Effects of Feeding Bt Maize to Sows during Gestation and Lactation on Maternal and Offspring Immunity and Fate of Transgenic Material
December 16, 2012 6:28 AM   Subscribe

Effects of Feeding Bt Maize to Sows during Gestation and Lactation on Maternal and Offspring Immunity and Fate of Transgenic Material (FULL TEXT HTML) (PDF)

ABSTRACT
Background
We aimed to determine the effect of feeding transgenic maize to sows during gestation and lactation on maternal and offspring immunity and to assess the fate of transgenic material.

Methodology/Principal Findings
On the day of insemination, sows were assigned to one of two treatments (n = 12/treatment); 1) non-Bt control maize diet or 2) Bt-MON810 maize diet, which were fed for ~143 days throughout gestation and lactation. Immune function was assessed by leukocyte phenotyping, haematology and Cry1Ab-specific antibody presence in blood on days 0, 28 and 110 of gestation and at the end of lactation. Peripheral-blood mononuclear cell cytokine production was investigated on days 28 and 110 of gestation. Haematological analysis was performed on offspring at birth (n = 12/treatment). Presence of the cry1Ab transgene was assessed in sows' blood and faeces on day 110 of gestation and in blood and tissues of offspring at birth. Cry1Ab protein presence was assessed in sows' blood during gestation and lactation and in tissues of offspring at birth. Blood monocyte count and percentage were higher (P<0.05), while granulocyte percentage was lower (P<0.05) in Bt maize-fed sows on day 110 of gestation. Leukocyte count and granulocyte count and percentage were lower (P<0.05), while lymphocyte percentage was higher (P<0.05) in offspring of Bt maize-fed sows. Bt maize-fed sows had a lower percentage of monocytes on day 28 of lactation and of CD4+CD8+ lymphocytes on day 110 of gestation, day 28 of lactation and overall (P<0.05). Cytokine production was similar between treatments. Transgenic material or Cry1Ab-specific antibodies were not detected in sows or offspring.

Conclusions/Significance
Treatment differences observed following feeding of Bt maize to sows did not indicate inflammation or allergy and are unlikely to be of major importance. These results provide additional data for Bt maize safety assessment.
posted by Blasdelb (24 comments total)

This post was deleted for the following reason: This post is already borderline too-technical, and the comments are becoming pretty soapboxy. This would go a lot better on your own blog. -- LobsterMitten



 
I'm afraid I need a bit more context here, Blasdelb--what is Bt Maize?
posted by the young rope-rider at 6:34 AM on December 16, 2012 [1 favorite]


...what is Bt Maize?
Genetically-modified corn.
posted by Thorzdad at 6:35 AM on December 16, 2012


Bacillus thuringiensis (or Bt) is a soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted from the bacterium and used as a pesticide. Modernly, the genes responsible for the production of the toxin have been inserted into various crops (both food crops and non-food crops such as cotton), making them resistant to certain insects.

The toxins produced by strains of Bt are highly specific. Often they affect only a single species or narrow group of species of insect larvae, and must be ingested to be effective. Different versions of the toxin proteins are used for different kinds of pests. Thus, the effect on non-pest species (e.g. beneficial insects and pollinators) is greatly reduced compared to traditional insecticides.
posted by jedicus at 6:39 AM on December 16, 2012 [3 favorites]


I don't care, not eating that shit or any of its derivatives. (Preety difficult task, mind you!)
posted by Neekee at 6:40 AM on December 16, 2012


Can anyone from the field assess the analysis and significance and tell us if there's any shady dealings in the research? I'm pretty good at reading scientific articles in a general sense but I'm not familiar with the tests or biological models.
posted by gusandrews at 6:45 AM on December 16, 2012


I don't care...

Just make sure you don't mistake that for "I care and you should too!" Because a lot of people who don't have running water or a grocery store within 1000 miles are going to be very interested in anything that puts food on their plates, regardless of how first-world hippies feel about it. Not picking on you, Neekee. Just using your comment as a springboard.
posted by cthuljew at 6:46 AM on December 16, 2012 [6 favorites]


Bt maize is a variant of corn, genetically altered to express the bacterial Bt toxin, which is poisonous to insect pests. In the case of corn, the pest is the European corn borer. Over the past couple years they have added traits against Corn ear worm, and Root worm. The gene being expressed comes from the microorganism Bacillus thuringiensis. It encodes for a toxin that in the very specific conditions of Lepidopteral (an order of caterpillar) larval digestive tract crystallize into hard sharp crystals that puncture the critter from the inside out. These pores allow naturally occurring enteric bacteria, such as E. coli and Enterobacter, to enter the hemocoel, where they multiply and cause sepsis. This all sounds really vicious, unless you are a farmer whose livelihood is endangered by corn borers.

