Very interesting article, Ray. Thank you. It raises so many profound questions, for me, ranging from the human relationship to other species, to the apparently automatic thought that humans have a right to alter the "natural" evolution of other species, the the value to humans of doing so, to initiatives taken by a few individuals without seeking consensus on the moral and perhaps existential implications for the rest of humans, to the notion of emergent primary allegiance, multi-species sub-unit systems.
Again, thanks. Lawry On Jan 22, 2013, at 12:24 AM, Ray Harrell wrote: > REH > Raising Devils in Seclusion > By CARL ZIMMER > Published: January 21, 2013 > > In November, a team of biologists journeyed to Maria Island, three miles off > the Australian island state of Tasmania, taking with them 15 plastic > cylinders. They loaded the cylinders into S.U.V.’s, drove them to an > abandoned farm and scattered them in the fields. > <image001.jpg> > A young disease-free devil emerged from a tube to its new home on Maria > Island. > <image002.jpg> > <image003.jpg> > Before long 15 Tasmanian devils emerged from the containers, becoming the > first ever to inhabit the island. > > “All indications are that they’re doing very well,” Phil Wise, a government > wildlife biologist who leads the project, said of the devils — > fierce-looking, doglike marsupials that have become an endangered species on > the much larger island for which they are named. > > This spring the team plans to take more devils to Maria (pronounced > ma-RYE-uh). The goal is to establish a healthy colony that will endure for > decades to come. The stakes of the project are high: the survival of the > entire species may depend on it. > > Many species are threatened with extinction, but the Tasmanian devil faces a > singular enemy: an epidemic of cancer. A type of facial tumor has in effect > evolved into a parasite, with the ability to spread quickly from one devil to > another, killing its victims in a few months. > > “We have very little time to save the species,” saidKatherine Belov, a > biologist at the University of Sydney. > > An international network of biologists has spent the past decade figuring out > this new kind of disease. “It’s been quite a struggle just to learn some of > the basics,” said Elizabeth Murchison, of the University of Cambridge in > England. > > But recently Dr. Murchison and other experts have gained important insights > into how the cancer evolved into a parasite. Some scientists are now trying > to translate that knowledge into a treatment, perhaps a cancer vaccine. > > There is no guarantee that these projects will save the devils, so Mr. Wise > and his colleagues are setting up a drastic Plan B: they are establishing > Maria Island as a cancer-free refuge for wild Tasmanian devils. > > Then, if the devils die out in Tasmania, Dr. Belov said, “the disease will be > gone from the mainland, and then they can be introduced back in the wild.” > > Biologists first encountered the cancer in the late 1990s. The tumors grew on > the devils’ faces or inside their mouths, and within six months the animals > were dead. The first cases appeared in eastern Tasmania, and with each > passing year the cancer’s range expanded westward. > > When scientists examined the cells in the tumors, they got a baffling > surprise. The DNA from each tumor did not match the Tasmanian devil on which > it grew. Instead, it matched the tumors on other devils. That meant that the > cancer was contagious, spreading from one animal to another. > > There are only a few reports of humans developing cancer from other people’s > tumors hidden in transplanted skin or other organs. Only one other example of > contagious cancer is known from the natural world, a benign tumor in dogs. > > Dr. Murchison led a team of researchers who sequenced the entire genome of > two tumor cells. They published the sequences last February, and since then > they have launched a project to sequence hundreds more genomes of Tasmanian > devil facial tumors. > > Their studies and others like them are revealing how the Tasmanian cancer got > its start. It probably originated in the 1980s or early 1990s in a single > animal, most likely a female. A nerve cell in her face underwent a drastic > mutation: its chromosomes shattered and then stitched themselves back > together. > > “The cell was still able to function, because there wasn’t too much DNA > lost,” Dr. Belov said. “It’s a bit of a freak of nature.” > > The cancer then spread to other devils by taking advantage of their behavior. > The animals frequently fight, biting their opponents’ faces. During these > battles, Tasmanian devils sometimes bite off bits of a tumor. The cells slip > into the attacker’s own bloodstream and travel to its face. There they grow a > new tumor. > > Dr. Murchison and her colleagues have identified some 20,000 mutations in the > tumors that are not found in normal Tasmanian devil DNA. But they do not know > which of those mutations originally gave rise to the cancer. > > Recent research is revealing that the cancer has been evolving. “Up until a > year ago we thought the tumor was completely stable,” Dr. Belov said. “But > now we know that’s not the case.” > > She and her colleagues recently examined cancer cells collected from > Tasmanian devils in 2007 and 2008, comparing them with cells collected from > 2010 to 2012. They surveyed molecular caps that cover some genes, known as > methylation marks. These marks can keep genes from producing proteins. > > (Page 2 of 2) > > In the Jan. 7 issue of Proceedings of the Royal Society B, Dr. Belov and her > colleagues reported that recent cancers have fewer methylation marks than > older ones, suggesting that the cancer cells are unmuzzling genes and using > their proteins to spread more efficiently. The cancer, she and her colleagues > wrote, “should not be treated as a static entity, but rather as an evolving > parasite.” > > Until recently, most scientists believed Tasmanian devils were uniquely > vulnerable to contagious cancers. They have very little genetic diversity, > and so they might not be able to recognize a tumor as foreign. > > But if that were the case, their immune systems would not reject tissue from > other devils. In fact, however, when devils were given skin grafts, “they > all rejected really nicely,” said Alexandre Kreiss, a research fellow at the > Menzies Research Institute in Tasmania. “So we knew then there was something > else to the tumor.” > > Instead, it turns out, the cancer cells camouflage themselves. They have > stopped making a molecular identity badge that mammal cells normally produce. > > All of the scientists studying the tumors know that they cannot afford to > dawdle. The cancer has already wiped out 84 percent of the Tasmanian devil > population and shows little sign of slowing. “You feel that the clock is > always ticking,” Dr. Murchison said. > > But she sees some reasons for hope. In the far northwest corner of Tasmania, > for example, a population of devils shows signs of resisting the cancer. > Some of the animals appear to have destroyed their tumors. As a result, only > about 20 percent of the devils there have died. > > If the devils do not escape the cancer on their own, scientists may be able > to help them. “I think the potential for a vaccine is pretty good if we can > understand what is going on there,” Dr. Murchison said. > > But Dr. Kreiss warns that with 35,000 devils left in the wild, no vaccine can > be a panacea. “Even if we had a perfect vaccine, we’d probably have to > vaccinate every animal more than once,” he said. “I don’t see us doing that > for the whole population.” > > In case no medicine works, the federal and Tasmanian governments are > quarantining a so-called “insurance population” of devils. The program now > has 500 cancer-free Tasmanian devils in zoos and sanctuaries. It is to ensure > they do not become too tame to survive on their own that Mr. Wise and his > colleagues are establishing the wild population on Maria Island. > > While Tasmanian devils are the first species known to be threatened by a > contagious cancer, they may not be the last. “It’s quite likely that there > are more out there that haven’t been identified,” Dr. Murchison said. “It > might have led to the extinction of other species.” > > > > > > > _______________________________________________ > Futurework mailing list > [email protected] > https://lists.uwaterloo.ca/mailman/listinfo/futurework
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