Fuck it we ball: the extreme algae of the yellowstone springs

These are red algae, pretty common members of the underwater landscape, they are an ancient group (much older than any animals) and the sister group of modern plants. They have plenty of interesting adaptations like their strange life cycle, or the capacity to fortify themselves with calcium (something like shells of clams)

Old “shells” can accumulate, forming these popcorn-like structures

Okay,

These are also red algae, unicellular, and also not red ): but a part of the same group nonetheless. But their appearance is not the most surprising thing about them because they are extremophiles meaning they are adapted to extreme conditions.

These little green fuckers can be found (among other places) in the Yellowstone caldera, chilling in extremely hot geothermal springs that are generally inhospitable to all complex life. 

The group is known as Cyanidiophyceae, and today I wanna talk a bit about them.

To understand what makes them so strange I’d like to go through some definitions first, so bear with me:

Algae are eukaryotes, complex organisms with a nucleus and organelles like mitochondria (and chloroplasts in some cases), this is the group we’re in, alongside all other complex, multicellular life like plants or animals (Though not all eukaryotes are multicellular).

In contrast, there are the prokaryotes, small, simple, single celled organisms without a nucleus or without organelles (mostly). This group includes bacteria and their cousins, the archaea.

Prokaryotes are generally much better at withstanding extreme conditions while us eukaryotes are much more restricted to milder places instead.

As you can see from this graph, everything that lives at above 50-600C is either bacteria or archaea (=prokaryotes) 

What makes the Cyanidiophyceae special is they occupy the limits of eukaryotic life, living and thriving in waters up to 56oC. Though this pales in comparison to the 122°C that some archaea can withstand, it’s very impressive when compared to all other eukaryotes, for example the limit for body temperature in humans is 42.3oC and anything above will kill us (according to google at least).

Because of this, these algae live very much free of competition or predators, because other eukaryotes can not keep up with the environment while prokaryotes are way too small to pose a threat. This lack of competition has resulted in hardcore simplification since they dont need complex structures to deal with other complex organisms, cyanidiophyceae in fact have  exactly 1 (one) chloroplast and 1 (one) mitochondria among other simplifications. 

This is interesting for scientists because it allows them to start understanding what goes on inside other more complex cells. Indeed, a lot of our understanding of plant cells comes from these little guys.

Another thing that has interested scientists about this group is their genes, which they don´t have that many of, since they are so simplified, however that’s not the remarkable thing about their genome, but what is found in it.

But to understand that, we’ll need some more definitions firs (look at me i’m building suspense).

Reproduction in prokaryotes does not involve sex and it’s mainly done by binary fission, producing two identical daughter cells.

This presents a problem, because they lose out on the genetic variation that comes with sex, which is extremely important for survival in a changing environment.  This problem is solved in many ways by these organisms and I wanna focus on one in particular, horizontal gene transfer. This simply involves two cells exchanging a piece of genetic information, which can happen between two entirely different species .

This is a complex process which can occur in many ways (which i’m not gonna go into detail with) (also oh god spacehey fucked up the formating here :( )

For many years, it was believed that us eukaryotes were way too complex to engage in horizontal gene transfer but recent discoveries have made us question this statement, discoveries like bacterial genes found inside the cyanidiophyceae genome.

As I've said before prokaryotes are great extremophiles able to live in extremely hot places, places like the boiling hot waters of the Yellowstone caldera, alongside the protagonists of this post. 

This piece of information gives us a pretty good idea of how cyanophyceae were able to colonize such a hostile environment. As it seems, sometime ago, in some way, somewhere, maybe near Yellowstone a red algae was able to horizontally acquire genes from an extremophile bacteria, allowing it to pioneer in waters were no other algae was able to compete with it, this gave it an advantage so then it did that again, and again resulting in the strange organisms we see today, fucking neat isnt it?.

It's actually not just temperature that they can withstand, but extreme acidity, toxic metals like mercury or complete darkness (which stops them from doing photosynthesis), they do all of this with genes aquired from bacteria!

All of this however is not unique to this group as we are starting to find out in this last decade, for example diatoms, another algae which has been found to use bacterial genes to survive not extreme heat, but the extreme cold of northern seas. 

https://youtu.be/Ygty9HxhFK4

Diatoms + a cool video about diatoms :)

Another example, this one between two eukaryotes, would be the oomycetes, a strange group of single celled  organisms that have been horizontally exchanging genes with fungi for so long that scientists initially thought they were a weird type of fungus.

https://youtu.be/WEirF67pOXw

An oomycete + a cool video about their similarity with fungi :)

What we can learn from these examples is that these algae are not some unique anomaly in the tree of life but an extreme example of a phenomenon that has shaped all life on the planet in ways we are just starting to understand.

And that is all for now, thank you reading, if you want further reading on this group you can check out this article: https://www.cambridge.org/core/journals/microscopy-today/article/red-algal-extremophiles-novel-genes-and-paradigms/D1488FE1F0DD2E96994144166DBDB4B6

as i’ve referenced it heavily for making this blog, also maybe check out the videos they pretty nice okay cool bye.