The Bt toxin has been used commercially since the 1920s and is pretty much the perfect pesticide, it is not stable in the environment, its toxicity is incredibly specific, it is very effective even in very low concentrations, and resistance does not readily develop. Researchers have been working with the genetics of the Bt toxin since the seventies, and people have been eating recombinant Bt toxin producing organisms for almost 20 years with no meaningful ill effects found so far.
posted by Blasdelb at 6:50 AM on December 16, 2012 [13 favorites]


"Can anyone from the field assess the analysis and significance and tell us if there's any shady dealings in the research? I'm pretty good at reading scientific articles in a general sense but I'm not familiar with the tests or biological models."

Well, the authors were funded through European science grants, and had no competing interests to declare if that is what you mean. The biggest weakness of this study would the relatively small sample size, using an N=24, but this is entirely appropriate to the model system they used (pigs are both cute and expensive) and the statistical tests look entirely standard and appropriate to me anyhow.
posted by Blasdelb at 6:55 AM on December 16, 2012 [6 favorites]


I found this mention of previous studies interesting:

Differences in immune response have previously been observed in sheep following Bt maize consumption for three years [52] and in mice after 30 and 90 days of Bt maize consumption [43]. Similar to results from our study, biological significance of these findings was also questioned by the authors and the inconsistency in results between studies is likely to be due to the use of different animal models. However, while neither of the above studies investigated Cry1Ab-specific antibody production, our results, as well as those of Adel-Patient et al. [53] for mice, indicate that no antibodies to the Cry1Ab protein are produced as a result of oral exposure to Bt MON810 maize.
posted by mecran01 at 7:13 AM on December 16, 2012 [1 favorite]


cthuljew: "I don't care...

Just make sure you don't mistake that for "I care and you should too!" Because a lot of people who don't have running water or a grocery store within 1000 miles are going to be very interested in anything that puts food on their plates, regardless of how first-world hippies feel about it. Not picking on you, Neekee. Just using your comment as a springboard.
"

yeah, because the colonial techniques that allowed the USA to put virtually every 3rd-world farm out of business are suddenly going to disappear now that we can make bug-proof corn.
posted by rebent at 7:17 AM on December 16, 2012 [3 favorites]


I am a biologist, but not this kind of biologist, which may be why the abstract was unclear to me. After skimming the article, the tl;dr is that genetically modified corn does not cause an allergic reaction in pigs. Since pig digestive tracts are similar to humans, this suggests that humans also aren't allergic to it.

The biggest weakness of this study would the relatively small sample size, using an N=24

12, no?
posted by Tsuga at 7:20 AM on December 16, 2012 [3 favorites]


Very interesting, thanks Blasdelb.
posted by jeffburdges at 7:21 AM on December 16, 2012 [1 favorite]



Many issues conflated in the discussion about GMOs. This is one good, peer reviewed study that appears to be tainted neither with Big Ag money, nor ideologically-anti GMO food prejudice, indicating that this material is safe under a small range of conditions.

It does not address Big Ag practices, colonialism, priorities of the food-industrial complex, philosophy of GMOs, the west's sins, hippies, organic foods superiority (or lack of), scaling of food production, capitalism, energy, food-miles, cultural dilution of native practices, and any of the much more complex issues that face a technology like GMOs.

Let's try and keep these issues separate when discussing the results and worth of the study.
posted by lalochezia at 7:23 AM on December 16, 2012 [11 favorites]


The problems caused by Bt crops aren't to do with inflaming pigs' stomachs or ours. In fact, this is so far off topic it's almost like saying "cigarettes don't increase the chances of athlete's foot".

I'm concerned about the development of resistance to Bt (which is happening, and which deprives organic farmers of a crucial insecticide: they spray pure Bt as a last resort). I'm worried about the effect of an indiscriminate insecticide on other insects (the effects of which are more contested). I'm worried that transfer to wild crops spreads artificially inserted genes without any way to recall them (and that's happening too).

lalochezia suggests we keep these issues separate. Fine. But let's not mistake this for any kind of evidence that GM crops are unproblematic.
posted by imperium at 7:36 AM on December 16, 2012 [8 favorites]


Reductionism has been leveraged do many very powerful things, in this case to improve the productivity of corn seed.
Holism reminds us that all of the implications haven't been considered, and in fact, can't be computed before the fact.

