The Sweet, Sour, Salty, Bitter, and Umami of the Taste Buds

Have you ever wondered how our tongue is able to taste all the flavors of food? How a cake can taste sweet, and vegetables taste bitter? We have taste buds on our tongue that allows us to taste each thing. There are small bumps on our tongue called the gustatory papillae that the sensory organs aka our taste buds are located at in order to perceive these flavors. 

            It has been recently discovered that deleting EphB receptors in the gustatory papillae led to a decrease in the number of nerve fibers in the tongue, but the deletion of ephrin-B ligands increased the number of nerve fibers (Treffy 2016). EphB receptors play an important role in a variety of cellular processes such as cell migration, axon guidance and synapse formation. Ephrin-B ligands bind to EphB in order to activate them. But how is this important or meaningful to the taste buds? Or even to our body?

            Well, like I said earlier, the EphB receptors play many roles in our body. Another role that they play is in the development of limbs! Completely different section of our body, right? The EphB receptors are expressed by motor axons and the ephrin-B ligands are expressed or connected to limb mesenchymal cells. These together direct the trajectory of motor axons. This discovery led to knowledge about the nerve-muscle connectivity (Luria 2017). With this signaling, humans and animals, basically any living thing that has a limb, is able to create such motor actions/behaviors to specific muscles. This is how we are able to bend down and pick up a ball that fell or how we can run and play and exercise.

            Isn’t it funny how different nerves or molecules or signaling can do different things to different parts of our body? Our body is a pretty fascinating thing to learn from our head to toe. It kind of makes you wonder what else your body is capable of huh.

 

References

Luria, V., Krawchuk, D., Jessell, T. M., Laufer, E., &; Kania, A. (2017). Specification of 

motor axon trajectory by ephrin-b:ephb signaling: Symmetrical control of axonal 

patterning in the developing limb. Neuron, 60(6), 1039–1053. 

https://doi.org/10.1016/j.neuron.2008.11.011

Treffy, R. W., Collins, D., Hoshino, N., Ton, S., Katsevman, G. A., Oleksiak, M., Runge, E. M., 

Cho, D., Russo, M., Spec, A., Gomulka, J., Henkemeyer, M., & Rochlin, M. W. 

(2016). Ephrin-B/EPHB signaling is required for normal innervation of lingual gustatory papillae. Developmental Neuroscience, 38(2), 124–138. https://doi.org/10.1159/000444748