Posted on 03/27/2013 8:56:43 PM PDT by Tolerance Sucks Rocks
You’re welcome.
I try, whenever I can, to spread scientific information and educate people. I have found that many people don’t want to be calmed with scientific fact, nor do they have any desire to rationally consider and weigh risks against each other. They would much rather live their lives in fear of technology. I do not know why this is so. Nevertheless, I will continue to spread scientific information and try to guide people towards positions based more on weighing facts and less on fear-mongering.
That is a link from Mercola. That is a well-known quack site devoid of accurate scientific information. I will not give Mercola the page views; I do not want him to profit by my visit.
"You know, if cooking were a new invention, the controversy over its safety would be deafening. Cooking food changes everything about it. It denatures proteins, causing them to take on properties they never had in nature. It breaks up cellular structure, and destroys the cell walls of plants."
"Just because they were detected, that means what, exactly?"
That, clearly, they've passed through the digestive tract intact and entered the blood stream. Not just the metabolites of a small molecule, but a fairly large, kD wise protein itself.
The feel good message wrt placing a pesticide protein in a commonly eaten food was 'it'll be digested and even if it isn't digested it's too big to pass through the intestine'. Which I believed.
That might have been a hasty statement. Which makes me wonder if the manufacturer ever bothered testing this before introducing it into the food supply.
And you're right about eating being an 'experimental' process. Which is why a lot of people would feel more comfortable with the new technology if the safety studies were intergenerational primate studies and for longer than 90 days. We've been told BPA is safe and any concern with it is just so much 'plastic hysteria'. As it turns out the intergenerational epigenetic effects of exposure might be just a little more than 'plastic hysteria'.
Would love to see a similar f3 study done, even a rat study, on the effects of exposure to GLYP and CryAb1. Until then I remember the denials of RJR.
You argue that manipulating a single gene results in less manipulation. As a molecular biologist turned software engineer, I see a flaw in that logic. You have injected a single feature stripped of the control and feedback mechanisms that evolved with it. A conventional hybridization effort creates a working system of processes that exhibit hybrid vigor or fail. The diversity provides protection against a single point failure.
I point to the single point failure when observing that Roundup Ready crops have a new competitor...Roundup Ready weeds. The single point wizardry has given us super weeds.
The farmer should counter sue for contamination of his land and products by Monsanto's experimental crap. Treat it like a superfund cleanup site. Insist that they clean up every bit of the contamination from their product.
Thanks for your insight.
That, clearly, they've passed through the digestive tract intact and entered the blood stream. Not just the metabolites of a small molecule, but a fairly large, kD wise protein itself.
I repeat my question: That means what, exactly? Just because you can detect a protein consumed in food in the blood does not mean anything. Proteins that you consume can and do enter blood. Unless it has been shown that the protein in question is a human pathogen, there is no particular reason to panic. Humans have already been consuming Bt proteins for millenia; now that a single Bt protein has been engineered to be expressed in plants, it's suddenly a problem? That makes no logical sense. The reason Bt was selected was precisely because it *is* a common component of food. Bacillus thurigensis is a common and ordinary bacteria found on food of plant origin. You cannot avoid consuming Bt proteins if you want to.
The jury is still out, as they say, on the BPA. There are procedural problems with the studies. In the study you linked, it appears that the rats were given extremely high doses--a practice which tells us about the effects of high critical exposure, but little about low dose exposures. Another recent study purported to have found high levels of BPA in blood; however, since most labware is made of plastic these days, it is difficult to say whether those supposed high levels are real, or came from the lab.
Lastly, I'm not sure why you think the Bt hasn't been tested. Decades of testing and characterizing that protein preceded its being engineered into corn, and more testing followed. It would not have been selected for that purpose if it was not something humans have consumed without ill effect for millenia.
” Unless it has been shown that the protein in question is a human pathogen, there is no particular reason to panic. Humans have already been consuming Bt proteins for millenia; now that a single Bt protein has been engineered to be expressed in plants, it’s suddenly a problem?”
Your prior statement that cooking denatured and inactivated proteins. Obviously that’s an incorrect statement.
Proteins that cross the intestinal barrier can and DO cause significant problems. Witness the issues people have with simple gluten intolerance. Their problem isn’t the entire protein, simply a snippet of it.
Prion diseases are also an issue. Those are just a few peptides.
Dose dependent. I’m not aware of any cultures that consume Bt as a food group. Most bacteria is washed off prior to food prep.
