Mice Inherit the Fears of Their Fathers
UPDATE (12/1, 2:37pm): This study was just published in Nature Neuroscience; you can read all of the juicy details here.
UPDATE (11/17, 11:22 am): I just published a new post showing how scientists reacted to this study on Twitter, with comments ranging from biology to skepticism. no question that trauma gets handed down from one generation to the next.
In one highly publicized example, researchers in New York studied several dozen women who were pregnant on September 11, 2001, and had been in the vicinity of the terrorist attacks. Some of these women developed post traumatic stress disorder (PTSD), and this group shows lower levels of the stress hormone cortisol in their saliva than do those who did not develop PTSD. But here the rub: At 9 months old, the babies of the women with PTSD have significantly lower cortisol levels than babies of healthy mothers.
In earlier work, the same researchers had reported low cortisol levels in adult children of Holocaust survivors with PTSD. And in yet another study,Kerry Ressler at Emory University showed that the so called response to a sudden stimulus a marker of anxiety is more pronouncedin kids whose mothers were physically abused as children then in those whose mothers were not abused. I could go on.
But how, exactly, does a parent stress leave such a deep impression on its progeny?
Part of it is nurture. A parent sadness and stress naturally affects how they interact with other people, including their children. The Holocaust study, in fact, found that the survivors with PTSD tended to emotionally abuse or neglect their children. And we know from some remarkable experiments in rats that parental care affects the offspring genes: Rat pups that get a lot of licking and grooming from their mothers show distinct changes in their epigenome, the chemical markers that attach to DNA and can turn genes on and off. Neglected pups, in contrast, don show these epigenetic tweaks.
Now a fascinating new study reveals that it not just nurture. Traumatic experiences can actually work themselves into the germ line. When a male mouse becomes afraid of a specific smell, this fear is somehow transmitted into his sperm, the study found. His pups will also be afraid of the odor, and will pass that fear down to their pups.
transfer information to their offspring, and they do so even before the offspring are conceived, saidBrian Dias, a postdoctoral fellow in Ressler at an engaging talk aboutthis unpublished dataon Tuesday at the Society for Neuroscience meeting in San Diego.
And why, evolutionarily, would a parent pass down such specific information? that when the offspring, or descending generations, encounter that environment later in life, they know how to behave appropriately, Dias said.
The researchers made the mice afraid Bradley Roby Jersey of certain odors by pairing them with a mild shock to the foot. In a study published a few years ago, Ressler had shown that this type of fear learning is specific: Mice trained to fear one particular smell show an increased startle to that odor but not others. What more, this fear learningchanges the organization of neurons in the animal nose, leading to more cells that are sensitive to that particular smell.
Dias trained mice to fear acetophenone which, according to this chemist, smells orange blossom with a bit of artificial cherry over three days, then waited 10 days and allowed the animals to mate. The offspring (known as the F1 generation) show an increased startle toacetophenone (with no shock) even though they have never encountered the smell before. And their reaction is specific: They do not startle to a different odor,propanol (which smells like alcohol). What more, the researchers found the same thing in the F1 generation offspring (known as F2).
The scientists also looked at the F1 and F2 animals brains. When the grandparent generation is trained to fear acetophenone, the F1 and F2 generations have more neurons in their noses, Dias said. These cells contain a receptor that detectsacetophenone. Their brains also have larger glomeruli, a region of the olfactory bulb that responds to this smell. father like son, we're getting some ancestral information, Dias said. how is that occurring? team performed an in vitro fertilization (IVF) experiment in which they trained animals to fearacetophenone and then 10 days later harvested their sperm. They sent the sperm to another lab across campus where it was used to artificially inseminate female mice. Then the researchers looked at the brains of the offspring. is striking is that the neuroanatomical results still persist after IVF, Dias said. something in the sperm. been to a lot of scientific talks. The excitement around this one was notable, with many scientists whispering about it in the room and more loudly buzzing in the hallways outside.
But I know what you wondering. It was the first question that Dias received from the audience after the talk: you have any idea of how this information being stored in the brain is being transmitted to the gonads? the questioner asked.
