How a Water Bear Survives When It’s Dry | Hacker News Reader

How a Water Bear Survives When It’s Dry

nytimes.com

164 pointshappy-go-lucky38 comments

Great to see this in the NYT. I'm working with Thomas (who, in addition to being a truly exceptional scientists is a really great guy) on understanding the underlying biophysics of how these disordered proteins facilitate stress protection.

We have some cool stuff coming along...

Do you know if a structure of any of these proteins is published anywhere? I checked the PDB, but didn't find anything.

The sequences have only recently been found, and the interesting proteins don't share much homology.

Check out http://kumamushi.org for a lot if technical detail in the genome. jfarlow in comments below points to one of the interesting proteins that apparently provides dna protection.

Thanks! It looks like I can generate a pdb from the fasta sequence they provide for the protein.

Many of these proteins are intrinsically disordered proteins (IDPs), meaning they don't actually have a set 3D structure, but instead existing in a kind of 'cloud' (ensemble) of interconverting conformations. A consequence of this is that there is no 'one' representative structure, due to this conformational heterogeneity.

People used to (very reasonably) assume that 'disordered' just meant totally random, so the thought was these disordered proteins behaved like a random polymer. However, just like in folded proteins, the amino acid sequence of these IDPs has a major impact on the way these clouds of conformations behave. Happy to discuss more here or 'offline' (see my profile for contact info) - this is basically my whole PhD, so, you know, I can go more in depth...

Yes (that's the fun part!) - I should have specified that I was just interested in getting an atomistic model of one of these tardigrade proteins to play around with in an MD simulation.

Can't help but to think about a very distant future where we use these same disordered proteins to truly freeze organic material, including ourselves. Maybe I could be dehydrated for a few thousand years on my way to another solar system no prob.

There's a cool element of this in the Three Body Problem, a sci-fi book, where aliens use dehydration to survive to disastrous conditions on their home planet. You might like the book: https://www.amazon.com/dp/B00IQO403K/

This is why tardigrades have such high radiation tolerance as well. It turns out that dehydration is incredibly damaging, especially to DNA, and the same repair/protection systems for dealing with dehydration (such as DNA repair) tend to protect against high radiation doses as well.

The big question is - what's the cost? There is no free lunch. They're paying for it, or are limited by it, somehow and somewhere.

There's a "feature budget" in any organism, and it's the main reason why you can't have creatures that could fly, and run fast, and live underwater.

At least part of that protection is conferred by the DNA-binding protein Dsup [1]. So minimally the cost is 1) producing the (unique, as far as we have searched) protein, and 2) dealing with DNA which has Dsup bound to it.

There is no free lunch, but it's actually a pretty interesting protein that seems to somehow sacrificially prevent double-stranded breaks of DNA by ionized radiation. It's likely not much more than a metabolic cost - though there is some possibility that it affects some gene regulation. When Dsup was put into mammalian cells it did confer to them protection from radiation damage.

[1] https://serotiny.bio/notes/proteins/dsup/

There's a feature budget only in that there's a cost/benefit restriction for every living thing. Usually the big cost is how many calories does this gene cost vs how much does this gene benefits the organism (or it's close relatives).

What's interesting about having high radiation resistance, is that I could see a cure or vaccine for cancer could be introducing (or possibly expressing) genes that cause our cells to spend a lot more calories to repair its DNA than they already do. And the skeptic in me thinks it'll probably be marketed as a diet pill :)

It's gonna sell like hot cakes.

"High metabolism and cures cancer? I'll take five!"

2,4-Dinitrophenol aka DNP sounds very similar to what you're talking about.

https://en.m.wikipedia.org/wiki/2,4-Dinitrophenol

As I remember, the studies using DNP alongside radiation therapy showed promising results for slowing and reversing malignant cancers.

Or more likely you don't see those kinds of creatures because there has been no reason for evolution to select for all those abilities in one species. It's good enough to have one of them.

But that says nothing as to whether genetic engineering could produce such creatures.

Trisolarans anyone?

haha ya I was thinking the same thing! They are already here!

I was thinking the Zerg. This is like an stepping stone to mutalisks.

Just about the coolest little critters on Earth! They're cute, they can survive just about anything reasonably thrown their way from hard vacuum to radiation, and now this. It makes me happy to know that regardless of how badly we as a species screw up ourselves or the biosphere, these little tardigrades won't even notice.

> can survive just about reasonably thrown their way from hard vacuum to radiation

Remind me not to be around when you are being reasonable.

Oh come on, reasonable people stand in front of the Bi-213 source and don't complain.

I am now imagining a perfectly reasonable pink bismuth-213 used to treat whatever radioactive drive through food is giving you indigestion.

Pepto-Bismol, Fallout edition, now with 20000% more Radiation!

Hey... truth in advertising; you will no longer have indigestion. Reason prevails!

I thought one of the first signs of radiation was nausea and diarrhea.

But those are only temporary until the death part sets in.

Oh no, if you were exposed to a naked source of the type used to test the limits of organisms like tardigrades... you'd just die. Really, really, really quickly.

Just in case you missed that delightfully weird story from last month:

Google was working on putting live tardigrades into Android phones:

http://venturebeat.com/2017/02/24/complicated-weird-beautifu...

I did miss it! Thanks, this made my day. There was a movie from the late 80's, early 90's... and I remember a pimp with platform shoes that were also an aquarium. This... is better.

You made my day in return when I viewed your list of submitted stories. So much cool stuff!

(And another sign HN needs to step up its submission/upvoting algorithms/UX. I do think so many HN-worthy stories get lost each day just because of this.)

Thanks, that's really kind of you to say.

Sounds like a project for Cody's Lab (self-contained biome):

https://youtu.be/We_6Sloh90s

Well, they can survive that stuff thanks to neat biochemical tricks.

We can survive that stuff too, probably even better, thanks to having big brains, culture and technology.

It remains to be seen whether you could have both the biochem tricks and the big brains in one and the same organism.

I wonder how did they evolve to survive such a variety of conditions

The biggest fascinating point about Tardigrades is that they can survive in space.

I think the implication of this should be explored further.

That's what the article is about; when they dry out, they produce an irregular protein which essentially stiffens and preserves the cells while protecting them from environmental damage. When they are rehydrated, the protein dissolves and the cells resume their normal functions.

It's pretty cool, and could indeed lead the way to hibernative naptosis.

Drying out wouldn't be the only problem in space though, there are other problems... (Btw how long they can survive like that though?)

https://en.wikipedia.org/wiki/Camel#Ecological_and_behaviora... store fat in their humps

Looks like the trisolarans weren't so bad after all.

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