Of Prions and People

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Spurred by a host of new findings in molecular and cellular biology, in recent years an increasing number of determined biologists have come to envision processes that contradict century-old biological assumptions and seem to defy the expectations of Darwinian evolutionary theory…

Naaah, I am not talking about ID. I am talking about prions, the specter of Jean Baptiste de Lamarck, and “heretical” views about biology. And what must be truly baffling for conspiracy-minded ID advocates, the inflexible “Darwinist orthodoxy” seems to positively dig this “heresy”. Now, that must hurt…

For many years after their discovery as the agents of some rare neurodegenerative diseases in mammals, such as scrapie in sheep and human Creutzfeldt-Jakob disease and kuru, prions have remained a truly esoteric research topic. However, they have recently become well-known to the public as the cause of bovine spongiform encephalopathy, a.k.a. BSE or “mad cow disease”, which can be occasionally transmitted to humans causing variant Creutzfeld-Jacob disease (vCJD). (Information about prion diseases can be found at the web sites of the WHO and the National Prion Disease Pathology Surveillance Center.)

Prions are unlike any other infectious agent in that they seem to have no nucleic acids at all. Indeed, after a long controversy, most scientists currently agree that prions propagate entirely as alternatively folded forms of certain proteins, through a mechanism that resembles crystal nucleation (see figure below) [4,8,12].

prionssm.jpg

Prion formation and replication. Click on image for larger version.

In the neurological diseases mentioned above, a prion protein can cause a “normal” folded protein of the same type (called PrPc for prion protein - cellular form) to assume a prion-like conformation. (For a PT primer on protein folding and some recent findings, see here.) Misfolded prion-like proteins tend to form filaments, and cause conformation changes in additional PrPc’s they come in contact with. This results in an amplifying cascade that eventually leads to accumulation of prion protein fibers (“amyloid”) which cause progressive neuronal cell death, and ultimately disease manifestation. Transfer of prion proteins alone from a sick organism to a healthy one causes the propagation cascade to start anew.

Let’s pause here. Does something nag you? It should. When prions propagate, what gets replicated is not really a material entity. Non-pathogenetic, correctly folded PrPc proteins exist in a host before prion infection. Unlike all other infectious agents, prions do not make new forms of themselves by synthesizing anything. Like in the case of crystal formation, what gets replicated is a structure. In other words, prions are not replicating proteins, but replicating shapes in a protein substrate world. There is even evidence that the same prion may exist in alternative forms (“strains”) with different properties, which may potentially compete with each other for the available substrates (PrPc’s), in a sort of Darwinian competition between “immaterial” replicators. Now, this is not unexpected: Darwinain evolution is a logically unavoidable consequence of replicators displaying heritable variation in a selective environment. Nevertheless, it’s just spooky, if you ask me. But that’s not all.

People have found prions not only in mammals, but also in other organisms, such as yeast and other fungi. Fungal prions are a great system to study prion biology, because they can be manipulated in the lab without excessive concern with potential infectivity, and their host organisms replicate and express the prion phenotype very fast (unlike the lag time for prion disease symptom development in mammals). In addition, fungal prions have attracted considerable interest because they actually mediate heritable phenotypes in their natural hosts, phenotypes that in some cases can be adaptive.

For instance, a yeast prion called [PSI+] causes defects in protein synthesis termination, and formation of new proteins [10, 11, 6, 8]. As most of you know, ribosomes are the cellular organelles which assemble proteins by linking amino acids according to the nucleotide sequence of messenger RNAs. In a nutshell, [PSI+] prevents the ribosome from reading the RNA nucleotide triplets (codons) that encode for “stop” signals. This causes elongation of the encoded proteins past their normal stop sites (i.e., proteins acquire extra amino acid sequences at their tail end), or in some cases allows translation of pseudogene transcripts that are otherwise crippled by stop codons.

In normal conditions, this phenotype spontaneously appears at low frequency in yeast populations, and is unstable ([PSI+] cells can revert to normal at low rates). The [PSI+] phenotype is generally non-adaptive (in fact, mal-adaptive), but in certain conditions (for instance, if the environment changes drastically) some of the aberrant proteins it generates may confer advantageous new functions. If that happens, prion-bearing organisms capable of synthesizing the new advantageous proteins will spread through the population. These phenotypically altered cells, by surviving in the new conditions, have now a chance to acquire favorable genetic mutations through conventional mutation processes. If this happens, the gene mutation can take over the population, while the [PSI+] population is again counter-selected and essentially disappears.

