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DNA "markings" may transmit learned experiences


Learn­ed ex­pe­ri­ences can be trans­ferred through ge­net­ic struc­tures-not by changes to genes them­selves, but rath­er, to how they are “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 behaviours.


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 behaviour. 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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Source : http://www.world-science.net/exclusives/130114_fairness.htm

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