Could Mars samples brought to Earth pose a threat to our planet? What the coronavirus (and 'Andromeda Strain') can teach us.

Catastrophe

"There never was a good war, or a bad peace."
Yes, of course there is a chance of some malignant strain, but this has to be VERY unlikely.

We are probably in MUCH more danger from a stray asteroid.

I am sure those responsible for bringing back a Mars sample would treat it with great care, probably an antibacterial spray, and safe isolation. Look at all the care taken in the opposite direction.

Now, some will say that alien microbes are immune to our safeguards. Again this is possible but VERY unlikely. Growth of organisms would have to start (and probably still be) very simple and be susceptible to our procedures. But here I am on weak ground - any microbiologists here please to advise? I am thinking in terms of disrupting lipid aggregations in cell walls.
But I am a chemical engineer, not a microbiologist.

Cat :)
 
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NASA and the European Space Agency plan to haul pristine Mars samples to Earth in the near future. Should we worry about a possible 'Andromeda Strain' scenario?

Could Mars samples brought to Earth pose a threat to our planet? What the coronavirus (and 'Andromeda Strain') can teach us. : Read more
As the post says, there has been regular exchange of meteorites and microbes between Earth and Mars for eons. Just about all earth microbes are harmless to us. The micro biomass of this planet is about ten times greater than the total mass of multi cellular life. Single celled anaerobic microbes have been found more than 2 kilometers below the surface, most microbial life is subterranean. Only specific pathogens are a threat. These are organisms that have evolved alongside their multi cellular host for eons. They have evolved to overcome the hosts natural defenses, biological warfare. An ongoing battle between new defense systems and new counter systems. If Mars microbes have evolved in the absence of multi cellular earth life, they simply will not have the capacity to overcome that multi cellular organisms defense mechanisms.
 
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Ignoring the theories that covid 19 was man made, It did have a host to evolve and grow (feed). Flesh eating bacteria, virus', and microbes must have it's food or it dies.
If they fear all the conditions exist in the soil to allow this kind of evolution the solution is quite simple:

Send Humans to Mars before bringing Martian dirt to the Earth !
 
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Cat noted: "Yes, of course there is a chance of some malignant strain, but this has to be VERY unlikely."

I would rate it as impossible. Nothing is going to evolve and persist on the surface of Mars with all that radiation, lack of liquid water, etc. It reminds me of our moon guys being stuffed into quarantine chambers so that "lunar bugs" did not wipe us out.

Gotta go with egribble on this one. Any life form evolving elsewhere is not going to be compatible with life on earth. It will likely have all the same stuff, DNA, RNA, proteins, lipids, etc. But structurally it would be highly unlikely for any biological interactions. The closest I can think of is trying to translate languages. And I think intelligent Martians have been ruled out for quite some time....

Never felt good about Spock being half-human either. But that is in the distant future, and sci-fi at that.

And just for the record, viruses are not life forms. You cannot kill it, so it cannot be alive. You can only prevent infections (receptor blockers, protease inhibitors), or inoculate (please work out on this one), or become immune from a viral infection (assuming it does not hyper-mutate like HIV, flu etc.).

If it cannot be killed, it cannot be alive.
 
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Catastrophe

"There never was a good war, or a bad peace."
Cat noted: "Yes, of course there is a chance of some malignant strain, but this has to be VERY unlikely."

I would rate it as impossible. Nothing is going to evolve and persist on the surface of Mars with all that radiation, lack of liquid water, etc. It reminds me of our moon guys being stuffed into quarantine chambers so that "lunar bugs" did not wipe us out.

Gotta go with egribble on this one. Any life form evolving elsewhere is not going to be compatible with life on earth. It will likely have all the same stuff, DNA, RNA, proteins, lipids, etc. But structurally it would be highly unlikely for any biological interactions. The closest I can think of is trying to translate languages. And I think intelligent Martians have been ruled out for quite some time....

Never felt good about Spock being half-human either. But that is in the distant future, and sci-fi at that.

And just for the record, viruses are not life forms. You cannot kill it, so it cannot be alive. You can only prevent infections (receptor blockers, protease inhibitors), or inoculate (please work out on this one), or become immune from a viral infection (assuming it does not hyper-mutate like HIV, flu etc.).

