“Earth’s ozone layer blocks the Sun’s shortest wave radiation, called UV-C, which is so damaging to cells in high doses that it’s a go-to sterilizer in hospitals,” writes Slashdot reader sciencehabit. “UV-C is such a killer, in fact, that scientists have questioned whether life can survive on worlds that lack an ozone layer, such as Mars or distant exoplanets.
“But research published this month in Astrobiology suggests one hardy lichen, a hybrid organism made of algae and fungi, may have cracked the UV-C code with a built-in sunscreen, despite never experiencing these rays in its long evolutionary history.”
Science magazine explains:
When scientists brought a sample of the species, the common desert dweller Clavascidium lacinulatusback to the lab, graduate student Tejinder Singh put the lichen through the wringer. First, Singh dehydrated the lichen, to make sure it couldn’t grow back in real time and mask any UV damage. Then he placed the lichen a few centimeters under a UV lamp and blasted it with radiation. The lichen seemed just fine.
So Singh purchased the most powerful UV-C lamp he could find online, capable of sending out 20 times more radiation than the amount expected on Mars. When he tested the lamp on the most radiation-resistant life form on Earth, the bacterium Deinococcus radioduransit died in less than a minute. After 3 months—likely the highest amount of UV-C radiation ever tested on an organism—Singh pulled the sample so he could finish his master’s thesis in time. About half of the lichen’s algal cells had survived. Then, when the team ground up and cultured part of the surviving lichen, about half of its algal cells sprouted new, green colonies after 2 weeks, showing it maintained the ability to reproduce.
The species may provide a blueprint for surviving on Mars or exoplanets, which don’t have an ozone layer to protect them.
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