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Aussie scientists sequence koala genome

Iconic genome The koala genome has been sequenced by two teams of Australian scientists.

The work by scientists from the Australian Museum and Queensland University of Technology could help researchers understand the biology of this iconic animal and develop treatments for devastating diseases such as chlamydia and koala retrovirus.

"We have sequenced the genome 100 times over, what's not complete is that we haven't put those pieces together yet," says Dr Rebecca Johnson from the Australian Museum's Australian Centre for Wildlife Genomics.

Using samples taken from a male and female koala, the teams have now identified 12,000 genes, and there could be more, Johnson says.

"We are working towards what we think is the complete set of 20,000, which is roughly equivalent to humans," she says.

Johnson says the genetic blueprint provides important insights into the evolution of koalas.

"The koala is so interesting because they haven't had a common ancestor for 35 million years so now we can look at … why have they been so successful."

It also has important implications for managing koala populations now and in the future, she says.

"This genome sequencing has revealed a massive number of genetic markers that enable us to make a really accurate assessment on population diversity ... or other indicators in a population that's potentially vulnerable," Johnson says.

So far the teams have identified genes that are implicated in their diet as well as immune systems, including the koala interferon gamma (IFN-g) gene.

The koala interferon gamma gene is a chemical messenger that plays a key role in the marsupials defence against cancer, viruses and intracellular bacteria.

Vaccine development

Until now, very little was known about the koala's immune system, says Professor Peter Timms from Queensland University of Technology's Institute of Health and Biomedical Innovation whose team is developing a vaccine to prevent the spread of chlamydia.

"We know that koalas are infected with various strains of chlamydia, but we do not know why some animals go on to get severe clinical disease and some do not," says Timms.

This gene discovery means it will now be possible to fully test the effectiveness of vaccines on wild populations of koalas, Timms says.

"We've been working for a whole year to get the sequence of that one gene so we can work it into an assay [for a vaccine] but we haven't been able to get it because it's different to the other animals we've been working with.

"So by having the genome sequence we've now got that gene.

"It means that we probably can make a vaccine that will be effective," says Timms.

The group plan to publish details of the genome in the next three to six months.

Australian and international experts will now be invited to participate in a larger new koala genome consortium which will supplement existing national and international koala research programs.

Timms draws a comparison between the work of the koala genome consortium and that of the human genome project.

"The human genome was sequenced a while ago, but people are still working on it and putting it together and still doing comparisons between individuals.

"It's never ending, but the first stage has been achieved."