The [PSI+] prion trait is transmitted in a non-mendelian fashion. When mating [PSI+] and [psi-] yeast strains, the progeny is [PSI+], and so are, counter to Mendel’s laws, all the progeny of this progeny (except for the low-frequency “reversion” rate to the normal phenotype). The possibility of generating the [PSI+] trait is genetically encoded in the sequence of the yeast gene for the normal version of the [PSI+] prion protein, called Sup35 (which has the ability to assume both prion and non-prion folds). Therefore, although the prion “option” is clearly subject to conventional Darwinian evolution, in the case of [PSI+] natural selection is acting on a non-mendelian, non-genetically encoded trait.

One of the most interesting aspects of these prion-dependent phenomena is that they seem to have evolved because they provide a “buffer” system against sudden environmental changes by allowing the rapid generation of large numbers of new phenotypes, one of which may turn out to be useful in the new selective conditions. Another mechanism with similar properties is the SOS response in bacteria, in which hypermutation occurs in environmentally stressful situations. “Evolvability” is an often misued term that refers to the evolutionary potential of certain traits or organisms, but it applies well in this case, to indicate the increased diversity of otherwise “hidden” phenotypes that are unmasked by the [PSI+] state [4-8].

Several scientists have also noted that prion-dependent phenotypes raise the very real possibility of specific direct environmental induction of a heritable phenotypic trait, a kind of Lamarckian evolution, or pre-programmed phenotypic switch [2-4,6,8,12]. In certain conditions, for instance when an organisms recurrently but unpredictably encounters a specific, strong selective condition, prion systems may result in the environmental induction of adaptive, acquired heritable phenotypes.

At this point, we don’t have any bona fide examples of this actually happening, but in principle it’s possible. Moreover, this model provides a real, testable mechanism to explain such a phenomenon, should it occur (scientists don’t mind testable mechanisms and hypotheses, even when they are “heretical”). Aplysia_JPEG.JPG In fact, something that comes tantalizingly close to this, at the cellular, if not organismic level, has been proposed to occur during long-term memory formation in the sea slug Aplysia californica[1,8,9]. This critter has been used experimentally for many years as a model for memory formation for its rudimentary learning processes and giant neurons. Long-term memory formation has been associated with the formation of stable functional contacts (synapses) between neurons, in a form of competition: many synapses form all the time, but only those that get progressively stabilized by repeated stimulation will persist. One of the proteins that has been associated with the synapse stabilization process in Aplysia is called ApCPEB. Its function is somewhat unclear but, like Sup35, it also may be involved in control of protein translation. ApCPEB localizes to the synapse region, and upon repeated synaptic stimulation it forms “clusters” with different regulatory properties compared to the monomeric protein. Once formed, these clusters remain stable despite protein turn-over, even in the absence of further stimulatory signals. In yeast, ApCPEB has been shown to act as a bona fide prion, which would explain the formation of clusters and their stable properties.

These findings have raised enormous interest, not only from prion specialists, but among biologists in general. Many papers have appeared in major journals discussing the data and their implications. The extent of these phenomena in the biological world is unclear: prion-based inheritance and evolution may be extremely rare, or perhaps it’s quite pervasive and we just missed it. Some scientists are already talking about “paradigm shifts” [e.g., 2], although that’s probably premature. Regardless, it certainly runs against the impression, which ID proponents are trying to project in their P.R. communiques, of a monolithic, censorial Darwinian orthodoxy bent on stifling dissent and hiding evidence inconsistent with mainstream evolutionary theory. It is hard to say at this point whether in 50 years evolutionary biology textbooks will devote prions a whole chapter, a page, or just a footnote. But prions, unlike ID, will most like be there.

References 1. Bailey CH, Kandel ER, Si K. The persistence of long-term memory: a molecular approach to self-sustaining changes in learning-induced synaptic growth. Neuron. 2004 44:49-57.

2. Bussard AE. A scientific revolution? The prion anomaly may challenge the central dogma of molecular biology. EMBO Rep. 2005 6:691-4.

3. Chernoff YO. Mutation processes at the protein level: is Lamarck back? Mutat Res. 2001 488:39-64.

4. Chernoff YO. Replication vehicles of protein-based inheritance. Trends Biotechnol. 2004 22:549-52.

5. Chicurel M. Genetics. Can organisms speed their own evolution? Science. 2001 292:1824-7.

6. Masel J, Bergman A. The evolution of the evolvability properties of the yeast prion [PSI+]. Evolution Int J Org Evolution. 2003 57:1498-512.

