Recent genetic discoveries - DNA can change and Microchimerism

[pureantigravity]

Ok, so I read somewhere that DNA in fact does change during a persons lifetime. That is it is affected by habits, drugs, stress and therefore is not the stable artifact of historical decent that people thought it was not so long ago.
(http://www.naturalnews.com/042157_DN...igenetics.html)

But this really freaked me out ...

Microchimerism.
Scientific American - Scientists Discover Children’s Cells Living in Mothers’ Brains

Swapping DNA in the Womb

BloodJournal - Fetal microchimerism—what our children leave behind

The idea is that the cells from a baby actually pass into the mothers body and stay there. Even through nipples.

The result, the baby's dna (a combo of father and mother) stays as part of the mother. This means that both partners DNA are actually integrated into the mother to some extent.

What are the ramifications? How does this change genetic study?

[jma233]

This sounds like a HUGE discovery (the dna changing in a lifetime)

Doesn't this change some principles of evolution?. Its not just that the weak get killed off but also that the strong get stronger within a lifetime. I guess they also have to get stronger before they mate in order to pass the adaptions along. Genetic mutations then play a smaller role in creating strong off-spring?

Am I way off on this?

[old goat]

This sounds like a HUGE discovery (the dna changing in a lifetime)

Doesn't this change some principles of evolution?. Its not just that the weak get killed off but also that the strong get stronger within a lifetime. I guess they also have to get stronger before they mate in order to pass the adaptions along. Genetic mutations then play a smaller role in creating strong off-spring?

Am I way off on this?

yes. Most of what these articles (which give no references to actual scientific research papers) are discussing is epigenetics--the idea that events during a person's life can influence how genes are expressed. This is much different than changing the genes themselves. The expression of the genes is not inherited, only the genes themselves. All of this has been known for many years. Genes of course can change during one's lifetimes--it's called cancer. And more generally some genes do mutate during one's lifetime, but other than cancer, those mutations have little or know effect because they do not affect all the cells in the body or even all the cells in a particular organ or tissue. Since the vast majority of genes are unchanged the mutations have no effect--unless they affect the germ cells--sperm and eggs--in which case their effect can of course be huge. It is well known that xrays and cosmic rays, among other things, can mutate DNA, so the finding that magnetic fields can alter DNA in the lab is not surprising, but what practical significance this might have is unknown. As far as changing the principles of evolution--evolution depends on the alteration of DNA in individuals. That's how new traits develop. So the assertion that DNA can change during one's lifetime does not contradict evolutionary principals; it supports them.

[pureantigravity]

yes. Most of what these articles (which give no references to actual scientific research papers) are discussing is epigenetics--the idea that events during a person's life can influence how genes are expressed. This is much different than changing the genes themselves. The expression of the genes is not inherited, only the genes themselves. All of this has been known for many years. Genes of course can change during one's lifetimes--it's called cancer. And more generally some genes do mutate during one's lifetime, but other than cancer, those mutations have little or know effect because they do not affect all the cells in the body or even all the cells in a particular organ or tissue. Since the vast majority of genes are unchanged the mutations have no effect--unless they affect the germ cells--sperm and eggs--in which case their effect can of course be huge. It is well known that xrays and cosmic rays, among other things, can mutate DNA, so the finding that magnetic fields can alter DNA in the lab is not surprising, but what practical significance this might have is unknown. As far as changing the principles of evolution--evolution depends on the alteration of DNA in individuals. That's how new traits develop. So the assertion that DNA can change during one's lifetime does not contradict evolutionary principals; it supports them.

edit: I didn't read that carefully before posting below. So I didn't really get it. But you say DNA can mutate, but not in every cell in the body. H

That's interesting. But I am starting to believe a bit more radically:

http://www.wisegeek.org/can-your-dna...-your-life.htm

Another interesting field that relates to this subject is that of epigenetics, which evaluates how environmental influence may affect the DNA of your children. Previously, DNA code in reproductive cells was thought to be unchanged, expect by mutation. Now scientists are evaluating how it may be changed by slight differences in the way people behave before they have children.

Your DNA may not just be a matter of inheriting family traits like hair or eye color or risk for certain diseases, but might also be influenced by how your parents behaved, such as being overweight or smoking prior to conceiving children. This has led some to conclude that people who wait until they are older to have children may have significantly changed the DNA of their future children though life choices and environmental exposure.

and like http://www.sciencedaily.com/releases...0624174849.htm

We're beginning to see that epigenetics stands at the center of modern medicine because epigenetic changes, unlike DNA sequence which is the same in every cell, can occur as a result of dietary and other environmental exposure," says Andrew P. Feinberg, M.D., M.P.H, a professor of molecular biology and genetics and director of the Epigenetics Center at the Johns Hopkins School of Medicine. "Epigenetics might very well play a role in diseases like diabetes, autism and cancer."

I'm just throwing those out because I didn't post any references in the OP. I don't understand it at all. All I know is it sounds more like change than expression per-se.


