Another feather in cap for genome researchers

The chicken has joined humans, chimps, rats and mice as the latest animal to have its genetic code laid bare. Made up of around one billion DNA base-pairs (chemical 'letters'), the chicken genome is a third the size of our own. Researchers at the US National Human Genome Research Institute (NHGRI) have unveiled the first draft of the red jungle fowl (Gallus gallus), the first bird species to have its DNA completely sequenced.

The entire chicken genome DNA sequence is now available to medical and agricultural researchers via the public GenBank database. Comparing human genes to those of other species is an invaluable tool for scientists trying to work out what human genes do. And since birds stand between fish and mammals in the evolutionary timeline, the chicken genome sequence will also help researchers identify sections of DNA that are not genes.

The chicken is widely used in biomedical research, especially in embryology and developmental biology - mainly because it is relatively easy to study chick embryos at any stage of development, compared to mammals. Commenting on the genome sequence, Dave Burt of the Roslin Institute in Scotland said: 'The project will bring together all the biological knowledge about the chicken'.

As well as the red jungle fowl, thought to be the ancestor of all breeds of domestic chickens, researchers at the Beijing Genomics Institute in China have identified genetic variations in three different strains of domestic chicken. Recent outbreaks of avian flu have triggered increased interest in the chicken genome, and in how genetic variation may play a role in susceptibility to different strains of the disease.

Meanwhile, US researchers have lined up the next set of creatures to have their genomes sequenced, Nature News reports. They include four fungi, three roundworms, a beetle, and an opossum. The grey short-tailed South American opossum will be the first marsupial to have its genetic code sequenced, which is of interest because marsupials and humans last shared a common ancestor around 130 million years ago - around 55 million years before mice, but 200 million years after birds. 'The opossum evolved at an interesting point in the evolutionary time-line' says Tim Hubbard of the UK Sanger Centre in Cambridge. Opossums are also the only non-human species known to develop melanoma, after exposure to UV radiation alone, so decoding the opossum's genome may help researchers develop new treatments for this form of skin cancer.