by Jeffrey Smith
23 February 2004
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The cauliflower mosaic virus (CaMV) promoter was found intact in rat tissues after a single meal, and was also confirmed to be active in human cells.
The full 1100 base pairs of the CaMV promoter was found:
*In stomach cells and in intestinal (mesenteric) lymph nodes two hours after eating;
*In mesenteric lymph nodes, kidney, and liver cells six hours after eating; and
*In mesenteric lymph nodes, spleen, and liver cells three full days after eating.
Future tests will determine if the CaMV is active.
Seven groups of six rats each were intragastrically intubated (fed through a tube to the stomach) with a balanced diet. Added to the a small portion of the diet was a single dose of a genetic construct similar to those used to create genetically engineered crops. This construct included a gene that codes for a green fluorescent protein. The negative control group had no promoter attached to the green fluorescent protein gene at all; the positive control used human cytomegalovirus promoter known to be active in all mammalian cells. The test group had the CaMV 35S promoter coupled to the gene. The design tested the DNA construct in both circular and linear form. A final control was not fed any DNA at all. About half of the CaMV fed rats in each of the circular and linear DNA groups were found to contain intact CaMV.
Tissue samples remaining to be tested will soon determine if the CaMV is active, causing the expression of the green fluorescent protein. In a separate but related study, the same three constructs described above were added directly to human intestinal epithelial cells (both small and large intestines), rat cells, and fish cells, in vitro. The fluorescent gene was expressed in all the cells tested.
Implications for human health
The CaMV promoter is attached to inserted foreign genes in nearly all genetically engineered foods. It overpowers the cells' own self-regulatory mechanisms so as to permanently turn on the foreign inserted gene and produce large amounts of the transgene proteins. Without the promoter, the gene would likely be dormant in the DNA, unexpressed. Scientists use the CaMV because it is aggressive and because it works in the DNA of all types of plants.
The assumptions used by biotech advocates as the basis of safety claims were that the CaMV:
* Is stable
* Will only turn on the gene to which it was attached
* Is plant specific and will not function in mammals, including humans, and
* Will not transfer from food to gut bacteria or internal organs;
Each of these assumptions have been contradicted.
1. Studies also show that the promoter creates a 'hotspot' in the DNA. This means that the whole chromosome can become unstable. This may cause breaks in the strand or exchanges of genes with other chromosomes. Research reported in June 2003 confirmed that genetically engineered crops exhibited broken DNA sections at the CaMV.
2. The CaMV promoter may turn on native genes over long distances up and down the strand of DNA. It can even turn genes on in a different chromosome. This can create a flood of proteins that may create toxins, allergens, carcinogens, or nutritional changes.
Some scientists believe that the CaMV promoter, in conjunction with other genetic material, might also create a growth factor that could result in excessive cell growth -- a potentially pre-cancerous condition. A study by Ewen and Pusztai demonstrated significant cell growth in the stomach and intestines of rats fed a genetically engineered potato. An Egyptian study also showed evidence of cell growth in rats fed a Bt potato, and a feeding study on genetically modified peas showed greater weights of rat intestines, supporting the possibility of extra cell growth.
While scientists believed that the aggressive nature of the CaMV promoter might have been responsible for these results, it was not confirmed whether the CaMV promoter was able to transfer intact to organs and whether it would be active in human cells.
The new evidence confirms the transfer and potential activity. The new evidence does not, however, show any specific links to cell growth, nor does it confirm that unstable hotspots or the turning on of dangerous genes will occur in mammalian DNA.
Waking Sleeping Viruses
Embedded into the DNA of many organisms, including humans, are ancient viruses that have worked their way in, perhaps in previous species. While most of this viral material has eroded, some may be complete but simply not turned on. In theory, the fact that the promoter can turn on genes up and down the DNA, combined with the fact that it can transfer to human or animal organs, means that it may be possible for it to turn on a previously dormant virus.
New findings: Terje Traavik PhD, +47 9581 7537, email@example.com
Further discussion: Jeffrey Smith in KL, 012-333-7495, firstname.lastname@example.org