via Sayer Ji of Sign Of The Times
A new study titled, "Detection of dietetically absorbed maize-derived microRNAs in pigs
," adds fuel to the fire of the growing controversy surrounding the EPA's recent and conspiculously underreported approval ofMonsanto/Dow's RNA interference (RNAi) corn
- a new type of genetically modified organism comprised of a multitude of genetically engineered traits (and therefore health risks) destined to make it to people's dinner tables by the end of this decade.
The Biotech/Chemical industry's new RNAi corn was quietly rubber stamped by the EPA on June 15th of this year under the premature, and likely patently false assumption that the RNA interference molecules in the maize can not directly affect the gene expression of those animals or humans who eat it.
The ongoing controversy relates to a fundamental difference of opinion on the age old aphorism: 'you are what you eat.' The GMO side answers NO, rejecting the idea. To them, food isn't imbued with any unique, biologically meaningful properties beyond the fact that it is a source of energy (calories) and bodily building-blocks (biochemicals such as carbs, fats and proteins, and a few key minerals and vitamins). Therefore, they contend that GMO food is substantially equivalent to conventional food, and therefore carries with it no additional safety concerns. Ironically, their marketing and lobbying efforts say otherwise: they claim their newly created genetically modified organisms are so exceptionally unique that they warrant receiving the patents they need to maintain market exclusivity. Essentially they want to have their Roundup-ready cake and eat it to.
The other side - what should be called the the pro-Real Science, and pro-Safety side - not only says YES to the concept that we are what we eat, but also understands intimately that food is a source of biologically/genetically indispensable information (like the software to our bodies' hardware), and that our co-evolutionary fates are, and always have been bound in intextricable co-dependency. Therefore when we tinker with its genetic/epigenetic properties we are tinkering with the genetic/epigenetic core of our species.
And so, this highly charged controversy has found itself playing out - at times looking like a full scale battle - within scientific journals. The key issue hinges on whether or not small interfering molecules known as microRNAs found in traditionally consumed foods such as corn are capable of inhibiting and/or altering gene expression in the animals and humans who consume them. Preliminary human research published in Nature from 2012 by Zhang et al revealed that, indeed, food RNAs can survive digestion intact and affect the expression of physiologically important gene targets within the human body. Since then, a barrage of opposing research has emerged. One side, finding that RNA interference molecules like miRNA are prime emissaries of the cross-kingdom relationship between plants and animals, and the other - mostly funded by the very corporations who benefit from the conclusion - that these are biologically inactive nucleic acids, with neither benefit or risk.
Ironically, Monsanto's own research shows that there are potentially hundreds of overlaps between these RNA interference molecules as found in common food and feed staples such as corn and soybean and mammalian genes. The implication is that these foods can significantly affect the expression of dozens of gene pathways essential for the the health of animals. Whereas Monsanto researchers concluded, counterintuitively, that since these (non-GMO) foods have formed the basis for the human diet for hundreds if not thousands of years, presumably with no observed deleterious side effects, that the GMO form of them must be safe as well - not unlike their debunked argument for "substantial equivalency" between conventional foods and their older generation transgenic GMOs, which have received FDA/EPA approval due to the same, highly suspect logic.
Regardless, the key question is still whether RNA interference molecules can and do survive mammalian digestion and affect gene expression. The latest study adds to an increasingly robust body of science that has concluded the answer is a likely YES. Here is the full study abstract:
"MicroRNAs are a class of small RNAs that are important in post-transcriptional gene regulation in animals and plants. These single-stranded molecules are widely distributed in organisms and influence fundamental biological processes. Interestingly, recent studies have reported that diet-derived plant miRNAs could regulate mammalian gene expression, and these studies have broadened our view of cross-kingdom communication. In the present study, we evaluated miRNA levels in cooked maize-containing chow diets, and found that plant miRNAs were resistant to the harsh cooking conditions to a certain extent. After feeding fresh maize to pigs (7 days), maize-derived RNAs could be detected in porcine tissues and serum, and the authenticity of these plant miRNAs were confirmed by using oxidization reactions. Furthermore, in vivo and in vitro experiments demonstrated that dietary maize miRNAs could cross the gastrointestinal tract and enter the porcine bloodstream. In the porcine cells, we found that plant miRNAs were very likely to specifically target their endogenous porcine mRNAs and influence gene expression in a fashion similar to that of mammalian miRNAs. Our results indicate that maize-derived miRNAs can cross the gastrointestinal tract and present in pigs, and these exogenous miRNAs have the potential to regulate mammalian gene expression."More specifically, the researchers identified 18 distinct maize miRNAs in intensely cooked maize containing diets (e.g. high temperature and pressure, and apparent starch dextrinization and protein denaturation), albeit at concentration levels that were 1/30 that found in fresh maize. Next they assessed the survival of these so-called exogenous miRNAs in pigs by measuring the relative expression levels of 18 maize miRNAs in the blood and solid tissues of three adult female pigs who were given fresh maize feed and water ad libitum for 7 days, by polymerase chain reaction technology. The researchers found 16 of the 18 maize miRNAs in detectable quantities in the blood and solid tissue of the animals. Interestingly, the researchers also discovered that all 5 tested maize miRNAs in porcine serum packaged in porcine exosomes, which they hypothesized enabled them to escape being broken down by enzymes within cellular compartments called nucleases (which break down nucleic acids like RNAs), enabling them to go from the gut to the bloodstream for systemic tissue distribution. As we have reported previously, exosomes are potentially universal epigenetic messengers within biological systems, used to transfer genetic/epigenetic information between individuals (inter-individual), and between species (inter-species), and ultimately across the entire biosphere of the planet, in what amounts to real time information transfer (versus the glacial pace of single nucleotide changes associated with classical protein-coding genetics).
Finally, in order to confirm the possibility that maize miRNAs are able to regulate target porcine messenger RNAs (mRNAs), and therefore inhibit/alter gene expression, the researchers performed in silico analysis of the porcine target genes for the microRNA zma-miR164a-5p, which they stated, "exhibited a relatively high level in porcine blood and tissues." Their results suggested that "dietetically absorbed maize miRNAs are very likely to specifically target endogenous porcine miRNAs and influence gene expression in a fashion similar to mammalian miRNAs." [bold emphasis added]
The research presented here has certain limitations. For instance, while a match and interference relationship between maize miRNA and porcine mRNA can be made, the degree to which the interference is significant depends largely on copy number. And so, the number of copies of zma-miR164a-5p, or any other biologically significant plant miRNA, will depend on a wide range of factors, namely, the concentration of that miRNA in the food being eaten, the quantity of that food, the microbiome and digestive condition of the host, etc.
That said, the identification of a cross-kingdom affect where ingested plant miRNA can survive digestion, accumulate in physiologically significant quantities in the host body, and interact with mammalian gene or messenger RNA targets is a vastly important finding by itself. Especially, when one considers that Monsanto/Dow's new genetically altered RNAi corn may contain hundreds of novel new type of RNA which may target hundreds of different mammalian genetic elements. Until this is known (if it is even possible to known in its vast complexity), the precautionary principle requires that these 'foods' not be released into the food chain because the unintended, adverse effects may far outweigh the purported benefits to the exposed populations.