Songbird genome may shed light on speech disorders

Scientists have cracked the genetic code of a songbird for the first time, identifying more than 800 genes linked to song learning in a finding that may shed light on human speech disorders.

Baby zebra finches learn to sing in virtually the same way as human babies learn to speak - by copying their elders - which means the tiny bird should serve as a valuable model for understanding human learning and memory.

"Song learning is an excellent paradigm for all types of learning," said Chris Ponting, a professor with the Medical Research Council Functional Genomics Unit at University of Oxford, who was involved in the research.

"There are experiments that can be done that immediately provide information as to what changes occur in neurons (brain cells) upon the learning of a song. The zebra finch genome provides a tool that allows this exploration," he told Reuters.

The Australian zebra finch, which weighs less than half an ounce (14 grams), is only the second bird to have its genome sequenced, after the chicken in 2004.

Baby finches, like human infants, start off by "babbling" before the young males learn to imitate their father's song and eventually pass it on to the next generation.

As they learn in such a predictable way and many of their genes are also found in humans, finches could provide a window onto the origins of speech disorders, such as autism, strokes, stuttering and Parkinson's disease.

It gives the zebra finch genome a "unique relevance to human neuroscience", a team of international scientists led by Wes Warren of Washington University's Genome Center reported in the journal Nature on Wednesday.

Still, untangling the vast web of genetic and molecular factors involved in learning will not be easy.

Experts previously thought there might be around 100 genes involved in zebra finch singing, however, the fact that at least 800 genes exist underlines the sheer complexity of learning.

Significantly, many of the genes activated by bird song do not act like genes in the usual way as code for making proteins. Instead, they belong to the non-coding part of the genome, or what used to be known as "junk DNA".

The analysis of the zebra finch genome adds to growing evidence that these stretches of DNA are not junk, but actually serve a key biological function.

They may have two birds in the bag, but scientists still want to learn more about these feathered descendants of the dinosaurs. Next up is the parrot genome, which researchers hope to complete by the end of this year.

SOURCE: Nature, April 1, 2010.