Sydney

Opossum and Paul Samollow: working well together. Credit: N. GOUIN

The humble opossum is set to become the first marsupial to have its genome sequenced — disappointing Australian researchers who want to study the kangaroo.

But the US National Human Genome Research Institute (NHGRI) in Bethesda, Maryland, which will lead the opossum effort, says that if the Australians raise the money to do half of the kangaroo sequence, it will complete the other half.

The South American grey short-tailed opossum (Monodelphis domestica), whose genome is roughly the same size as that of humans, joined the NHGRI's list of high-priority organisms on 14 October. “We expect sequencing to be under way within a year,” says Francis Collins, director of the institute. The tammar wallaby (Macropus eugenii), a small kangaroo species, is ranked as a moderate priority.

Geneticists want a marsupial genome sequence so that they can carry out comparative studies to identify new genes and investigate chromosome evolution. “Mice are too close to humans, and chickens are too far away for comparative genomics — marsupials are just right,” says Jenny Graves, a geneticist at the Australian National University in Canberra.

“The tammar wallaby is a better choice because so much more is known about it in terms of physiology and genetics,” says Graves. But she adds that she is excited about the possibility of funding for the kangaroo initiative, “as that means we could mount a big genomic enterprise in Australia. It would be a sad state of affairs if we couldn't even sequence our own national emblem.”

The choice came down chiefly to the ease of working with opossums, researchers say. “There's no comparison — the opossum is much smaller, breeds prolifically and is easy and cheap to keep,” says Paul Samollow, an evolutionary geneticist at the Southwest Foundation for Biomedical Research in San Antonio, Texas, which houses the oldest and largest opossum colony in captivity.

The US kangaroo offer depends upon Australia agreeing to do half of the sequence. An Australian centre for kangaroo genomics was set up in July with a government grant of A$3.3 million (US$2.3 million) over five years. But it won't have either the infrastructure or the funding to do the sequencing, which would have to take place at the government-supported Australian Genome Research Facility (AGRF).

“We'll need to raise close to A$6 million,” says Susan Forrest, director of the AGRF. While hoping for government support, she is also preparing to pass the hat around potential sponsors, including the airline Qantas, whose emblem is a kangaroo.