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ZeroZero

work on retrovirus's role in evolution?

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Does anyone know about academic work on the role of retroviruses in evolution. 

I am thinking that these viruses could insert preformed code into alien species and thereby alter their path of evolution. I cant seem to find much material about this in the literature

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There is ton of work on retroviruses and evolution. It should be rather obvious why there no work on aliens, however.

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22 hours ago, CharonY said:

There is ton of work on retroviruses and evolution. It should be rather obvious why there no work on aliens, however.

can you give me a decent source please

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32 minutes ago, ZeroZero said:
Quote

It should be rather obvious why there no work on aliens, however.

can you give me a decent source please

Barack Obama: "aliens would not allow it to happen".. ;)

 

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7 minutes ago, ZeroZero said:

Just for the record, it's a serious question and does not infer little green men

How can it be serious question without physically having aliens genetic material to be able to work with it and make experiments on it.. ?

 

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12 minutes ago, Sensei said:

How can it be serious question without physically having aliens genetic material to be able to work with it and make experiments on it.. ?

 

I am not sure if you understand. A virus is itself an alien to the host. Retro viruses that insert themselves into germ cells are called endogenous retroviruses, because they can, via the germ cell pass their DNA code onto future generations

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7 minutes ago, ZeroZero said:

I am not sure if you understand. A virus is itself an alien to the host. Retro viruses that insert themselves into germ cells are called endogenous retroviruses, because they can, via the germ cell pass their DNA code onto future generations

Wait, do you mean alien as in "different species" rather than "extraterrestrial" alien? In that case my suggestion is to look into the concept of horizontal gene transfer. It is best analyzed in bacteria, though typically it is not retroviruses that play a major role there. In fact, due to the amount of literature I would recommend a textbook for starters.

In  multicellular organisms this mechanism is much rarer. You do find genes passing on to viruses from their host, but their stable integration in metazoan hosts is far less likely as in single-celled organisms. Nonetheless, I recall a study on rotifers by Meselson and Arkipova (Science, ca. 2008) where they found evidence for horizontal gene transfer crossing domain boundaries (not exclusively via retroviruses, IIRC). And there a handful other examples, but I do not have them on the back of my mind.

 

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Yes, not little green interplanatery men. thank you. I shall research horizontal gene transfer.

Essentially I am looking at the possibility of DNA sequences  (snips) transferring from one species to another, at any level and by any mechanism. It seems to me that this would have a powerful effect on evolution if this occurred. An analogy

If you were to make a comparison to a computer and compare DNA to machine code. In a computer you have machine code - this is binary bits (AKA sequences of DNA) . These collections of bits are collated into useful functions or "procedures". From these basic building blocks the higher behaviours are built. 

If there were random mutation in a similar way to machine code, every so often a "procedure" might occur that was useful, and this could be incorporated into future generations. This would be metaphorically equivalent to "random mutation".  

Now if there were a mechanism that could pass a whole procedure from one species to another, this would have an additional advantage over simply  randomising bits. The procedure would already possess functionality at some level, as verified in the original organism, and would have a much stronger chance of being useful to the new host.

My analogy obviously does not bear too close scrutiny, but I think it's enough to show my thinking. In short, can sequences of DNA code be transferred between alien organisms? Possibly via endogenous retroviruses, possibly by other means?

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Just now, ZeroZero said:

Essentially I am looking at the possibility of DNA sequences  (snips) transferring from one species to another, at any level and by any mechanism. It seems to me that this would have a powerful effect on evolution if this occurred. An analogy

One of the things you'll have to keep in mind is that organisms have elaborate protection from having random DNA inserted. Essentially the mechanism acts like a mutagen and can easily be detrimental to the host cell. Essentially you are more  likely to disrupt functional code with gibberish rather than creating new functional code. Especially in metazoans (multicellular organisms) tight control is very important. It comes as no wonder that viruses basically act as mutagens and therefore e.g. cause cancer. 

Also, I suggest you avoid the term "alien" unless you clearly define what you mean, as it rather unusual lingo in this context. 

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18 minutes ago, CharonY said:

One of the things you'll have to keep in mind is that organisms have elaborate protection from having random DNA inserted. Essentially the mechanism acts like a mutagen and can easily be detrimental to the host cell. Essentially you are more  likely to disrupt functional code with gibberish rather than creating new functional code. Especially in metazoans (multicellular organisms) tight control is very important. It comes as no wonder that viruses basically act as mutagens and therefore e.g. cause cancer. 

