To solve the puzzle, the researchers put anatomical studies aside and tried to understand whether a molecular “axis” could be recognized in starfish to mark different areas of the body.
“First – explains Formeri – we dissected the arms of the starfish and used RNA tomography to determine which genes were expressed in each section. Then we reassembled everything using computer models. This way we obtained a 3D map of its expression. Gene.” Then, using advanced in situ hybridization technology, “we stained the tissue and visually examined the samples to see where certain genes were expressed.”
The results show that the starfish has a “head” in the center of each arm and a “tail” around the circumference. Surprisingly, the 3D gene expression map revealed the absence of a true trunk, suggesting the possibility that the starfish are essentially five-headed heads that move.
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