Tuesday, January 18, 2011
Convergence of Infrared Vision in 3 Snake Clades
Three families of snakes use infrared waves to detect prey and differences in environmental temperatures. The mechanism involved in this has only been recently discovered to involve the transient receptor potential (TRP) ion channels. TRPs are involved in various biological processes, including calcium and magnesium homeostasis, neuronal growth, temperature sensation, and pain sensation. The sensations caused by the pungent agents of wasabi and other mustard plants are generated by our transient receptor potential ankyrin 1 (TRPA1) channel. Recently, it has been discovered that the orthologous receptors (receptors sharing a common ancestral gene) of the western diamondback rattlesnake (Crotalus atrox), ball python (Python regius), and garden tree boa (Corallus hortulanus) detect infrared radiation, while those the Texas rat snake (Pantherophis obsoletus lindheimeri) does not. The genetic mechanism of infrared sensitivity of these snake-specific TRPA1 proteins is unknown. Yokoyama et al. (2011) have now identified the amino acid changes that are responsible for the dramatic functional changes in the three groups of snakes. They suggest three parallel amino acid changes (L330M, Q391H, and S434T) are responsible for the development of infrared vision in the three groups of snakes. Protein modeling shows that the three amino acid changes alter the structures of the central region of their ankyrin repeats. The article can be found on-line.
Yokoyama, S., A. Altun, and D. F. DeNardo. 2011. Molecular convergence of infrared vision in snakes. Molecular Biology and Evolution 28(1): 45-48. doi:10.1093/molbev/msq267