D. rad Bacteria

Palomar · 2004-04-27 06:52:25

http://antwrp.gsfc.nasa.gov/apod/ap040425.html]Click

*An unusual offering from the folks at Astropix.

Can repair their own DNA in 48 hours.

--->"D. rad are of interest to NASA partly because they might be adaptable to help human astronauts survive on other worlds."<---

Among other things. Interesting.

"A recent map of D. rad's DNA might allow biologists to augment their survival skills with the ability to produce medicine, clean water, and oxygen."

--Cindy

SBird · 2004-05-04 09:55:14

Ah, good 'ol D. radiodurans. IIRC, it's still one of the record holders for radiation tolerance. It can shrug off loads of over 1000 rad as if nothing had happened. One of the big D. radiodurans researchers, Mary Lidstrom, works on the floor above me. The mechanism it uses to survive radiation is not well understood but seems to be an adaptation to be able to survive drying out. (which damages DNA in ways similar to radiation)

Rxke · 2004-05-04 10:53:43

hey, that's interesting... remember the recent tests with plants in low pressure? they reacted like they were drying out... Hmmm... So the radiodurans might be 'trained' (selective breeding) to survive lower pressure? And they could posibbly make oxy, too? sounds too good to be true...

(just a wild flicker of a thought)

Shaun Barrett · 2004-05-04 22:12:55

It's a good "wild flicker of a thought", Rik!

I suppose you heard that, when Deinococcus Radiodurans (known to its fans as 'Conan the Bacterium') was discovered breeding happily in nuclear reactors, the Russians hypothesised that it may have developed on Mars(?).
Its amazing durability, especially to radiation, combined with known conditions on Mars and the probability of frequent impact transfer between there and Earth, led them to this tentative conclusion.

So, in the event we actually use this remarkable little critter on Mars to change conditions in our favour, we may just be sending some long-lost bugs on a sentimental journey home!

SBird · 2004-05-04 22:55:55

As much as I'd love to throw in behind that theory, molecular cladistics (tracing evolutionary lineage by looking at DNA sequences) shows that D. radiodurans is a pretty ordinary bacterium.

For a while, it was thought that its really wierd quadruple nucleoid DNA structure and incredible double strand DNA break repair ability was the source of its radiation resistance but recently, evidence has come out that calls that into question.

Unfortunately, whatever gives radiodurans its rad resistance, it's probably quite compatible and not something that would work with human DNA.

Rxke · 2004-05-05 05:41:37

Hmmm... Why try it for humans?

I was thinking of 'terraformer' primitive lifeforms, D. rad. as a vehicule for 'useful' traits like errrmmm... producing oxygen, methane, greenhouse gasses... or transforming the surface Fe to 'black' (more insolation) Maybe you can splice it in more advanced lifeforms like lichen (doubtful)

splice in some suicide-genes, so they die off when too productive (release of a metabolism byproduct that triggers said sequence)

yip, i make it sound sooooooooo easy.

SBird · 2004-05-05 09:39:44

There's something along those lines going on. Right now, there's no way to easily treat mixed radioactive wastes. (mixed rad wastes are things like toxic organic compounds that are also radioactive and therefore need to be detoxified but are too radioactive for safe handling with the standard detoxification techniques.) D. radiodurans is being engineered to put the genes for breaking down organics like carbon tetrachloride into it so that you can use bioremediation on the mixed wastes. It's slow going, I know Lidstrom's lab's been working on their D. radiodurans projects for years now with very little success. The wierd genomic structure of radiodurans probably futzes up a lot of standard genetic manipulation techniques.

Palomar · 2004-05-05 11:26:12

http://science.nasa.gov/newhome/headlin … 1.htm]From cow patties to Conan

*This is a really fabulous article. I was wondering about its origins (precisely), and of course Googled.

"'Deinococcus radiodurans beats most of the constraints for survival of life on Mars - radiation, cold, vacuum, dormancy, oxidative damage, and other factors,' said Dr. Robert Richmond, a research biologist at NASA's Marshall Space Flight Center."

[Even resistant to acid baths!]

Says "it could be genetically altered to produce medicines for astronauts in the short-term, rather than hauling an entire pharmacy along on the trip,..." [alluded to in first post]

Its beginnings thought to be "from early Earth."

Discusses terraforming aspect as well. I know some folks here already know all this, but I'm still new to this topic and presume others are as well.

--Cindy

P.S.: My cat is in here, meowing like crazy :-\

Shaun Barrett · 2004-05-08 08:05:44

A very good article, Cindy.
I haven't seen this one before or, at least if I have, I don't remember it specifically. I note it also includes the very popular and amusing 'Conan the Bacterium' nickname. (I've always loved that label.)

Hi SBird!
Thanks for the comment about molecular cladistics. I understand where you're coming from with this argument, which puts the kibosh on some of the wacky theories of the fringe-dwellers who maintain humans are actually descended from aliens (or some variation on that theme). If we're truly from another star system, what an amazing coincidence that chimpanzees have an all but identical genome!
However, in the case of primitive bacteria, I don't think the same constraints necessarily apply. If you imagine a situation whereby bacterial or archaean life arose on either Earth or Mars and then factor in the frequent transfer of viable spores, first in one direction and later in both directions, the appearance of Deinococcus Radiodurans becomes less enigmatic.

There are various possible scenarios but let's imagine life originating on Earth some 4 billion years ago. Impact transfer then would have been more common than it is today because of the higher impact rate in the younger solar system. Viable spores of terrestrial bacteria soon arrive on Mars; a Mars with a magnetic field and a denser wetter atmosphere. They don't notice much difference between Earth and Mars and set about breeding - business as usual!
As conditions worsened on Mars - the air thinned while the magnetic field faded, the water dried up, and the temperatures plunged - our intrepid bacteria had to adapt to a situation far grimmer, and perhaps more varied in its lethal nature, than any endured by its relatives on Earth. The far higher radiation levels would have been one of the most obvious problems to overcome. Enter 'Conan the Bacterium'!! (I can almost imagine a particularly aggressive one of their number raising a blob of cytoplasm in the shape of a clenched fist, towards Earth, and growling: "I'll be back!")
Again, impact transfer enters der moofie .. sorry, I meant the picture (! ) .. and transports viable spores of what we now call D. Radiodurans back to Earth.
Molecular cladistics tells us that this radiation-proof critter is just another Earth-bug. And so it is. But that doesn't preclude for it an evolutionary development period on a radiation soaked Mars.

None of the above need have happened, of course. I'm just outlining a situation which would have at least allowed it to happen.
[In case you're unaware of it, I feel I should warn you I'm firmly of the opinion that Mars harbours a thriving biosphere today; if not on the surface, then not too far below it.]

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#1 2004-04-27 06:52:25

Re: D. rad Bacteria

#2 2004-05-04 09:55:14

Re: D. rad Bacteria

#3 2004-05-04 10:53:43

Re: D. rad Bacteria

#4 2004-05-04 22:12:55

Re: D. rad Bacteria

#5 2004-05-04 22:55:55

Re: D. rad Bacteria

#6 2004-05-05 05:41:37

Re: D. rad Bacteria

#7 2004-05-05 09:39:44

Re: D. rad Bacteria

#8 2004-05-05 11:26:12

Re: D. rad Bacteria

#9 2004-05-08 08:05:44

Re: D. rad Bacteria

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