7. Partridge L, Barton NH. Evolving evolvability. Nature. 2000 407:457-8.

8. Shorter J, Lindquist S. Prions as adaptive conduits of memory and inheritance. Nat Rev Genet. 2005 6:435-50.

9. Si K, Lindquist S, Kandel ER. A neuronal isoform of the aplysia CPEB has prion-like properties. Cell. 2003 115:879-91.

10. True HL, Lindquist SL. A yeast prion provides a mechanism for genetic variation and phenotypic diversity. Nature. 2000 407:477-83.

11. True HL, Berlin I, Lindquist SL. Epigenetic regulation of translation reveals hidden genetic variation to produce complex traits. Nature. 2004 431:184-7.

12. Uptain SM, Lindquist S. Prions as protein-based genetic elements. Annu Rev Microbiol. 2002 56:703-41.

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Andrea Bottaro has an excellent review of prion genetics over at Panda's Thumb. He notes that this is a "heresy" that the science community has embraced. Read More

95 Comments

So this is basically a virus-in-the-software-sense inside a biological system… very interesting read. Wonder how long it’ll take for creas to use it a straw man?

And here is an illustration of what can happen when you make a successful hypothesis and present evidence that contradict century-old biological assumptions and seem to defy the expectations of Darwinian evolutionary theory…

One jangling bad note in an otherwise beautiful symphony:

“they seem to represent systems that have evolved to “buffer” against sudden environmental changes by providing a quick way … “

My graduate supervisor had me flogged for making teleological statements like this!

This type of statement “evolved to…” implies a purpose to evolution, a certain goal-directedness to evolution (shades of [shudder] an intelligence behind the process).

Traits don’t ‘“evolve to” do anything; they arise in a population randomly and then MAY spread if they confer an advantage to the bearer lineage: i.e., they evolve “because” they do something.

I suggest this as a better construction: “they seem to represent systems that have spread throughout the population because they can provide a “buffer” against sudden environmental changes by providing a quick way…”

PUHLEEEZ don’t do this; it’s the kind of presentation that confuses the ‘lay’ reader and fosters misunderstanding of the evolutionary process.

Or how long before the DI uses it hack their virus into the obedience software in the human mind. You have to give them credit though it is much easier to herd (group thinking) sheep than (free thinking) cats .

djlactin - thanks for noticing that. I corrected it.

Between viruses, prions, and autoimmune diseases, there’s a lot more out there to challenge “orthodox” germ theory than there is to challenge the theory of evolution. I wonder when the “evolution is an atheistic lie” crowd will do more than carp about HIV not causing AIDS and mount a full-blown attack on germ theory on the basis, perhaps, that a lot of diseases are really caused by sinful (or some carefully secular equivalent term) lifestyle.

It is interesting that the evolutionary implications of the PSI system, although proposed some 5 years ago, have never been rigorously tested using experimental evolution, although that would be relatively easy to do in yeast (the data in the 2004 paper also falls well short). I will have to reserve judgement on this mechanism until then: it is not enough that it sounds plausible. (Indeed, similar criticisms can be raised about the related claims on the evolutionary role of Hsp90 by the same lab.)

Germ theory sherm theory. A prion is a chemical. Proteins are chemicals. I’m nearly certain that a toxicologist must have pointed out by now that if you don’t have any genes involved its kinda silly to be talking about inheritance. ***ITS A POISON***! Inheritance would come in when a gene encoding a protein that can do this is selected for, such as what you could invision happening with the fungal prion described above. Change the wording and you’ll see things in a more helpful context. Prions don’t infect, they contaminate. Its more than just non-mendelian, its non-genetic. The problem is that we’re not used to thinking of biological organisms as bags of chemicals. There’s still more than a little vitalism alive and kicking in biology.

Ricardo: I thought the 2004 Nature paper data were pretty good as far as determining the mechanism of action of [PSI+]. As for the role in evolution, I agree it’s largely speculative at this point. A recent paper in PNAS that I have not listed in my piece concludes that [PSI+] is not found in a number of wild yeast strains, suggesting that it may be deleterious overall (Nakayashiki et al, PNAS 102, 10575, 2005). If that’s the case, it is unlikely that this prion plays a significant role in determining yeast “evolvability” - although this may still be the case in specific environmental niches. Still, it’s an interesting phenomenon, well worth speculating about, in my opinion.

