They may not be as cute as koala, as iconic as kangaroos, or as just-plain-weird as the platypus but Australia would still be a poorer place without the Tasmanian Devil. Sadly the devil is headed for extinction within five years, decimated by a deadly, infectious facial tumour (The Age, ABC, AAP, Tasmania’s Mercury). Research has now uncovered why the animals have no immune response at all to the tumours – genetic diversity in a key set of genes is so low that the devils’ immune systems do not recognise the tumours as foreign.
The research, published online in PNAS, shows that the tumours are actually clonal cell lines – a tissue graft being passed from one animal to another when they bite each other in fights or during mating (abstract, pdf). “We found that the Devils do not mount an immune response against the tumour,” says author Katherine Belov from Sydney University’s School of Veterinary Science (press release).
“This was due to a loss of genetic diversity in the most important immune gene region of the genome: the Major Histocompatibility Complex (MHC). Matching of MHC genes is the key to successful tissue or organ transplants. In the case of the devil, genetic diversity at MHC genes is so low, and the MHC type of the tumour and host are so alike, that the host does not see the tumour as ‘non-self’.”
On the plus side isolated populations of devils might have different MHC genes, and be able to fight the tumour (Mercury). The finding might help stop the spread of the disease, but it’s bad news for those already infected. “Essentially, there are no natural barriers to the spread of the disease, so affected individuals must be removed from populations to stop disease transmission,” said Belov (press release).
The Sidney Morning Herald last month noted that a set of healthy animals has been sent to zoos and sanctuaries on the mainland under the auspices of the imaginatively titled ‘Project Ark’. The UK’s Independent has picked up on this and provides a remarkable example of how similarly journalists think noting: “Less cuddly than the koala, less quirky than the kangaroo, the Tasmanian devil is not everyone’s cup of tea.” But you’ll miss them when they’re gone…
See also: Nature’s feature from last year.