A little over a decade ago, prestin（膜动力蛋白） was found to be a key gene¹ responsible for hearing in mammals. Prestin makes a protein found in the hair cells of the inner ear that contracts and expands rapidly to transmit signals that help the cochlea（耳蜗）, like an antique phonograph horn, amplify² sound waves to make hearing more sensitivity. Now, in a new study published in the advanced online edition of Molecular³ Biology and Evolution, Peng Shi, et al., have shown that prestin has also independently evolved to play a critical role in the ultrasonic⁴ hearing range of animal sonar, or echolocation, to help dolphins navigate⁵ through murky⁶（朦胧的） waters or bats find food in the dark.

 

Although both toothed whales and echolocating bats can emit high frequency echolocation calls, which show a substantial diversity in terms of their shape, duration, and amplitude⁷, they receive and analyze⁸ the echoes returned from objects by their high-frequency hearing. The research team finely dissected⁹ the function of the prestin protein from 2 sonar guided bats and the bottlenose dolphin compared with non-sonar mammals.

 

Evolutionary¹⁰ analyses of the prestin protein sequences showed that a single amino acid change in prestin, from a threonine (Thr or T) in all sonar mammals to an asparagine (Asn or N) in all non-sonar mammals, was subject to parallel evolution, suggesting that it may play a critical role for mammalian echolocation. Further experiments supported this assumption and identified 4 key amino acid differences amongst the sonar mammals, which may contribute to their unique features . Taken along side evolutionary analyses, these findings offered the first functional¹¹ evidence supporting the notion that the hearing gene of prestin evolved to play a key role in the sonar system of mammals.

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