
Tardigrade genome has been sequenced – most foreign DNA of any animal - henriquemaia
http://www.sciencealert.com/the-tardigrade-genome-has-been-sequenced-and-it-has-the-most-foreign-dna-of-any-animal
======
yread
Key quotes

>Before this, the rotifer – another microscopic water creature – was believed
to have the most foreign genes of any animal, with 8 or 9 percent. But the new
research has shown that approximately 6,000 of the tardigrade’s genes come
from foreign species, which equates to around 17.5 percent.

>The team hasn't investigated exactly how this gene-stealing is happening just
yet, but they propose that it's a result of one of the tardigrade's other
crazy survival mechanisms – the ability to dry out until its body is less than
3 percent water, and then come bounce back once they're rehydrated.

> When this desiccation happens, scientists know that their DNA breaks down
> into tiny pieces. They also know that when their cells rehydrate, there's a
> point in time when the cell nucleus is leaky, allowing DNA and other
> molecules to pass through. That means that while the tardigrade is quickly
> patching up its own genome, it may accidentally be stitching in another
> organism's genes.

~~~
fuzzythinker
Ah, so that's where Cixin Liu got the idea from for Three Body aliens.

------
adwn
All adult tardigrades of the same species have the exact same number of cells
in their bodies [1] – for some reason, I find that extremely fascinating. I
wonder how this interacts with the large amount of foreign DNA in their genes.

[1]
[https://en.wikipedia.org/wiki/Tardigrade#Anatomy_and_morphol...](https://en.wikipedia.org/wiki/Tardigrade#Anatomy_and_morphology)

------
scotty79
> The foreign DNA comes primarily from bacteria, but also from plants, fungi,
> and Archaea.

Or it's the other way around. Maybe singular cell life on Earth were just
tardigrade cancer cells that managed to survive outside of their bodies.

~~~
adrianN
Tardigrades arrived via comet and we're the descendants of their cancers?

~~~
ucho
Maybe[1]. Scientists don't like to waste time on alien life origin theory as
it doesn't really solve anything, we still would want to know how tardigrades'
home planet created life.

[1] with chance damn close to zero

------
pvaldes
Worth it just for the water bear gif. Fascinating history.

~~~
robin_reala
That’s CG, not a microscope.

~~~
ant6n
Here's a short documentary shot with microscopes:
[https://www.youtube.com/watch?v=o9kPQ0GY_W8](https://www.youtube.com/watch?v=o9kPQ0GY_W8)

~~~
cenanozen
This is beautiful

------
scardine
My kid loves the PBS show "cat in a hat". There is an episode about the
Tardigrade (#207):

> Synopsis: Nick and Sally are trying to guess what animal is the toughest one
> — is it a lion? Oh no, it must be the enormous elephant! Why not at all,
> says The Cat. The toughest of all is a teeny tiny Waterbear. Huh?

> Educational Objective: How TARDIGRADES (also known as Waterbears) survive
> extreme heat, cold and even being a trip into space.

------
sklogic
Zerg collecting the " _essence_ ". Nice.