If it cannot be killed, it cannot be alive.
This is your expertise, mine is surface active agents.
Would you say that you can disassemble a virus?
By that I mean that you can use soap (long fatty chain ca. C12) with sodium carboxylate for example to break down the cell wall. The cell wall components can be solubilised or emulsified into micelles or emulsion droplets depending on how you want to describe their size. Obviously, as you post, you are not killing it but you are opening out the walls and spilling the contents around. Does that make sense? Would disassemble come close?

Cat :)
 
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Cat, it is interesting that you work with surface active agents. I have done a lot of work with them. They are very commonly used in protein research to separate them from other things, etc.

Yes, a virus can be disassembled, and surfactants would be one way to do that. It really depends a lot on the virus and what you want to do with it. Some viruses are pretty simple - nucleic acid bundled up in a protein "coat". Others are much more complex, like the one going around now. That is a retrovirus that uses RNA as its genome, and has a membrane/protein coat (wall).

For all viruses, you have the genome (RNA or DNA) surrounded by a coat.

The simpler viruses could probably be disassembled by urea and some heat. Urea at high concentrations will unwind proteins and make the whole thing fall apart. Some of these could likely be reassembled, and possibly have been. Not sure about that.

A retrovirus with a membrane is much more difficult because the membrane is composed of fatty acid - glycerol conjugates (di- and tri-glycerides). Just like you mentioned, using fatty acids.

You posted: "By that I mean that you can use soap (long fatty chain ca. C12) with sodium carboxylate for example to break down the cell wall." I believe you meant virus "wall".

Soap will certainly mess up the virus, and destroy its activity if you hammer it long enough. That is what the hand washing is all about. Enough surfactant, and a powerful one like a soap will penetrate the membrane and wreck havoc. "Disassembling" (suggesting it could be put back together) a retrovirus would be much more difficult because of this membrane, but it certainly could be done. It would make a much bigger mess of RNA, protein and fats, but it would not be active, that is certain. Reassembly might not be possible, unless great effort was made

One of the most practical virus-inactivating compounds is isopropanol (IPA, around 70%). This solution will allow IPA to penetrate the membrane and wreck havoc on the proteins embedded in it. This include the spike protein the allows docking of the virus with your cell's receptor(s). Inactivation in this case is nearly 100% in a few seconds of contact.
 
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Catastrophe

"There never was a good war, or a bad peace."
Not to be too obvious, my working life was virtually all spent on the alternative name for zwitterionic sfa's. I edited (and wrote most of) the Marcel Dekker Surfactant Science Series (the book not the Series) on this type of sfa.

I also had a number of granted patents worldwide on reduction in irritation in sfa products such as shampoos, bath and hand dishwashing products using multiple N groups.
Yes, you could say I worked with sfa's ;)

My apologies for the over simplistic bit above.
 
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That is very impressive Cat. I have a few patents on injectable formulations, one using sucrose monolaurate to solulbilize an insoluble active.

The science of surface active agents is impressive, and requires a bit of reverse thinking - often outside the aqueous phase, in an aqueous phase!
 
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Catastrophe

"There never was a good war, or a bad peace."
That is very impressive Cat. I have a few patents on injectable formulations, one using sucrose monolaurate to solulbilize an insoluble active.

The science of surface active agents is impressive, and requires a bit of reverse thinking - often outside the aqueous phase, in an aqueous phase!
Thank you. Of course I am long retired; the book was in the 80's.
However, after that we spent 10 years running sfa training at an elevated level for major companies.
My first name was also the last four letters of the sfa type, and I was called the **** in . . . . . . * * * *. The *s do NOT represent a different type of 4 letter word of course.
Now my hobby is everything from BB and before to the world we stand on - from cosmology and astronomy, planetary sciences, to geology - which brings us back to samples and Marseology.
Cat :)
 
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Cat, what exactly do you mean by "Now my hobby is everything from BB and before".....

I have heard notions about "things" before the BB. Are you being a tad presumptuous, or are you onto something here? Hawking said he knew what happened before the BB, but I don't think it made a lot of waves. I could be wrong since never paid much attention to it. But you appear to be suggesting this too, and so an interrogation seems to be in order!

Do you have something to add, or even elaborate on? Anything at all would be new to me.
 

