Experts race to save Tasmanian devil
Chicago - Scientists are using high-tech gene sequencing machines in a desperate attempt to save the Tasmanian devil from an infectious cancer called devil facial tumour disease that is threatening to wipe out the species.
"The disease is like nothing we know in humans or in virtually any other animal. It acts like a virus but it actually is spread by a whole cancerous cell that arose in one individual several decades ago," Penn State University's Stephan Schuster, who is working on the project, said in a statement.
The cancer, first observed just 15 years ago, is quickly spreading among populations of the already endangered Tasmanian devil, the world's largest surviving carnivorous marsupial that lives on the Australian island state of Tasmania.
Devil facial tumour disease disfigures the victim and causes death from starvation or suffocation.
"It has 90% to 100% lethality in a few months. In many regions of Tasmania, it is completely lethal," said Schuster, who worked on the study published in the journal Proceedings of the National Academy of Sciences.
Conservation experts have been isolating and breeding a population of healthy animals and plan to release them in the wild once the cancer runs its course.
To help select the best animals for the effort, a team led by Schuster and Webb Miller of Penn State and Vanessa Hayes of the Venter Institute in San Diego sequenced two Tasmanian devils, Cedric and Spirit, from the extreme northwest and southeast regions of Tasmania, respectively, to determine the genetic diversity of the animals.
Then they compared the range of genetic diversity to that of humans, the most studied species on the planet.
"In the case of the Tasmanian devil, those two only have 20% of the genetic diversity that living humans have," Schuster said in a telephone interview.
The study is one of the first to use whole genome sequencing as a tool to conserve an endangered population, Schuster said.
Whole genome sequencing technology allows researchers to read all the little bits of code - the A, C, T, G sequences - that are the building blocks of DNA.
It took 10 years and $3bn for the international Human Genome Project to get the first draft of the human genome a decade ago.
The scans now cost $10 000 to $20 000 each, but companies such as Illumina, Life Technologies Corp, Pacific Biosciences and Roche Holding are working hard to bring the cost down even more.
Schuster's scan of the two Tasmanian devils showed the population already had low genetic diversity, which likely made them vulnerable to the infectious cancer, which is spread by skin-to-skin contact.
"Transmission is through biting, fighting and mating," he said, and the disease has the potential of "burning through the entire population within a decade".
Using the genetic code from the two animals, the team devised a test that could look for specific genetic differences within the species to find the most genetically diverse animals for the breeding programme.
"It costs $150 per animal, whereas the sequence of the complete genome is in the $10 000 range," Schuster said.
The team used a new gene sequencing platform from Roche Holding AG, which helped pay for the research.
Schuster said the findings show that whole genome sequencing can be a useful tool in conservation. He said future studies are planned in cattle and other domestic animals.