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Epigenetics
January 17, 2006 3:22 PM   Subscribe

"Epigenetics : the lives of your grandparents – the air they breathed, the food they ate, even the things they saw – can directly affect you, decades later, despite your never experiencing these things yourself. This work is at the forefront of a paradigm shift in scientific thinking, in which the environment can impact our health for generations to come."
posted by stbalbach (40 comments total) 1 user marked this as a favorite

 
Hmmm. See also.
posted by Gator at 3:28 PM on January 17, 2006


So, I may be harming my grandchildren by living in a smoggy part of the country? If I really cared about future generations, should I move away from the coastal states?
posted by JekPorkins at 3:29 PM on January 17, 2006


Please do move away from the coastal states.
posted by rxrfrx at 3:35 PM on January 17, 2006


Seems like this would have or should have come as a theory from the evolutionary biology area of science instead of genetics. Interesting article.
posted by billysumday at 3:37 PM on January 17, 2006


The notion posted by Gator seems to me just plain silly. The post is something I have read about and, oddly, points to what evolutionary folks have been saying for some time: we are a combination of both our heritability (genes) and our culture, if we include environment etc as part of the culture--that which we pick up via our living . Now this new area of study is not truly accepted as yet by many at this point and so I think calling it a "paradigm shiftg" is simply another overuse of the phrase.
posted by Postroad at 3:39 PM on January 17, 2006


Yeah, genetic memory does seem silly (though, as pointed out on that page, it's very popular in scifi). But when I read these two links and saw suggestions that things people experience, like stressful events, can cause actual, heritable traits in their descendants, the first thing I thought of was, "Oh, like racial memory. Like that shit in Clan of the Cave Bear."

I also cringe at the word "paradigm." Someone whose Simpsons-Quotery is more up to snuff than mine will surely come along and explain why.
posted by Gator at 3:53 PM on January 17, 2006 [1 favorite]


It's been known for years that epigenetic phenomena exist, and that, to some extent, those phenomena can be passed along in the germline DNA. It's still DNA. This isn't some ghostly transmission, but rather things like CpG island methylation, events that are easily influenced by environment, but have lasting effects on the germline. The breathless article is just to get the lay people all roiled up.
posted by Mental Wimp at 3:56 PM on January 17, 2006


Lamarckian heresy. These "scientists" should recant or be burnt.
posted by orthogonality at 3:59 PM on January 17, 2006


Network Executive: We at the network want a dog with attitude. He's edgy. You've heard the expression "Let's get busy"? Well, this is a dog who gets biz-ay; consistently and thoroughly.

Krusty: So he's proactive?

Executive: Oh, God yes! We're talking about a totally outrageous paradigm.

Writer: Excuse me, but "proactive" and "paradigm"? Aren't those just buzzwords that dumb people use to sound important? Not that I'm accusing you of anything like that... I'm fired aren't I?
posted by designbot at 4:08 PM on January 17, 2006


those phenomena can be passed along in the germline DNA. It's still DNA

I'm no biologist, but isnt' the germline a continuous series of cells; ie there hasn't been a de-nuovo creation of an animal cell for billions of years?

I did some wikipedia reading up on this just last month, it seemed to me that any "epigenetic" changes to the germline MUST necessarily be present in the offspring, for they don't just inherit DNA from the germline, they ARE the germline (or more precisely a recombination thereof).
posted by Heywood Mogroot at 4:08 PM on January 17, 2006


I doubt that our experiences directly effect our genes, but I do have a good idea that our experiences probably affect our phenotype (and those of our descendants). After all, we share what--50% of our genes with the banana, but we obviously don't share 50% of our biology with the banana. Phenotypes are just as crucial to defining species as are genotypes, say I.
posted by Citizen Premier at 4:09 PM on January 17, 2006


Paradigm lends itself more to Dilbert quotes anyhoo.
posted by Citizen Premier at 4:11 PM on January 17, 2006


There's 2 things here: honest "non-genetic" modifications that are passed from one cell to another (e.g. self-propagating markers or other structures situated in the cell membrane), and also "non-genetic" modifications that are actually genetic, such as methylation of a base (what Mental Wimp said). We might still write methyl-C as C, so some dumbass science reporter decided that we should pretend this isn't a genetic change.
posted by rxrfrx at 4:18 PM on January 17, 2006


This immediately came to mind:
Even maternal emotions can be passed to fetal genes and then to the next generation. Gottlieb has prenatally stressed mice, who are as adults found to be more aggressive, and then taken the male mice and mated them with other females and found that their grandsons were also more aggressive than non-stressed males-thus showing how environmental stress can be passed down genetically. Perry and others have shown dramatically how stressed children "change from being victims to being victimizers" because of imbalanced noradrenaline and serotonin levels, which then can be passed down through both genetic and epigenetic changes.
Crazy stuff.
posted by mullingitover at 4:30 PM on January 17, 2006


i've been calling Israeli domestic/foreign policy a product of inter-generational PTSD for some time now.

[how many minutes before someone says i'm anti-semitic?]
posted by RedEmma at 4:46 PM on January 17, 2006


Nothing weird about this.

