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As if it weren't bad enough that deadly prions can survive boiling and radiation, now comes word that aerosolized forms of the pathogen can enter the nose and find their way to the brain, with fatal consequences.
Prions, you may recall, were the reason you avoided beef in Europe in the 1990s. They triggered the infamous mad cow disease epidemic in the U.K., which spread to the rest of Europe and other parts of the world.
In summary, our results establish aerosols as a surprisingly efficient modality of prion transmission. This novel pathway of prion transmission is not only conceptually relevant for the field of prion research, but also highlights a hitherto unappreciated risk factor for laboratory personnel and personnel of the meat processing industry. In the light of these findings, it may be appropriate to revise current prion-related biosafety guidelines and health standards in diagnostic and scientific laboratories being potentially confronted with prion infected materials. While we did not investigate whether production of prion aerosols in nature suffices to cause horizontal prion transmission, the finding of prions in biological fluids such as saliva, urine and blood suggests that it may be worth testing this possibility in future studies.
This previously unappreciated risk for airborne prion transmission may warrant re-thinking on prion biosafety guidelines in research and diagnostic laboratories.
Although aerial transmission is common for many bacteria and viruses, it has not been thoroughly investigated for prion aerosols ... Our results establish that aerosolized prion-containing brain homogenates that aerosols are efficacious prion vectors.
Incubation time and attack rate after exposure to prion aerosols depended primarily on the exposure time, the PrPC expression level of recipients and, to a lesser degree, the prion titer of the materials used to generate prion aerosols in a standardized inhalation chamber.
Originally posted by Violater1
Someone would have to be ...using a chain saw in order to aerosol the blood.
None the less, prions are probably the most deadly "organism" known to man.
Originally posted by TheWill
My greatest concern for this is that they'll start using it as a bio-weapon.
I wouldn't have even thought about that if the author hadn't said that this finding was particularly relevent to research into prions
Originally posted by soficrow
...I happen to think they are the primary agents of evolution...
Originally posted by tgidkp
Originally posted by soficrow
...I happen to think they are the primary agents of evolution...
sorry friend, but i am having a very difficult time imagining a scenario where, at this late stage of evolution, ...
i am having a very difficult time imagining ... prions can have anything but a destructive effect on living tissue.
your quote above literally stuns by brain into silence.
“We think that the fact that prions are sometimes beneficial and sometimes detrimental for the yeast is at the heart of their biology – that they present a sort of bet-hedging strategy, where in some circumstances it’s good to be in the prion state and in some cases it’s not,” says Whitehead Member and Howard Hughes Medical Institute Investigator Susan Lindquist.
...prions possess a hazardous status. Regardless of this depressing nature, a recent research describes certain essential positive responsibilities of prions in brain function. A persistent problem in the study of memory is how molecules in the brain can “remember” a memory for years, even a lifetime. How it is that our brain’s cells can permanently store information that we learn?
Researchers at the Stowers Institute of Medical Research reveals that prion like protein may participate in persistence of memory in eukaryotes. The research led by Kausik Si of Stowers Institute for Medical Research and Nobel laureate Eric Kandel suggest that prions may be the best solution to the problem. Prions marked the ability to assume two distinct conformational states – one is dominant and self perpetuating. Once a protein switches to prion state it has the ability to convert other non prion proteins to that state. Thus once engaged the prion state, it continues to be self-renewing and stable.
The study concludes that memory traces may depend on a fairly unique mechanism involving a prion-like protein known as CPEB. CPEB (cytoplasmic polyadenylation element binding protein) was involved in memory formation in the sea slug Aplysia.
Special proteins known as prions, which are perhaps best known as the agents of mad cow and other neurodegenerative diseases, can also serve as an important source of beneficial variation in nature. Whitehead Institute researchers have quintupled the number of identifiable prion proteins in yeast and have further clarified the role prions play in the inheritance of both beneficial and detrimental traits.
…Prions in cells are known to switch back and forth between a clumping, infectious stage and a non-infectious stage. When yeast is stressed, this switching occurs at a higher rate, which may give the yeast a better chance to adapt to challenging conditions.
Are there any beneficial prions? It is thinkable, and in fact there is an example of it. In yeast, a prion has been identified which in certain circumstances is beneficial, see for example Prions act as stepping stones in evolution. The remarkable thing is that the effect can be passed on to the offspring.
…when it misfolds into a prion conformation, Sup35 gets sloppy, and the cell reads beyond the stop codons, translating genetic information that previously had been dormant. As a result, the cell's phenotype changes.
And here's where evolution comes in.
On those rare occasions when, due to a particular environment, the altered properties of the cell provide it with a survival advantage, the cell passes that trait on to its progeny. But when the daughter cells are mated and genetic reassortment takes place, they can subsequently pass along this same trait without the prion. That is, the trait becomes fixed in the cell's lineage and no longer depends on the prion state. "We don't know yet exactly how the daughter cells do this, but they do it quickly, often after a single mating," said Lindquist.
The prion thus appears to function as an evolutionary stepping stone, affording the population of cells a chance to survive in a new environment where they need a different phenotype until they can acquire the genetic changes that produce the same effect.
These new traits are genetically complex. When Sup35 misfolds into a prion form, it affects a number of genes in one fell swoop.
"This prion has a capacity to hide and release genetic information throughout the entire genome that can contribute to new traits in a complex way," explained Lindquist.
nevertheless, obtaining a clearer understanding of the pathways of protein folding is essential to the forward momentum of biotechnology.
Investigating protein conformation-based inheritance and disease in yeast.
Lindquist S, Krobitsch S, Li L, Sondheimer N.
Our work supports the hypothesis that a protein can serve as an element of genetic inheritance. This protein-only mechanism of inheritance is propagated in much the same way as hypothesized for the transmission of the protein-only infectious agent in the spongiform encephalopathies; hence these protein factors have been called yeast prions. Our work has focused on [PSI(+)], a dominant cytoplasmically inherited factor that alters translational fidelity. This change in translation is produced by a self-perpetuating change in the conformation of the translation-termination factor, Sup35. Most recently, we have determined that new elements of genetic inheritance can be created by deliberate genetic engineering, opening prospects for new methods of manipulating heredity. We have also uncovered evidence that other previously unknown elements of protein-based inheritance are encoded in the yeast genome. Finally, we have begun to use yeast as a model system for studying human protein folding diseases, such as Huntington's disease. Proteins responsible for some of these diseases have properties uncannily similar to those that produce protein-based mechanisms of inheritance.
Prions are unusual proteinaceous infectious agents that are typically associated with a class of fatal degenerative diseases of the mammalian brain. However, the discovery of fungal prions, which are not associated with disease, suggests that we must now consider the effect of these factors on basic cellular physiology in a different light. Fungal prions are epigenetic determinants that can alter a range of cellular processes, including metabolism and gene expression pathways, and these changes can lead to a range of prion-associated phenotypes. The mechanistic similarities between prion propagation in mammals and fungi suggest that prions are not a biological anomaly but instead could be a newly appreciated and perhaps ubiquitous regulatory mechanism.
Researchers have known for some time that prions are transmissible via contaminated surgical instruments, food, milk, saliva, faeces, urine, and blood transfusions, although the latter is a rare occurrence. However, information about whether prions can be transmitted through the air was lacking.
The scientists ...tested immunodeficient and immunocompetent mice to determine whether they were susceptible to airborne prions.
They placed the mice in special inhalation chambers and exposed them to prion-containing aerosols, which resulted in disease. They found that just 1 minute of exposure to aerosols was enough to trigger disease in each subject. Furthermore, the longer they were exposed to the aerosols, the faster the first symptoms of disease emerged.