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Biotech Science

Air Pollution Causes Sperm Mutations In Mice 53

Posted by kdawson from the are-you-pondering-what-i'm-pondering dept.
Reservoir Hill writes "Epidemiological studies in humans have suggested a link between air pollution and reduced male fertility, but such studies are often confounded by other lifestyle differences such as diet, genetic background, and economic class. Now a study of mice, reared in cages kept in a shed downwind of two steel mills and a busy highway in a Canadian city, showed a host of genetic changes compared to similarly housed mice breathing filtered air. DNA in the sperm of the mice in the polluted area contained 60% more mutations, had more strand breaks, and had more bases that had been chemically modified via the addition of a methyl group. Precisely how the pollution caused the DNA damage remains unclear but changes may be a more general response to particulate pollution. 'It's important to move this forward to the next step: determining whether there are any human corollaries to this,' says Jonathan Samet, an epidemiologist at Johns Hopkins University."
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Air Pollution Causes Sperm Mutations In Mice More

Air Pollution Causes Sperm Mutations In Mice

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  • Mutations (Score:2, Funny)

    by Seumas ( 6865 )
    The sperm mutations aren't only in *mice*.

    And no, I don't want to talk about it.
  • I, for one, welcome our new mutant Canadian mice overlords.

    • Re: (Score:1, Redundant)

      by JordanL ( 886154 )
      I think you need *at least* a four digit account for that joke to be "funny".

      In which case you should probably be welcoming our low-digit-Slashdot-commenter Overlords. ;)

  • The REAL question is... (Score:3, Funny)

    by Anonymous Coward on Tuesday January 15, 2008 @03:37AM (#22047500)
    How does the sperm get INTO the mice? I mean, science for science's sake, but wtf.. that's sick!

  • First, a grain of salt. There hardly seems to be anything that doesn't screw mice up. Their physiology is extremely fragile compared to that of humans.

    But this seems like a pretty significant argument to take pollution seriously. Perhaps some of the methylation sites in particular will have human analogues that can be easily tested for (though, too, at least from the nutrient studies I've read, mice seem to be ridiculously sensitive to methylation).

    I think there'll be lots and lots and lots of things about
  • How exactly did they harvest the ...erm... samples?

  • Reactive Oxygen Species (Score:4, Informative)

    by Wilson_6500 ( 896824 ) on Tuesday January 15, 2008 @04:02AM (#22047594)
    As is mentioned in the article, I would take the wild guess that one of the culprits in this situation is probably the collection of good old reactive oxygen species--hydroxyl radicals from peroxides formed via enzymatic transformation of superoxide ions, for instance. Naturally, the guess is worthless without being tested and proven. However, increased free radical production is fairly well implicated in similar DNA damage (base damage, double and single strand breaks, etc.) due to some types of ionizing radiation. You can show that cells in a high-oxygen environment will "respond better" (i.e. be more likely to be "killed" (i.e. transformed in a way that makes them not reproduce)) upon low-LET radiation exposure compared to cells that are poorly oxygenated. This implicates oxygen (and, eventually, reactive oxygen species) as a _partial_ explanation for DNA damage due to ionizing radiation. (This happens to be important when you consider that cells that are closer to the centers of some tumors are poorly oxygenated--not enough that they necessarily die, but enough so that they are not as easily killed as those cells on the periphery.) Similar damage might be caused by similar chemical, if not physical, processes, but my speculation is just that: speculation.

    It bears mentioning, though, that much like the picture for radiation, it is just about certain that there is more to the story than just oxygenation. High LET radiation (think alpha particles compared to, say, low-energy x-rays) cause damage that is virtually unaffected by oxygen concentration, so we know there's more to the story.

    Given how relatively poorly understood are the biological changes due to ionizing radiation, it's a little surprising to me, at least, that we don't know more about the mechanistics of damage due to "pollution." Many, many more people deal with high doses of pollution than deal with high doses of radiation, and it's a lot easier (usually) to control who gets the radiation as opposed to who breathes in the pollution. Anyhow, I suppose what I'm saying is that it shouldn't be surprising that ROS-es might be fingered as _a_ cause, but it'd be shortsighted to think of them as the only cause--not that it seems that's happened here, fortunately.
  • Though it's pretty much automatic to exclude it presently out of scientific habit in our concepts of hereditability (like the summary seems to), don't forget epigenetics [sciencemag.org] now tells us we have "mutated", "unmutated", and... "other", in terms of things that cause particular effects via descent.

    Personally, I find it rather fascinating to be at the point of genetics that we can be mapping such subtle causal relationships, genetic and environmental.

    Also interesting to me, as a side thought-experiment, is it appea

    • Re: (Score:2)

      by Sique ( 173459 )
      It's not that easy, and it is surely not Lamarckism, e.g. animals don't inherit abilities their parents got during their life. It's more that the process of inheritance itself gets disturbed, and the descendents thus don't get the original gene codes of their parents but a variant of it (and that's what mutation originally meant).