The short answer is that the researchers don have any idea, though they thought about several possible explanations. Apparently a study in cats and pigeons showed that after smelling an odor, the odorant receptor molecules can get into the blood stream, and other studies have reported odorant receptors on sperm. So maybe the odor molecules get into the bloodstream and make their way to sperm. Another possibility is that microRNAs tiny RNA molecules involved in gene expression get into the bloodstream and deliver odor information to sperm.
For now, though, Dias said, are two Bradley Roby Womens Jersey science fiction hypotheses. more about Ressler work in afeature on stress and resiliencethat I wrote for Nature last year.
Just from reading the title, I had a gut feeling this had Louis Vasquez Womens Jersey something to do with the epigenome. Surprising it gets mention in the article but the scientists don consider it as a hypothesis. It seems to me there has been a lot of evidence indicating that the epigenome works as an ancestral memory and tweaks hormonal triggers to better adapt to the last few generations conditions. Even before this study, I had really been wondering where instinctual fears come from, like those exhibited in domestic cockatiels that had never seen snakes when they encounter something that looks like one. Basically, they will panic seemingly out of nowhere, even if they never seen a living snake in their lives.
Without a published paper to read it hard to deduce much from this. Eric Nestler did similar research in 2011 using defeated rodents, compairing the inheritance effect in offspring conceived through IVF to natural conception. He found a big difference, but still did www.broncosnflofficialproshop.com/Nike-Derek-Wolfe-Jersey.html find an inheritance effect in IVF, but more subdued.
Nestler considered that the IVF harvesting process itself might have preselected immature sperm.
That an inheritance effect is occurring in these IVF studies looks plausible to me, but there is a wild card option still left. To collect the Sperm in Nestlers experiments the rodents were killed, leaving the door open on a field type effect, that has not yet been ruled out.
When or even if this paper gets published we might get to know more.
It interesting that the negative reaction to this story in tweets is all about the reported phenomenon whereas I rather interested in the immediate assumption that it would necessarily fit into some baseless, unevidenced scenario of natural selection. The fact is that even if the phenomenon can be irrefutably established and a mechanism of its inheritance firmly attached to it, the purported place it would have as an evolutionary adaptation could never be anything but speculative since it is impossible to www.broncosnflofficialproshop.com/Nike-Montee-Ball-Jersey.html go back in time and research its presence in varying strength and its effect on reproduction rates. Yet that enormous leap into the unknowable seems to be considered less outrageous than the presentation of a presumably observable phenomenon which could be reproduced.
My cats exhibited an astounding behavior partner brought a snakeskin into the house to show me. It got put down. One by one, as the cats found it, they began behaving as if there were a deadly predator in the house universally they began to avoid the floor and walk around the house on top of available furniture, the backs of couches, jumping to tables, etc. Their tails would jerk as if they were preternaturally on edge. Finally after observing this for a few days, we took pity on them and put the snakeskin outside, and life returned to normal! I don believe a single one of them ever encountered a snake in real life. Where did the reaction come from?
The process described in the article involves inheriting a negative experience. Could it be, I wonder, if what is really going on is that Louis Vasquez Kids Jersey all experiences are inherited, both good ones and bad ones. That would be only a small step to inheriting skills, such as spiders web building and infant bird migration to a country that they have never seen before, etc.
As for any connection with evolution, it would be informative to track whether the increase in neurons in the noses of subsequent generations was maintained as the number of generations not exposed to the supposedly harmful smell increased and the of the harm became more distant.
for Gray Matters, my weekly email newsletter
Although fairly lax about approving comments, I don't have much patience for profanity and/or incoherence and/or spam.
Follow me on TwitterMy TweetsVirginia ElsewhereUprooted, a longform narrative published in MATTER, investigates the rapidly growing industry of genetic genealogy. Deep down, everybody wants to know who they are and where they came from. But what happens if you discover that everything you thought was true was, in fact, a lie?
Re Awakenings, a story about a strange sleeping sickness published on The Last Word on Nothing, was deemed best post of 2012 by Science Seeker.
Our Body the Ecosystem, published in Popular Science, was included in the 2012 Best American Science and Nature Writing anthology.
Keywords: Mice Inherit the Fears of Their Fathers