Mike: Prions are indeed chemicals, but chemicals that, unlike poisons, reproduce themselves (in the unusual manner described above). Also, I should probably say that in the most basic meaning of the term “gene” (e.g., a physical unit responsible for stable inheritance of one or more phenotypic traits) prions are in fact genes of sort, although of course they do not fit the common, modern molecular definition of the term.

Andrea Bottaro wrote: “Prions are indeed chemicals, but chemicals that, unlike poisons, reproduce themselves (in the unusual manner described above).”

But they aren’t actually reproducing themselves, are they? They are inducing a conformation shift in other protein molecules, something that some poisons do. Its not inheritance. The unique thing is that its acting in “cis”. Is there something other than entertainment value to be gained from insisting that this is a form of inheritance? It is still the genotype that must be altered in selection. Sorry to be a wet blanket, but I don’t get it.

“Now, this is not unexpected: Darwinain evolution is a logically unavoidable consequence of replicators displaying heritable variation in a selective environment. Nevertheless, it’s just spooky, if you ask me.”

The spookiness is probably a function of being a biologist having much more specific ideas about what kind of thing usually happens.

My intuition would be to look at this as a random graph (for lack of a more informed model). Suppose we have nodes labeled with pairs (X,s) representing a protein with sequence X and conformation s. The graph has directed edges labeled (Y,t) with endpoints (X,s) and (X,u). We interpret this as “X with conformation s will change to conformation u in the presence of Y with conformation t.” Any possible edge can be in the graph with some fixed (rather low) probability p.

Depending on the density of such a random graph, it would be downright spooky if we were miraculously prohibited from finding edges labeled (X,u) that go from (X,s) to (X,u). Not only that, the probability would likely be higher than our first guess, because it would look a lot like the birthday paradox (http://en.wikipedia.org/wiki/Birthday_paradox), i.e. the fact that in a room of 23 people the probability is better than 50% that two share a birthday.

Mike,

These are abstract arguments, to be sure, but you could say that there’s a hint of vitalism in creating a distinction between gene inheritance and conformation inheritance. Both represent a self-replicating phenomenon; DNA has the property that a copy of its molecular arrangement happens under the right conditions, just as the prion induces new conformation copies in the presence of the normal protein. There’s no reason that selection couldn’t apply to the prion case, just as selection can happen to cultural phenomena. Selection simply needs a mechanism for replication of system states and variable probability of survival for different states. Natural selection occurs all the time in the replication of songs on teenagers Ipods.

“But they aren’t actually reproducing themselves, are they? They are inducing a conformation shift in other protein molecules”

They induce a conformation shift in other proteins, that results in more proteins of the same conformation. One could say that DNA/RNA do a similar thing, since they act as a template for the creation of a new macromolecule in the same “conformation.” The important aspect is that PSI+ is a phenotype passed from fungal parent to offspring.

Maybe another analogy would be an infection. Often a viral or bacterial infected organism passes it to the offspring. In many cases, this bacterial infecting agents act as symbionts, and at some point, the host often loses the ability to survive without them. Many creatures, like termites, use such a system for digestion. If the agent is viral, such as that which carries cholera toxin, the host is often adapted to reproduce with the virus. Often this results in permanent provirus status and incorporation to the genome.

The whole point is we have our simple model of inheritence, but when we see other mechanisms for which there exists evidence we embrace them enthusiastically, rather than hold onto them dogmatically as some have alleged. We can quibble about what defines words like “inheritance,” but when new discoveries challenge previous understandings in biology, we are bound to have to redefine.

Well ok, just one more thing then I’ll shut up.

“There’s no reason that selection couldn’t apply to the prion case, just as selection can happen to cultural phenomena.”

What would be selected on in the case that is of primary interest to us, BSE? Nothing much in the cow. What might be selected against is the human stupidity of feeding a cow’s brain to a bunch of other cows. This cow prion, at least, hasn’t developed as a result of selection for one protein conformation to reproduce itself in other cows, unless there are zombie bovines that I’m unaware of. Isn’t this simply an example of a random event? One protein molecule conferring a conformation shift on another, a common event in protein-protein interaction, but this time there’s an extreme deleterious effect.

Would we be thinking of it in these terms if the people looking for it hadn’t been looking for an infectious agent?

