Horizontal DNA transfer to gut bacteria
Posted: 12 July 2014
The industry frequently claims that its transgenes cannot survive digestion and thus could not end up ensconced in the human digestive tract.
In 2004, the only human transgenic feeding study on record was done to determine the accuracy of this claim -- i.e., does the body or its gut bacteria accept horizontal DNA transfers, common between bacteria. The potential consequences of its being inaccurate are immense, particularly the possibility of human gut bacteria taking in the Bt insecticide producing gene.
Since the study itself is behind a paywall, I've included here a summary of it that someone took from one of Jeffrey Smith's talks. It will give you the idea. I've also included an excerpt from a German paper on the topic, and the abstracts of the study and several others, including one that found the foreign plant DNA in the blood of 900 people. But I have found no specific followup to the 2004 experiment.
Transform Your GI Tract Into a Toxic Factory
One obvious goal of genetic plant modification is to make the plant resistant to insects. This is commonly done by inserting a bacterial gene into the plant. This bacterial gene codes for a protein which is toxic to insects, such as the Bt gene from the Bacillus thuringiensis.
In 2004, Dr. Trudy Netherwood of Newcastle University studied the fate of these ingested plant genes (GM soya) after human ingestion. However, before even starting the study, Dr. Netherwood found copies of the plant trans-genes already colonizing the gut bacteria of 3 of 7 human subjects. Apparently, these three human subjects had already consumed food contaminated with GMO products, just like all the rest of us trusting consumers.
If you remember from high school biology class, bacteria have the ability to transfer genetic material from one to another, called horizontal gene transfer. What this means is that our friendly bacteria of the gut take up and incorporate the bacterial genes from GMO food and manufacture the protein instructed by the new code. These proteins are the expected toxins and pesticides coded by the trans-genes, as well as the totally unexpected protein byproducts inherent in today’s crude technology. Thus we have transformed our own GI tract into a toxic factory. An even greater problem arises for genes coding for antibiotic resistance which are commonly spliced into plants and used in the GMO manufacturing process. These genes coding for antibiotic resistance are then incorporated into our own gut bacteria. Thus we have created a new race of super antibiotic resistant bacterial organisms already in place waiting for a chance to cause an antibiotic resistant infection.
To make matters worse, not only is the new genetic code from GMO food incorporated into friendly gut bacteria, it is also incorporated into the epithelial cells of the GI tract, and the liver. Dr. Netherwood's work was confirmed in a 2006 study by Dr. Sharma in Alberta Canada who found that transgenic DNA from Roundup Ready Canola Meal could be found in the gut epithelial tissues [and some visceral organs] of pigs eating the GMO meal.
Roundup Ready Soybean -- Reapproval in the EU? 2007
From page 9:
As different works have pointed out, ingested DNA is not immediately and completely decomposed, but is able to enter the gastrointestin al tract and the cells of different organs and possibly also microorganisms. DNA fragments as big as several hundred to over one thousand base pairs that are found in food are able to survive not only the gastrointestinal passage, but can also enter the peripheral leukocytes, spleen and liver cells, and even overcome the placental barrier and reach the cells of foetuses and new-born mice. The ingested tagged DNA was found in cell nuclei, partly bound to chromosomes (Schubbert et al. 1997, 1998, Doerfler 2000). It is largely unknown whether transgenic promoter sequences are active in the case of DNA ingestion by cells in mammalian systems. The focus here is on the 35S CaMV promoter, which controls transgene expression in the RR [Roundup-Ready] soybeans as well as in most of the GMOs authorised for commercial use. At the very least, it is active in cultivated human intestinal cells, as Myhre et al. (2006) have recently demonstrated. However, research into the possible activity of the se promoters in vivo is lacking, as Traavik & Heinemann (2007) determined in their critical study.