I’d like to see a safety study that determined before and after blood levels of Bt toxin. And a longer term study that determined the epigenetic and intergenerational effects.
Also a study to determine any changes in the intestinal microbiome. That would be the biggie. Does the presence of Bt toxin, in macro doses, change the biome enough to cause long term health issues? Does it change the microbiome of primates in a different way than in the FDA approval test rats? Why haven’t we seen any studies on this food longer than 90 days? We certainly haven’t consumed it for 3m and then stopped.
A 90 day study on the effects of smoking cigarettes would undoubtedly indicate they were safe and effective appetite suppressants. It would also be incomplete.
If you’re happy with the safety studies done so far, by all means consume these foods and feed them to your children. I sincerely hope your trust in the workings of government and industry is well placed. I’m sure the science of global warming is just as rigorously tested. And neither of these fields is tainted by any outside funding or bias.
Right, how can you possibly know which DNA organisms can or can't acquire "naturally"? Organisms receive exogenous DNA all the time. The last I checked, we were still symbiotic organisms dependent on microbial DNA for our very survival. Mitochondria and chloroplasts are ancient bacteria. Virus genes are necessary for placenta formation. Our genome is packed with thousands of viral genomes. Personally, I think the focused targeting of a single gene is trivial when compared to the vast amount of random mixing of DNA both between and within species that occurs "naturally" all by itself.
You claim to have some background in molecular biology. In that case, I'm surprised you aren't aware that whenever an exogenous gene is inserted into an organism, it is inserted as a cassette with all kinds of translational controls attached. You can't get gene expression without the regulatory elements being present. Inserting a gene all by itself without controls will only result in a minimal increase in the size of the genome with no other effect.
The fact is, when you randomly mix genes from two related organisms through older breeding methods, you have no way of predicting what the final outcome will be. You might come up with a hybrid that is 20% more productive--or a hybrid whose fruit is caustic and unsuitable for food. You have far more control and far less uncertainty about the outcome by using modern molecular biology methods.
BTW, before you try any more to intimidate me with your superior knowledge of molecular biology, let me point out that my PhD in Biochemistry and Molecular Biology gives me a HUGE body of knowledge in this area. I understand this subject VERY well.
Right, how can you possibly know which DNA organisms can or can't acquire "naturally"? Organisms receive exogenous DNA all the time.
How can you claim that the Bt genes aren't being passed to the gut flora or intestinal wall cells of food consumer? How can you possibly know which ones can or can't pick it up? The EcoR1 mutant was a favorite target organism when I was in school.
There is evidence of harm to both humans and livestock from Bt modified corn and cotton. Ignoring it doesn't make it less true. Getting back to the topic of the thread...writing law to protect corporations from legal jeopardy when their products cause great harm is corrupt politics in action. Nobody buys politicians better than Monsanto.
One of the first widely available cloning vectors, pBR322, was created in 1977 by two postdocs at UCSF, Bolivar and Rodriguez (hence the name, plasmid Bolivar Rodriguez, the 322nd one tested). Many years later, I was fortunate to have Dr. Rodriguez as a professor, and learned much about the early history of genetic engineering and the creation of pBR322.
The sheer volume of knowledge that exists on the subject of molecular biology these days is staggering.
How can you claim that the Bt genes aren't being passed to the gut flora or intestinal wall cells of food consumer? How can you possibly know which ones can or can't pick it up? The EcoR1 mutant was a favorite target organism when I was in school.
There is a whole lot going on here (that the fear-mongers probably have no clue about).
First of all, as a front-line defense against microorganisms, we are saturated with DNases. DNases cover our skin and our bodily fluids are full of them. Even if that plant DNA (containing the one Bt gene) were to somehow survive the cooking process, it is highly unlikely to survive being exposed to the DNases in our skin and mucous membranes lining our digestive tract.
Even if we were to eat the plant material raw, that DNA still wouldn't be able to gain direct access into our cells, because plants have no mechanism for inserting their DNA into animal cells.
