Reminds me of the Gamma Forest at Brookhaven National Labs. From 1961 thru 1978 they irradiated a section of the pine barrens forest with a cesium-137 source just to see what would happen. It sterilized the soil and hardly anything grows there, almost 50 years later.
If there's enough radioactive material and it is mobile enough (due to ground water or wind driven mixing) to stay near the surface it could sterilize any organic material that comes in faster than it can accumulate.
I'm guessing the distinct lack of Google Streetview on that circular bit of road nearby and the tracks implies a certain amount of resistance to access if you get off that dual carriageway to the west?
This is great, if you have significant amounts of free oxygen to work with, which early earth evidently did not. Would be interesting to see if anaerobic metabolism could also occur without cellular confinement.
In the second part of the article there is an explanation which for me is the most plausible, and which would not be applicable to Martian soil.
Even if they killed all living beings in the soil, after their death the enzymes that are the catalysts for metabolism would just become dispersed in the soil and they continue to catalyze reactions like those of the Krebs cycle.
After many years of storage the molecules of the enzymes will be degraded, i.e. they will break into fragments. That again does not mean much, because the catalytic action of the enzymes is typically caused by very small parts of the enzymes, which can remain intact even after fragmentation.
In general, the biggest part of an enzyme is just a scaffold that attaches the enzyme in precise places of a cell, usually on some intracellular membranes, so that a great number of enzymes can be assembled like a production line in a factory, to coordinate the metabolic reactions for maximum efficiency.
After death and enzyme fragmentation, even after many years the catalytic fragments of the enzymes can still catalyze reactions like those of the Krebs cycle.
It is also possible that some of the observed chemical reactions are catalyzed by minerals present in the soil and not by remnants of the enzymes from the dead cells, but for now no evidence has been gathered about this.
Moreover, there are enzyme residues which are difficult to distinguish from abiotic minerals. Some of the enzymes involved here contain a catalytic part formed by a cluster of iron and sulfur atoms, which are attached to a protein molecule. That iron-sulfur cluster is pretty much identical with a very small fragment of an iron sulfide mineral.
We've found amino acids almost everywhere we look, including astroids [1].
It seems that the building blocks of life pretty naturally and readily form. Which is a pretty strong indicator that life is likely fairly common outside earth.
The amino acids that can be found everywhere include ten of the simpler amino-acids that are used in proteins.
The other 11 amino-acids from proteins have never been found where life does not exist. They are more complex and they seem to have been developed by living beings long after the appearance of life and the appearance of the genetic code (they seem to have substituted later the simpler amino-acids in certain locations of the map of the original genetic code, which encoded fewer amino-acids).
Moreover, while the simple amino-acids, including the ten that are used in proteins, can be found pretty much everywhere, wherever they were not produced by living beings they have been found in racemic mixtures, i.e. in equal amounts of left-handed and right-handed isomers, while in proteins only the left-handed isomers are used, so the living beings normally produce almost only left-handed isomers. Very small quantities of right-handed isomers are produced by some living beings, for other purposes than making proteins.
So it is relatively easy to distinguish amino-acids that have been produced by living beings from amino-acids that have been produced in abiotic conditions.
Tangentially related, this is a bit trying to sell upcoming book, but the discussion of origins of life was interesting to me. https://www.newscientist.com/article/2526959-how-a-radical-n...
YMMV but It’s free via my local library and Libby if you are stopped by the subscription nag.
Reminds me of the Gamma Forest at Brookhaven National Labs. From 1961 thru 1978 they irradiated a section of the pine barrens forest with a cesium-137 source just to see what would happen. It sterilized the soil and hardly anything grows there, almost 50 years later.
https://maps.app.goo.gl/pJYr6qiZnMdVwLJS6
https://www.atlasobscura.com/places/brookhaven-gamma-forest
https://www.youtube.com/watch?v=GsuiLxcDuHY&t=925s
That's a bit odd - why wouldn't wind blown non-sterile organic matter from the surrounding forest re-colonize the area?
