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December 01, 2013

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DNA “markings” may transmit learned experiences

Dec. 1, 2013
Courtesy of Nature Neuroscience
and World Science staff

Learn­ed ex­pe­ri­ences can be trans­ferred through ge­net­ic struc­tures—not by changes to genes them­selves, but rath­er, to how they’re “marked” by oth­er mole­cules, a study re­ports.

Such “mark­ings” are called epige­net­ic changes. Sci­en­tists in re­cent years have in­creas­ingly rec­og­nized them as play­ing im­por­tant roles in bi­o­log­i­cal in­her­it­ance.

The find­ing that learn­ed ex­pe­ri­ences may be trans­ferred this way is part of a re­cent wave of re­search over­turn­ing what bi­ol­o­gists used to as­sume—that only in­forma­t­ion in the DNA it­self is passed across genera­t­ions.

The stu­dy, pub­lished on­line Dec. 1 in the re­search jour­nal Na­ture Neu­ro­sci­ence, ar­gues that mice bi­o­log­ic­ally in­her­it in­forma­t­ion learn­ed by their grand­fa­thers.

Genes can be turned on or off semi-permanently with mo­lec­u­lar changes to the DNA, known as epige­net­ic marks. Some of these changes are main­tained across genera­t­ions, oth­ers aren’t. Through epige­net­ic changes, past stud­ies have linked trau­mat­ic or stress­ful ex­pe­ri­ences in an­i­mals to ef­fects on lat­er genera­t­ions’ emo­tion­al be­hav­iors.

In the new work, Bri­an Di­as and Ker­ry Ressler of the Em­o­ry Uni­vers­ity School of Med­i­cine in At­lan­ta, Ga. found that spe­cif­ic learn­ed in­forma­t­ion can al­so be trans­mit­ted through epige­net­ic changes in sperm.

The re­search­ers trained mice to fear a cher­ry blos­som-like smell and then let these mice mate and con­ceive off­spring. These off­spring showed more fear­ful re­sponses to whiffs of cher­ry blos­som than to a neu­tral scent de­spite nev­er hav­ing en­coun­tered the smells be­fore, the sci­en­tists said.

More­o­ver, they added, the next genera­t­ion of off­spring showed the same be­hav­ior. This fear re­sponse was passed to off­spring even if they were con­ceived with ar­ti­fi­cial in­semina­t­ion us­ing sperm, ac­cord­ing to the re­search­ers.

They al­so found that both in the trained mice and their off­spring, the fear re­sponse was as­so­ci­at­ed with changes to brain re­gions used to de­tect the feared scent, and with epige­net­ic marks in the sperm on the gene re­spon­si­ble for de­tecting the smell.


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Learned experiences can be transferred genetically—not by changes to genes themselves, but rather, to how they’re “marked” by other molecules, a study reports. Such “markings” are called epigenetic changes. Scientists in recent years have increasingly recognized them as playing important roles in biological inheritance. The finding that learned experiences may be transferred this way is part of a recent wave of research overturning what biologists used to assume—that only information in the DNA itself was passed across generations. The study, published online Dec. 1 in the research journal Nature Neuroscience, argues that mice biologically inherit information learned by their grandfathers. Genes can be turned on or off semi-permanently with molecular changes to the DNA, known as epigenetic marks. Some of these changes are maintained across generations, others aren’t. Through epigenetic changes, past studies have linked traumatic or stressful experiences in animals to effects on later generations’ emotional behaviors. In the new work, Brian Dias and Kerry Ressler of the Emory University School of Medicine in Atlanta, Ga. found that specific learned information can also be transmitted through epigenetic changes in sperm. The researchers trained mice to fear a cherry blossom-like smell and then let these mice mate and conceive offspring. These offspring exhibited more fearful responses to whiffs of cherry blossom than to a neutral odor despite never having encountered the smells before, the scientists said. Moreover, they added, the next generation of offspring showed the same behavior. This fear response was transmitted to offspring even if they were conceived with artificial insemination using sperm, according to the researchers. They also found that both in the trained mice and their offspring, the fear response was associated with changes to brain regions used to detect the feared scent, and with epigenetic marks in the sperm on the gene responsible for detecting the smell.