James and the Giant Corn Genetics: Studying the Source Code of Nature

October 22, 2009

Agriculture in Popular Culture: CSI Miami

Filed under: biology,Entertainment — Tags: — James @ 7:54 pm

Sorry for missing my daily post yesterday. Still trying to get over whatever I caught last week.

Last week, 13.3 million people watched CSI Miami in prime-time. That’s more people than live in the state Illinois. It doesn’t consider reruns, Tivo recordings, or piracy.** So to the untrained eye (mine), it seems likely the show is making enough money to hire a scientific consultant or two. Clearly the untrained eye is wrong and budgets are so tight that that the expense of finding someone who’d taken intro biology anytime in the past fifteen years was far too much. As demonstrated in this weeks episode “Bad Seed.”

Before I continue, let me say first of all I’m not one of CSI:Miami’s regular viewers. They don’t have to worry about losing me as a fan. I never was one. Second, I don’t get angry when shows like Fringe or the SyFy (<–that’s really how they spell their name now) Channel’s disaster and/or monster movie of the week completely mangle science. They are, and acknowledge themselves to be, science fiction. Shows based on fictional science. On the other hand, shows such as the CSI and Law&Order families set fictional stories in what, we are supposed to believe is, the  real world. As such, the burden on them to get their facts straight is much stronger.

A burden the writers of CSI Miami clearly can’t be bothered to live up to. (Oh, if it wasn’t obvious already, spoilers ahead).

The plot goes like this: A woman comes into the hospital and then dies, afterwards they discover her body tests positive for e. coli and conclude she died of food poisoning. Then her boyfriend also gets sick and becomes paralyzed. The strain of e. coli that caused her death is traced to an organic farmer whose irrigation water is contaminated with excrement from a local cattle farm. It turns out the boyfriend ate sweet corn from the same farm that was genetically engineered to produce an enzyme that breaks down cellulose to make corn kernels more digestible. Except the enzyme was isolated from a species of bacteria related to Clostridium botulinum, the bacteria that makes botulin, the toxin that can kill people who eat improperly prepared foods and is used to make old people’s faces less expressive through controlled paralysis (botox). So through the magic of bacteria conjugation, the fictional transgenic corn will occasionally start producing toxin, killing whoever eats it.

Let’s take it apart step by step shall we?

  1. Her body tests positive for e. coli, therefore she was killed by food poisoning! Unfortunately for the logic of the story, I defy you to find a person who wouldn’t test positive for e. coli. The bacteria can be found in the gut of almost every warm blooded animal. Mostly it’s harmless, which is why a diagnosis of the e. coli as causing the food poisoning would require a bunch of cases with each person carrying not just e. coli, but the same exact sub-strain of the bacteria. Otherwise it’s impossible to tell normal e. coli living in symbiosis with the human body from new pathogenic (disease causing) e. coli.
  2. We found e. coli on the farm therefore this is the source of the infection. As mentioned above, almost any farm will have e. coli present at some level, especially organic farms that get their fertilizer from animal excrement that has (by definition) recently been in the gut of a warm blooded animal, primarily cows and pigs. That’s why the key to the recent outbreak of food poisoning from spinach was the identification of the same sub-strain of e. coli (O156:H7) on a farm owned by Mission Organics, as had sickened more than 200 people across the country, killing 5 of them.
  3. Breaking down cellulose makes sweet corn more digestible, so let’s put in a trans-gene to do that. Yes, people can’t digest cellulose. That’s why even if you are starving you shouldn’t try to eat grass. It will likely make you throw up, which will put your body in even worse shape. However since we as a species have had to survive for millions of years, we’ve learned to eat foods we can digest because instead of cellulose their energy is stored as sugars, carbohydrates or protein. Everything from soybeans, to eggplant, to corn. Corn kernels are full of energy to fuel a new corn seedling. Plants can’t extract energy from cellulose any more than we can (plants use cellulose as a building material, not to store energy), so the energy a plant gives to its offspring has to be in other forms, like starch and oil that are as useful to people as they would be to the seedling. Unless people suddenly start munching on corn cobs or chewing corn leaves, being able to digest the cellulose in corn isn’t going to make corn better to eat.  (The only reason I can think of to want to express a cellulose digesting enzyme in corn would be for biofuels production, and the episode clearly states that the trans-gene was to make corn better to eat and feed people.)
  4. Since we took a gene from a species related to the one that produces botulism toxin, the corn we put the gene into could start producing botulism toxin (or anything else the bacteria or any of its relatives produce) at any time. One gene->one RNA->one protein.*

