Guest guest Posted September 1, 2004 Report Share Posted September 1, 2004 > 1 Sep 2004 12:39:19 -0000 > Synthetic Genes in Food Crops > press-release > > > The Institute of Science in Society Science Society > Sustainability http://www.i-sis.org.uk > > General Enquiries sam Website/Mailing > List > press-release ISIS Director > m.w.ho > ======================================================== > > > ISIS Press Release 01/09/04 > Synthetic Genes in Food Crops > ********************* > > Prof. Joe Cummins explains why genes inserted into > GM crops > are not " substantially equivalent " to genes in their > native > state > > A fully referenced version of this article is posted > on ISIS > members' website > http://www.i-sis.org.uk/full/sgigmcFull.php. > Details here > http://www.i-sis.org.uk/membership.php. > > > In North America, genetically modified (GM) foods > unlabeled > and untested are taking over the food supply. Such > foods are > promoted on the fiction that the foreign genes - > usually > taken from bacteria and viruses - inserted into GM > crops are > " substantially equivalent " to the natural genes. > > In reality, the genes used to create GM crops are > synthetic > approximations of the natural genes. They contain > synthetic > DNA sequences tuned to maximize production of > foreign > proteins in the plant, such as toxins killing > insects or > enzymes degrading herbicides, which also provide > firm patent > protection on the GM crop. Synthetic genes are used > because > the genes actively expressed in bacteria or humans > are not > very active in crop plants. There are several ways > to solve > the problem. > > The first is to adjust the DNA code to suit the > 'codon bias' > typical of the crop plant species into which genes > from > bacteria or mammals are introduced. > > The genetic code is made up of 64 three letter > codons > (triplets, or code words) for twenty amino acids > plus words > for translation start and stop. Some amino acid such > as > methionine (met) and tryptophan (tryp) have only one > codon, > while arginine (arg), leucine (leu) and serine (ser) > each > have six codons. The degeneracy of the code allows > for > alternative DNA sequences for a single protein. The > frequencies with which different codons are used > vary > between groups of organisms, which is why genes from > > bacteria are poorly read in higher plants (and vise > versa). > For optimum gene expression, the code for a > transgene often > needs to be rewritten to achieve adequate > performance. The > number of possible gene sequences that can code for > a single > protein is staggering, it is estimated to be about > five > times ten to the 47th power. That number is within > three > orders of magnitude of the number of atoms making up > earth > and five times larger than the number of water > molecules on > earth. In synthesizing the genes used in GM crops, > say, in > altering a Bacillus thuringiensis (Bt) Cry toxin > gene for > plants, a table of plant-preferred codons is used to > > substitute the plant preference for the bacterial > preference. > > Sometimes it is necessary to substitute one or more > of the > amino acids so that the final Cry toxin can function > in the > plant cell environment. As plant genetic engineering > has > " advanced " , the crucial active domains of toxins and > enzyme > are defined and " improved " to such an extent that > the > original source protein from living organisms is > hardly > recognizable. > > A third modification of the transgene is in the > regulatory > sequences (frequently referred to as cis elements) > such as > promoters, introns and transcription termination > signals, > which are usually taken from higher plants or their > viral > and bacterial pathogens. Synthetic promoters have > also been > created, loosely based on the cauliflower mosaic > virus > (CaMV) commonly used in plant genetic engineering. > The use > of synthetic genes in food crops has not been taken > into > account sufficiently in the regulatory approval of > the food > crops. In spite of the obvious differences between > the > synthetic and the natural genes from which they > arose, > regulators have allowed the genes and proteins > produced in > bacteria to be considered appropriate surrogates in > safety > testing for the synthetic genes and the proteins > produced in > food crops. This exposes the unhealthy collusion of > corporations and their regulators. > > There seems to be a convenient fiction propagated by > > corporations, government bureaucrats and academics > who > depend on grant money from corporations and > government, that > genes from bacteria are used in producing food crops > or that > genes from humans are used to produced plant > biopharmaceuticals, when, in fact, the genes used > are > synthetic approximations to the real things. Even > the courts > seem to have accepted this convenient fiction as > fact. > > The next generation of GM crops is evolving towards > a > minimal assembly of active protein domains (domains > are > active area of proteins that serve as signals for > activates > such as toxicity or enzyme function or environment > sensors > for regulation) that are frequently patched together > from a > number of different proteins. Safety testing is > based, once > again, on unreal surrogates and the products are not > labeled > in the marketplace so that subtle changes caused by > a few > amino acid changes or failure to heed secondary > protein > modifications such as glycosylation will be > difficult to > trace as people are adversely affected by consuming > the > synthetic products in GM crops. > > It is imperative that the synthetic genes and their > products > be tested thoroughly, not only for potentially toxic > side > effects but for stability and recombination > properties as > well. These synthetic genes have not had an > evolutionary > history and it is a major mistake to assume that the > genes > can be expected to behave in all ways like the genes > that > they were built to represent. > > > ======================================================== > > This article can be found on the I-SIS website at > http://www.i-sis.org.uk/ > > If you like this original article from the Institute > of > Science in Society, and would like to continue > receiving > articles of this calibre, please consider making a > donation > or purchase on our website > > http://www.i-sis.org.uk/donations. > > ISIS is an independent, not-for-profit organisation > dedicated to providing critical public information > on > cutting edge science, and to promoting social > accountability > and ecological sustainability in science. > > If you would prefer to receive future mailings as > HTML > please let us know. If you would like to be removed > from our > mailing list at > > http://www.i-sis.org.uk/mailinglist/.php > ======================================================== > > CONTACT DETAILS > > The Institute of Science in Society, PO Box 32097, > London > NW1 OXR > > telephone: [44 20 8643 0681] [44 20 7383 3376] > [44 20 > 7272 5636] > > General Enquiries sam Website/Mailing > List > press-release ISIS Director > m.w.ho > > MATERIAL IN THIS EMAIL MAY BE REPRODUCED IN ANY FORM > WITHOUT > PERMISSION, ON CONDITION THAT IT IS ACCREDITED > ACCORDINGLY > AND CONTAINS A LINK TO http://www.i-sis.org.uk/ > > Quote Link to comment Share on other sites More sharing options...
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