( A discovery that may someday help to ex...)Rodent social behavior encoded in junk DNA

The researchers traced social behavior traits, such as monogamy, to seeming glitches in DNA that determines when and where a gene turns on. The length of these repeating sequences ?once dismissed as mere junk DNA ?in the gene that codes for a key hormone receptor determined male-female relations and parenting behaviors in a species of voles. Drs. Larry Young and Elizabeth Hammock, Emory University, report on their findings in the mouse-like animals native to the American Midwest in the June 10, 2005 Science.

The discovery is the latest in a two decades-old scientific quest for the neural basis of familial behavior begun at the NIMH Intramural Research Program in the mid l980s by now NIMH director Thomas Insel, M.D. By l993, his team had discovered that the distribution of brain receptors that bind to the hormone vasopressin differed dramatically between monogamous and polygamous vole species and accounted for their divergent lifestyles. Yet, how such behavioral differences could have evolved in animals that otherwise appear almost identical remained a mystery.

"This research appears to have found one of those hotspots in the genome where small differences can have large functional impact," explained Insel. "The Emory researchers found individual differences not in a protein-coding region, but in an area that determines a gene's expression in the brain. This is an extraordinary example of research linking gene variation to brain receptors to behavior."

Hammock and Young were particularly intrigued with microsatellites, repeating sequences of letters in the genetic code peppered throughout these regulatory areas of the vasopressin r
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Source:NIH/National Institute of Mental Health