In the long view, genetic engineering of crops is a new tool. We should use it very carefully, as lab tests can not find all of the implications. We should carefully label where it is used, the results of it, and note in a central public database all of the results, good and bad.

The tools to allow for anecdotal evidence to be collected into a coherent whole are absent, in my mind. Things like metafilter are better than slashdot, reddit, etc... but insufficient for long term knowledge gathering.

There has to be something even better.....
posted by MikeWarot at 8:06 AM on December 16, 2012 [1 favorite]


This paper has also been accepted for publication by the Journal Of The Proceedings Of The Academy To Selectively Breed Bt-resistant Insects.
posted by the painkiller at 8:11 AM on December 16, 2012 [2 favorites]


Let's try and keep these issues separate when discussing the results and worth of the study.

Pretty hard, given that this study by itself is not really that meaningful to the layperson unless you have conflated its subject matter with the validity of Monsanto-style GMO as an approach to food production in general.
posted by parudox at 8:12 AM on December 16, 2012


imperium:"I'm concerned about the development of resistance to Bt (which is happening, and which deprives organic farmers of a crucial insecticide: they spray pure Bt as a last resort)."

The paper you linked to discusses the developing resistance of the corn root worm (Diabrotica virgifera virgifera) to a specifically designed recombinant alteration to the Bt toxin that was transgenically introduced into corn. The ordinary Bt toxin is ineffective against the corn root worm and impossible to apply to them in a meaningful way conventionally anyway, this will have precisely zero effect on what resistance organic farmers may see.

imperium:"I'm worried about the effect of an indiscriminate insecticide on other insects (the effects of which are more contested)"

Contested is putting it mildly:
A case of “pseudo science”? A study claiming effects of the Cry1Ab protein on larvae of the two-spotted ladybird is reminiscent of the case of the green lacewing
A recent report on the potential negative impact in a laboratory setting of the Cry1Ab protein on larvae of the two spotted ladybird Adalia bipunctata (Schmidt et al. 2009) has gained notoriety. It was used in Germany, along with some other studies supposedly showing a negative impact of the transgenic MON810 maize on non-target organisms, to temporarily ban the cultivation of this Bt-maize under a safeguard clause conforming with Article 23 of the EU directive 2001/18/EC. This decision, although officially communicated as based on new evidence, was in fact based on flawed science and has been recognized to be politically motivated by a number of the stakeholders involved (Sinha 2009). The present temporary ban of MON810 by the German Government will now be considered by the EU commission, which will consult the European Food Safety Authority (EFSA), and then decide on the merits of the scientific data. Whether the ban will then be lifted or not lies within the commitological decision making process within the European Union. The data on A. bipunctata was first published in the Proceedings of the German Society for General and Applied Entomology half a decade ago (Schmidt et al. 2004). Thus, it does not even constitute “new evidence”.

Laboratory toxicity studies demonstrate no adverse effects of Cry1Ab and Cry3Bb1 to larvae of Adalia bipunctata (Coleoptera: Coccinellidae): the importance of study design.
Scientific studies are frequently used to support policy decisions related to transgenic crops. Schmidt et al., Arch Environ Contam Toxicol 56:221-228 (2009) recently reported that Cry1Ab and Cry3Bb were toxic to larvae of Adalia bipunctata in direct feeding studies. This study was quoted, among others, to justify the ban of Bt maize (MON 810) in Germany. The study has subsequently been criticized because of methodological shortcomings that make it questionable whether the observed effects were due to direct toxicity of the two Cry proteins. We therefore conducted tritrophic studies assessing whether an effect of the two proteins on A. bipunctata could be detected under more realistic routes of exposure. Spider mites that had fed on Bt maize (events MON810 and MON88017) were used as carriers to expose young A. bipunctata larvae to high doses of biologically active Cry1Ab and Cry3Bb1. Ingestion of the two Cry proteins by A. bipunctata did not affect larval mortality, weight, or development time. These results were confirmed in a subsequent experiment in which A. bipunctata were directly fed with a sucrose solution containing dissolved purified proteins at concentrations approximately 10 times higher than measured in Bt maize-fed spider mites. Hence, our study does not provide any evidence that larvae of A. bipunctata are sensitive to Cry1Ab and Cry3Bb1 or that Bt maize expressing these proteins would adversely affect this predator. The results suggest that the apparent harmful effects of Cry1Ab and Cry3Bb1 reported by Schmidt et al., Arch Environ Contam Toxicol 56:221-228 (2009) were artifacts of poor study design and procedures. It is thus important that decision-makers evaluate the quality of individual scientific studies and do not view all as equally rigorous and relevant.

