Those poor devils

Tasmanian devils are notoriously nasty, even to each other. They have teeth and aren’t afraid to use them. As a result, they tend to bite and nip at the faces of their brethren. And unfortunately, this has resulted in the spread of a contagious form of cancer that has wiped out 70% of the population.

But there is good news. Researchers have discovered that the reason the tumors are able to spread so efficiently (escaping immune system detection) is that its cells lack major histocompatibility complex molecules, or MHC molecules. The Tasmanian devil’s immune system can’t ‘see’ what’s coming. This, of course, isn’t unique amongst cancer cells, but what is a little different is that these MHC molecules aren’t simply broken via mutation. They are actually turned off due to regulation. This means they are intact and can be turned back on. (It also means that, in conjunction with the contagious factor, it wouldn’t be inappropriate to consider this cancer a separate organism, however parasitic.)

There is hope for the Tasmanian devil, albeit far down the road. Until then, quarantine and luck are the only viable solutions for saving this animal from extinction.

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Never mind, Cedric

Turns out that, in addition to updates on this being surprisingly frequent, Cedric the Tasmanian devil is not immune to the cancer afflicting his population.

Two coin-sized tumours were cut out of his face and, although it is hoped he will make a full recovery, it casts doubt on much of the research work conducted over the past two years, the BBC’s Nick Bryant reports from Sydney.

Double update update: Actually, I was getting articles from a recent blog post which had out-of-date references. Cedric proved to be a dead-end close to a year ago.

Devil cancer update

The devastating cancer spreading through the Tasmanian devil population has so far met resistance in at least one devil (Cedric), and possibly in his brother (Clinky).

Both were injected with dead tumours by scientists. Clinky produced no antibodies, but Cedric did and appears to have built-in defences against the mystery illness.

The experiments have now moved up a gear.

Researcher Alex Kriess says the pair have had live cancer cells inserted into their faces.

“They haven’t developed a tumour so far,” he said. “We injected very few cells so it might take a while until they develop anything that we can see.”

The next step is to see why Cedric may be resistant to the disease, which Jerry Coyne has deemed “can be regarded as a separate organism, genetically free to undergo independent evolution.” (The syntax is correct, but for clarity, it’s the disease that can be regarded as a separate organism.)

The most interesting aspect of all this is that Cedric comes from the side of the island not yet especially devastated by the disease. As more research is done, it will be interesting to find out if there is any sort of special history with cancer, even this specific cancer, that Cedric’s part of the island has had. That could be one driving cause behind the genetic difference to consider in addition to simple drift or geographical barriers.

Image via Jerry Coyne

Devil Facial Tumour Disease

Devil Facial Tumour Disease (DFTD) is a particularly nasty tumor currently afflicting Tasmanian devils. It is responsible for the destruction of around 70% of the island population. One step, fortunately, has been made through the discovery of its specific cause.

The research collaboration, led by Australian scientists, has found that DFTD originates from cells called Schwann cells, which protect peripheral nerve fibres.

The results have been published in the journal Science.

Through the discovery, the team has now identified a genetic marker that could be used to accurately diagnose the perplexing cancer, which has seen the devil listed as endangered and facing extinction.

What happens is that these devils – so appropriately named – tear into each others’ faces because, well, that’s what they do. They’re about as nasty as the tumor itself. This then transmits the disease from one animal to the next. The research, in fact, has shown that the tumors all share the same characteristics, thus showing that it’s essentially the same faulty genes that are getting passed around, not new, individual tumors. Once the disease is passed, a massive tumor grows on the face of the unfortunate devil. If it doesn’t die directly from the cancer first, it starves from its inability to eat with a massive growth all over its face.

Associate Professor Greg Woods from the University of Tasmania’s Menzies Research Institute said the Schwann cell find was an important step in the process to further understand the disease.

“Devils develop tumours of all different types and the genetic markers we have identified are useful for telling apart the tumours that occur in DFTD from other kinds of tumours,” Associate Professor Woods said.

The propensity for devils to develop cancer so easily is distressing. They’re like the anti-naked mole rats. I would specifically be interested in learning about the quality of contact inhibition of the devils. My suspicion is that it simply sucks.