I’m going to break out of the list format here, because I have a lot to say about point 4. A gene is an individual part of the genome a living thing inherits from its parents. Different genes within the genome contain the code needed to make a singe protein that performs some function in the cell.

Think of the genome as an engineering library. Each gene is a book (with blueprints) about how to make a single machine from a universal set of parts found in every living cell. People from the town around the library (the rest of the cell) come in, make photocopies of books, and using the copies to build all the different machines they need. Through inter-library loan (genetic engineering) a book on how to build a rototiller arrives from a second library. Now the people in the town around the first library (the rest of the cell) know how to make rototillers and can use this new machine to turn over laws that they’ve decided to replant with vegetables and native prairie plants.

The book on how to make rototillers was previously stored in the second library as a book on how to build patriot missiles, but that doesn’t mean that getting the book on rototillers will tell the cell how to build missiles. Even if the second library messes up and sends the book on patriot missiles instead of the book on rototillers, it will be immediately obvious since its easy to check whether there’s a book on how to build a rototiller on the shelves(checking the DNA sequence), check for the presence of rototillers themselves around the library(checking for the protein),  and even look for whether land is getting churned up so new things can be planted (assays for activity of the protein). The town fails any of these checks, the scientist knows something was wrong (whether the wrong book was sent, or it was damages in transit, or put somewhere deep on the shelves where no one could find it), and he or she will get rid of the failed experiment and start over.

(Sorry that took so long but the problem with the truth is that it’s usually more complicated to explain than a well crafted lie.)

In summation genes only do single, specific things. The made-up cellulose digesting enzyme of CSI Miami is encoded for by a single  (also made up) gene, botulism toxin by another gene somewhere else in the genome. After a gene is moved, you check to make sure the gene is what you think it is, and it’s doing what you expect it to be doing. There is absolutely no way moving a gene that tells a plant how to degrade cellulose could make a plant produce botulism toxin. Plants don’t know how to make that toxin, and unless someone specifically puts the gene that encodes for botulism toxin (not anything else) into them, they can’t learn how to.

It’s a stupid and easily catchable error from a show that claims to show fictional stories set in the real world. I haven’t touched any of the various evil characters the show had trying to cover up the evil toxic corn. The crime on these shows is supposed to be fictional. If they decide they want to make farmers, seed companies, and government regulators look bad, that’s their business. But when they mislead people about the fundamental science behind their stories that I and people like me will have to work hard to fix, as a Graduate Student Instructor, as (hopefully one day) a professor or lecturer, and as a scientific advocate online (what I’m doing right here).

*This is called the central dogma of biology. Which is a horrible term because it’s not dogma in the religious sense. Scientists celebrate finding exceptions to the rule, like ribozymes which are RNAs that are encoded by genes but instead of making a protein ribozymes perform some task in the cell themselves.

**Although I hope anyone smart enough to figure out how to illegally download off the web is smart enough to see the problems with this weeks episode


  1. Sweet corn is a particularly interesting choice for this terribly illogical fictional transgene insertion. Sweet corn is already missing an enzyme required for production of normal starches which are found in commercial corn. This is why its sweet.

    I wonder what most people make of this. I suppose it speaks to how little people know about where their food comes from.

    Comment by Greg — October 22, 2009 @ 9:06 pm

  2. I think you’re right on with that last point. People know less and less about agriculture and food production. That makes it hard to distinguish plausible fiction from scary nonsense.

    Comment by James — October 22, 2009 @ 9:39 pm

  3. I didn’t know the difference between sweet corn and field corn until I showed up to work at a field corn lab in MN and someone showed me the two plots side by side. And now I’m working on our food supply, bwahaha! (sorry, the evil laugh doesn’t help our cause, does it?)

