[ExI] why tardigrades are indistructible

Tue Nov 19 14:47:13 UTC 2019

Cool article.  This claims the tardigrade can preserve itself indefinitely
because it can turn itself into glass.

If so, this is really cool.  I am already 60% of the way to being able to
turn myself into glass: I am already good at making an ass of myself.  Now I
just figure out how to do the other two letters and I can survive hell.

spike

Scientists finally figure out why the water bear is nearly indestructible

Freeze it, boil it, or expose it to radiation. The water bear shrugs it off.
Now we know why. 

   <https://bigthink.com/u/philip-perry> PHILIP PERRY

17 March, 2017

Medically accurate model of a tardigrade or water bear.

The
<https://www.nytimes.com/2017/03/16/science/tardigrades-water-bears-dried-ou
t.html> tardigrade, also known as the moss piglet or water bear, is a
bizarre, microscopic creature that looks like something out of a Disney
nightmare scene: strange but not particularly threatening. The pudgy,
eight-legged, water-borne creature appears to be perpetually puckering. It's
the farthest thing from what you'd expect an unstoppable organism to look
like.

Yet,
<https://www.wired.com/2017/03/secret-crazy-tough-water-bear-finally-reveale
d/> water bears can withstand even the vacuum of space, as one experiment
showed. A sort of microscopic Rasputin, tardigrades have be frozen, boiled,
exposed to extreme doses of radiation, and remarkably still survive. How
they do this has been a mystery to science, until now.

Being a water-borne creature, scientists in this experiment examined how it
survived desiccation, or being completely dried out. When it senses an
oncoming dry period, the critter brings its head and limbs into its
exoskeleton, making itself into a tiny ball. It'll stay that way, unmoving,
until it's reintroduced into water.

It's this amazing ability that piqued Thomas Boothby's interest. He's a
researcher at the University of North Carolina, Chapel Hill. Boothby told
The New York Times, "They can remain like that in a dry state for years,
even decades, and when you put them back in water, they revive within
hours." After that, "They are running around again, they are eating, they
are reproducing like nothing happened."

Originally, it was thought that the water bear employed a sugar called
trehalose to shield its cells from damage. Brine shrimp (sea monkeys) and
nematode worms use this sugar to protect against desiccation, through a
process called anhydrobiosis. Those organisms produce enough of the sugar to
make it 20% of their body weight.

 <javascript:void(0)> 

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to life inthermal vent experiment

Not the water bear. Trehalose only takes up about 2% of its entire system,
when it's in stasis. Though employing a sugar to preserve one's body sounds
strange, the newly discovered process that the water bear goes through is
even more bizarre. It turns itself into glass.

In this study, tardigrades were placed into a drying-out chamber, which
mimicked conditions the organisms would encounter in a disappearing pond. As
the water bears underwent anhydrobiosis, scientists examined what genes were
activated. These genes produced a certain protein, which they named
tardigrade-specific intrinsically disordered proteins (TDPs).

When the genes which produce TDPs were blocked, the water bears died. "If
you take those genes and put them into organisms like bacteria and yeast,
which normally do not have these proteins, they actually become much more
desiccation-tolerant," Boothby said.

It's when the drying out process begins that such genes are activated,
flooding the water bear's system with the protective protein. The process
occurs in much the same way as trehalose preserves sea monkeys, according to
Boothby. This is an example of
<https://www.sciencedaily.com/terms/convergent_evolution.htm> convergent
evolution, when two unrelated organisms develop the same trait for survival.

Usually, proteins are formed in orderly, 3D chains of amino acids. But TDPs
operate differently, in a kind of random, somewhat disorganized manner. Dr.
Boothby said, "It's a really interesting question about how a protein
without a defined three-dimensional structure can actually carry out its
function in a cell." Another question, is this protein used by any other
organisms?

When desiccation begins and TDP is activated, it engages a process known as
<http://www.dictionary.com/browse/vitrify> vitrification. Boothby said, "The
glass is coating the molecules inside of the tardigrade cells, keeping them
intact." From there, it goes into a form of stasis until it detects water.
When that occurs, the protein is dissolved into the liquid and the
tardigrade is revived.

There could be some practical uses to this discovery. For instance in
medicine, vaccines often require refrigeration. But in the developing world,
it isn't always available, which makes delivering vaccines to vulnerable,
rural communities difficult.

Dr. Boothby believes that we may be able to use TDP to sort of freeze-dry
vaccines or medications, for easy storage and transport. What about putting
humans in stasis for space travel or when they have terminal diseases, to
await a cure? No word on that, yet. Scientists have years of research ahead
of them already, just to understand the inner-workings of TDP.

Some believe tardigrades may have "alien" DNA. To find out more, click here:

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