April 12, 2010

Songbird Genome Yields Insight Into Vocal Communication

Photo of a zebra finch Researchers have sequenced the genome of the zebra finch. L. Brian Stauffer, University of Illinois News Bureau

Researchers have identified more than 800 genes that appear to play a role in the male zebra finch's ability to learn elaborate songs from his father. A better understanding of the songbird's communication may lead to insights into human communication.

Only a few animals are known to communicate through learned vocalizations. The male zebra finch (Taeniopygia guttata) learns complex songs from his father, making the species a valuable model for studying human speech, communication and neurological disorders. At first, a fledgling finch makes seemingly random sounds, much like the babble of human babies. With practice, the young bird eventually learns to imitate his father's song. Once the bird has mastered the family song, he will sing it for the rest of his life and pass it on to the next generation. This ability to communicate through learned vocalization is lacking in female zebra finches and in chickens, the only other bird thus far to have its genome sequenced.

The zebra finch genome sequence and analysis was published in the April 1, 2010, issue of Nature. The research consortium responsible was funded in part by NIH's National Human Genome Research Institute (NHGRI) and led by Dr. Richard K. Wilson, director of the Genome Center at Washington University School of Medicine in St. Louis.

The researchers found that the chicken and zebra finch genomes are similar in many ways. Both have about 1 billion DNA base pairs—roughly one-third the size of the human genome. However, the analysis suggested 214 candidate genes that may be involved in the evolution of the zebra finch’s unique vocal behavior. Of these, 49 are suppressed, or turned off, in response to song. A disproportionately high number in this group are ion channel genes. Ion channels allow the movement of ions (electrically charged particles) across cell membranes. Human ion channels have been shown to play key roles in many aspects of behavior, neurological function and disease. The researchers suspect that the evolution of this group of genes in songbirds may be essential for learned vocalization.

The scientists also identified portions of the zebra finch genome crucial to regulating the activity of genes involved in song behavior. In particular, their analysis suggests that non-protein coding ribonucleic acids (ncRNAs), which have been proposed to contribute to the evolution of greater complexity in humans and other animals, may be a driving force behind learned vocal communication.

"By comparing the finch genome with the human genome, we should now be able to expand our understanding of learned vocalization in humans. Such information may help researchers who are striving to develop new ways to diagnose and treat communication disorders, such as stuttering and autism," says NHGRI Director Dr. Eric D. Green.

"Although scientists understand much about how songbirds acquire and modify their vocal patterns, the availability of the genome sequence will allow insight into the molecular underpinnings of this natural behavior," says Dr. Story Landis, director of NIH’s National Institute of Neurological Disorders and Stroke (NINDS), which also provided support for the study. "This could lead to better understanding of learning and memory, neural development and adaptation, and speech and hearing disorders."

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