(ORDO NEWS) — In the development of hearing cells in the human inner ear, the same gene is involved that is responsible for the formation of tactile cells on the tentacles of sea anemones.
The discovery sheds light on the evolution of hearing that began hundreds of millions of years ago, at the end of the Proterozoic.
Cnidarians, or cnidarians, are a type of multicellular animals, these include jellyfish, corals and sea anemones. They appeared at the end of the Proterozoic and probably became the ancestors of animals with bilateral, that is, two-sided symmetry, which include most highly organized modern organisms, including vertebrates.
The study of cnidarians is extremely important for understanding the evolution of vertebrates, since the common features of bilateral animals and modern cnidarians were present in their common ancestor. One such trait was the development of the nervous system, which is controlled by similar sets of genes in cnidarians and bilateral animals.
An international team of scientists focused on the study of hair cells – receptors in the inner ear of vertebrates that convert sound vibrations into electrical nerve impulses that are sent to the brain. Unlike vertebrates, cnidarians are deaf.
However, some of them, such as sea anemones, have hair cells on their tentacles. The same transformation process that takes place in the ear of vertebrates helps sea anemones to sense the mechanical touch of prey or the vibrations of water.
It was known that the pou-iv gene is involved in the development of hair cells in mammals, including humans. Experiments have shown that mice lacking this gene are born completely deaf. Scientists also knew that sea anemones had this gene, but had never before explored its role in the development of their hair cells.
Using genetic engineering methods, the authors of the work blocked the pou-iv gene in sea anemones. This led to abnormal development of tentacle hair cells and rendered the animals unable to respond to touch. In addition, it was found that pou-iv is required for the normal functioning of the polycystin-1 gene in sea anemones.
In vertebrates, the same protein is needed for the perception of fluid flow by kidney cells. Thus, the role of the pou-iv gene in the development of mechanoreceptors goes back at least to our last common ancestor with sea anemones.
The results of this work open up a completely new field of research into the development and functions of mechanoreception in cnidarians. In addition, the discovery indicates that the evolution of our hearing has a very ancient history, which dates back to the late Proterozoic and has been going on for more than 500 million years.
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