Science Monday

First, a necessary disclaimer, even though I am publishing under a pseudonym, I need to specifically say this is the opinion of someone who knows a bit more than average biology, but this is not a professional opinion.

Long time lefty and current left coast inhabitant Scott  (do not ask him about his secret identity), asked if I would weigh in on this article in the Atlantic. Unrepentant DC United fan BDR  has also linked to this article so uncaracteristically, this post is "topical" and doesn't involve discussions of David Caruso poetry. I took my time because I wanted to be careful in an area not directly related to what I do and because I was slow, the inevitable pushback from science bloggers had already occurred. And as is not uncommon with scientists, their response was to unfairly dismiss the main point because the author got some scientific facts wrong. 

A lot of info is already in the article and counter articles, but I will use my own words for a few key ideas so my arguments will be a little clearer:

The central dogma for biologists is that information goes from DNA to RNA to protein, i.e. the most stable form of info is DNA and everything needed create a cell is encoded in the DNA, but the functioning cell is made from the translation of the RNA into protein. This is still fundamentally true, and completely true for the arguments being made in the Atlantic article, although Levaux got a little confused on this point when discussing feedback mechanisms. What isn’t true is that the rate of making proteins from RNA is the same across all the mRNA’s (the ones that make proteins). Some RNA’s make thousands of proteins per mRNA, and others barely get one protein molecule made before they are “shut down.” There are all kinds of feedback mechanisms the cell uses to fine tune how much protein to make. One trick the cell uses was only recently discovered, and it is called “microRNA” (miR) These little RNA’s are like hunter drones, they identify target RNA’s (by having a short sequence that matches with the target) and once it finds a target, it activates cellular machinery that destroys the target mRNA. This is a feedback mechanism that prevents too much protein from being made. This degradation pathway has only really been studied for about the last 10 years. The new discovery that sparked the Atlantic article was made by a Chinese group. They showed that miR’s from rice eaten by mice were actually getting into the bloodstream and organs, altering gene expression in the body. I.e. it is possible to eat food and miR's from that food can actually change how genes are expressed in your body. Levaux made the assertion that this discovery had important ramifications in terms of assessing whether genetically modified organisms (GMO) were safe.

Now Levaux originally made a hash of the science (he has fixed some of the worst parts), and the two bloggers, Wilcox and Willingham were correct in pointing out those errors. However, I don’t agree with their conclusions, and Levaux was making some important points in his article that address a very important issue, that of the validity of the “substantial equivalence” standard. Willingham disputed the scientific errors and then shitcans the discussion of substantial equivalence because of those scientific errors. Wilcox focuses on the fact that the miR came from non-GMO foods and so YOUR AGRUMENT IS INVALID. I don’t agree with either assessment. For example, in the original article, Levaux references the Flavor Savr tomato. This GMO tomato prevents expression of a gene that causes the tomato to ripen too fast. It uses an “anti-sense” RNA (essentially an RNA that codes the exact opposite of the desired target, making an RNA double helix). It was originally believed that this double helix simply repressed protein production of that gene. We now know that what really happens is the cell processes the anti-sense RNA into lots of miR’s and the "normal" RNA then gets targeted for destruction. So this tomato now makes miR’s that are not “natural.” We do not know what genes they would target if they got into our bloodstream, it has never been tested. I doubt it is dangerous, but we just don’t know. So the Chinese discovery is already directly relevant to a GMO that is currently being sold.

The arguments against the substantial equivalence standard made by Millstone, Brunner, and Mayer 13 years ago are still relevant:

The concept of substantial equivalence has never been properly defined; the degree of difference between a natural food and its GM alternative before its 'substance' ceases to be acceptably 'equivalent' is not defined anywhere, nor has an exact definition been agreed by legislators. It is exactly this vagueness that makes the concept useful to industry but unacceptable to the consumer. Moreover, the reliance by policymakers on the concept of substantial equivalence acts as a barrier to further research into the possible risks of eating GM foods.

Levaux does a service by resurfacing this issue, even if some of the details were screwed up. Wilcox and Willingham do a disservice by not addressing the larger point.  

My summary opinion is this: there are GMO’s that do not use miR or miR-related technologies, and their likelihood of expressing new mIR’s that are health dangers, or even health altering, are relatively low (although not impossible). This does not mean that the modification is safe and a real standard of toxicology testing should be done for many if not all GMO's. There are also GMO’s such as the Flavor Savr tomato that use miR or miR-related approaches and the effects of this remain completely untested because they satisfy the “substantial equivalence” criterion and this is a problem. Shorter summary: Levaux fucked up the science, but Monsanto is still a bag of dicks.