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Title: UV-C Light Kills Nearly Everything - Except This Unusual Organism

Link: https://science.slashdot.org/story/25/06/30/0...

"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 lacinulatum, back 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 radiodurans, it 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.

Read more of this story at Slashdot.

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