If there's enough radioactive material and it is mobile enough (due to ground water or wind driven mixing) to stay near the surface it could sterilize any organic material that comes in faster than it can accumulate.
I'm guessing the distinct lack of Google Streetview on that circular bit of road nearby and the tracks implies a certain amount of resistance to access if you get off that dual carriageway to the west?
That "circular bit of road" is the Relativistic Heavy Ion Collider, the second highest-powered particle accelerator on the planet.
https://en.wikipedia.org/wiki/Relativistic_Heavy_Ion_Collide...
This is great, if you have significant amounts of free oxygen to work with, which early earth evidently did not. Would be interesting to see if anaerobic metabolism could also occur without cellular confinement.
It feels next would be trying isolate the component that make CO2. Try to use smaller sample. Put them under microscope, etc.
I might be dumb, but I figured they would just continuously subdivide the sample until they isolated it. Maybe CO2 sensors wont be sensitive enough?
Obligatory Asimov: 'The most exciting phrase to hear in science, the one that heralds the most discoveries, is not "Eureka!" but 'That's funny...”'
This is huge news if true for evaluating soil experiments on Mars. They could give false positives for life if they only look for metabolic products.
In the second part of the article there is an explanation which for me is the most plausible, and which would not be applicable to Martian soil.
Even if they killed all living beings in the soil, after their death the enzymes that are the catalysts for metabolism would just become dispersed in the soil and they continue to catalyze reactions like those of the Krebs cycle.
After many years of storage the molecules of the enzymes will be degraded, i.e. they will break into fragments. That again does not mean much, because the catalytic action of the enzymes is typically caused by very small parts of the enzymes, which can remain intact even after fragmentation.
In general, the biggest part of an enzyme is just a scaffold that attaches the enzyme in precise places of a cell, usually on some intracellular membranes, so that a great number of enzymes can be assembled like a production line in a factory, to coordinate the metabolic reactions for maximum efficiency.
After death and enzyme fragmentation, even after many years the catalytic fragments of the enzymes can still catalyze reactions like those of the Krebs cycle.
It is also possible that some of the observed chemical reactions are catalyzed by minerals present in the soil and not by remnants of the enzymes from the dead cells, but for now no evidence has been gathered about this.
Moreover, there are enzyme residues which are difficult to distinguish from abiotic minerals. Some of the enzymes involved here contain a catalytic part formed by a cluster of iron and sulfur atoms, which are attached to a protein molecule. That iron-sulfur cluster is pretty much identical with a very small fragment of an iron sulfide mineral.
Not as much as you might think.
We've found amino acids almost everywhere we look, including astroids [1].
It seems that the building blocks of life pretty naturally and readily form. Which is a pretty strong indicator that life is likely fairly common outside earth.
[1] https://www.nasa.gov/news-release/nasas-asteroid-bennu-sampl...
The amino acids that can be found everywhere include ten of the simpler amino-acids that are used in proteins.
The other 11 amino-acids from proteins have never been found where life does not exist. They are more complex and they seem to have been developed by living beings long after the appearance of life and the appearance of the genetic code (they seem to have substituted later the simpler amino-acids in certain locations of the map of the original genetic code, which encoded fewer amino-acids).
Moreover, while the simple amino-acids, including the ten that are used in proteins, can be found pretty much everywhere, wherever they were not produced by living beings they have been found in racemic mixtures, i.e. in equal amounts of left-handed and right-handed isomers, while in proteins only the left-handed isomers are used, so the living beings normally produce almost only left-handed isomers. Very small quantities of right-handed isomers are produced by some living beings, for other purposes than making proteins.
So it is relatively easy to distinguish amino-acids that have been produced by living beings from amino-acids that have been produced in abiotic conditions.
Tangentially related, this is a bit trying to sell upcoming book, but the discussion of origins of life was interesting to me. https://www.newscientist.com/article/2526959-how-a-radical-n... YMMV but It’s free via my local library and Libby if you are stopped by the subscription nag.