Name: Meet Our Nitrogen-Breathing Bacterial Relative
Uploaded: 2021-06-03T02:37:42.000Z
Duration: 6 min 12 s
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there's nothing better than breathing a couple of lungs full of fresh O2, right?

But some organisms couldn't care less about oxygen.

In fact, in 2021, scientists announced the discovery

of an organism, distantly related to us, that breathes nitrogen.

This single-celled critter offers a window into how the type of cells

Our bodies are constructed from eukaryotic cells

a complex cell that contains a central pocket called a nucleus.

And because we're made of eukaryotic cells, we're classified as eukaryotes,

which is that big, noisy family that includes us, other animals,

The eukaryotes evolved a little under 2 billion years ago.

Back then, days were four hours shorter, continents were just becoming a thing,

and the population consisted largely of sunlight-eating,

Oxygen-farting was a good thing for eukaryotes, since we rely on oxygen to power our cells.

We can only do that thanks to mitochondria, which, as you may have heard,

And mitochondria's origin story is very cool.

Scientists think an early single-celled organism swallowed a bacterium

And amazingly, this was the beginning of a beautiful friendship.

Together, these partner cells formed the first eukaryotes,

and the ingested bacteria eventually evolved into mitochondria.

Eukaryotes let that bacteria-turned-mitochondria stay

They use oxygen to make adenosine triphosphate, or ATP,

the molecule that stores and transfers energy throughout the cell and the body.

Mitochondria can draw energy from sugars via a cascade of electrons,

Oxygen is a great tool for this because it's good

So, when you're breathing, you're taking in oxygen

and using it to generate the energy that keeps you going.

But some eukaryotes developed ways to generate energy that don't rely on oxygen.

may not have reached current atmospheric levels

So ancient eukaryotes needed to develop alternate ways of creating energy.

Today, there are still eukaryotes adapted to living in areas with low or no oxygen,

like the bottom of the ocean or the digestive systems of some animals.

These organisms mostly rely on fermentation,

which is a less efficient way to produce ATP

by breaking down sugars into CO2 and hydrogen.

But some have developed a way to breathe something other than oxygen.

Like the organisms recently discovered at the bottom of Lake Zug in Switzerland

that breathe nitrate, a molecule with one atom of nitrogen and three oxygens,

Unlike most oxygen-breathers, who breathe in O2 and breathe out CO2.

The waters at the bottom of this lake are oxygen-depleted but brimming with nitrate.

So you can see why these little Swiss survivors

need to make use of the ingredients in their environment.

They still seem pretty strange, though, because they do not have mitochondria

But they are living, breathing eukaryotes.

They just don't breathe the same stuff we do.

Well, like the first eukaryotes, they aren't doing it solo.

a little buddy living inside them that performs functions that keep them alive.

This inner partner does the same job as mitochondria,

only instead of transferring electrons to oxygen, it transfers electrons to nitrogen.

The partnership is so successful that researchers think it's been around

We know of some other organisms that can breathe nitrate,

but it's very unusual to find one that doesn't also use O2.

Also, there's an intriguing difference between the endosymbiont and mitochondria.

When mitochondria evolved, they started as swallowed bacteria

that gradually ditched some of their genome

and integrated more closely with their host cell.

And then eventually they became an organelle, or little organ, of their host cell.

But in the Swiss eukaryotes, the endosymbiont isn't an organelle.

And the researchers think it may be on its way to becoming an organelle.

similar to the one that took place billions of years ago,

first teamed up with another cell to form eukaryotes.

There are a lot of things we still don't know about this, though.

Like, this relationship could be totally unique.

Maybe the fact that it's similar to what we think happened with ancient mitochondria

suggests that this kind of relationship happened in other eukaryotes,

And if endosymbionts can help their host breathe nitrate or oxygen,

Also, where did this relationship evolve?

Like, probably not in Lake Zug, which is only ten thousand years old.

In fact, researchers have found the Lake Zug

endosymbiont's genes in other parts of the world,

So, it's a prolific little thing, with an origin story that's still a gigantic mystery.