miércoles, diciembre 24, 2008

This one is from On Line Opinion, Australia


Greg Revell

With the abrupt and uninvited introduction of genetically modified (GM) food into our supermarkets and restaurants, many of us are looking more closely into the food we eat.

Recently, Monsanto's apparent transformation from agrichemical giant to philanthropic institution was cynically trumpeted to the world's media: "We will double crops yields!" Such grandiose promises can only be offered if there is a parallel narrative that portrays genetic engineering as being able to permit the precise control of life processes and by extension, provide predictable and controllable agricultural outcomes.

The Biotechnology Industry Organization's public relations campaign explains:

Through modern methods found in biotechnology, researchers can accomplish the desired results, but in a more efficient and predictable manner (than in conventional plant breeding). In this process, a specific gene, or blueprint of a trait, is isolated and removed from one organism then relocated into the DNA of another organism to replicate that similar trait (my emphasis).

But are the techniques that give rise to GM foods as precise and controlled as the PR blurb suggests?

First of all, the scientist has to identify a gene that he or she believes will confer a trait to another organism. Using chemical shears, the foreign gene is cut and pasted into a viral "ferry". Viruses are used because of their unique ability to transfer genetic material across species boundaries, which is usually required in most GM products. To this viral vector are attached controversial "promoter" and "antibiotic-resistant marker" genes.

The entire package is duplicated many times, coated onto microscopic gold and tungsten "bullets" and literally blasted from a gene gun into the Petri dish containing the host cells. The scientist hopes upon hope that the entire package will be neatly inserted into the DNA of a host cell. Most miss their target. Some pass right through without delivering their payload leaving behind damaged DNA. Some cells end up with only portions of the package, some multiple copies. The fact that the DNA of the host organism can withstand such a violent barrage and survive relatively intact, says more of nature's resilience than the precision of the scientist.

Michael Antoniou, molecular geneticist at King's College London says of the biolistics process, "It's the imprecise way in which genes are combined and the unpredictability in how the foreign gene will behave in its new host that results in uncertainty. From a basic genetics perspective, GM possesses an unpredictable component that is far greater than the intended change."

READ THE REST AT: http://www.onlineopinion.com.au/view.asp?article=8283


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