Read The Tasmanian Devil, Australia's only carnivorous marsupial, may yet be saved from extinction. The already endangered animals have been threatened for some years by an infectious cancer, which is most likely transmitted by the saliva of the animals. However, Australian researchers led by Kathy Belov of the University of Sidney, in northwestern Tasmania, have discovered some specimens that are genetically different from the rest of the populations and may be resistant to the deadly disease. Once strongly persecuted by humans, the Tasmanian devil is today under protection. For some years, however, he has been decimated by the infectious disease "Devil Facial Tumor Disease" (DFTD), a type of facial cancer. Since the cancer was first diagnosed in 1996, it has killed 70 percent of the Tasmanian devils. Due to a genetic peculiarity, the devil's immune system does not recognize the tumor cells as degenerate. Once infected, the disease is fatal to the marsupial: The animals die of organ failure, infection or starvation because the tumors on the face make feeding impossible. DFTD is most likely transmitted through bites, which are not uncommon among the devils in the battle for carrion or mating.
The researchers analyzed genetic material from 387 Tasmanian devils from across Tasmania. They found that some animals from the northwestern part of Tasmania with respect to one gene group are very different from the rest of the population: The gene group MHC is responsible for the production of certain proteins that characterize a cell as the body's own. In the case of cancer, however, the tumor cells have very similar gene groups, which is why the identification of the degenerate cells and thus their control fails.
The now discovered devils have a very different version of the gene group, as the researchers found. "We therefore assume that this devil's immune system recognizes and responds to cancer cells, " says Belov. But this is not yet certain, as the spread of the disease has just reached the northwestern part of the island. If the devils from the Northwestern population are actually resistant to the cancer, isolation of the animals would be necessary so that they would not be endangered by mixing with other populations in their resistance, the researchers say.
Kathy Belov (University of Sidney) et al .: Proceedings of the Royal Society B, doi: 10.1098 / rspb.2009.2362 ddp / science.de? Thomas Neuenschwander advertisement