Any thoughts on Microchimerism?

[huckbucket]

As a geneticist I feel obligated to respond.

Human cells mutate throughout the lifespan of the cell. The rate of mutation is either standard error rate inherent in the process of replicating cells or accelerated due to environmental factors. The vast majority of mutations are silent. Some mutations cause disease. Some mutations impart an advantage. If there is pressure on you such that having this advantageous mutation helps with survival or breeding AND if you breed you may (or may not) pass it along to your offspring. If there is pressure on your offspring such that having this advantageous mutation helps with survival or breeding AND if they breed they may (or may not) pass it along to their offspring. This continues until a mutation gains a foothold in a population. This is evolution.

This is a very crude description. I don't know enough about fetal microchimerism to comment but would believe it to be plausible.


Edit: What Goat said too.

[creaky fossil]

I don't know enough about fetal microchimerism to comment ....

didn't stop "journalists" from talking about it. sci-fi is so hot, especially among the sci-ignorami.

[jma233]

As far as changing the principles of evolution--evolution depends on the alteration of DNA in individuals. That's how new traits develop. So the assertion that DNA can change during one's lifetime does not contradict evolutionary principals; it supports them.

Thank you. Its obvious that my understanding of evolution is at probably a 4th Grade level. I've got some googling to do. Its all very fascinating though.

[huckbucket]

didn't stop "journalists" from talking about it. sci-fi is so hot, especially among the sci-ignorami.

That fetal microchimerism editorial linked by the OP was written by a physician in a peer-reviewed, respectable journal (with references to other paper written in high-quality journals). Definitely not sci-ignorami although as I mentioned, I'm not familiar with the work and can't share an opinion.

[creaky fossil]

I should try to forget that well "respected" in medical world means "smooth liar" or "rich". Maybe I will.

[PB]

So if I come on my Lady's face she's absorbing my DNA?!?!
Sweeeeet!

[irul&ublo]

As a geneticist....

I thought you were a dentist...

[huckbucket]

I thought you were a dentist...

genetic dentist ... duh

[Viva]

Hey! Teeth have DNA, too.

[jma233]

Hey! Teeth have DNA, too.

Not if you shoot it in the back of her throat

[old goat]

edit: I didn't read that carefully before posting below. So I didn't really get it. But you say DNA can mutate, but not in every cell in the body. H

That's interesting. But I am starting to believe a bit more radically:

http://www.wisegeek.org/can-your-dna...-your-life.htm



and like http://www.sciencedaily.com/releases...0624174849.htm




I'm just throwing those out because I didn't post any references in the OP. I don't understand it at all. All I know is it sounds more like change than expression per-se.


Any thoughts on Microchimerism?

AS huckbucket points out individual cells do mutate. For these mutations to affect the host organism they would need to occur identically and widely through the body or at least through an organ--the brain for example. And for those traits to be passed on they would also have to affect the sperm or eggs. The articles you cite claim changes in behavior or body function due to acquired changes in DNA without any explanation of how they (either the DNA changes or the behavioral/health changes) occur or providing any evidence that they do occur. As far as microchimerism--since mother and fetus share a circulatory system for 9 months it isn't surprising that fetal cells could find their way into the mother. But what affect such cells have is speculative at this point--and reputable scientists publishing in peer-reviewed journals are not immune from speculation.

Thank you. Its obvious that my understanding of evolution is at probably a 4th Grade level. I've got some googling to do. Its all very fascinating though.

Even if you are only at the fourth grade level--which I doubt-- you are doing a lot better than the 60% or so people who don't believe in evolution.

That fetal microchimerism editorial linked by the OP was written by a physician in a peer-reviewed, respectable journal (with references to other paper written in high-quality journals). Definitely not sci-ignorami although as I mentioned, I'm not familiar with the work and can't share an opinion.

I am in no way disputing the presence of microchimerism, just the unfounded speculation about its effects.

One of the more fascinating, although I believe also speculative ideas is that the mitochondria--which contain the energy metabolism apparatus of the cell--started out as bacteria infecting larger primitive cells and then became incorporated into the cell's machinery. That idea was around back when I was in school; whether it still has any credence I don't know, but if it is true it is certainly a profound example of chimerism.
Another fascinating example of coexistence is of course the bacteria living in the gut--I believe all of us have more bacterial DNA in our bodies (although not actually part of our bodies) than human DNA.

As far as magnetic fields changing DNA--when I was in med school one of my classmates believed that human disease was caused by the effects of magnetic fields. He left school after his freshman year--maybe too soon?

A lot of popular scientific writing is like this stuff--taking a seed of scientifically demonstrated fact and growing a forest of speculation out of it.

[Mofro261]

As far as magnetic fields changing DNA--when I was in med school one of my classmates believed that human disease was caused by the effects of magnetic fields.

Not sure about causing human disease, but they can mess with your head a bit if you get a tune stuck in there.

