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So here's something to wake up to:
NASA researchers found living microorganisms on Earth which incorporate arsenic as a building block in their DNA.
I'd seen something about this on TV a few months back. They were working on it and talking about the significance of it, but they hadn't actually proven it was happening.
There's a lake out in California with really high levels of arsenic. There were bacteria growing in it. Arsenic is highly toxic to all known life on Earth. This is because arsenic is chemically very similar to phosphorus. (I've talked before about phosphates.) Put arsenic in a living cell, and mistakes are liable to happen. It'll get substituted for the phosphorus in some of the most vital molecules in the cell - including DNA, RNA, ATP (the basic unit of energy storage - fuel for every process), cell walls, and internal membranes. Those molecules won't work quite right, and then everything will break down. It's absolutely fundamental to just about everything going on in every living cell of every organism on the planet.
At least, every living organism we knew about until now.
At first, when they found life in the lake, they thought it might have just somehow adapted. They tried putting it in solution with more and more arsenic. It survived. So they looked at it more closely. And they've now shown that not only is it okay with living in arsenic, it thrives on it. It uses arsenic in place of phosphorus. Its DNA is made of arsenic.
This is even more revolutionary than Robert Ballard's discovery of chemosythesis (the ability of certain organisms to live off the toxic chemicals spewing out of undersea vents, far from any light or other energy source).
This is an organism with a fundamentally different biochemistry from anything else we've encountered.
There are two possibilities for how this happened and what it means, and both are huge.
One is that ordinary bacteria somehow adapted to an arsenic-rich environment. Nearly impossible. Phosphorus is one of the most important building blocks of just about everything in the cell. It would be like learning to live drinking hydrogen peroxide instead of water. Of course, if you have billions and billions of bacteria falling into this lake over millions of years... maybe somehow one of them managed to survive and reproduce. But even that is a major long shot. It would mean life is far more adaptable than we ever dreamed possible.
The other (IMO more likely) option carries even bigger implications. We don't know how life started on Earth. We know the right chemicals were around and if you hit them with lightning they'll form into more complex chemicals like amino acids and phospholipids (what cell membranes are made of). Given enough time, maybe they'll come together in just the right way to create a basic living cell. But we haven't be able to do it, and we have no idea how long it would take to happen. What we also don't know is how often it happened. Clearly, it was at least once. But if it can happen once, why not more than once? An entirely different track of life living here on Earth with us this whole time, unnoticed by the one that became dominant. They call it a "shadow biosphere." That could be exactly what we're looking at here. Organisms that first formed in an arsenic-rich environment, but didn't spread (or spread and died off) in places where arsenic isn't so common. As some put it - alien life on Earth.
More reading:
It's the front page article on NASA's astrobiology page, but the server is overloaded today. So NASA has another article on a different server. Of course, there are plenty of other people covering it, including this write-up on Gizmodo and this one from the AP.
NASA researchers found living microorganisms on Earth which incorporate arsenic as a building block in their DNA.
I'd seen something about this on TV a few months back. They were working on it and talking about the significance of it, but they hadn't actually proven it was happening.
There's a lake out in California with really high levels of arsenic. There were bacteria growing in it. Arsenic is highly toxic to all known life on Earth. This is because arsenic is chemically very similar to phosphorus. (I've talked before about phosphates.) Put arsenic in a living cell, and mistakes are liable to happen. It'll get substituted for the phosphorus in some of the most vital molecules in the cell - including DNA, RNA, ATP (the basic unit of energy storage - fuel for every process), cell walls, and internal membranes. Those molecules won't work quite right, and then everything will break down. It's absolutely fundamental to just about everything going on in every living cell of every organism on the planet.
At least, every living organism we knew about until now.
At first, when they found life in the lake, they thought it might have just somehow adapted. They tried putting it in solution with more and more arsenic. It survived. So they looked at it more closely. And they've now shown that not only is it okay with living in arsenic, it thrives on it. It uses arsenic in place of phosphorus. Its DNA is made of arsenic.
This is even more revolutionary than Robert Ballard's discovery of chemosythesis (the ability of certain organisms to live off the toxic chemicals spewing out of undersea vents, far from any light or other energy source).
This is an organism with a fundamentally different biochemistry from anything else we've encountered.
There are two possibilities for how this happened and what it means, and both are huge.
One is that ordinary bacteria somehow adapted to an arsenic-rich environment. Nearly impossible. Phosphorus is one of the most important building blocks of just about everything in the cell. It would be like learning to live drinking hydrogen peroxide instead of water. Of course, if you have billions and billions of bacteria falling into this lake over millions of years... maybe somehow one of them managed to survive and reproduce. But even that is a major long shot. It would mean life is far more adaptable than we ever dreamed possible.
The other (IMO more likely) option carries even bigger implications. We don't know how life started on Earth. We know the right chemicals were around and if you hit them with lightning they'll form into more complex chemicals like amino acids and phospholipids (what cell membranes are made of). Given enough time, maybe they'll come together in just the right way to create a basic living cell. But we haven't be able to do it, and we have no idea how long it would take to happen. What we also don't know is how often it happened. Clearly, it was at least once. But if it can happen once, why not more than once? An entirely different track of life living here on Earth with us this whole time, unnoticed by the one that became dominant. They call it a "shadow biosphere." That could be exactly what we're looking at here. Organisms that first formed in an arsenic-rich environment, but didn't spread (or spread and died off) in places where arsenic isn't so common. As some put it - alien life on Earth.
More reading:
It's the front page article on NASA's astrobiology page, but the server is overloaded today. So NASA has another article on a different server. Of course, there are plenty of other people covering it, including this write-up on Gizmodo and this one from the AP.
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But glad you liked, in any case - the post and the strip. :)