Also, I suggest you avoid the term "alien" unless you clearly define what you mean, as it rather unusual lingo in this context. 

Thank you. When you say that the introduced code is  likely "gibberish" of course I agree, but this is the point, random mutation IS gibberish, whereas sequences introduced by other organisms (perhaps endogenous retroviruses) are more likely not to be gibberish, even if it is still true that mostly they WILL be gibberish, or will be silenced by gene defence mechanisms - or possibly (I guess)  epigentic meachnisms such as methalisation, or some other form of defence.  Even though this is the case, it's still more likely that such a sequence is more useful than a random mutation because it has spent generations of development in it's original host. In short random mutation could be called "pure gibberish" and transfer of gene materials from other species (see I did not use the world alien :) ) could be called "partial gibberish" as it makes sense in fragments

 

Thank you all for the helpful input

Edited by ZeroZero

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14 minutes ago, ZeroZero said:

Thank you. When you say that the introduced code is  likely "gibberish" of course I agree, but this is the point, random mutation IS gibberish, whereas sequences introduced by other organisms (perhaps endogenous retroviruses) are more likely not to be gibberish, even if it is still true that mostly they WILL be gibberish, or will be silenced by gene defence mechanisms - or possibly (I guess)  epigentic meachnisms such as methalisation, or some other form of defence.  Even though this is the case, it's still more likely that such a sequence is more useful than a random mutation because it has spent generations of development in it's original host. In short random mutation could be called "pure gibberish" and transfer of gene materials from other species (see I did not use the world alien :) ) could be called "partial gibberish" as it makes sense in fragments

Not really. Imagine a gene gets inserted in a coding area. The result is that the existing gene is disrupted and unless the inserted bit also has all the required bits for transcription the net effect will be gene disruption. I.e. a loss of functionality. Imagine it jumps into an intergenic region with regulatory functions. Here, you will alter or disrupt regulation, again a loss of proper function. Imagine it jumps into an area with no function but does not have all that is required for transcription. It ends up being junk at this stage. 

So just to have something translated requires a) that everything is compatible with the host for initiation/transcription etc. or b) that it jumps just at the right position in the genome where it can actually be expressed. Even if a gene is expressed, it is more likely than not detrimental, when we look at more complex organism. At which point the cells are usually targeted for elimination. Also having large chunks transferred is usually more disruptive (and therefore protected against) than smaller, single nucleotide mutations. 

As a whole, especially for multicellular organisms the transfer of external DNA is problematic and one theory is that large areas of the non-coding sequences are areas where e.g. viruses can insert and lay dormant or inactive without disrupting important functions. That is not to say that HGT may not play in role also in metazoans (it certainly does in prokaryotes). But the role is diminished due to the overall destructive nature. I.e. most of it has to be rendered non-functional as it otherwise may reduce the fitness of the carrier. Then, of course you mentioned generational transfer, which would only work if germlines are infected, which is an even smaller target, of course (and again, the reason why it is probably more relevant for single-celled organims).

 

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10 minutes ago, CharonY said:

Not really. Imagine a gene gets inserted in a coding area. The result is that the existing gene is disrupted and unless the inserted bit also has all the required bits for transcription the net effect will be gene disruption. I.e. a loss of functionality. Imagine it jumps into an intergenic region with regulatory functions. Here, you will alter or disrupt regulation, again a loss of proper function. Imagine it jumps into an area with no function but does not have all that is required for transcription. It ends up being junk at this stage. 

So just to have something translated requires a) that everything is compatible with the host for initiation/transcription etc. or b) that it jumps just at the right position in the genome where it can actually be expressed. Even if a gene is expressed, it is more likely than not detrimental, when we look at more complex organism. At which point the cells are usually targeted for elimination. Also having large chunks transferred is usually more disruptive (and therefore protected against) than smaller, single nucleotide mutations. 

As a whole, especially for multicellular organisms the transfer of external DNA is problematic and one theory is that large areas of the non-coding sequences are areas where e.g. viruses can insert and lay dormant or inactive without disrupting important functions. That is not to say that HGT may not play in role also in metazoans (it certainly does in prokaryotes). But the role is diminished due to the overall destructive nature. I.e. most of it has to be rendered non-functional as it otherwise may reduce the fitness of the carrier. Then, of course you mentioned generational transfer, which would only work if germlines are infected, which is an even smaller target, of course (and again, the reason why it is probably more relevant for single-celled organims).

 

I accept all that you say above, but I still claim that the probability of a tested sequence of DNA being "useful" is better than simple random mutation, probably by a significant factor

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