As published in Nature's advanced online edition yesterday, researchers from the Beijing Genomics Institute have successfully completed the sequencing and initial analyses of a draft version of the giant panda genome. One surprising discovery is that the Chinese bear lacks any recognizable genes required for digesting its staple food, bamboo. "The panda's bamboo diet may be dictated by its gut bacteria rather than by its own genetic composition," says Wang Jun, deputy director of the Beijing Genomics Institute in Shenzhen, Guangdong province, who led the sequencing project.

The researchers used the Genome Analyzer from Illumina to tackle the more than 2 billion base genome. Using a whole genome shotgun approach, the team sequenced paired-end libraries constructed from a three-year-old female panda named Jingjing - who just happened to also be the mascot of the 2008 Beijing Olympics. To verify their sequence assembly efforts, they also relied on Sanger sequencing of nine bacterial artificial chromosomes.

Overall, contigs generated so far contain 2.25 billion bases of DNA covering roughly 94 percent of the giant panda genome. The sequencing efforts revealed that pandas have about 21,000 genes residing on 21 pairs of chromosomes - including one pair of sex chromosomes. Although they were able to fill many small sequence gaps, the team noted, some remain - likely corresponding to repeats, including tandem repeats and carnivore-specific transposable elements.

This is the first member of the bear family to have its full genome sequenced and reported. Of all the mammals that have been sequenced, pandas seem most similar to dogs - with 80% similarity - and are only 68% similar to humans.

However, the bear's genome has undergone fewer genetic changes over time than those of dogs and humans, suggesting that it evolved more slowly. The panda is often regarded as a 'living fossil' because its ancestors are thought to have lived in China more than eight million years ago.

The study also shows pandas have a high degree of genetic diversity — about twice as much as humans. "This shows that the panda has a good chance of survival despite its small population size," says Wang.

Source: http://www.nature.com/news/2009/091213/full/news.2009.1141.html