Like the genetic predisposition to bipolar disorder-one can carry that predisposition and yet not have the illness-but then something can happen to trigger it, and voila, there you go. It isn't a stretch to believe that a parent can experience such a trigger, "turn on" the bipolar switch, then pass that switch on.

I am no scientist but think of it like this- if a parent is exposed to radiation, this can have an effect on the offspring. Not exactly the same thing, but this is how it seems it would work.
posted by konolia at 4:49 PM on January 17, 2006


Damn. My grandfather must have been one perverted sonofabitch.

Don't ask.
posted by pmbuko at 5:00 PM on January 17, 2006


This is extraordinarily unusual and I reserve judgment on it.
posted by Optimus Chyme at 5:00 PM on January 17, 2006


Published in science, a peer reviewed academic journal that is very hard to get into. The papers aren't pseudo-science crap, at least to the reviewers who approved them.
posted by dibblda at 5:27 PM on January 17, 2006


Sounds like a cop-out excuse I've heard from people who didn't want to drop acid with the rest of us.
posted by GooseOnTheLoose at 5:32 PM on January 17, 2006


Intergenerational PTSD? Well this is juuuust great. My parents had me right after they were stationed in Vietnam in the early 1960's - I was conceived because the VC mortar attacked the local movie theater. OTOH this would explain a great deal.
posted by tkchrist at 5:48 PM on January 17, 2006


I'm with orthogonality.

Torches, anyone?
posted by docgonzo at 6:10 PM on January 17, 2006


Like I said above, this makes more sense when you realign your perspective from the organism to the germline. Each one of my 10^14 cells can be traced to a single egg cell that had been alive 20-odd years in my mother's body, and THAT germ cell came from another egg cell that had been alive 1905-1943 in her mother's body.

We think we are each so independent & a special creation, but really the chain of life goes back billions of years.

Fascinating stuff when you get your head around it.
posted by Heywood Mogroot at 6:10 PM on January 17, 2006


It's also what you eat. Bad diet, smoking, drinking influence the health of later generations.
posted by stbalbach at 6:17 PM on January 17, 2006


I'm not doubting there is real science behind it, but is anybody up to a layman's explanation of how this differs from Lamarkianism?

I can understand how stress effects in a pregnant woman during 9/11 could affect the fetus and future development of that child, who then grows up sickly and then she herself has a problematic pregnancy with consequences for that fetus's future development.

So, is what is being discussed something that would only pass from women to offspring (and then multigenerationally through female children) through conventional pregnancy?

Or is it being said that these effect can also pass from the male through semen and would also affect "test tube babies" that develop with no physical interaction with the woman.

Maybe this is clear in the links provided but I'm not getting it if it is and layman's explanation would be appreciated.
posted by obfusciatrist at 6:44 PM on January 17, 2006


Oh dear. After all the abuse I've boshed snorted and inhaled into my body over the decades I guess I can now expect my offspring to sport laser eyes and extraneous limbs. Maybe even a wing or two.
posted by soiled cowboy at 7:49 PM on January 17, 2006


OK, let's see if we can't clear this up.

Lamarckianism was a theory that was based on observations. It wasn't bad science; it just turned out to be wrong. As it turned out, the Lamarckian theory didn't explain all the observations, and in fact there was another set of theories which did, which came to be called 'evolutionary biology'.

it seemed to me that any "epigenetic" changes to the germline MUST necessarily be present in the offspring

No, this is exactly the point; such changes, if any, could be mutable during the life of the organism, before it generates offspring. This is what 'epigenetic' means, as distinct from 'genetic'.

The famous example of CpG island methylation is Angelman syndrome (wikipedia link; I wrote the relevant text myself, so it's assured to be relatively lucid until someone comes along and botches it up).

The thing about the article linked by the OP is that it's not proposing a mechanism for the observations. It's demonstrating some observations - some of them of natural phenomena (experiments of nature), some of carefully-conducted experiments done with lab mice. And these observations show that certain factors - stressors, mostly - influence characteristics of the offspring in ways that the experimenters can't explain with reference to classical genetics.

It'll be up to future workers to try to figure out exactly what the real explanation is.
posted by ikkyu2 at 7:52 PM on January 17, 2006


Thanks mullingitover, That, indeed, was a very interesting read.

I wouldn't discount it at all.

There are probably many things right before our eyes which we are missing.
posted by alicesshoe at 9:28 PM on January 17, 2006


Remember, folks, you can't spell "Lamarck" without Karma!
posted by soyjoy at 9:29 PM on January 17, 2006


Well, we've known about maternal effects for years. It would seem like this is a plausible explanation - g by e interaction, indeed.
posted by redbeard at 9:30 PM on January 17, 2006


I'm withholding judgement on the linked article itself, but:

Published in science, a peer reviewed academic journal that is very hard to get into.

