Air is full of DNA

(nature.com)

121 points | by howrude 3 days ago ago

27 comments

  • azalemeth 4 hours ago

    I do often wonder about stories like this in the context of forensic science – my (incomplete!) understanding a lot of the time suspect DNA samples are taken from small areas and amplified significantly with high-cycle count PCR. I'd worry that any jury presented with a statistical argument about a fragment of somebody's DNA being very unlikely ("1 in 100 million") to be different to the sample found at the scene would not be aware of all of the potential systematic reasons why the actual true probability may be much, much higher.

    • Terr_ 3 hours ago

      Probability seems to be one of those things humans habitually mess-up at.

      "The chances of this person's unique DNA showing up at the scene are a zillion to one!"

      "What does that really mean when the sample also contains unique DNA for a hundred other people? Did all of them commit the crime as a group?"

      • chiph 24 minutes ago

        Depends on how they're using it. To find an unknown person and prove they were at a scene - yeah you'll have the 100 person's worth of DNA to sort through and then match against a (presently) incomplete DNA database. But if you already have a suspect and need to place them at the scene, if their DNA is one of the 100 then they have shown that.

        • ch4s3 22 minutes ago

          But we’re they at the scene or did they just bump into someone or something that was there?

          • chiph 14 minutes ago

            That's something that would have to be addressed at the trial by the defense attorney raising challenges.

            If the DNA is present, it's present - barring any procedural mistakes by the forensics technicians (mislabeled sample, dirty lab equipment, didn't follow manufacturers instructions, etc). Or deceit by one or more members of the forensics team to implicate the suspect.

  • butvacuum 2 days ago

    buried the lede, imho: we have enough DNA profiles to match their sampling up with.

    I'm always stunned when reminded that a full genome sequencing has gone from Human Genome Project's extreme cost and (edit: glacial) speed to using seqencing as the easy button.

    I hear we've also got machines that'll seqence, fit on a bench, and cost high five/low six figures. They've got issues to work out still though- iirc something about damaged sections causing issues.

  • nelox 2 hours ago

    What a wonderful title, a breath of fresh air.

  • dkobia 2 hours ago

    This always blows my mind. We are currently breathing in the DNA of the trees, animals, and people around us—and we’re leaving ours behind for them, too. We’re all one big genetic soup.

    • red75prime an hour ago

      "Soup" is a good word. Pieces of DNA resulting from destruction by nucleases and other enzymes.

    • SideburnsOfDoom 2 hours ago

      > This always blows my mind. We are currently breathing in the DNA of the trees,

      At this time of year, believe me, I am aware of the inhaled tree DNA setting off my pollen allergies.

    • gus_massa an hour ago

      The immune system destroy all the DNA in unexpected places in case it's a https://en.wikipedia.org/wiki/Viroid or something. Better safe than sorry.

      One of the important steps in mRNA vaccines was to surround the mRNA with a lipid to ensure it can survive long enough to enter a cell. Naked mRNA would not have worked.

  • seydor 4 hours ago

    Let's wait for smartphones with nanopores

    • alansaber 7 minutes ago

      Imagine the potential for targeted ads

  • madaxe_again 5 hours ago

    I was chatting with a biologist friend a while back, and one tidbit he dropped in was that any sample of air from anywhere on earth will likely contain the dna of organisms unknown to science, so abundant the tree of life is.

    • rcxdude an hour ago

      Yeah, there's just so many microorganisms (and some evolve so quickly) it would basically be impossible to really enumerate the species.

    • scotty79 2 hours ago

      I firmly believe that there are thousands of times more species of viruses in circulation that influence human health, almost always in minor fashion, than we currently know. Any random, sub-clinical symptom is in my belief highly likely to be caused by one of such viruses.

  • dang 6 hours ago

    [stub for offtopicness]