Australian researchers have successfully identified the genetic origin of the deadly cancer wreaking havoc among the Tasmanian devils. The discovery raises hopes over the preservation of the fast vanishing breed.
The Tasmanian Devil (Sarcophilus harrisii
) is a carnivorous marsupial now found in the wild only in the Australian island state of Tasmania. The Tasmanian Devil is the only extant member of the genus Sarcophilus
. The size of a small dog, but stocky and muscular, the Tasmanian Devil is now the largest carnivorous marsupial in the world after the extinction of the Thylacine in 1936. It is characterized by its black fur, pungent odour when stressed, extremely loud and disturbing screech, and ferocity when feeding.
The Tasmanian Devil was extirpated on the Australian mainland at least 3000 years ago, well before European settlement in 1788. Because they were seen as a threat to livestock in Tasmania, devils were hunted until 1941, when they became officially protected. Since the late 1990s, devil facial tumour disease has reduced the devil population significantly and now threatens the survival of the species, which in May 2009 was declared to be endangered. Programs are currently being undertaken by the Tasmanian government to reduce the impact of the disease.
Australian National University scientists said they have unlocked the genetic "fingerprint" of the contagious cancer which starves the dark, furry marsupial to death by disfiguring its face so badly it cannot eat.
"It's a uniquely horrible cancer, and it is critical to know about it at the genetic level," Professor Jenny Graves said.
"It has wiped out around 60 percent of the world's devils and is likely to lead to their extinction in the wild within 30 to 50 years."
The scientists made the discovery by comparing the genes active in both healthy and sick Tasmanian devils, an animal now found only on the southern Australian island from which it derives its name.
They found that the origin of the cancer was a tumour of a type of cell that normally wraps itself around nerves to insulate them.
The development offers hope that the disease, which causes a painful death, can be more easily identified at earlier stages.
"We realised the tumour profile was fairly unusual and included genes that made some strange proteins," Graves said.
"The good news is that one of the active proteins is easy to detect and it will give us the chance to diagnose the cancer early, which is important for setting up cancer-free 'insurance populations'.
"It also allows us to study the way the cancer changes over a long period, which potentially offers new insights for all cancer research."
The finding reveals that the tumour arose from one cell in one animal probably less than 20 years ago but has been spread throughout the Tasmanian devil population by biting.