[Mofro261]

unrelated, there was recent study in Science linking the majority of cancers to random chance as opposed to genetic predisposition or environmental factors.

Cancer- it's not your fault, it's just bad luck.

[jfost]

unrelated, there was recent study in Science linking the majority of cancers to random chance as opposed to genetic predisposition or environmental factors.

Cancer- it's not your fault, it's just bad luck.

So Uncle Crud still posting on TGR is just due to random chance?

[hutash]

The being fat affecting your offspring is wrong, unless you already have fat genes to begin with. Being fat can change gene expression, but those genes are in your somatic cells (the cells of your body), and the actually DNA doesn't change, just what bits of DNA are actually working at any given time. The genes in germinal cells, sperm/egg, are not actively expressing anything. You can change your egg/sperm DNA with great difficulty by exposing it to radiation and the like, but it is a pretty slim chance of changing anything, and as pointed out above, the vast majority of mutations are neutral, and few are detrimental, decreasing survival and a rare few are advantageous and increase survival. This is evolution, which of course do sent occur in humans just lower life forms

Mutation is change in the gene, or actual DNA sequence. Epigenetics is change in gene expression, without actually changing the gene (DNA sequence. )

As for incorporation of fetal genes, yeah it can occur (it is debatable just how much), but that fetal DNA is incorporated in somatic cells, so does not affect future generations. It also happens every time we get a virus. the virus sticks itself into are genes telling the cell to make more of the virus. Same is true in a much more limited way with bacteria, but again, this is occurring in somatic cells which are not passed on to the next generation.

[huckbucket]

Mutation is change in the gene, or actual DNA sequence. Epigenetics is change in gene expression, without actually changing the gene (DNA sequence. )

As for incorporation of fetal genes, yeah it can occur (it is debatable just how much), but that fetal DNA is incorporated in somatic cells, so does not affect future generations. It also happens every time we get a virus. the virus sticks itself into are genes telling the cell to make more of the virus. Same is true in a much more limited way with bacteria, but again, this is occurring in somatic cells which are not passed on to the next generation.

Just to clarify a bit. Epigenetics indeed does not involve change to DNA sequence but it shouldn't be mistaken for normal changes in expression related to cell signaling (i.e transcription factors and loosening of chromosomal structure). Epigenetics, in the classic sense refers to global repression of expression by mechanisms such as methylation and is a less refined way to regulate expression (in general). These changes generally have to be heritable for them to be referred to as epigenetic.

Secondly, we do indeed pass along remnant viral sequences every time we procreate. In fact, the human genome is littered with them as a result of viral integration of retro elements over the years. To your point, I'm not sure how often we inherit them via common infection though. Interesting fun fact ... there's a new class of cancer drugs on the market that empowers the immune system to mount a response to the tumor. They are called checkpoint inhibitors. Recent studies have shown that those patient that respond best to these therapies are those who's tumors are the most "immunogenic" or foreign to the body (makes sense). While scientists were trying to figure out how to define "immunogenic" in this case, they discovered that only those tumors that created new proteins (neo-epitopes) out of existing bacterial and viral elements (via mutations that impact normal transcription) in their genomes responded well to the drugs. The sicker the patient, the better they end up responding primarily because their tumors harbor more mutations that created more of these neo-epitopes.

See here for a decent review ... http://www.sugarconebiotech.com/?p=834

[RootSkier]

I should try to forget that well "respected" in medical world means "smooth liar" or "rich". Maybe I will.

Are you related to Walt Peschel?

[kootenayskier]

I recently listened to a podcast from Canadian CBC radio, in which Dr Tim Spector, author of "identically different" talked about epigenetics. The mechanisms by which environmentally triggered biological mechanisms (such as lung cancer from smoking, or stunted growth from childhood calorie depravation) echo through multiple generations was fascinating. Adds an extra dimension to the nature vs nurture debate.

[creaky fossil]

Are you related to Walt Peschel?

Yeah I was architect, engineer, builder, plumber, landscaper, and realtor for his condos on ww hill.

More importantly I'm pleased nothing new in genetics since I took the class in 83, though the theories are now pop sci as this thread shows.

[huckbucket]

Yeah I was architect, engineer, builder, plumber, landscaper, and realtor for his condos on ww hill.

More importantly I'm pleased nothing new in genetics since I took the class in 83, though the theories are now pop sci as this thread shows.

Well .. if you think there's nothing new in genetics since '83 than in addition to being an architect, engineer, builder, etc. you're also an idiot.

[old goat]

I recently listened to a podcast from Canadian CBC radio, in which Dr Tim Spector, author of "identically different" talked about epigenetics. The mechanisms by which environmentally triggered biological mechanisms (such as lung cancer from smoking, or stunted growth from childhood calorie depravation) echo through multiple generations was fascinating. Adds an extra dimension to the nature vs nurture debate.

On the other hand the Dutch went from being the shortest people in Europe, due to the starvation of WWII, to the tallest in one generation.

Thanks to huckbucket for straightening me out on what epigenetics means.