Wednesday, January 21, 2004

Gutbuster
Scientists led by Harry Gilbert at the university of Newcastle in the UK set out to study the survival of the transgene epsps from GM soya in the small intestine of human ileostomists -- people with a colostomy bag.

They found that DNA can survive to the small intestine, and that low frequency gene transfer to the gut microflora of gene fragments may have occurred.

However, the study showed that whole genes were not present in the microflora, and that it was unlikely that there was DNA transfer to the intestinal epithelial cells, and risk to human health was thought to be 'highly unlikely'.

Nature Biotechnology advanced online publication:
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.
Let's break this down, because I'm sure the media is going to confuse you about it.

1. First of all, a little DNA isn't going to hurt you. Don't panic. However,

2. The fact that DNA of any kind survives all the way into your small intestine is surprising.

3. But it's not like like it's going to do anything there -- stop freaking out about your frankencolon.

4. What is freaky (aside from #2 above) is the discovery that once that DNA gets into your intestine, it can be "taken up" by some (small fraction of) intestinal microflora. This is huge. Once the bugs get it, there's no telling what will happen to it. It's like a violation of the nonproliferation treaty.

5. The reason this is actually relevant is that some of the the genes you will find in GM crops confer antibiotic resistance. Whoops.

6. Finally, the hidden bombshell:

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.
In other words, this already happened to you.

Update: Alison Abbot has some, uh, deep background in the new Nature:

For better or worse, faeces provide the best window into the microbial life of the human gut....

The average human intestine contains about 1.2 kilograms of bacteria plus a smattering of yeasts. So far, few of these microbes have been characterized or even identified....

the Defense Advanced Research Projects Agency, a research arm of the US military, is sponsoring a project to read all the genomes in the gut ecosystem with the same 'shotgun' method used for the privately funded effort to sequence the human genome.

Bonus hed: Colonic closed shop

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