sábado, enero 23, 2010

The Science Simplified: How genetic material from GMO corn finds its way to our gut

By Krista Beckley

There have been several reports recently about genetic material from GMO corn making its way into soil, animals and insects. (The study these reports refer to appeared in the Journal of Chemical Ecology in July - Hart et. al 2009) The concept of how these genes enter into other organisms and food systems is often convoluted, and worth laying out again for readers who may have questions.

However the implications for the uptake of certain genes into the food system could have far reaching effects on human health well before scientists are aware of what is actually going on.

The process of how genes move from crops, for instance RoundupReadyⓇ corn, to the environment is not an effect of the use of GMOs, it is a process that occurs naturally in every ecosystem because of bacteria. Bacteria is present in everything in the food system from the soil to the plants themselves. Bacteria undergoes what is called transformation- DNA is taken up through cell-to-cell connections and is utilized by the bacteria in several ways. It is generally believed that this occurs in order to aid the bacteria such that new DNA can help it evolve, gain higher fitness, or for other novel functions. The DNA during transformation does recombine with the bacterial DNA, however, this does not necessarily mean that the DNA will be expressed or change any function of the cell.

The concern raised by this recent study is that bacteria which undergoes transformation is also present in the gut of animals and insects. This means that even though the odds are low that the DNA taken up by eating plant material with transgenic modification will effect our gut cells, the possibility for a change in function of these cells is always there. Although this is true with anything we ingest, the human population has evolved with the plants we eat and thus problems associated with transformation are rare and due to novel genomes of food stuffs.

Although studies have yet to be conducted in large scale human populations, animals can uptake foreign DNA into the blood stream and intestinal cells (Schubbert et. al. 1993) and mice fed transgenic Bt crops have shown structural changes in their intestines (Fares, et, al. (1999). These findings are in addition to the fact that transgenic feed can alter the level of nutrients actually available for the body to use (Malatesta (2009)- which could, for instance, decrease the strength of the body to fight infection and disease.

The reality is that given the amount of transgenic food we eat over our lifetimes, the odds that our gut bacteria will take up the part of the DNA that has been altered -which could negatively effect the function of our cells- increases significantly. The implications for these radical alterations to our cells due to transgenic crops are not well studied. However, it is well known that these constant assaults on our gut bacteria can lead to higher mutation rates of cells- which can lead to higher rates of disease and cancer.

Fares, Nagui H. and Adel K. El-Sayed (1999). Fine Structural Changes in the Ileum of Mice Fed on -Endotoxin-Treated Potatoes and Transgenic Potatoes. Natural Toxins Vol. 6 Iss. 6, 219-233.

Hart et. al.(2009) Detection of transgenic cp4 epsps genese in the soil food web. Agron. Sustain. Dev. 29, 497-501.

Malatesta, M. (2009). Animal feeding trails for assessing GMO safety: answers and questions. Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 4, 068, 1-13.

Schubbert, R., Lettmann, C., Doerffler, W. (1994). Ingested foreign (phage M 13) DNA survives transiently in the gastrointestinal tract and enters the bloodstream of mice. Mol. Genet. 242, 495

SOURCE: http://www.foodfirst.org/en/node/2763


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