Catastrophe

"There never was a good war, or a bad peace."
Cat, what exactly do you mean by "Now my hobby is everything from BB and before".....

I have heard notions about "things" before the BB. Are you being a tad presumptuous, or are you onto something here? Hawking said he knew what happened before the BB, but I don't think it made a lot of waves. I could be wrong since never paid much attention to it. But you appear to be suggesting this too, and so an interrogation seems to be in order!

Do you have something to add, or even elaborate on? Anything at all would be new to me.
I know that you are very well read on these subjects so I doubt that I can surprise you except with respect to the purely hypothetical.

Of course there is no proof in any direction and I do not want to get banned for going off topic (again) so I will be brief. If we need to continue we should start a thread elsewhere.

I don't like the reverse straight line argument. It seems facile.
Without being able to offer any proof, I see the Universe (3D model) as an egg timer on its side. The "BB" is the neck. Space time curves gently through a nexus and 'continues' on the other side as (who knows?) perhaps a big bounce, white hole . . . . . . take your pick. Possibly just unknowable. I don't like a plurality of universes containing every possibility - seems a bit egocentric and anthropomorphic.

I suppose this brings us back bang on topic with an alternate universe (back to lower case 'u') with no coronavirus covid 19 from Mars or with any other origin.
Shame there is a black hole or whatever in the way.

Cat :rolleyes:
 
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"Possibly just unknowable." is certainly where I lean. Really, how could anyone know what happened before the BB when they aren't even certain about many aspects of the BB itself (how could they)? Talk about egocentric. So much is derived from extrapolation, as you have so correctly pointed out.

"I don't like a plurality of universes containing every possibility - seems a bit egocentric and anthropomorphic." Agreed once again. It was like I was telling someone here back when, "why" something happens is an anthropomorphic question. Who says anything has to have a why? It simply "is" might be the only answer. There has to be such a thing as "irrational questions". And "Why are we here?" tops the list.

My primary principle in evaluating scientific issues:

Always pay the most attention to empirical data. It usually decides things unambiguously.
 
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Catastrophe

"There never was a good war, or a bad peace."
It is good to have such agreement.

I do find it another anthropomorphic delusion that humans, with a very limited sense set (5+?) can even think that they have the equipment to 'understand' even if an answer exists at all.
You can laugh at this if you like, but it has extended my knowledge.
I tried to give your post more than one 'like' o_O but it toggles on and off. Anyway, an odd number gives the correct result I have also learned that o_O gives, I hope you see the result, so I'll separate the components o _ O. I am suffering from knowledge overload.

To get back on topic - do you suppose that those little yellow faces are the result of a virus from Mars.

Enough, I will start a thread about the consequences of human anthropomorphic delusion in seeking the answer to why our presence is not universally accepted, ney adored, by other less human denizens of the multiverse. Hope to see you there :)

OK it is up and running . . . . . . . . .
 
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Just a brief note on the notion that any life from Mars might be unable to directly interact with earth's life due to biochemical constraints, etc.

Many compounds of life have what are known as chiral centers. These typically result from a carbon atom, within a molecule, which has tetrahedral bonds. Such a configuration provides mirror-image molecules (non-superimposable), with both forms having the same physical properties! These are known as stereoisomers. They are distinguished in solution by how they rotate polarized light, designating a D-form and a L-form.

Amino acids are a prime example. If you make them from scratch (non-biologically), one usually ends up with a 50:50 mixture of the D-form and the L-form. Life on earth however "chose" one form - the L-amino acids - for proteins, during its earliest formative period. This is rather curious since one would expect that both forms were present in equal amounts during abiogenesis as the process must have used amino acids from an abiotic source. (Some D-forms are used for peptides and other small compounds.) Whatever the species, for humans, and all life on earth, all proteins are composed of L-amino acids, and D-amino acids can actually be toxic!

So it is a distinct possibility (50:50 for a good guess!) that any life from Mars (or anywhere else aliens might come from) could have evolved using the D-stereoisomers of amino acids (and that is just for their proteins!). Since it is the mirror image of the L-form, this could really happen! As noted before, they have the same physical properties.

The same is true for most chiral biochemicals. And chiral centers are everywhere in earth's biochemical "repertoire". Some are L-forms, and some are D-forms. An alien would probably have some serious problems "fooling around" with life on earth based simply on variations in stereochemistry!

