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Hulk Bugs
October 20, 2007 8:31 AM   Subscribe

Gamma rays make certain microscopic fungi grow faster Researchers have found that melanin—the same pigment that's the natural ultraviolet filter in people's skin—might enable some fungi to harness the energy of gamma radiation as well as to shield themselves from it.

Earlier this year, a robot sent into the defunct Chernobyl reactor discovered a thick coat of black slime growing on the walls. The fungus uses radioactivity as an energy source for making food and spurring their growth.

Wikipedia sez: Whether melanin-containing fungi employ a similar multi-step pathway as photosynthesis, or some chemosynthesis pathways, is unknown.

I welcome our new radiotrophic overlords!
posted by KokuRyu (24 comments total) 1 user marked this as a favorite

 
Mmmm... Hulk fungi smash!
posted by rokusan at 8:38 AM on October 20, 2007


Makes sense. Gamma radiation's still light, so why waste the energy?

I wonder how much gamma/uv light there used to be coming though our atmosphere though. A high-energy light absorption pathway must have been costly to evolve, but was there enough gamma/uv radiation millions of years ago to allow it to compete with standard photosynthesis?
posted by Orange Pamplemousse at 8:54 AM on October 20, 2007


Attack of the Fifty Foot Microscopic Fungi!
posted by StickyCarpet at 8:57 AM on October 20, 2007


Just wait until a fungus evolves into a massive biomass with huge 10 meter-wide melanocytes that are able to absorb radio waves and synthesize them into energy.

"Hey this is KKRZ FM the HOME of PAT BENETAR! Coming up next is......oh hey theres a giant blob eating the tower! Rock on, dude!"
posted by Avenger at 9:16 AM on October 20, 2007


So, in sterilizing medical devices with gamma, these things might not only not get killed, but enhanced? Scary.
posted by caddis at 9:21 AM on October 20, 2007


Wow, if thats true, it would provide a way to produce fuel directly from nuclear reactors, assuming there was a way to make sure the fuel wasn't radioactive afterwards...
posted by delmoi at 9:24 AM on October 20, 2007


I wonder how much gamma/uv light there used to be coming though our atmosphere though. A high-energy light absorption pathway must have been costly to evolve, but was there enough gamma/uv radiation millions of years ago to allow it to compete with standard photosynthesis?

It doesn't take bacteria millions of years to evolve, it can adapt very, very quickly. Certainly in the years since nuclear reactors have been around.
posted by delmoi at 9:25 AM on October 20, 2007


Any claims of these black fungi having superior athletic ability yet?
posted by srboisvert at 9:27 AM on October 20, 2007


Yeah, but what does it do to man in the moon marigolds?
posted by klangklangston at 9:36 AM on October 20, 2007


"This research brought to you by the Yuggoth Expat Association: building a new future for the Mi-Go, everywhere..."
posted by Iosephus at 9:37 AM on October 20, 2007 [1 favorite]


"Hey this is KKRZ FM the HOME of PAT BENETAR! Coming up next is......oh hey theres a giant blob eating the tower!

Sounds more like Debbie Harry to me.
posted by rokusan at 9:55 AM on October 20, 2007


delmoi, developing an entire metabolic pathway is quite the adaptation.

Up-regulating melanin production, to develop a sort of barrier against gamma rays I can understand. But converting the gamma energy into chemical energy is much more complicated, likely requiring a series of enzymes, cofactors and organelles (just look at photosynthesis).

The development required may have been small, especially if they already had a method of scavenging free radicals for energy, but given the widespread use of melanin in other organisms I figured this was more a case of an old trait resurfacing than a new one being developed.

Post: Looking at the actual paper on radiotropic fungi doesn't really indicate where they got their samples from, aside that they were gifts from American Universities. They do indicate that one of the species has flourished in/near Chernobyl, but don't say that any change in the fungi has occurred.

Oh, and fungi are eukaryotes, not prokaryotes like bacteria.
posted by Orange Pamplemousse at 10:28 AM on October 20, 2007


Oops, the paper.
posted by Orange Pamplemousse at 10:29 AM on October 20, 2007


Caddis - I wouldn't worry too much about that, at least not yet. Nothing's been found that suggests that these fungi are pathogenic or the least bit harmful to humans, especially since they may be at a disadvantage in non-gamma environments. Very cool link though.
posted by fermezporte at 12:04 PM on October 20, 2007


Yeah, but what does it do to man in the moon marigolds?

