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Epigenetics: Possible reason mice are so timorous…

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Maybe their fears haunt them from generations past

Well, that’s the word from this Nature story:

Ressler and his colleague Brian Dias opted to study epigenetic inheritance in laboratory mice trained to fear the smell of acetophenone, a chemical the scent of which has been compared to those of cherries and almonds. He and Dias wafted the scent around a small chamber, while giving small electric shocks to male mice. The animals eventually learned to associate the scent with pain, shuddering in the presence of acetophenone even without a shock.

This reaction was passed on to their pups, Dias and Ressler report today in Nature Neuroscience1. Despite never having encountered acetophenone in their lives, the offspring exhibited increased sensitivity when introduced to its smell, shuddering more markedly in its presence compared with the descendants of mice that had been conditioned to be startled by a different smell or that had gone through no such conditioning. A third generation of mice — the ‘grandchildren’ — also inherited this reaction, as did mice conceived through in vitro fertilization with sperm from males sensitized to acetophenone. Similar experiments showed that the response can also be transmitted down from the mother.

These responses were paired with changes to the brain structures that process odours. The mice sensitized to acetophenone, as well as their descendants, had more neurons that produce a receptor protein known to detect the odour compared with control mice and their progeny. Structures that receive signals from the acetophenone-detecting neurons and send smell signals to other parts of the brain (such as those involved in processing fear) were also bigger.

Some researchers are incredulous because they say that a mechanism that would pass on the fear has not been identified. Clearly, that is the next step.

Note: This research may have market value. If we could just get rats to fear granaries and deer to fear highways at night …

So not necessarily primaeval. Axel
Or mice are born with an instinctual, spiritual inheritance, doubtless taking many forms; as are male and female human beings - mammals for that matter. Axel
What this shows is that a mouse's brain can directly rewrite portions of its own genome based on experience. The implications are mind boggling. Mapou
Oops the link again: Supplementary information selvaRajan
It is very interesting experiment though it needs to be checked by few other scientists. The methodology is flawless. They not only used cross fostering, they also used in-vetro fertilization. It is impossible that Methylation can produce the required protein for detecting the smell in F1 and F2 generation, but the bisulfite sequencing proves that smell did lead to hypomethylation of the relevant gene, so what the heck is the method by which the Pavlovian response was transfered to F1 and F2 gen? I think this is incredible.Though the article is not open access, the supplementary information is free, so the data can be checked. selvaRajan
Weren't all Darwinists completely against epigenetics at one time or another? What happened? A paradigm shift? Mapou

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