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Synthesis/Regeneration 21   (Winter 2000)

Of Cabbages and Cancer

by Henry Robertson, Gateway Green Alliance

Agribusiness corporations and their genetic engineers assure us that it's safe to grow and eat their products. But these biotechnological masters of the universe may be overlooking threats to human health. Two possible threats emerge in separate reports from the United Kingdom.

The Joint Food Safety and Standards Group of the British Ministry of Agriculture, Fisheries and Food (MAFF) warned the US Food and Drug Administration in a letter dated December 4, 1998, about the spread of antibiotic-resistant genes which are commonly used as markers in genetic engineering.

Because it takes place at the submicroscopic level, it's impossible to see if a gene splice is successful. A "marker" gene attached to the transgenetic material makes detection possible. In the case of an antibiotic resistance marker, you expose the target cells (e.g. bacteria) to an antibiotic. You then know that whichever cells survive have incorporated the transgene with its accompanying marker.

...not a good idea at a time when doctors are finding a growing number of disease strains, including tuberculosis bacteria, that are resistant to all known antibiotics.

When genetically modified seeds are planted in fields, the marker gene will still be in every cell of the growing plant. MAFF warned, "The widespread use of transgenics carrying antibiotic resistance marker genes will involve a massive amplification of these genes in the biosphere." This is not a good idea at a time when doctors are finding a growing number of disease strains, including tuberculosis bacteria, that are resistant to all known antibiotics.

The MAFF letter reported that bacteria in the environment can take up the antibiotic resistance genes and "could also act as a gene pool that may interact with human pathogens." Recent publications show that pathogenic bacteria can carry transgenic DNA into mammalian cells. Bacteria in the human mouth and respiratory tract can also incorporate foreign DNA.

MAFF used the example of the ampicillin resistance marker gene, which deactivates penicillin and similar antibiotics. It is used in genetically engineered maize in a "disrupted" form, meaning that it is not expressed. However, it is highly mutable and so could be reactivated in bacteria and possibly become resistant to a wider spectrum of antibiotics.

The second development was reported by Dr. Mae-Wan Ho of the biology department of the Open University in a letter to the British Society of Plant Breeders dated July 13, 1999. Dr. Ho discussed the possible link between the cauliflower mosaic virus (CaMV) and human cancer.

Part of this virus is used as a "promoter" in nearly all genetically modified plants now being marketed or field-tested. Foreign genes won't work unless accompanied by a genetic promoter that the host cell will respond to and activate the new gene. Viruses are strands of DNA or RNA with a protein coat. Incapable of surviving or replicating on their own, they invade other cells and use their life processes. Conveniently for genetic engineers, viruses have evolved powerful promoters to commandeer the genetic machinery of their host cells.

The CaMV promoter is "naked" DNA, without the protein coat. The intact virus, including the coat, is host-specific—it infects cabbages and cauliflower, not human beings. But the naked promoter may be able to invade mammalian cells. Dr. Ho cited the example of DNA from the human polyoma virus which can infect rabbits while the intact virus is harmless.

Foreign DNA usually degrades inside a cell unless it integrates into the cell's genome. The CaMV promoter has a "recombination hotspot" which lets it easily slip into the cell's own DNA so that it can divide and reproduce along with the cell itself. "Integration of foreign DNA into the genome of mammalian cells is well-known to have harmful effects such as inactivation or activation of host genes that could lead to cancer," wrote Dr. Ho.

Another potential hazard of having the cauliflower viral promoter in the genome is that it could reactivate dormant viruses, which are in the genomes of all higher organisms including plants and animals, or it could generate new viruses by recombination. The CaMV is known to be closely related to human hepatitis B virus and also to retroviruses including HIV and others that cause cancer.

DNA is wild; it resists being turned into a corporate assembly line. Once a changed organism is released into the environment all the patents in the world won't bring it back. Corporate mastery over nature and corporate concern for the public good are the profit motive's bluff, corrupting science and putting the gene pool at risk..

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