Can Animals Taste Light? New Type of Photoreceptor Found in Invertebrates

Scientists composed of an international team spearheaded by the University of Michigan has presented a new type of photoreceptor in animals that is 50 times more efficient at capturing light than the rhodopsin in the human eye. This photoreceptor is just the third to be found in animals, specifically a family of taste receptors in invertebrates.

In a study published in the journal Cell, the new receptor protein, LITE-1, was shown to have unusual characteristics that suggest potential future applications ranging from sunscreen to scientific research tools. Found in the eyeless, millimeter-long roundworms known as nematodes, Xu and his colleagues discovered that LITE-1 directly absorbs light, rather than being an intermediary that senses chemicals produced by reactions involving light.

"LITE-1 actually comes from a family of taste receptor proteins first discovered in insects," shared Shawn Xu, senior study author, faculty member of the University of Michigan Life Sciences Institute, and professor from the Department of Molecular and Integrative Physiology at the University of Michigan Medical School. "Our experiments also raise the intriguing possibility that it might be possible to genetically engineer other new types of photoreceptors."

The genetic code of these receptor proteins is markedly different from other types of photoreceptors found in plants, animals and microbes according to Xu. "LITE-1 is unusual in that it is extremely efficient at absorbing both UV-A and UV-B light, 10 to 100 times greater than the two other types found in the animal kingdom: opsins and cryptochromes. The next step is to better understand why it has these amazing properties."

With further research, Xu believes it could be possible to utilize LITE-1 to further scientific research by fostering light sensitivity in new types of cells. It could also have widespread use as a sunscreen additive that absorbs damaging sunlight.