Is the German suspension of Mon810 maize cultivation scientifically justified?
Besides, transgenic applications of pesticide are pretty much the opposite of indiscriminate, especially when compared to conventional spraying.

imperium:"I'm worried that transfer to wild crops spreads artificially inserted genes without any way to recall them (and that's happening too)."

This represents a fundamental misunderstanding of the article you linked to. Round-Up resistance genes are not spreading from crops to weeds, if anything the transfer was the other way around. The genetic materiel for Round-Up Ready products came from weeds that were growing outside of a Monsanto factory producing glyphosphate, which were then put into crop plants. In this case, GMOs are not accelerating the pesticide treadmill but simply catching up to it. Similarly, recombinant genes probably are leaking out into the environment, where they are quickly selected against absent the human intervention that makes them useful to us, but this has been the state of affairs for the last eight to ten thousand years of agriculture. GMOs are harnessing pretty much the exact same forces that turned inedible wild bananas into one of the worlds major crops and a largely useless grass into corn; the biggest difference is that we are actually paying attention.
posted by Blasdelb at 8:15 AM on December 16, 2012 [5 favorites]


because the colonial techniques that allowed the USA to put virtually every 3rd-world farm out of business . . .
Rather strong claim. Got a cite?
posted by quadog at 8:19 AM on December 16, 2012


"I'm afraid I need a bit more context here, Blasdelb--what is Bt Maize?"

Also, thanks for asking. I try to shoot for average internet science nerd in making posts but it is sometimes hard to tell where that is.
posted by Blasdelb at 8:19 AM on December 16, 2012 [1 favorite]


rebent: "because the colonial techniques that allowed the USA to put virtually every 3rd-world farm out of business . . ."

quadog: "Rather strong claim. Got a cite?"

They are probably referring to the Green Revolution, which has saved billions of lives from the mass starvation that would have otherwise been inevitable in the 70s and 80s, prevented a political world defined by a scarcity of food and wars to acquire and defend it, created a meaningful food independence in most of the 3rd world replacing the desperate handouts that would have quickly run out, and paved the way for a world defined instead by food security. All largely due to the selfless work of the greatest man who has ever lived.
posted by Blasdelb at 8:37 AM on December 16, 2012 [4 favorites]


[blasdelb, please cool it and let the discussion flow on its own.]
posted by LobsterMitten (staff) at 8:41 AM on December 16, 2012


I'm concerned about the development of resistance to Bt (which is happening, and which deprives organic farmers of a crucial insecticide: they spray pure Bt as a last resort).
Well, the idea is that you can use a lot less total BT if you use the GMO crops, so you're actually less likely to have Bt resistance.

Anyway, the whole GMO thing just seems like something it isn't really worth arguing about - if people want to be paranoid about what they eat... okay? It doesn't really affect me in any way. It's somewhat annoying but ultimately who cares? It's not like global warming denial which is destroying the planet.

The thing is though you can never "prove a negative" (or really disprove an existentially qualified statement), so even though this study proves one thing, people will stay Bt corn might cause some other problem. And the trouble is that even if nothing is there, some studies might find something just through statistical noise.

One thing I think about though is that there are so many natural substances we eat that no one ever thinks might be bad. Take the whole sucrose vs. HFCS thing. If it's true that your body does react differently to a mix of fructose/glucose then it does to sucrose (which I doubt) then why assume that it's HFCS that's somehow worse? Couldn't it actually be the case that sucrose is actually worse?
They are probably referring to the Green Revolution, which has saved billions of lives from the mass starvation that would have otherwise been inevitable in the 70s and 80s, prevented a political world defined by a scarcity
Well, people would argue that actually the earth is overpopulated now and that by saving those people from starvation all we've done is made the problem worse. I don't agree with that at all, personally. It totally ignores the fact that in terms of pollution a single westerner actually causes far, far more then a typical third world person.
posted by delmoi at 8:46 AM on December 16, 2012 [3 favorites]


...a lot of people who don't have running water or a grocery store within 1000 miles are going to be very interested in anything that puts food on their plates...

As long as it's only poor people who're forced to eat it, we're OK!
posted by DU at 8:46 AM on December 16, 2012


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