So if an alien from Mars (or anywhere else) that evolved using D-amino acids came here, it would have a rough time just making a living (forget about fooling around!) : Most of what it might eat would be deadly, since they are of opposite stereochemistry. It is a little comforting to know there is some probability that an alien would not eat you, at least not right away! If they got here at all, they would surely know of the possible stereochemical toxins awaiting them. One suspects they would have test animals to feed to find out if we were safe to consume!

The variables here are so enormous as to boggle the mind. If you could make a copy of yourself with the opposite stereoisomers that you use now, and looking at the finished copy like a mirror, one would see the same face looking back at you, with no indication whatever that it is composed of completely different biochemistry! We could call such things "mirror life forms."

This is only one aspect of how life could vary from one origin to the next. There are others to be pondered, but this is one of the most obvious, with an unquestionably big difference.

And that really was a brief note on this subject!


 
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Catastrophe

"There never was a good war, or a bad peace."
Just a brief note on the notion that any life from Mars might be unable to directly interact with earth's life due to biochemical constraints, etc.

Many compounds of life have what are known as chiral centers. These typically result from a carbon atom, within a molecule, which has tetrahedral bonds. Such a configuration provides mirror-image molecules (non-superimposable), with both forms having the same physical properties! These are known as stereoisomers. They are distinguished in solution by how they rotate polarized light, designating a D-form and a L-form.

Amino acids are a prime example. If you make them from scratch (non-biologically), one usually ends up with a 50:50 mixture of the D-form and the L-form. Life on earth however "chose" one form - the L-amino acids - for proteins, during its earliest formative period. This is rather curious since one would expect that both forms were present in equal amounts during abiogenesis as the process must have used amino acids from an abiotic source. (Some D-forms are used for peptides and other small compounds.) Whatever the species, for humans, and all life on earth, all proteins are composed of L-amino acids, and D-amino acids can actually be toxic!

So it is a distinct possibility (50:50 for a good guess!) that any life from Mars (or anywhere else aliens might come from) could have evolved using the D-stereoisomers of amino acids (and that is just for their proteins!). Since it is the mirror image of the L-form, this could really happen! As noted before, they have the same physical properties.

The same is true for most chiral biochemicals. And chiral centers are everywhere in earth's biochemical "repertoire". Some are L-forms, and some are D-forms. An alien would probably have some serious problems "fooling around" with life on earth based simply on variations in stereochemistry!

So if an alien from Mars (or anywhere else) that evolved using D-amino acids came here, it would have a rough time just making a living (forget about fooling around!) : Most of what it might eat would be deadly, since they are of opposite stereochemistry. It is a little comforting to know there is some probability that an alien would not eat you, at least not right away! If they got here at all, they would surely know of the possible stereochemical toxins awaiting them. One suspects they would have test animals to feed to find out if we were safe to consume!

The variables here are so enormous as to boggle the mind. If you could make a copy of yourself with the opposite stereoisomers that you use now, and looking at the finished copy like a mirror, one would see the same face looking back at you, with no indication whatever that it is composed of completely different biochemistry! We could call such things "mirror life forms."

This is only one aspect of how life could vary from one origin to the next. There are others to be pondered, but this is one of the most obvious, with an unquestionably big difference.

And that really was a brief note on this subject!


The stereochemistry of amino acids in the Murchison meteorite
Article inPrecambrian Research 106(1-2):35-45 · February 2001

“We hypothesize that comet and meteorite impacts during the early stages of Earth's formation provided at least some of the essential components with the correct stereochemistry for the origin of life.”

Presumably this might mean that, at least locally, we might share the same stereochemistry with Mars and maybe asteroids (not just the ones in the belt)?

Cat :)
 
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I cannot readily access that paper you reference. But I can give some "maybes".

It cannot be ruled out that some chiral-centered compound catalyzed the formation (abiotic) of only one form of stereoisomer in amino acids. But if you look at the next meteor from a different source, those amino acids might be of the mirror image! So abiotic origins of amino acids could provide a range of all R-forms, all L-forms, or a mixture of the two.

It is also important to appreciate that amino acids racemize over time - i.e. they shift from one form to the other. So ancient amino acids found in meteors are not likely to be the same stereoisomers of their original form. This presents a situation where the abiotic amino acids on earth would still retain substantial content of both stereoisomers.

