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NPR's "The Salt" column carries the grusome (but interesting) story of a medical mystery:
When researchers made their way to the highlands of Papua New Guinea in the 1950s, they found something disturbing. Among a tribe of about 11,000 people called the Fore, up to 200 people a year had been dying of an inexplicable illness. They called the disease kuru, which means "shivering" or "trembling."
Once symptoms set in, it was a swift demise. First, they'd have trouble walking, a sign that they were about to lose control over their limbs. They'd also lose control over their emotions, which is why people called it the "laughing death." Within a year, they couldn't get up off the floor, feed themselves or control their bodily functions.
Shirley Lindenbaum, a medical anthropologist with the City University of New York, who continues to write about the epidemic, knew it couldn't be genetic, because it affected women and children in the same social groups, but not in the same genetic groups. She also knew that it had started in villages in the north around the turn of the century, and then moved south over the decades.
...
Lindenbaum had a hunch about what was going on: In many villages, when a person died, they would be cooked and consumed. It was an act of love and grief. ... Women removed the brain, mixed it with ferns, and cooked it in tubes of bamboo. They fire-roasted and ate everything except the gall bladder. It was primarily adult women who did so, says Lindenbaum, because their bodies were thought to be capable of housing and taming the dangerous spirit that would accompany a dead body.Finally, after urging from researchers like Lindenbaum, biologists came around to the idea that the strange disease stemmed from eating dead people.
The story goes on to explain that the disease wasn't spread by a virus or a bacterium, fungus, or parasite. It could survive being boiled into soup, and had no DNA. It was a totally new infectious agent.
It was a twisted protein called "prions," or "proteinaceous infectious particles", that could cause normal proteins in nerve cells to twist just like them, and slowly over long periods of time kill areas of nerve cells in the brain.
The story goes on to cover the similarity to Mad Cow Disease, a species jumping disease also caused by prions, and Chronic Wasting Disease that is affecting mule deer, white-tailed deer, elk, and moose in 21 states.
The CDC is working with public health authorities in Wyoming and Colorado to monitor hunters for signs of prion disease.
If the Zika doesn't get us, the Kuru probably will.
(Score: 4, Insightful) by Immerman on Thursday September 08 2016, @12:10AM
I'm not sure I agree with your concept of passivity - far from your "bent paperclip" analogy, proteins are generally extremely sophisticated molecular machines already designed to manipulate other molecules. It would be more like tossing a Terminator into a warehouse full of protocol droids, and coming back to discover the robot apocalypse had begun.
As for it not being purposeful - what is your threshold on "purpose"? A virus is scarcely more "alive" or "purposeful" than an active protein - an inert shell that injects a complex molecule into a cell that causes the cell's replication machinery to build to different specs.
Even human consciousness emerges from a big sack of complexly interacting molecules. Did it arise spontaneously, or is it a more sophisticated expression of something that already exists in the components?
(Score: 2) by LoRdTAW on Thursday September 08 2016, @12:55PM
Yea, my paperclip analogy was meant to be as simple as possible.
Good point. The way I look at it, even though a virus is not alive, it is DNA based like every other infectious disease. It needs to propagate otherwise it can be wiped out by isolation and completely eliminated. That's just as purposeful as bacterial and cellular pathogens that reproduce. They arent spontaneously formed in an animal by its natural bodily function.
A prion on the other hand is a normal part of a bodily process that is malformed by accident. It's a biological screw up that is spontaneous. This malformed molecule then somehow influences other healthy protein molecules to also take the same messed up shape. It doesn't have to purposefully attack and inject anything and it doesn't reproduce. It's simply a spontaneous molecular mistake made inside of the animal which influences the same mistake on other healthy proteins which unfortunately kills it. That should be the end of the mistake but that mistake can propagate to other animals.
Here is evidence of the spontaneous theory: http://www.nature.com/news/2010/100726/full/news.2010.376.html [nature.com]
(Score: 3, Informative) by Immerman on Thursday September 08 2016, @07:53PM
Regardless of whether they occasionally arises spontaneously, it still must "attack and refold" victims to propagate, and propagating is the only thing that makes it dangerous. Probably most spontaneously misfolded proteins are relatively harmless, prions though represent a robot that has been reprogrammed for self-replication, and it performs its new function every bit as purposefully as it performed its original one, presumably killing the host due to the original function no longer being performed at adequate levels as an ever-growing percentage of proteins "rebel".
Prions may even represent a throwback to our early protolife ancestors - there are those that argue that protolife may have started as self-replicating proteins which only later incorporated DNA as they began began forming more sophisticated communities like protocells. If that's the case then it's less surprising that some proteins might retain limited self-replication abilities not normally expressed.
Even if it's nothing but a particularly dangerous "programming error" of a machine "designed" by a much more sophisticated DNA-based machine, I don't see that it's any less impressive. Our proteins have after all been evolving as long as we have, with designs refined and repurposed across billions of years. I imagine a certain level of protein versatility offers a dramatic long-term evolutionary advantage. And if not, well it's still a machine designed to rebuild molecules into other molecules...
And the fact that it can spread between organisms is hardly surprising - within a species of course, if you don't "kill" the protein it will replicate. And between species, well I'd say that's evidence that at a sub-cellular level we're still extremely similar -not surprising considering the radical slowdown in evolution that accompanied the leap to multicellular organisms. When generations are measured in days or years rather than hours, you just can't change as quickly. I mean we still share what, 30% of our DNA with yeast? I'll bet you good money that that mostly covers pretty heavily optimized sub-cellular machinery.
(Score: 2) by LoRdTAW on Thursday September 08 2016, @08:03PM
You put it very succinctly. Thanks.