Now, it is true that bacteria exchange DNA with each other all the time (they don't care about species), and viruses commonly carry DNA from species to species. And some microorganisms do like to pick up DNA. I suppose, by some circuitous route, it would be possible for a virus to pick up that segment of DNA that contains the Bt gene, and somehow pass that gene to an animal virus capable of infecting humans, which could inject it into a human cell. But if that happens, it's much more likely that any genes inserted would be plant genes (because a single gene of, for example, 10,000 nucleotides is a tiny part of a plant genome of billions of nucleotides). Even if, by that long chance, a Bt gene made it into a cell through viral action, that would most likely be the end of the story. A piece of DNA by itself does nothing. Even if the cell didn't immediate destroy that tiny fragment of DNA, and the DNA were inserted into a chromosome--the chance that it would have an effect is infinitesimal.
Furthermore, humans have been consuming Bacillus thurigensis probably for as long as we have been consuming food. It is a common soil bacterium. It commonly gets onto plants. If the presence of a minuscule piece of Bt DNA stuck into the corn genome, or of a single Bt protein stuck among the thousands of corn proteins, is worrisome, then, certainly, eating countless intact bacteria that all contain that specific gene and protein (along with thousands of other bacterial genes and proteins) must be extremely distressing. The reason the Bt protein was selected to engineer into plants is because it *is* a commonly consumed bacteria, and the mechanism of action of that protein is very well known. It is inert except at high pH--a condition that does not exist in human bodies. We like low to neutral pH environments.
I'm not sure what you mean by "the EcoR1 mutant." I've used the restriction endonuclease designated as "EcoR1" countless times in genetic engineering experiments. It cleaves the sequence "GAATTC" right after the G. Would an "EcoR1 mutant" be a strain of E. coli in which that specific restriction endonuclease is defective?
There is evidence of harm to both humans and livestock from Bt modified corn and cotton. Ignoring it doesn't make it less true. Getting back to the topic of the thread...writing law to protect corporations from legal jeopardy when their products cause great harm is corrupt politics in action. Nobody buys politicians better than Monsanto.
As I said before, the characteristics of that one protein from B. thurigensis were well known long before it was selected to insert into plants. If that protein causes harm, then we've all been damaged by it continually throughout our lives--independent of its use to engineer plants to be pest resistant. And the "organic" farmers who spray live B. thurigensis onto their crops would be guilty of intentionally adulterating food to make it unsafe. Aside from the claims of a few fear-mongers trying to sell books, there is no credible evidence that Bt proteins are harmful. You eat uncharacterized and unidentified proteins all the time--aren't you worried about how safe they are?
Down the hill from the Revelle campus, Kerry Mullis at Scripps was polishing his new PCR technique for multiplying his DNA samples into useful volumes. Some of my fellow students opted for the genetics lab where Dan Lindsley taught them the fine details of Drosophila. Pulling their tongues out to access the giant polytene chromosomes in the salivary glands was one of the exercises. Achieving a nice "squash" with subsequent staining to reveal the banding patterns was a big deal to my buddies.
Suffice to say, the field was young and crude at the time I graduated. Cold Spring Harbor and Scripps were two of the "hot" possibilities. Hybritech and Genentech went into business right around the corner from my office at PacBell in the early 80's. I came to the field just a bit too early.
Please check in the conclusions section around line 681 of the paper at link. The presumptive safety of Bt toxin applied to plants that requires the high mid-gut pH to activate is not applicable to the circulating Bt toxin synthesized inside a transgenic plant. That Bt toxin is already active. It is active when you stuff it in your mouth.
Every strain of E. coli used for genetic engineering has various (introduced) defects in DNA modification, repair, and replication enzymes, as well as a host of other defects. These defects are introduced in order to reduce the chance that the bacteria will alter or destroy the engineered DNA we're trying to force them to produce. So the EcoR1 mutant had a defective EcoR1 enzyme.
DNA does not normally pass through the cell wall (of bacteria or anything else). If we want to put DNA into an organism, we typically have to use some fairly harsh methods which involved chemically weakening the cell wall, and then using heat shock to physically introduce holes in it and the cell membrane through which the DNA can pass, or we electrocute the organism (it is unclear how that works). Making organisms "competent"--that is, able to receive DNA--is a fairly time-consuming and laborious process. Competent microorganisms are very fragile; once, I was trying to introduce DNA into yeast, and dropped the vial of yeast on the floor. You can throw vials of ordinary yeast on the floor all day, and they won't even notice--but that small shock killed my competent yeast. Several days' worth of work died right then...
Bacteria use pili to transfer DNA amongst themselves, and they are not really picky about the species they transfer it to. All of the bacteria I used were F'--they expressed the pili--but I never exploited the pili for lab use.