Just to add to the comments above. Prions do reproduce themselves (with the caveats described in my piece, i.e. that what reproduces is the protein fold, not the protein itself). If you inject an animal with a “poison”, as suggested by Mike, then transfer its tissues into an other animal, and so on sequentially, eventually you run out of poison and lose toxicity. Not so for prions. Second, the traits prions generate can be heritable in the “classic” sense - as in the case of the yeast prions, or some human forms of Cretzfeldt-Jakob disease.

Would we be thinking of it in these terms if the people looking for it hadn’t been looking for an infectious agent?

Perhaps not. But the disease is, indeed, “contagious”, so it stands to reason that that is how it would first be approached. You can measure “infectious units” just like for other infectious diseases, and those infectious units multiply in an “infected” animal - just like they do for other infectious diseases. The fact that we use the language of infectious disease to describe the phenomenon is no more arbitrary or misleading than the use of the word “virus” for those nasty computer software constructs.

Prions do reproduce themselves… what reproduces is the protein fold, not the protein itself.

So, prions are just self-replicating quantum computers?

If so, could understanding (variation in) their machinery help us bring further insight to biochemistry’s (quantum physic’s) “protein folding” questions?

By the way, there’s a suspicious cluster of CJ disease right now in Idaho

I must be as dense as Mike here. The prion is not reproducing copies of itself. It is catalysing a deformation of an exisiting protein to the prion configuration. The protein which deforms exists anyway in the organism, and is, in effect, “poisoned” by being catalysed into the prion configuration. I don’t see any NS driving this. Sorry, if this is simplistic.

“I must be as dense as Mike here. The prion is not reproducing copies of itself. It is catalysing a deformation of an exisiting protein to the prion configuration.”

I must be even denser. How is your claim different from saying “The DNA is not reproducing copies of itself. It is merely catalysing a collection of existing nucleotides to bond in the same order as the DNA’s sequence.”

I.e., sequence and structure are both informatic objects. DNA has no power by itself to create the nucleotides whose assembly it guides. These are synthesized elsewhere. In both cases, only the pattern is replicated, but in both cases it seems fair to me to call it a process of replication.

I grant that the prion mechanism may not be as robust a form of information reproduction as DNA copying (I’m also not saying it isn’t; I don’t know) but I don’t see the obvious distinction. In both cases, we are talking about reproduction of a pattern on a substrate. Likewise, if I use a pencil to plagiarize your writing, I’m merely catalysing some graphite to the same configuration rather than sending your written letters into some kind of magic doubling machine.

What kind of reproduction is there other than the recreation of a pattern on previously existing substrate?

Comment #52413

Posted by Russell on October 17, 2005 03:25 PM (e) (s)

By the way, there’s a suspicious cluster of CJ disease right now in Idaho

A biostatistics professor friend at NCSU told me that BSE has occured several times in the US already, but it’s been hushed. FWIW.

They have some rodent that have PrP knockouts and they can’t get the prion disease. They are talking about making transgenic knock out cattle. There doesn’t seem to be anything very wrong with the knockout rodents, and it probably wouldn’t matter if we made cattle any more brain damaged. I remember the Suzuki nature show where he had cattle on and the narration went something like “fed to stupifaction” with a close up of cattle in a feed lot.

I’d eat PrP knockout transgenic cattle, it could be a turning point for agriculture and transgenic livestock. I’d want it to be a deletion knockout instead of an insertion knockout for obvious reasons.

Syntax Error: not well-formed (invalid token) at line 3, column 103, byte 302 at /usr/local/lib/perl5/site_perl/5.16/mach/XML/Parser.pm line 187.

PUHLEEEZ don’t do this; it’s the kind of presentation that confuses the ‘lay’ reader and fosters misunderstanding of the evolutionary process.

It’s just this kind of wording that this website: http://www.creationsafaris.com/crevnews.htm and others use the fool the unsuspecting reader. The constantly use biolgists’ tendency to “anthropomorhpize” molecular and cellular structures and functions as evidence for divine influence in biology.

Example:

http://creationsafaris.com/crev2005[…]tm#20051004a

I used the tage correctly but it keeps saying I have a syntax error.

“What would be selected on in the case that is of primary interest to us, BSE?”

“I’d want it to be a deletion knockout instead of an insertion knockout for obvious reasons.”

I’m not a prion expert (how many are there in the world anyways? very few I’d guess), but the presence of similar prions, with compatible conformation changing abilities in many mammals ie sheep, cows, humans, mice etc., suggests there may be a selective pressure preserving it. I don’t think it is known what the protein involved does, even in the non-prion state, but it wouldn’t be surprising to find that both a) the gene does something, which is how it was selected and conserved, and b) the conformation changing capacity contributes to that function, which is how it was selected and conserved.

