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Sci-Fi Science

One Species' Genome Discovered Inside Another's 224

Posted by Zonk
from the it's-a-mad-house-a-mad-house dept.
slyyy writes "The Universtiy of Rochester has discovered the complete genome of a bacterial parasite inside the genome of the host species. This opens the possibility of exchanging DNA between unrelated species and changing our understanding of the evolutionary process. From the article: 'Before this study, geneticists knew of examples where genes from a parasite had crossed into the host, but such an event was considered a rare anomaly except in very simple organisms. Bacterial DNA is very conspicuous in its structure, so if scientists sequencing a nematode genome, for example, come across bacterial DNA, they would likely discard it, reasonably assuming that it was merely contamination--perhaps a bit of bacteria in the gut of the animal, or on its skin. But those genes may not be contamination. They may very well be in the host's own genome. This is exactly what happened with the original sequencing of the genome of the anannassae fruitfly--the huge Wolbachia insert was discarded from the final assembly, despite the fact that it is part of the fly's genome.'"
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One Species' Genome Discovered Inside Another's

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  • by Anonymous Coward on Thursday August 30, 2007 @07:05PM (#20418157)
    There are multiple retroviral genomes in our own genome. So I am not too surprised.

    http://genomebiology.com/2001/2/6/reviews/1017 [genomebiology.com]
  • by Erris (531066) on Thursday August 30, 2007 @07:14PM (#20418243) Homepage Journal

    This discovery is unsetling and I hope that it's an error. There's already evidence that pesticide resistance from GM crops has turned up in weeds. Gene swapping in the wild might happen more often than we would like. Some of the unpleasant possibilities include food you can't eat, cotton you can't wear and weeds you can't get rid of.

  • by rastoboy29 (807168) * on Thursday August 30, 2007 @07:17PM (#20418275) Homepage
    Of course I'm being high, here, and talking out of my ass, but it does lend a whole new perspective on our role as a part of the ecosystem, as opposed to separate from it.
  • by Absolut187 (816431) on Thursday August 30, 2007 @07:46PM (#20418581) Homepage
    I think it is safe to say that retroviruses (a virus that inserts its DNA into the host genome) has influenced our own evolution.
    According to this article "retroviruses (ERVs) comprise roughly 5% of the human genome."
    (Note that the HTML translation is unclear - open the PDF to see that it says 5%)
    http://www.hindawi.com/GetArticle.aspx?doi=10.1002 /cfg.216&e=cta [hindawi.com]

    Hard to imagine that viral DNA is 5% of our genome without having any impact..
  • by Ethanol-fueled (1125189) on Thursday August 30, 2007 @07:59PM (#20418709) Homepage Journal
    It dosen't stop there. Certain parasites [wikipedia.org] are apparently able to change the behavior of their hosts.
  • Re:scifi tag? (Score:3, Interesting)

    by yabos (719499) on Thursday August 30, 2007 @08:38PM (#20419035)
    Are there mitochondria in a woman's egg before fertilization? I'm wondering how they get there in the first place if it's not in the DNA of the 2 parents.
  • by eli pabst (948845) on Thursday August 30, 2007 @09:38PM (#20419523)
    Wolbachia are kind of funky though. They can live inside of host cells (as an intracellular symbiont) which is a bit uncommon for most bacteria. They do weird things like infect female gametes (eggs) and kill male offspring, that way only infect females will be produced. Still doesn't take away from the fact that you have a bacterial genome integrated into it's host. But they're definitely not a run of the mill bacteria.
  • by smellsofbikes (890263) on Thursday August 30, 2007 @11:46PM (#20420501) Journal
    I just read a superb book called "Survival Of The Sickest" that went on at *length* about parasite control of parasitized animals, from wasps that sting spiders and implant eggs, that during their development cause the spiders to weave cocoons for the hatching wasps, through the effects of toxoplasmosis on altering how mice behave so they get eaten by the toxoplasmosis host, to other things I'd never even considered. Guinea worm is this horrible disease where a worm bores through your skin with acid. It hurts, a lot, so people go find rivers and pools because the water makes it hurt less -- and the guinea worm dumps eggs as soon as it's in water, to get the next person who drinks from that water. Rabies infects brains, making animals aggressive, and also concentrates in saliva, so the aggressive animals are more likely to bite and transfer the disease. The book even went over some guidelines for predicting how lethal a disease would be, based on its mode of transmission: typically, we've thought that diseases get less lethal over time because that increases their ability to spread, but the book says it depends on the transmission path. Malaria wants -- inasmuch as a disease can want anything -- people to be very ill indeed, so that they spend lots of time not moving, giving mosquitoes a better chance of finding the people, while colds do want people to be as mildly sick as possible so they can maximize their distribution. A particularly neat case is cholera, which can be spread by human-human contact, or more usually by contamination of drinking water. In the latter case, the sicker the person, the better, because more bacteria will be voided by the person through diarrhea, while in the former case, milder infections spread more because there's longer-term contact with heath care personnel, meaning more chances to spread. Watching cholera epidemics in South America, that's exactly what they observed: in countries that were poor, where there wasn't really any official health care, the disease became progressively more lethal over time, while in countries where infected people got immediate health care, the disease got less lethal over time. It's not a bad read, although the doctor who wrote it, Sharon Morel (I believe) should've just written it, instead of hiring a ghost writer who turned it into a succession of USAToday-feeling articles.
  • Re:Dawkins (Score:3, Interesting)

    by tukkayoot (528280) on Friday August 31, 2007 @01:43AM (#20421175) Homepage
    Yep. Of course, we've always known for a while that it's possible for biological agents to co-opt other organisms ... viruses co-opt cellular functions to reproduce themselves and retroviruses will co-opt the host's DNA itself, often to the detriment of the host organism. Non-viral parasites can also co-opt the metabolic functioning of a host organism or even control the hosts' minds [wikipedia.org].

    So this sort of dog-eat-dog, inter-species warfare (as well as friendly symbiosis and back-scratching) between genes for the purpose of gene replication is nothing new or surprising to people familiar with biology, but what is new is the fact that bacteria apparently interact with the DNA of organisms in ways we didn't quite expect. It's just not something most people quite expected ... this is probably a flawed analogy, but it'd be like learning that some turtles can fly. Sure, you can imagine there might be an advantage to the genes belonging to the turtle that can fly, but it's still not something you expect to discover ... of course, we understand the qualities turtles have which would prevent them from evolving the necessary characteristics for flight perhaps better than we understand the way bacteria work.

    Incidentally, these findings seem to be an additional point of evidence against the common creationist argument that you can't add information to the genome through any known naturalistic mechanism (there is a video out there where Dawkins is supposedly stumped when asked for an example of how this might occur). These findings seem to demonstrate that in addition to other known and speculated mechanisms of genetic change, bacteria can integrate aspects of their genome into that of another organisms. As the article indicates, this may have significant implications for our models of biological evolution. Pretty incredible stuff.

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