Improved radiotolerance of human cultured cells by tardigrade-unique protein | Hacker News Reader

Improved radiotolerance of human cultured cells by tardigrade-unique protein

nature.com

52 pointsricardolopes21 comments

It's interesting to imagine a hypothetical future where something like this leads to genetically engineered humans that are far more fit for space exploration than those of us walking around today.

Sounds a bit like the Culture humanoids in Ian M Banks's Culture book series.

Often when looking at things like this, the reason that most organisms don't have the protein is that it's not cost free. It's expensive to make, or there are other downsides so it got evolved away by natural selection.

For example bacteria that evolve resistance can often lose them fairly quickly if they are not needed as they are not without cost.

Interesting though :)

You're right but maybe they can turn that into pills or shots to be taken when needed.

Or engineer it into future Mars colonists.

Mars would be great. Though if things to go as usual it would be future soldiers and Fukushima&Chernobyl cleanup workers. May be not Fukushima(Japan), yet definitely at least in countries where people are cheaper than high-tech robots.

Or Venus, which is closer to earth, has a magnetosphere to protect us from radiation, similar gravity, and similar atmospheric pressure (which affects the boiling point of water).

I'm not convinced of our ability to build permanently floating habitats and mining a 900 degree surface for materials.

Believe it or not, that's more manageable than the lack of a magnetosphere, gravity and a thick atmosphere.

Source? This runs counter to all the academic research on the topic I've come across.

Everything is like this though. Humans can't synthesize their own vitamin C, because, as frugivorous apes, we got enough of it in our diets that evolution decided the energy savings of omitting the vitamin C pathway was worth it. Same thing with cats and taurine.

But we still have the non-functional GULO pseudogene in our DNA. Every part of the vitamin C pathway is still present, except for that one broken step.

If you inject L-gulonolactone oxidase into your liver, you will produce vitamin C. Evolution didn't decide to save energy. It decided that if the users don't notice the bug before the warranty period expires, it isn't worth working the issue.

The rest of the vitamin C synthesis machinery may be there, but it's obviously not consuming any energy if it's not producing anything.

There's also some speculation that eliminating vitamin C synthesis had other beneficial effects, beyond saving energy: https://en.wikipedia.org/wiki/L-gulonolactone_oxidase#Conseq...

It takes energy to maintain and replicate that machinery... but then we're full of DNA that seems to be mostly along for the ride.

Evolution doesn't decide of course, although your comment just brought to mind another thought:

Evolution exhausts the lowest energy possibilities first, before moving on to higher energy configurations. The surviving lower energy configurations are then in effect used as legos to create higher energy, more expensive configurations. If any of those building blocks are "deprecated", perhaps this effects things up the line, leading to the probability that cheaper, more basic constructions will survive longer because they have fewer steps in a given dependency chain.

Maybe this is obvious to people that understand evolution well, but I hadn't considered it that way before.

In this way, upon reaching some equilibrium where there are base features that reliably survive, evolution "decides" to try more complicated things. My abstraction could be totally off though, so feel free to tell me so if that's the case.

> Evolution doesn't decide

> Evolution exhausts

So, the remark is not about evolution being passive, but that the ability to decide requires sapience? I think, decidability is elementary to programming and in that sense completely mechanic. Anything else is begging the question of free will and the jury's still out on that one, so your "of course" is illegitimate.

> Evolution exhausts the lowest energy possibilities first, before moving on to higher energy configurations.

that's basic arithmetic. You can't have all the other numbers without the first.

> higher energy, more expensive configurations.

Expense and state are not equal. First, energy from the current state has to be expensed to activate some process, that will in turn increase or decrease the energetic state.

> If any of those building blocks are "deprecated", perhaps this effects things up the line, leading to the probability that cheaper, more basic constructions will survive longer because they have fewer steps in a given dependency chain.

That's a non sequitur motivated by observation. The idea of entropy is from thermodynamics and I'm not fit at that, but I think it is just defined for closed systems. Same basic Issue as with the free will, it depends on your knowledge of the limits of the system. If you deem free will a thing, why would you consider a bigger system, that works on a much larger timescale than humans, that is virtually limitless, to have a lesser degree of freedom, ie. none?

> so your "of course" is illegitimate.

> that's basic arithmetic.

> That's a non sequitur motivated by observation.

Gotta say I'm unconvinced by your argument.

I was tempted to delete the "illegitimate". I'm sorry for that, I'm a bit tempered. I was going to insert to write more on thermodynamics and philosophy, ie. metaphyiscs, and canceled that edit all together.

Note that "observation" is a literal translation of theory and your statement is purely theoretic. In practice we have all kinds of complex "energetic configurations" roaming the earth, locally increasing the entropy.

> Evolution doesn't decide

In a sense it does, doesn't it? And even if it does not, it is a very useful mechanism to explain something: model it against other known things.

    https://en.wikipedia.org/wiki/Conceptual_metaphor

Isn't that what epigenetics and methylation-tagging is for? Keep the code for the protein in the genome, but don't express it until some biochemical condition is met.

Copying long chains of barely-used DNA is relatively cheap for higher-order multicellular organisms with intergenerational intervals spanning 25 years instead of 12 hours.

Bacteria are better poised to re-evolve the capability when necessary, but if your species only expects ten thousand generations between solar or geomagnetic events, keeping that anti-radiation gene around for 250 kiloyears makes more sense. Of course, during that time, it may get damaged by mutation and not be repaired by sexual reproduction, but you only need one male with a functional antiradiation gene and enough females to not die before reproducing, and you can repopulate the species within 10 generations of a radiation crisis, instead of spending 100k generations reinventing radiation resistance.

Evolution doesn't foresee the catastrophic event that may happen in ten thousand generations.

If there is no selective pressure, this gene is free to build up mutations and diverge away.

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