Development: Bird ears in the making

Molecules key to the development of the ear of mammals and birds are identified in two studies published in Nature Communications. The studies advance the understanding of the mechanisms leading to hearing and may have implications for understanding how to tackle regeneration in situations when hearing is impaired.

For animals that hear by detecting sounds that travel in air, for example, birds and mammals including humans, identifying different frequencies is fundamental in order to distinguish similar sounding words, like “bat,” “cat,” and “hat”. Cells in the auditory system of these species are known to be organised in a precise manner whereby cells in a given position will respond to specific frequencies. The processes leading to this type of organisation are, however, largely unknown.

Zoe Mann, Matthew Kelley and their colleagues studied ear development in chicks and identified a molecule, Bmp7, which acts as a key regulator of the cellular organisation in the ear, leading to accurate perception of frequencies. In a second study, Benjamin Thiede, Jeffrey Corwin and colleagues discovered that retinoic acid also plays a role in this process. Interfering with retinoic acid’s actions leads to irregular organisation within the ear.

Together, the two studies advance the understanding of the molecular mechanisms leading to sound discrimination.