A research team from the University of Arkansas has made a link between the developmental gene for touch in sea anemones and the development of auditory cells in humans.
An international team of investigators, including several researchers in biological sciences from UA, have published a paper in eLife that reports the discovery of a developmental gene linked to touch in the tentacles of sea anemones as well as hearing in humans. The gene, called pou-iv, is important for the development of auditory cells in the human inner ear.
How was this gene discovered?
Cnidarians, which include jellyfish, corals, and sea anemones, are the closest living relatives of animals with bilateral symmetry, such as humans and other invertebrates. Therefore, cnidarians are useful for studying human evolutionary history. This is because features shared by bilateral animals and cnidarians were likely present in our last common ancestor. A shared feature that scientists have observed is the nervous system, and both bilaterians and cnidarians utilise similar sets of genes in neural development.
Auditory cells in the vertebrate inner ear pick up vibrations to enable hearing and are known as ‘hair cells.’ While they are not known to be able to hear, sea anemones have similar-looking cells on their tentacles — also called hair cells — that they utilise to sense the movements of their prey.
What does this gene mean for the development of auditory cells?
In mammals, pou-iv is required for hair cell development, and the mice that lack pou-iv are deaf. Sea anemones also have a pou-iv gene, but, prior to the research team’s experiment, no one had ever examined its role in anemone hair cell development.
Scientists eliminated the pou-iv gene in a sea anemone and discovered that it resulted in abnormal development of tentacular hair cells, removing the animals’ response to touch. They also discovered that pou-iv is required to turn on the polycystin 1 gene in sea anemones, which is necessary for normal fluid flow sensing by vertebrate kidney cells.
Thus, this suggests that pou-iv has a very ancient role in the development of touch sensation – as well as the development of auditory cells – that goes back at least as far as our last common ancestor with sea anemones.
What does this discovery mean for science?
UA researchers worked with the Nakanishi Lab for this experiment and were overseen by Assistant Professor of Biological Sciences, Nagayasu Nakanishi, corresponding author on this study, and recent recipient of an NSF CAREER award for his work on the evolution of the nervous system.
“This study is exciting because it not only opened a new field of research into how mechanosensation develops and functions in a sea anemone, which has ample potential for novel and important discoveries (to be reported in the future),” concluded Nakanishi. “But it also informs us that the building blocks of our sense of hearing have ancient evolutionary roots dating back hundreds of millions of years into the Precambrian.”
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