Echolocation and Prestin (the protein :D)
Prestin is a transmembrane protein (10-12 transmembrane domains) with the ability to convert a change in membrane potential into a mechanical force (Gleitsman et al., 2009). It is a “direct voltage-to-force converter” and plays a crucial role in sound amplification in various organisms and thus play an important part in an organism’s ability to sense sound waves (Dallos and Fakler, 2002, Li et al., 2010). What does the protein look like? From Dallos and Fakler, 2002 (Figure 1).
Figure 1: Prestin protein. From Dallos and Fakler, 2002.
Recent studies suggest that not only echolocating, but the Prestin gene that plays a role in echolocation, converged in several different species (different species of bats, dolphins, toothed whales) to perform the same function with convergent changes in the coding DNA of the gene (Li et al., 2010, Teeling, 2009).
Interestingly, the Prestin gene is found in an organism (Trichoplax adhaerens) with no nerve cells, sensory cells or muscle cells. Trichoplax adhaerens emerged before biletarians, way before any organisms without any sound sensing organs (Figure 2:)
Figure 2: Tree of life (Adapted from discoverlife.org)
The organism only has four cell types (Figure 3).
Figure 3: Link
So what is the Prestin gene doing in the genome of an organism with no hearing apparatus or nervous system and emerged long before these kinds of organisms or organs for sound wave mechanosensing?
Perhaps echolocation relies on a common design? Well these guys say so…
I donno about that (sounds like the words of IDiots, but I digress), perhaps the manifestation of echolocation relies on a distinct form of matter…the coding of Prestin? The emergence of this protein form just guaranteed that echolocation was on the cards over vast evolutionary time scales even though it was present way before echolocation even played an important role in nature.