The genome of the Australian zebra finch -- being published April 1 in Nature -- sets a framework that could provide insights into how humans learn language and new ways of studying speech disorders.
Researchers who collaborated on the finch genome found a much higher proportion of the bird's DNA is actively engaged by the act of singing songs.
"The system for singing has much more complexity than we imagined," said co-author Erich Jarvis, Ph.D., Duke professor of neurobiology and a Howard Hughes Medical Institute Investigator. "In the part of the brain that controls learning how to sing, about 5 percent of the genes are regulated by the action of singing. I thought there might be 100 genes, but our laboratory found that there are at least 800 regulated genes turning off and on, and there may be many more."
Jarvis was the first to discover that singing altered genetic activity in songbirds. "We were also able for the first time to use the genome sequence to infer the regulatory regions that turn genes on and off and the manner in which they may interact," he said.
The new work may help scientists understand how humans learn language. It also could help identify the genetic and molecular origins of speech disorders, including those related to autism, stroke, stuttering and Parkinson's Disease, the researchers say. The findings could also have an impact on research into deafness and language learning after the critical learning period.
"Overall, the genome will help researchers worldwide learn about the genes responsible for developing neural circuits for critical periods of learning, study the effect of hormones on brain and behavior, and provide further information for a model of sex-related brain differences," Jarvis said. "During juvenile development, the female song-learning brain regions and ability atrophy."
Among some songbird species, like the zebra finch, females select the best male based on the quality of his song. As babies, the males learn to sing by listening to their fathers. A good pupil will attract a mate and pass on successful vocal skills to the next generation.
Jarvis noted that sequencing additional genomes, like the parrot genome his lab is working on with the Warren laboratory, would contribute valuable information about spoken language.
The zebra finch is only the second bird to have its genome decoded. The first was the chicken. Unlike the chicken, which clucks but does not communicate by vocal learning, the zebra finch contains a specialized forebrain pathway to learn bird song.
In order to perform comparative analyses between these and other species, the Jarvis lab has developed a public bird genome web site called aviangenomes.org.
The study was funded by the National Human Genome Research Institute, part of the National Institutes of Health (NIH). Jarvis' contribution to the project was funded by the NIH Director's Pioneer Award, the National Institute of Deafness and Communication Disorders, and the Howard Hughes Medical Institute.
Other co-authors from Duke University include Osceola Whitney, Andreas Pfenning, and Jason Howard. More than 20 institutions worldwide collaborated on the zebra finch genome project. The organizing committee of the zebra finch genome sequencing project included Wes Warren of Washington University School of Medicine; David Clayton of the University of Illinois at Urbana-Champaign, Hans Ellegren of Uppsala University in Sweden; and Arthur P. Arnold of the University of California-Los Angeles.
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