So were Hwang Woo Seok's human stem cell cloning results, as I recall. Look how well that went.
posted by stavrosthewonderchicken at 9:53 PM on January 17, 2006


Jeez. If stress and certain lifestyle choices are really that influential, even potentially, I'm beginning to wonder if having children isn't for me... I mean, I've changed over the years, but damn.
posted by exlotuseater at 10:02 PM on January 17, 2006


That BBC article was some of the worst science reporting I've read in a long time. Either the author didn't understand the difference between prenatal development and epigenetic effects or he was deliberately blurring the two to create a controversy that wasn't there. For example he claims that the swedish study shows hereditary effects but purely environmental effects could also be at work. (e.g. the famine caused the grandparent's children to be malnourished which meant that they were less able to provide for their children).

epigenetic is very interesting, but that article was just crap.
posted by afu at 10:06 PM on January 17, 2006 [1 favorite]


This is a writer trying to make a big stink about nothing.

Epigenetic modification has been known about for years. Basically do a little research on methylation and acetylation. It basically involves modifying how accessible the chromatin (the macro structure of DNA) is to a variety of enzymes and cellular components involved in DNA replication. Tee Wiki article is a bit short, but not to bad. Gives a basic rundown of acetlyation which is nice.

The truly hot and revolutionary stuff going on in biology right now is the field of microRNAs and RNAi. Bascially we now know that most studied organisms, people included, have an endogenous system of regulating gene expression that involves certain, small pieces of RNA (approx 20-25 nucleotides long) binding to a a particular part of a gene and stopping it from being expressed.

We can also use this for in vitro settings (i.e. in experiments) to stop gene expression, which is very nice considering the alternative is to make transgenic organisms/cells by knocking out the gene interest through complicated, time-consuming, and very expensive methods.

This is probably the biggest advance in the scientific toolbox since Kary Mullis invented PCR, Polymerase Chain Reaction which allows us to amplify quantities of DNA to the level that we can use them experimentally (sidenote: He purportedly came up with the idea while on LSD), or since Bob Weinberg figured out how to genetically alter cells so that they can be grown indefinitely in culture (i.e. they don't crap out and die after a few days/weeks/months).

Too bad science journalism concerning lab biology is so...inattentive.
posted by Redgrendel2001 at 10:49 PM on January 17, 2006


such changes, if any, could be mutable during the life of the organism, before it generates offspring. This is what 'epigenetic' means, as distinct from 'genetic'.

right. Genetic is what the DNA encodes. "epi-genetic", to my layman's understanding, is everything else in the germ cell, including the funky controlling proteins and stuff.

My point was the human line can also be looked at not as ambulating organisms -- these are just the environmental survival packages -- but as the germ cells we all carry.

My present ~190lbs of protoplasm stems directly from my mother's germ line, so theoretically it would be physically possible for me to be carrying "epigenetic" information that had been inserted into the germ cell that eventually became me.

(but as a male, this particular branch of the human germ line ends with me ... hmm, the Jewish idea of ancestry makes a lot more sense now).
posted by Heywood Mogroot at 11:22 PM on January 17, 2006


The Wellcome Trust website has the best concise explanation of epigenetics.

http://www.wellcome.ac.uk/en/genome/thegenome/hg02b002.html
posted by Redgrendel2001 at 11:29 PM on January 17, 2006


Heywood: the "everything else in the germ line, including the funky controlling proteins and stuff" is what is refered to as "Maternal effect" that is also mentioned elsewhere above. Again, something that has been know about already.
posted by The Bishop of Turkey at 6:44 AM on January 18, 2006


obfusciatrist: I'm not doubting there is real science behind it, but is anybody up to a layman's explanation of how this differs from Lamarkianism?

Lamarkianism proposes that the use or disuse of organs is inherited. So for example, the children of blacksmiths should have well developed arms. As a result, the inherited trait is inherently adaptive. Your total physiological experience is somehow encoded into your sperm and eggs.

With epigenetics the claim is that there are factors that affect how genes are expressed but which don't affect the underlying genetic sequence. Genes are not just a simple strip of DNA, but have masses of protein and RNA hanging on to them that influence which genes are activated, and how the genes are edited and processed. Also human ova are not just sacks carrying 1/2 of a complete genome, but have a complex cytoplasm and associated helper cells that also influence gene expression.

A key difference between epigenetic changes and Lamarkian evolution is that epigenetic effects are not necessarily adaptive. In much the same way, mutations are not necessarily adaptive or maladaptive. As mentioned above, this is not necessarily new. But it is exciting because there is a lot that biologists don't know about how eukaryotic genomes actually work.
posted by KirkJobSluder at 7:15 AM on January 18, 2006


/stops masterbating furiously.
posted by Smedleyman at 4:35 PM on January 18, 2006


right. Genetic is what the DNA encodes. "epi-genetic", to my layman's understanding, is everything else in the germ cell,

No, wrong. Classical genetics is an elegant, fully formed theory which has nothing to do with DNA and in fact predates any understanding of DNA's structure or role by nearly a half-century.

The biochemistry of DNA explained a lot of the chemical substrates of genetics, but when folks refer to 'genetics' they're often only referring to the theories engendered by the grand old men of the field, like Gregor Mendel and Morgan and so on.

It's very difficult to get to any real understanding of the current literature without being aware of the historical way the fields of genetics and biochemistry merged from entirely separate places.
posted by ikkyu2 at 5:57 PM on January 18, 2006


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