Damn. I so wanted to make that reference, but got hung up on the first half of the title. Couldn't make it work.
posted by five fresh fish at 1:31 PM on October 20, 2007


It doesn't even take years for bacteria to mutate. They reproduce hourly, share genetic material every time they bump into another bacterium, and have a cell division process that lends itself to frequent mutation (As opposed to human DNA replication, which is double-checked in a way). Really, it's no wonder bacteria were one of the first lifeforms and will probably be one of the last, as they are so adaptive.
posted by mccarty.tim at 1:50 PM on October 20, 2007


The Earth was once a much more radioactive place. Think about half-lives; the half life of standard uranium is 760 million years. Over the 4.2 billion or so years the Earth has existed, the uranium would have halved 5.5 times... so there was originally 48 times as much as we see today. Other elements that we still find, with much shorter half-lives, would have been far more abundant. So it's virtually certain that the Earth was once a hellishly radioactive environment.

We also have numerous examples of traits that are dormant in an organism's genome. I was reading about this awhile ago. I don't remember the specific insect, but they were able to show that under strong selective stress, individual insects could regain the ability to grow wings and fly, where that ability was atrophied in most examples of the species.

From this layman's perspective, it seems more likely to me that they would have reactivated an old evolution rather than creating an entirely new one; the costs would be far lower.

Occam's Razor would also appear to apply: if they could already do this, that would be easier/simpler than creating it wholly from scratch. The simplest explanation is that they could already 'eat' radioactivity, but didn't because there wasn't enough anymore to make that a viable strategy.

Could it have evolved? Absolutely. It must have at least once. But did it happen this time, in this particular twenty-year time window, as opposed to all the billions of years that have gone before? That seems exceedingly unlikely to me.
posted by Malor at 3:54 PM on October 20, 2007


"Doc Bruce Banner!
Belted by gamma rays!
Turns into The Hulk!
(even though it takes years for bacteria to mutate!)"


sometimes fiction is just more fun than truthiness.
posted by ZachsMind at 4:01 PM on October 20, 2007


From this layman's perspective, it seems more likely to me that they would have reactivated an old evolution rather than creating an entirely new one; the costs would be far lower.

Occam's Razor would also appear to apply: if they could already do this, that would be easier/simpler than creating it wholly from scratch. The simplest explanation is that they could already 'eat' radioactivity, but didn't because there wasn't enough anymore to make that a viable strategy.

Could it have evolved? Absolutely. It must have at least once. But did it happen this time, in this particular twenty-year time window, as opposed to all the billions of years that have gone before? That seems exceedingly unlikely to me.


I'm pretty sure your idea is the opposite of what should be chosen according to that guy from Ockham's shaving tool. A preexisting but dormant ability is a more complicated theory than simple natural selection in a high mutation environment. Not that I know or am willing to even guess if you are right or wrong in your speculation.
posted by srboisvert at 5:51 PM on October 20, 2007


this leads me to theroize that one day very black humans will be able to survive IN SPACE!!
posted by MNDZ at 5:58 PM on October 20, 2007


One multi-syllable word. Nucleobiodiesel.
posted by Balisong at 7:31 PM on October 20, 2007


srboisvert, you can inactivate a pathway with a single point mutation by disabling that gene's "on button", or promoter (or the transcription factors that bind to that promoter, or the genes that code for said TF, etc.).

Also, there isn't really a high degree of selective pressure acting on inactive genes, at least in the larger genomes.

The result of these two factors is dormant traits. If melanin was completely useless (or worse, dangerous), a point mutation inactivating the melanin production pathway would be favoured, and 'albino' fungi would become common. Since they still have 99.999% of the gene intact, if melanin becomes favoured again a new point mutation can reactivate the pathway. Stopping the protein production prevents the waste of hundreds of thousands of amino acids (assuming the gene is a roughly average length of 5kbp), at the cost of 5000 nucleotides every replication. (bakers yeast is 12 million base pairs long)

To make a rough analogy between a point mutation and evolution, it's the difference between switching off a light bulb and installing electricity in your house.

See also: Atavism
posted by Orange Pamplemousse at 9:07 PM on October 20, 2007


I've read enough headlines on science blogs to recognize that OP is more correct. It's turning out there's tons of crap in our genetic code, stuff that's never used. It makes sense to me that it's all "archived" code: negligble cost in keeping it, tremendous advantages should it ever be required again.

I am doubtful that we're so lucky as to have gamma-using genes in our systems. Or at least if we do, they're ultimately harmful to our more advanced genes. Kinda like trying to run obsolete system code on today's advanced CPUs. System crashes. Cancers.
posted by five fresh fish at 11:09 PM on October 20, 2007


Malor: The Earth was once a much more radioactive place. Think about half-lives; the half life of standard uranium is 760 million years.

Minor fact check - don't know what you mean by standard uranium:

U-238 : 4.468e9 a
U-235 : 7.038e8 a
U-234 : 2.455e5 a

( Get your isotopes here )
posted by the number 17 at 1:01 AM on October 21, 2007


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