The idea of a random graph (representing entities, sheep, cattle, people, etc.) with connections representing infection routes for prions (and I guess for other things) makes me think of a percolation problem.

As percolation is a eigenvalue problem, perhaps some epidemiological models should show this behavior. Under a certain connectivity threshold, few if any entities would be infected; above that threshold, all would. It’s like dissolving boullion in water, only the surface gets wet; with bigger pores, saturation occurs instantly.

Yup. Percolation on heterogeneous networks as a model for epidemics.:

We consider a spatial model related to bond percolation for the spread of a disease that includes variation in the susceptibility to infection. We work on a lattice with random bond strengths and show that with strong heterogeneity, i.e. a wide range of variation of susceptibility, patchiness in the spread of the epidemic is very likely, and the criterion for epidemic outbreak depends strongly on the heterogeneity. These results are qualitatively different from those of standard models in epidemiology, but correspond to real effects. We suggest that heterogeneity in the epidemic will affect the phylogenetic distance distribution of the disease-causing organisms. We also investigate small world lattices, and show that the effects mentioned above are even stronger.

RBH

Yes the Darwinian fundamentalists are quite accomodating when the theory doesn’t contradict their mechanistic dogmas.

However, given evidence that challenges the reductionist mindset, their sense of curiosity suddenly departs.

I don’t see a lot of difference between dogmatic reductionistic materialists who ignore evidence which contradict their dogmas, and dogmatic young-earth creationists who ignore evidence which contradicts their dogmas.

aww matt, your response is so replete with standard creationist buzzwords:

darwinian (fundamentalist) mechanistic dogma recuctionist etc etc

one wonders if you have any original thoughts? ever thought about applying the same terminology to your own “mindset”? those terms are far more applicable there.

especially when it comes to “ignoring evidence”… care to present any actual scientific evidence to support your own dogma??

addendum:

before you repost your supposed “given evidence” link; understand what it is that you propose as “evidence” first. what exactly do you think this link provides as real scientific evidence, and what does this evidence actually support, eh?

i think the big thing you missed there was the actual title of the article you linked to:

“Science is a method, not a position “

indeed. now if you understood what that meant, you would also understand how silly it is to apply your misused buzzwords to scientists in general.

OTOH, the paranoiac in me starts to think of the potential for prions as biological weapons and that would be the first area of research i would start to play with: just how much can a prion be altered and still catalyze folding, and would new shapes produce even more lethal cascade reactions.

*sigh*

As I mentioned in another thread, I do know a few things about the US’s biowarfare “defense” research. Although someone made light of it, it should scare the living crap out of you.

One of the proposed vectors for transfer of CJD from cattle to humans at the height of the BSE epidemic in the UK was Hamburgers. Spiked hamburgers might work as a BW, but you couldn’t get too many in a nosecone. “Incubation” time being so long is also a drawback.

Re prions and memory. With DNA all the machinery for copying, replicating etc. is there. The catalyzing and crystal-forming analogy seems to describe prion “behaviour” well. Is there variation in amino-acid sequence of prion proteins? If so there could be a way of storing information. But you would need a template and a read-write system. Encoding info. in protein sequences which can then be replicated doesn’t happen elsewhere in biological systems, AFAIK. As there is only one conformation for the folded prion, I doubt there is much scope there.

BW, Don’t you just hate analogies, especially those involving Mt. Rushmore or mousetraps?

Found this article: UCSD Study Shows ‘Junk’ DNA Has Evolutionary Importance . Funny (serendipitous?) that this article happened to come out just as the subject was being discussed here. :)

But, it doesn’t get into what the “junk” dna does, just the fact that it seems to be preserved from some percentage of the possible mutations - which implies selection for some function but doesn’t name the function. The article implies that the specific function isn’t known yet. (Or at least not by the author of said article?)

Henry

It’s a shame it got called junk DNA in the first place.

It’s a shame it got called junk DNA in the first place.

About this Entry

This page contains a single entry by Andrea Bottaro published on October 16, 2005 11:15 PM.

Iconoclasts of Evolution: Haeckel, Behe, Wells & the Ontogeny of a Fraud was the previous entry in this blog.

Response to Luskin / Calvert story on “theistic evolution” is the next entry in this blog.

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