New research published this week reveals that our skin is able to "sense" ultraviolet light in the same way as our eyes because skin cells contain rhodopsin, the same photosensitive receptor that the eye uses to detect light.
specialized skin cells that produce the pigment melanin, detect ultraviolet light using rhodopsin, a light-sensitive receptor previously thought to exist only in the eye. This ability starts the production of melanin within hours, much sooner than previously thought.
Previous to this study, scientists thought that melanin production only kicked in after a few days, about the same length of time as it takes to develop a "tan".
In the first experiment, they used ultraviolet light to see if it prompted the calcium signalling, but it didn't. So acting on a hunch that perhaps the skin behaves like the eyes in sensing light, they added retinal, a "co-factor" that combines with the protein opsin to make photosensitive receptors, including rhodopsin.
source : http://www.medicalnewstoday.com
