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After a day in the sun, you'll notice the beginnings of a tan (or, if you're me, a painful sunburn). But at the molecular level, getting that sun-kissed glow is anything but simple.
What scientists previously knew about tanning went something like this: Your skin senses UV radiation from the sun and reacts by producing more melanin, the pigment that darkens the skin and reduces damage.
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Until now, researchers didn't know exactly what causes this process during and after exposure to UVA rays.
But a recent experiment suggests that a familiar protein -- one already found in the retina portion of the human eye -- seems to be present in the skin to spur tanning.
The research, published in the journal Current Biology, suggests that the same photosensitive protein that helps the eye detect light, rhodopsin, can be found in skin cells.
When exposed to the sun, these cells produce calcium that set melanin production in motion. Before, it wasn't clear what caused the calcium signals to change. Scientists decided to tackle the problem by studying skin cells in a lab dish and exposing them to UV light.
After reducing rhodopsin levels in the cells, they noticed a drop in calcium and melanin, too, which indicates the three were linked in some causal way. When rhodopsin was present, the cells normally began producing melanin as a response to the light.
Because the cells immediately react to UV exposure, the study supports the idea that the body reacts to the sun during tanning, not entirely after the fact.
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Even then, rhodopsin might not be the only protein at play, one of the team's researchers said in a press release. It will likely take more research to get to the bottom of the tanning mystery.
For now, stick with wearing sunscreen to avoid skin damage, and potentially, skin cancer, experts say.
Tags: Cancer, Health, Safety and Prevention, Skin
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