Yeah.....our food supply is safe

[onlyme]

This is ridiculous:

The Bush administration can prohibit meat packers from testing their animals for mad cow disease, a federal appeals court said Friday.
http://news.aol.com/article/court-us-can-block-mad-cow-testing/153372?cid=14

And people complain about the "communist government" that Obama will bring?

[Conveyor Belt]

How are they testing for prions, anyway?

[jmb]

That's ridiculous. Any business should be able to test the product coming in.

[onlyme]

How are they testing for prions, anyway?

Check the brain after the animal died. It's the only way I know :smt102
I have not eaten US beef in ages because of those inadequate tests. Other countries manage to test all their cattle, why is that impossible in the US? Why stop someone who wants to do it voluntarily and bear the costs out of his own pocket??

[Conveyor Belt]

As it stands, there are few tests that can pick up prions in blood.

I did a little googling, and there are some research universities working on it, and a few thing they've got it. They're using PCR (polymerase chain reaction) to test for the prions, which makes sense. I wonder which genes in the prion they're polymerizing in order to create enough to detect...

I really don't know enough about prions. Maybe I'll research it a bit during Christmas break.

[JimmyJam]

As it stands, there are few tests that can pick up prions in blood.

I did a little googling, and there are some research universities working on it, and a few thing they've got it. They're using PCR (polymerase chain reaction) to test for the prions, which makes sense. I wonder which genes in the prion they're polymerizing in order to create enough to detect...

I really don't know enough about prions. Maybe I'll research it a bit during Christmas break.

It was my understanding that prions don't have genes. They are just protein. If they had genes (DNA) or RNA, they would then be viruses....:smt102

Now you have me curious. I have too much to do today, but now I've got to spend some internet time looking for info on this. Thanks for making my day even MORE hectic CB......:smt118

[Conveyor Belt]

It was my understanding that prions don't have genes. They are just protein. If they had genes (DNA) or RNA, they would then be viruses....:smt102

Now you have me curious. I have too much to do today, but now I've got to spend some internet time looking for info on this. Thanks for making my day even MORE hectic CB......:smt118

Genes are nothing more than certain arrangements of the amino acids in DNA.

you're right in that prions don't have genes, per-se.

But they would have is certain sequences of amino acids that would make them unique to an infectious protein.

[Conveyor Belt]

My questions that I'd like to have answered at this point in time:

How do prions reproduce?

What is the infectious sequence of amino acids that they are looking for?

Does this sequence resemble anything else in the body?

How do you prevent the false negatives?

[JimmyJam]

OK. I did a LITTLE bit of research, but I was interrupted by unexpected company. Genes are composed of nucleic acids (nitrogen base sequences, more specificially) that code for the amino acid sequence in proteins. According to what I found, one commonly used test detects certain proteins by using antibodies. I also found this test description that is used for Creutzfeldt-Jakob in humans (very similar to BSE in cows).

"The method, known as known as Protein Misfolding Cyclic Amplification (PMCA), enables the level of prions to be increased so that they can be recognised by existing detection methods."

http://www.sciencedaily.com/releases/2007/07/070705094120.htm (http://http://www.sciencedaily.com/releases/2007/07/070705094120.htm)


I also found a paper that cited the use of polymerization of "recombinant prion protein" for detecting the presence of prions.

http://lib.bioinfo.pl/pmid:18096717

There is also a page that explains how many scientists believe prions reproduce; they use a "contamination" model that claims the prions are normally sequenced proteins that have mis-folded, and contact between mutated proteins and "normal" proteins cause the normal proteins to mis-fold as well. These mis-folded proteins are passed to other animals by contaminated feedstock or arise spontaneously.

http://www.wiley.com/legacy/college/boyer/0470003790/cutting_edge/prions/prions.htm (http://http://www.wiley.com/legacy/college/boyer/0470003790/cutting_edge/prions/prions.htm)


I did not have time to look for statistics on false-positives. However, it would seem that since the normal and mis-folded proteins have the exact same amino acid sequence, it would be difficult to QUICKLY separate normal proteins from prions. I also noted that many of the pages I found contained information that was several years old. As a current student, you are certainly exposed to more up-to-date information that I, having received my degree 10 years ago. :-D

Thanks for getting a science geek excited about a post! :clap: Great stuff!

[Conveyor Belt]

Unless there's a binding site for the misfolded protein, I'm not sure why they'd have an allosteric affect in passing other proteins and making them misfold as well.

I'm not sure I'm buying the normal protiens that are misfolded line. If that were so, how many proteins misfold in the human body?

Granted, there might be translation errors in the mRNA...

I have more questions... I really don't have the time, though.

[JimmyJam]

Unless there's a binding site for the misfolded protein, I'm not sure why they'd have an allosteric affect in passing other proteins and making them misfold as well.

I'm not sure I'm buying the normal protiens that are misfolded line. If that were so, how many proteins misfold in the human body?

Granted, there might be translation errors in the mRNA...

I have more questions... I really don't have the time, though.

I don't get that either. The number of mis-folded or mis-translated proteins in the human body must be innumerable. Most don't cause any problems. I also don't get how these proteins could make it through a digestive tract intact. The gut is designed to allow the uptake of small particles; most proteins are huge, but don't make it into the intestines intact anyway. :smt102

[countrygirl]

Interesting conversation...just a little deep for a Saturday night though...makes me think too much.

[BayFly]

Interesting conversation...just a little deep for a Saturday night though...makes me think too much.
Made my head hurt!!!!!!!!

[amanda]

Interesting conversation...just a little deep for a Saturday night though...makes me think too much.

Made my head hurt!!!!!!!!

:smt103 Ditto here....bet Butterball will love it though.

[BayFly]

I might if I knew what they was talking about??? Naw just kidding .

[Conveyor Belt]

I might if I knew what they was talking about??? Naw just kidding .

Jeez... I made a similar comment to my classmates when we were discussing parasites in the tutorial on friday.

I said, "listen to us! We're just throwing around these terms we didn't even know 5 days ago like we've known them our whole lives"

I was pretty proud of us.

[JimmyJam]

Nothing like a little education to raise your self esteem....:laugh:

[Conveyor Belt]

Nothing like a little education to raise your self esteem....:laugh:

Or your paranoia...

Cryptosporidium parvum... it's in 95% of water!!! and chlorine in the water does nothing to stop it...

Giardia lamblia and swimming pools... 1 gram of stool has 300,000,000 spores, and the infectious dose is 10 spores...

I could go on... but I'm not going to.

[BayFly]

Yeah a little too much knowledge is scary sometimes !!!!! I got the jist of what yall was saying and the rest I don't need to know.

[JimmyJam]

Or your paranoia...

Cryptosporidium parvum... it's in 95% of water!!! and chlorine in the water does nothing to stop it...

Giardia lamblia and swimming pools... 1 gram of stool has 300,000,000 spores, and the infectious dose is 10 spores...

I could go on... but I'm not going to.

The human immune system is a wonderful thing. Most people have few issues with these organisms. Young, old, and immuno-compromised are susceptible, but most healthy adults have few issues. I have a friend who had "Back-Packer's disease" a few years ago. He went to several doctors before someone finally checked for Giardiasis. He had not been camping anywhere, but probably got it from a swimming pool.