Down the hill from the Revelle campus, Kerry Mullis at Scripps was polishing his new PCR technique for multiplying his DNA samples into useful volumes.
Kary Mullis developed PCR in the 1980s while working at Cetus Corp. in Emeryville (which is not far from where I grew up, but that's another story). I have never had the pleasure of meeting Dr. Mullis, although I've met people who knew him. I've met 3 Nobel laureates--Dr. Watson twice--and would love to meet Dr. Mullis. Having used PCR for many years and designed hundreds of PCR experiments, I am awed by Dr. Mullis' genius.
I don't recall ever pulling the tongues out of Drosophila larvae. I do recall pulling off their heads to get at the polytene chromosomes. Just thinking about it makes me kind of queasy... I'm not normally sympathetic to insects, but yanking off their heads, poor little things--it really makes me wonder about the mental status of the person who discovered/developed that method.
Please check in the conclusions section around line 681 of the paper at link. The presumptive safety of Bt toxin applied to plants that requires the high mid-gut pH to activate is not applicable to the circulating Bt toxin synthesized inside a transgenic plant. That Bt toxin is already active. It is active when you stuff it in your mouth.
Okay. That paper you linked is a term paper, which appears to be written by a university senior chemistry major, probably as a graduation requirement. It is clear that the writer does not have a strong biochemistry background, and knows next to nothing about protein chemistry. This is *not* a peer-reviewed study or literature review.
Quoting from the paper: Previous pesticides using Cry proteins 680 through spray application released toxins in an inactive state and only expressed toxicity 681 under specific midgut conditions in organisms[3]. However, active Cry toxins released by 682 transgenic plants already express insecticidal properties and do not need to be activated [25]
Reference #3 is a paper describing the insecticidal properties of Bt toxin, and is referenced appropriately here. However, reference #25 is a paper talking about resistance to Bt toxin (presumably insect resistance, but the title does not make that clear), published in an obscure journal in 1990, before anyone cloned Bt toxin into corn (or while people were working on it). So that reference does not even support the claim that it presumably supports.
And this is where we get into the fact that the student who wrote the paper has minimal understanding of biochemistry. What she meant by "active Cry toxins" is unclear. The Bt Cry protein is changed to its receptor binding conformation (shape) only under alkaline conditions--which do not exist in B. thurigensis, humans, or plants. This change exposes the receptor-binding site. Once exposed, that binding site is very specific about the receptors it will bind. It shows very high affinity for gut receptors of certain species of caterpillars--and that's it. Without binding those receptors, the protein can do nothing. Like all enzymes, it must bind to its substrate before it can act on it. It is unclear how the Cry protein would be induced to fold into its receptor-binding conformation in the acid environment of corn cells, since that is a purely chemical reaction driven by pH--and even if it did, it still has nothing to bind to. Except receptors on the cells of insect guts--which might be a problem for the guy in that old movie, "The Fly", but not anyone else.
Here is an interesting factoid: most people know that ricin is an extremely potent toxin. You don't want to eat it. But toxins nearly identical to ricin are made by plants we eat every day. Ricin acts by killing ribosomes so that cells cannot make proteins. So do the almost identical toxins produced by wheat and many other plants we routinely eat. The difference is that the toxin has two parts--the cell receptor binding part, and the enzymatic part. Ricin has both parts. The food plants only have the enzyme part. Without the binding part, that enzyme part does nothing. If I remove the binding part from ricin, the ricin enzyme also does nothing.
It occurs to me that I am becoming very technical here. I think these details are necessary for understanding exactly how the fear-mongerers attempt to hoodwink people--the more you understand protein structure and function, the better you can judge their claims.
Beaver dams made for a beaver's purpose are a good and wonderful part of nature.
Human dams made for a human’s purpose are evil and an affront to nature.
Toxins are anything they want it to be, and nothing natural is a toxin.
Unregulated herbal remedies kill people due to there being no standards as far as dose, no required data on efficacy or drug drug interactions; and that is fine because they are “natural”.
GMO foods are well characterized and studied out the wazoo, but they will always require more regulation and further studies because they are NOT “natural”.
There is that. I've run into that attitude many times.
I also think there is more to it than that. There is also a basic distrust: of the government, of anything that is determined through a systematic examination of physical facts, of conclusions based in logical analysis.
I do not understand why some people are so repelled by logic--perhaps because I have a strong affinity for logical people (Mr. Spock on the original Star Trek was my hero).
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