Thursday, February 6, 2014

GMOs are not the evil we think they are

I haven't had much of a chance to do much writing these days, besides the writing of my thesis.  Despite my best intentions, I haven't had the time to devote to really thinking about a topic enough to write something meaningful and coherent.  So, I'm gonna cheat a little bit and write a post about the genetic modification of plants.  I want to make it clear here though - this is a post about the science behind GMOs, NOT an argument about Monsanto!

First, some history: the first transgenic crop that was approved for consumption in the U.S. was the Flavr Savr tomato in 1994.  This tomato was designed to delay ripening after being picked to prolong its shelf-life for shipping.  This was done by silencing the plant enzyme polygalacturonase, which breaks down pectin in the cell wall, making the fruit susceptible to fungal infection.  Flavr Savr tomatoes failed because of the business model of the company producing it.

Then came Bt corn, named for the integration of genes from the bacterial species Bacillus thurigiensis, a soil-dwelling bacteria historically used as a pesticide.  This bacteria is an awesome pesticide because it produces a Cry protein, which paralyzes the digestive tract of insects and they starve to death.  Boom.  Nature.  I know it sounds scary, but the important thing here is that the Cry proteins bind to specific receptors in the insect gut - these receptors only exist in Bt susceptible insects.   HUMANS DO NOT HAVE THESE RECEPTORS.  So if you were to happen to consume some of this bacteria, it wouldn't do anything to you.  Likewise, corn that has been modified to express Cry proteins is only harmful to the bugs eating it, not to the humans eating it.  Bt corn has been accused of killing off monarch butterflies and bees, which has been found to be untrue.

Ah yes, then came Golden rice.  In my third year of university, I sat in my plant physiology class hearing about golden rice for the first time.  I was in complete awe, and in that moment I decided I wanted to be involved in biotechnology in one way or another.  Golden rice was modified to produce beta-carotene, a precursor of vitamin A.  The idea was to prevent vit A deficiency, which is caused by malnutrition, and kills almost 700 000 children under the age of 5 annually.  Naysayers argued and argued against golden rice, first saying there wasn't enough vitamin A being produced, so scientists went in and made new strains producing even more beta-carotene.  Then came the arguments that the use of golden rice would create a slippery slope for more widespread GMO use.  Because that's the real concern, forget the millions of people who are affected by vitamin deficiencies.  Golden rice is still being argued over, but has generally been shown to have sufficient levels of beta-carotene, and that the levels are better than those in spinach, or in the supplements anti-GMO activists recommend instead of golden rice.

Update (March 15th, 2014): the delay in making Golden Rice available has cost 1.4 million life years lost since 2002 in India alone.  This accounts not only for those people who have died from vitamin A deficiency, but also productivity losses for people who have vitamin A deficiency-associated blindness and health disabilities.  This accounts for approximately $199 million (USD) in economic losses, PER YEAR in India alone!

Now some of the more common arguments I hear against GMOs are along the lines of "how are the genes able to kill bugs but magically don't affect humans, I don't buy it."  This is a legitimate argument someone made to my sister about GMOs.  When she read it to me, I chuckled and replied "not magic, science!"  See, the problem is that science literacy is very very low among the general public.  But genes and proteins that are toxic to humans and animals are well known and easily identified in short-term lab studies.  Making a genetically modified crop is not just making a guess and hoping for the best.  No scientist is ever trying to get away with inserting compounds into plants that are going to kill humans.  That's a really quick way to lose your funding and your lab.
There's also an ick factor about eating a plant that's been infused with bacterial genes, like Bt corn.  But the thing is, there's bacteria all over all of your food at all times.  You eat the food, and some of the bacterial genes get integrated into the genomes of your internal bacterial flora.  That's just a natural process.  It happens if you eat organic food too.

Clearly, given the length of this post, I could talk about this all day.  Bear with me, I have one last point to make.  Genetic modification has been going on for thousands of years.  Plant breeding is genetic modification, and farmers have been using breeding to enhance traits in crops.  The large size of an ear of corn is not something that was found naturally, it was created by breeding.  Anti-GMO activists argue that breeding is safer than lab-based modifications.  But they're not.  See, when you make a modification in the lab, you modify ONE gene or pathway, and you have to perform test after test after test to prove its safety before you can even apply to do field trials, then more testing before your crop is approved for human consumption.  But when farmers breed plants, all kinds of genes are being modified or affected, and there are no tests to prove safety or efficacy.  

Of course, I completely understand the skepticism, it's your body and you deserve to know what you're putting into it.  But I'm also a scientist who works in this stuff, so I understand the process, and all the thinking that goes into making GMOs.  In fact, the more people understand the science behind the process, the more they come to agree about the benefits of GMOs.


  1. Love this post! :) I am currently in a Biotech program in College! Though there wasn't to much venture into GMOs (didn't know about the bacteria for corn), though I knew there was an abundance of corn that are GMO.

  2. No... Selective breeding is NOT genetic modification. Selective breeding doesn't alter an organisms genome (genome is sum total of species' genes). Selective breeding simply raises or lowers the frequency (how often they occur) of those genes.

    GMOs on the other hand, or rather GE (genetically engineered) organisms change an organism's genome through physically altering DNA.

    Selective Breeding = 100% same genes in genome (different frequency).
    GMO's = Altered (or MODIFIED) genome by adding or deleting genes.

    In addition to this glaring and important difference, there has been a VERY RECENT discovery that some amino acids code for gene expression as well as protein synthesis. It has become CLEAR that every GMO made to date is coding correctly for proteins, but incorrectly for gene expression. With 41% of GE genes making to the next generation (% from GE salmon who bred with local trout and salmon) this is a serious problem and shows without a doubt we don't know enough about amino acids and DNA to be permanently changing the world's genome.

    Sometimes being a scientist means being pragmatic, like you attempted with this article, but other times it involves fighting ignorance, like I just did.

    1. Can you provide a link (or article title or author) to this very recent discovery? Because I'd like to check it out, as you've explained it, it makes no sense, but I'm sure there is some validity to it. I just can't make a judgement on that information based on my limited knowledge of it.