As as I noted before, that last post of mine only refers to amino acids. There are a large number of chiral compounds in biochemistry, and they are not all L-forms. Only the amino acids in proteins come to my mind as being so constrained. I suspect that is also true in nucleic acids, but do not have the interest in tracking it down. The premise of variant stereochemistry between life forms from various "planets", at least for me, sufficiently complicates intermingling of alien life forms.
 
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Catastrophe

"There never was a good war, or a bad peace."
I can reply right away on one point:
"But if you look at the next meteor from a different source, those amino acids might be of the mirror image! "

I am only aware of one meteorite which has been so tested. I will see if I can find more.

Beyond that you have me out of my comfort zone ;)
I shall have to do some serious revision. I was under the impression (only from casual reading) that all living components were 'left handed'. Sorry to ask a silly question but if 'they' change over time, why are 'they' all left handed"?
Obviously, I have got my 'they's confused.

But a very interesting contribution!

Cat :)
 
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Recemization is conversion of one stereoisomer into its mirror image, ending with both forms - both D and L. So if you have a pure form, it will end up being a racemic mix (50:50) given sufficient time.

I don't believe that all of our 20 amino acids can racemize (glycine is the only one which is not chiral).

Wiki:

"In chemistry, racemization is a conversion, by heat or by chemical reaction, of an optically active compound into an optically inactive form which half of the optically active substance becomes its mirror image (enantiomer) referred as racemic mixtures (i.e. contain equal amount of (+) and (−) forms). If the racemization results in a mixture where the D and L enantiomers are present in equal quantities, the resulting sample is described as a racemic mixture or a racemate."

https://en.wikipedia.org/wiki/Racemization
 
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I can reply right away on one point:
"But if you look at the next meteor from a different source, those amino acids might be of the mirror image! "

I am only aware of one meteorite which has been so tested. I will see if I can find more.

Beyond that you have me out of my comfort zone ;)
I shall have to do some serious revision. I was under the impression (only from casual reading) that all living components were 'left handed'. Sorry to ask a silly question but if 'they' change over time, why are 'they' all left handed"?
Obviously, I have got my 'they's confused.

But a very interesting contribution!

Cat :)
Cat, I missed your question as to why all the amino acids of life are of the L form, and it almost certainly has to do with complex interaction of other bio-mechanisms involved in the construction of proteins from these amino acids. Since the construction mechanism was likely chiral, it picked up on the best match, but it had to be only one form for biopolymers, which would eliminate variables in the protein's final structure. You would have to limit it to only one form or else the sequence in the protein would be infinitely variable - the mixture of D and L amino acids would eliminate the possibility of forming a reliable protein structure en masse. Each protein must work just as it is supposed to, or the whole show will shut down.

On the other hand, small, single molecules could be selected from either the D or L form depending on how other mechanisms are evolving around it. I suspect chiral "templates" at various steps was driving much of that selection. Quite simple really.

And then there is the extraordinarily complex formation of the 3-D structure of the protein as it "folds" into its final form, essentially a "ball of string" from a long, molecular, snaking, amino acid polymer, displaying certain reactive groups in a cluster on the surface if it is an enzyme.

One of the most important discoveries in all of biochemistry was the self-directed "folding" of a protein. The complex conformation is based solely on the sequence of amino acids in the protein and its interaction with its aqueous milieu. It is largely based on the entropic driving force that lowers the energy of the system by forcing the protein to take on a specific conformation. Quite remarkable to be sure. Protein folding in water was demonstrated with incredible techniques used by Chris Anfinsen, who won the Nobel Prize in 1972 for this work. One of his student's was my Ph.D. advisor. I have a reasonable perspective on the issue.

What you brought up regarding the stereoisomeric ratios also dredged up a long ago memory. It was just about this issue : could a mirror image D-form protein work in water as the same as the known L-form does, which is isolated from life. I am quite sure that an enzyme was lab-synthezed using nothing but D-amino acids. It was assumed to fold the same way since water, the primary entropic driving force of folding, is not chiral and should not have a stereochemical influence on either form. And it did not. The D-protein was just like the L-form, showing identical functional activity. The structure at atomic resolution was shown to be the exact mirror image as well. In the lab, we call this "no doubt about it".
 
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