Songbird genome gives insight into memory and speech

The stocky little Australian zebra finch, Taeniopygia guttata, which has just had its genome sequenced, has one key feature in common with humans: it learns how to vocalise by listening to the vocalisations of others.

By exploring the genome of the zebra finch, researchers are hoping to find insights into this process, both in birds and in humans.

An international consortium of scientists collaborated to sequence the genome of the zebra finch - only the second bird to have its genome sequenced, the other being the chicken - which was published in the journal Nature today.

The researchers identified more than 800 genes that appear to play a role in the male zebra finch's ability to learn elaborate songs from its father, although these genes contained a surprise.

Instead of being garden variety protein-coding genes, these genes coded for non-coding RNA that activated complex gene regulation networks in the brain.

Thus it may be that the gene regulation is the key to learning rather than just genes themselves.

For example, the researchers found a disproportionately high number of ion channel genes among the 49 genes in the finch genome that are suppressed, or turned off, in response to song.

Ion channels allow the movement of ions across cell membranes. Human ion channel genes have been shown to play key roles in many aspects of behavior, neurological function and disease. Consequently, the researchers suspect that the evolution of this group of genes in songbirds may be essential for learned vocalisation.

Teams across the USA, Europe and the Middle East, including seven UK-based research groups, have contributed to this substantial project, which includes funding from the National Human Genome Research Institute in the US and Biotechnology and Biological Sciences Research Council in the UK.

The zebra finch genome also revealed some interesting facts about the evolution of the bird.

As expected, the finch genome shares certain characteristics with that of the chicken. But a comparison of the two also reveals some striking differences.

Some families of genes have expanded in the zebra finch, for example, and individual chromosome rearrangements have occurred since the two lineages diverged about 100 million years ago.

"One of our key findings was the genetic basis of a lot of the variation between chickens and zebra finches," said Professor Darren Griffin, an author on the paper from the University of Kent.

"Clearly the two birds are very different but the evidence we had before suggested their genomes were actually very similar. In fact, we now have a clear idea of why this is not the case.

"The chicken was a great start for genomic studies because of the agricultural and embryology angle. In evolution chickens are a bit out on a limb and the zebra finch is a much better representative of the majority of birds."

It's also expected the genome will give some insights into immunity.

"Having the chicken genome sequenced helped to inform us about the zebra finch but it also worked both ways, with the zebra finch genome telling us more about the chicken," said Professor Dave Burt, an author on the paper from The Roslin Institute.

"At The Roslin Institute we were able to use this link to discover a gene previously thought to be missing in birds, the Colony Stimulating Factor 1 protein (CSF1). This gene is found in mammals and is important in fighting infections, and was identified in the zebra finch and with a bit of detective work we then discovered it in the chicken. This will then help us develop new ways of producing vaccines to prevent disease in birds."