    The financial incentives to produce a transgenic sweet corn are so low – less than 1% of all corn planted is sweet corn. You could perhaps get an return on investment for great farmer incentive trait like Bt (I think Bt sweet corn was developed but never went to market), but only because a lot of the regulatory legwork was already done. The likelihood of getting a ROI for a weak consumer incentive trait like “we made this perfectly digestible corn slightly more digestible” is zero.

    Comment by Amy — October 24, 2009 @ 12:22 am

  4. Can you restate your argument in one paragraph?

    I saw FOOD, Inc. and though I am not able to follow the science I get the point: agribusiness is messing with our food supply and we do not know the long-term effects.

    CSI Miami drew our attention to this fact; so it was true in that sense (and some of it may have been factual). The point was not to teach us biology but to draw our attention to what is going on with Monsanto, ADM and all the rest.

    I appreciate your posting, however. But if you could rephrase it for us pop culture folk who have high school science back grounds, I, for one, would appreciate it.


    Comment by Rose — November 2, 2009 @ 5:09 pm

  5. The episode said genetic engineering was things that it isn’t. Because the show is supposed to be set in the “real world” it probably scared a lot of people with pseudo-science and hand-waving.

    (I tried to explain HOW it was pseudo-science and hand-waving in the above post, but I can’t explain why something is scientifically wrong without science itself.)

    That said, there are plenty of things to be worried about in our nation’s food supply. But this show got people upset about the wrong things. I don’t think lying to people is the right way to get them more interested in where their food comes from.

    That’s my position in six sentences. Please let me know if I can do anything more to address your questions or if I simplified too much. The point of this blog is to reach out to people not actively involved in doing research, but I’m still feeling my way into the role.

    Comment by James — November 2, 2009 @ 5:41 pm

  6. Hi,

    Between this episode and some other stuff I’ve heard about corn, I started wondering what all the concern is about corn lately. I thought the information on CSI seemed a bit off even before reading your article, but thanks for explaining it so well. Can you now help shine some light on why the corn industry has been getting such a bad reputation lately? I never imagined that eating plain corn on the cob could be bad for me. Am I being too naive, thinking there’s nothing wrong with all the fruits and veggies out there, while others will only eat organic (organic is way too overpriced for me)? Or are others being too paranoid?


    Comment by Lisa — November 4, 2009 @ 6:13 pm

  7. That’s a great question Lisa, and I don’t know the answer for sure. I’d guess corn’s reputation started to change as people in the US started to become more concerned about being overweight than about not having enough to eat.

    The major grains, especially corn, rice, and wheat are very good at producing lots and lots of calories. For most of human history that’s been a very good thing because there often wasn’t enough food to feed everyone who was hungry. But even though there are still 800 million people around the world who aren’t getting enough to eat, in the US we’re more concerned about getting too many calories and getting fat instead of not enough and starving. So things like corn, potatoes, rice, bread and pasta (the last two made from wheat) became “empty calories” because they give us lots energy that turns into fat if we don’t use it, and people became more interested in foods like spinach and tomatoes that don’t produce nearly as much food per acre or have as many calories, but have more vitamins and minerals.

    Add in the facts that corn is important in feeding animals at a time when more and more people are becoming vegetarians (often the same people who are interested in organic food) and that corn was the first crop to be genetically engineered (because it was and still is the biggest source of food in America) and it was easy for it to become a symbol to some people of what they don’t like about the way we produce food today.

    Corn is perfectly safe to eat. I never buy organic unless I can’t find the normal kind of food I’m looking for. Just make sure you also eat fruits and vegetables to get all the vitamins you need. And it’s completely ok if the fruits and vegetables are not organic, just be sure to wash anything you don’t peal before you eat (like apples and tomatoes). Even if they are organic it’s just as important to wash them because all sorts of things can get on fresh food before you buy it, and remember that organic farms use products based on animal manure to fertilize their plants.

    Be sure to ask if there’s anything else I can help out with.

    Comment by James — November 4, 2009 @ 6:46 pm

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