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Can DNA from an animal ever end up in bacteria or viruses?

  1. Mar 10, 2016 #1
    I was wondering if it is possible for a bacteria to enter a body and somehow get some amount of that animal's DNA in itself if and when it leaves the body? Or if it just continues to live in the body. Basically does DNA ever linger around? I heard about "DNA dropping" in organisms, if that's the official terminology.

    Then there are Viruses, who actually do into DNA areas. Would they ever pick up some DNA while in the nucleus? Or in some other way?

    Thoughts appreciated :)
     
  2. jcsd
  3. Mar 10, 2016 #2

    Ygggdrasil

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    Yes, retroviruses (which insert themselves into our DNA) are capable of picking up nearby genes and inserting these genes into the viral genome. Often, when such viruses re-infect other cells, the inappropriate expression of the cellular gene they picked up will cause cancer in a process called retroviral oncogenesis.

    Transfer of human DNA to bacteria would be called horizontal gene transfer. It would certainly possible as many bacteria are capable of taking in DNA from their surroundings, and there is extensive evidence for bacterial genes making their way into different animal genomes. A quick search didn't turn up any good examples of bacteria acquiring genes from humans, however.
     
    Last edited: Mar 10, 2016
  4. Mar 10, 2016 #3
    A bacterium has a lot less DNA than a cell or even a yeast. They would have a hard time absorbing human DNA directly.

    Bacteria do exchange DNA a lot across bacterial species, though, in little packets called plasmids. And viruses can pick up DNA. I guess a virus could give that DNA to a bacterium.
     
  5. Mar 10, 2016 #4
    Thanks for all the answers, fascinating to realize that DNA transfers occur so commonly in small organisms.

    A few more quick questions/conformations:
    - Looks like, besides exchanging plasmids, the DNA can also cross from plasmids to chromosomal DNA?

    - I remembered the term: DNA transposition. Does/can DNA transposition play a part in all this? From what I've read on, this process can happen in any cells.

    Thanks again.
     
  6. Mar 10, 2016 #5

    Ygggdrasil

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    Yes, in human cells, foreign DNA that you introduce in the cell can get stably incorporated into the chromosomal DNA (for example, see https://www.thermofisher.com/us/en/...transfection-methods/stable-transfection.html). This happens fairly inefficiently, but it can happen, nonetheless.

    DNA transposition can be a mechanism of horizontal gene transfer.
     
  7. Mar 10, 2016 #6
    Great, great! Many thanks. Now on to reading about it all! :)
     
  8. Mar 22, 2016 #7
    I remember reading that there was DNA in the mitochondria of human cells so outside of the nucleus and this was thought to be a remnant of bacterial DNA which had become integrated into our biology. I'm not sure how current this idea is but its interesting as the DNA was also thought to influence reproduction, I think this was discussed in the "RED Queen" by Matt Ridley.
     
  9. Mar 22, 2016 #8

    Ygggdrasil

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    Yes, mitochondria originated from a bacterium that formed a symbiotic relationship with the ancestor of all eukaryotes (this eukaryotic ancestor which would later evolve into plants, animals, fungi, etc.). The most of the genetic material from this bacterium made its way into the nucleus of the eukaryotic ancestor, such that eukaryotic genomes contain a mixture of bacterial genes originating from the ancestor of the mitochondrion and archaeal genes originating from the host cell that swallowed the mitochondrial ancestor.

    For more information see my recent insights article on mitochondrial evolution:
    https://www.physicsforums.com/insights/when-did-mitochondria-evolve/
     
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