      • Re: (Score:2)

        by Empiric ( 675968 )
        Well, it's an... evolving field, compounded by there being lots of scoping questions in terminology when discussing.

        It would appear not all would agree with your summary dismissal of the characterization, though. [bio-pro.de]

        • Re: (Score:2)

          by Sique ( 173459 )
          There is a difference between Lamarckism and the fact, that not every trait that gets inherited is transfered by encoding into the genetic code. There is the mitochondric genetic code, there are special proteins that cause certain parts of the genetic code to be switched off or interpreted differently etc.pp. (There are also parts of the genetic code that generate a protein that switches exactly this part of the genetic code off, and there are other parts of the genetic code that needs a protein present to
  • Where do I sign up for the human studies? Can I choose to be housed in the filtered air cabin?

    Not that I would be adverse to living in a smoggy hell-hole - so long as they pay for room & board and "collect" my sperm on a regular basis.

    • Re: (Score:1, Funny)

      by Anonymous Coward
      Collection is not necessarily too pleasant [colostate.edu].

      • Artificial vaginas (AV's to the initiated) are used to collect semen from many species, most prominently cattle and horses, but also sheep, goats, rabbits and even cats.

        Prerequisites to use of an AV are that the male be conscious, not significantly frightened of people, and more interested in ejaculating than in killing humans.
        Why can't all directions be this direct?
    • Sure. We'll send your mother down to the basement on a daily basis to pick up the specimen containers and to leave you with some empties.
    • We'll send Nurse Bubba to help you with that...
  • it mad my mouse smartur for a littul bit but...
  • Say you have a contaminant in the environment that is currently dangerous to the way the system (ie the mouse) works. That means you want to change the system, in order to compensate for the changed environment. So you induce random changes in the sperm and see which baby survives.

    In other words : the system works. Hoorray ! Perhaps it does the same in humans.

    Isn't this therefore perfectly normal ? Or are you all believers in intelligent design ? This is a good thing, and regardless, we can't stop it (and w

    • Re: (Score:2)

      by blueg3 ( 192743 )
      First, that's not the way it works -- mutations occur regardless of mutagenic factors. There's no "you" here that can determine from an outside perspective what the dangerous factor is and decide to cause greater variability because of it. These mutations are caused by chemical damage, which is something of a different story.

      Evolution is great, by the way, unless you're the one doing the evolving.
  • This is quite disturbing! This just proves that in a few years all our children will be mutant mice!

  • Remember kids (Score:2, Funny)

    by GroeFaZ ( 850443 )
    It isn't pollution that's harming sperm. It's the impurities in our air and water that are doing it!
    • In the water....

      Flouridation.

      Hmm.
      • Ripper: Mandrake?
        Mandrake: Yes, Jack?
        Ripper: Have you ever seen a Commie drink a glass of water?
        Mandrake: Well, I can't say I have.
        Ripper: Vodka, that's what they drink, isn't it? Never water?
        Mandrake: Well, I-I believe that's what they drink, Jack, yes.
        Ripper: On no account will a Commie ever drink water, and not without good reason.
        Mandrake: Oh, eh, yes. I, uhm, can't quite see what you're getting at, Jack.
        Ripper: Water, that's what I'm getting at, water. Mandrake, water is the source of all life.
  • I mean, it's a mouse. What did they use? A tiny version of the device they use on prize bulls and horses?

    This got to be one in the top ten lousiest jobs ever: mouse sperm gatherer

  • Children of Men (Score:3, Interesting)

    by hansamurai ( 907719 ) <hansamurai@gmail.com> on Tuesday January 15, 2008 @09:34AM (#22049230) Homepage Journal
    I just saw the movie Children of Men the other day, for those that don't know, it takes place about 20 years in the future where a baby has not been born in over 18 years. No one knows why everyone is infertile but one of the many theories was air pollution! Seems like an interesting coincidence.
  • This is great news for Congressman "Smoky Joe" Barton's friends at the smelter upwind of Dallas [downwindersatrisk.org]. Next time they get hauled before the clean air folks, they can just say "We're not generating air pollution! We're controlling Dallas' rodent population!"
  • It's worth noting that they have yet to find any evidence of negative effects. Odds are high, given the content and packaging of sperm, that there will be serious detrimental effects, but as of yet they have proven no such thing. Also, humans are vastly larger creatures than mice, so it is quite feasible that the causal agents can be in far less concentration by the time they reach our bits.

    Besides, 60% could easily be 16 mutations instead of 10.
  • FTA:
    "The mice, reared in cages kept in a shed downwind of two steel mills and a busy highway in a Canadian city, showed a host of genetic changes compared to similarly housed mice breathing filtered air."
    "No such research has been done on people in Hamilton Harbour, Canada, where the mouse studies were carried out."
    "Canadian researchers found that filtering out particles from polluted air lessened the risk of heritable mutations in mice caged near Hamilton."
    "After three weeks of breathing the Hamilton air,
  • Sperm on mice.. understandable.. in mice... sick.. just sick..

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