Air Pollution Causes Sperm Mutations In Mice

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."

Mutations

The sperm mutations aren't only in *mice*.

And no, I don't want to talk about it.

The REAL question is...

How does the sperm get INTO the mice? I mean, science for science's sake, but wtf.. that's sick!

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Easy, the Intelligent Designer put it into every male mice.

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So that's what he was doing on the Sunday!

Mice

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 methyl

Reactive Oxygen Species

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.

Specifics get interesting

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 c

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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 th

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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]

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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

I will gladly volenteer

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.

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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.

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We'll send Nurse Bubba to help you with that...

Startling conclusion...

This is quite disturbing! This just proves that in a few years all our children will be mutant mice!

Remember kids

It isn't pollution that's harming sperm. It's the impurities in our air and water that are doing it!

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In the water....

Flouridation.

Hmm.

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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, y

Children of Men

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.

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That isn't a coincidence...

Build a Better Mousetrap

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!"

Uh-oh...

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 Hamilto

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I would guess that for something disposable like mice that they are euthanized and then the testes are removed.

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I've known a few women who thought that way.

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Official job title: mousterbator

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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