From page 10: Research Article
Simulated digestion trials with RR [Roundup-Ready] soybeans show that a part of the ingested transgenic DNA can also survive the passage through the human gastrointestinal tract (Martin-Orue et al. 2002). Netherwood et al. (2004), using individuals with colostomy bags, observed that, following the consumption of RR soy products, up to 3,7% of the transgenic DNA survived the passage through the small intestine. However, this percentage diminished during the pass age through an intact gastrointestinal system and the final intestine. In three of the seven test subjects using colostomy bags, evidence was even found of the transfer in bacteria of the gastrointestinal tracts of the transgenic EPSPS sequence, which, according to the authors, can’t have taken place during the test, but following a previous consumption of RR soy products. Consequently, the stability of transgenic DNA following consumption, as well as horizontal gene transfer, should be given greater attention (Heritage 2004, Traavik & Heinemann 2007).
[Note: I have linked the above reference to this, rather than to the original page (URL below) because it is behind a paywall and it is just as straightforward to offer the abstract here.]
Assessing the survival of transgenic plant DNA in the human gastrointestinal tract
Trudy Netherwood, Susana M Martín-Orúe, Anthony G O'Donnell, Sally Gockling, Julia Graham, John C Mathers & Harry J Gilbert
Nature Biotechnology 22, 204 - 209 (2004)
Published online: 18 January 2004 | doi:10.1038/nbt934
The inclusion of genetically modified (GM) plants in the human diet has raised concerns about the possible transfer of transgenes from GM plants to intestinal microflora and enterocytes. The persistence in the human gut of DNA from dietary GM plants is unknown. Here we study the survival of the transgene epsps from GM soya in the small intestine of human ileostomists (i.e., individuals in which the terminal ileum is resected and digesta are diverted from the body via a stoma to a colostomy bag). The amount of transgene that survived passage through the small bowel varied among individuals, with a maximum of 3.7% recovered at the stoma of one individual. The transgene did not survive passage through the intact gastrointestinal tract of human subjects fed GM soya. Three of seven ileostomists showed evidence of low-frequency gene transfer from GM soya to the microflora of the small bowel before their involvement in these experiments. As this low level of epsps in the intestinal microflora did not increase after consumption of the meal containing GM soya, we conclude that gene transfer did not occur during the feeding experiment.
News and Views
[This appears to be a response to the Netherword article above, but it, too, is behind a paywall, and there is little to suggest what it's conclusions are.]
The fate of transgenes in the human gut
John Heritage is in the Division of Microbiology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK. e-mail: email@example.com
Nature Biotechnology 22, 170 - 172 (2004)
Gut microbes that cannot be recovered in artificial culture may acquire and harbor genes from genetically modified plants.
Can transgenic DNA in a genetically modified (GM) crop be transferred to the people or animals that eat the crop or to their intestinal microflora (Fig. 1)?
[This article describes the use of very high-powered tools and sequencing to find significant foreign plant DNA in the blood streams of a sample of 900 people. The complete text is available from the PubMed link.]
Complete Genes May Pass from Food to Human Blood
Sándor Spisák, Norbert Solymosi, Péter Ittzés, András Bodor, Dániel Kondor, Gábor Vattay, Barbara K. Barták, Ferenc Sipos, Orsolya Galamb, Zsolt Tulassay, Zoltán Szállási, Simon Rasmussen, Thomas Sicheritz-Ponten, Søren Brunak, Béla Molnár, and István Csabai
Andrew Dewan, Editor
July 30, 2013
doi: 10.1371/journal.pone.0069805 PMCID: PMC3728338
Our bloodstream is considered to be an environment well separated from the outside world and the digestive tract. According to the standard paradigm large macromolecules consumed with food cannot pass directly to the circulatory system. During digestion proteins and DNA are thought to be degraded into small constituents, amino acids and nucleic acids, respectively, and then absorbed by a complex active process and distributed to various parts of the body through the circulation system. Here, based on the analysis of over 1000 human samples from four independent studies, we report evidence that meal-derived DNA fragments which are large enough to carry complete genes can avoid degradation and through an unknown mechanism enter the human circulation system. In one of the blood samples the relative concentration of plant DNA is higher than the human DNA. The plant DNA concentration shows a surprisingly precise log-normal distribution in the plasma samples while non-plasma (cord blood) control sample was found to be free of plant DNA.
NIH's Pub Med lists several articles that found no transgenic genes in the lower digestive tract or other parts of pigs and chickens, but the tools used for detection seem remotely less sensitive than what were used in the above article.