Could human skin be photosynthetic?


I've always thought that, were it possible for biology to harness
ionizing radiation for energy, some organism would already have done
so. The ground contains vast fungal and bacterial communities, but
also contains "light sources" in the form of uranium ore deposits.

Well, it looks like my suspicions were correct:

Inside the Chernobyl reactor: fungus feeds on radiation
http://www.wtnrradio.com/news/story.php?story=262

But there's more... Apparently the fungus uses an unsuspected
photosynthetic molecule: melanin. It's not green like light-loving
plants, instead it's brown and eats gamma rays.

What other organism deals with hard radiation and employs the melanin
molecule? People?

Expose caucasian skin to ionizing radiation (hard UV sunlight) and it
ramps up melanin production. Melanin absorbs UV and acts as a
shield. "Getting a sun tan." Or be of non-European ancestry and
you're already shielded.

But wait a minute. What if human skin was bright green. Would you
think to yourself "ah, our skin contains a dye molecule which shields
against visible light?" Or instead would you think "ah, skin
contains an energy-harvesting molecule which uses visible light to
synthesize it's own fuel?"

In other words... if I have a dark tan, and I go sit in summer
sunlight without eating, will avoid starvation longer than if I stayed
indoors without eating? Maybe vitamin-D isn't the only thing made by
human skin in sunlight.

Another question: does human melanin production respond to ALL
ionizing radiation? If I stick my hand under a high-power gamma ray
source for a few minutes per day, will I receive a nice dark tan?
(I'd be sure to start slowly so I don't get a bone-deep sunburn at the
start.)

And just how effective is melanin as a shielding material for high
energy photons? (When compared to equal mass of, say, metallic lead?)


((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty a chem washington edu UW Chem Dept, Bagley Hall RM74
billb a eskimo com Box 351700, Seattle, WA 98195-1700
ph425-222-5066 http://staff.washington.edu/wbeaty/

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