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September 12, 2007 | 6,812 views

Scrambling and Gambling with the Genome

By Jeffrey M. Smith, author of Seeds of Deception

Advocates of genetically modified (GM) food often use this popular analogy: "With genetic engineering, transferring genes from one species‘ DNA to another is just like taking a page out of one book and putting it between the pages of another book."

The words on the page of their hypothetical book are comprised of the four letters, or molecules, of the genetic code, which line up in "base pairs" along the DNA. The inserted page represents a gene, whose code produces one or more proteins. The book is made up of chapters, which represent chromosomes-large sections of DNA.

The analogy makes the process of genetic engineering appear to be as simple and precise as inserting a new page.

Is It Really That Simplistic?

A groundbreaking report, however, shreds the book analogy. Written by three UK scientists and published in Biotechnology and Genetic Engineering Reviews, it reveals that the process of genetic engineering results in widespread mutations-within the inserted gene, near its insertion, and in hundreds or thousands of locations throughout the genome. And these mutations are overlooked by many scientists and regulators. [1]

The report is an extensive review of research that overturns the central arguments by biotech advocates-that the technology is precise, predictable, and safe, and that current studies are adequate. As it turns out, these arguments are not true at all. On the contrary, this report demonstrates that GM crops represent a significant gamble to public health and the environment (see

Gene Insertion Methods Create Absurd Changes

There are two popular methods for creating GM crops. Both create mutations.

The first method uses Agrobacterium-bacteria that contain circular pieces of DNA called plasmids. One section of this plasmid is designed to create tumors. Under normal conditions, Agrobacterium infects a plant by inserting the tumor-creating portion into the plant‘s DNA.

Genetic engineers, however, replace the tumor-creating section of the plasmid with one or more genes. They then use the altered Agrobacterium to infect a plant‘s DNA with those foreign genes.

The second method of gene insertion uses a gene gun. Scientists coat thousands of particles of tungsten or gold with gene sequences and then shoot these into thousands of plant cells.

Years ago, sequences that were shot into cells included genes intended for transfer (gene cassettes) as well as extraneous DNA from the plasmid, used for creation and propagation of the cassettes in bacteria. These days, many scientists take the added step of removing the extraneous, mostly bacterial DNA, and coat the particles with just the cassette.

Scientists speculate that both methods trigger wound responses in the plant cell, helping its DNA integrate the foreign gene. Only a few cells out of thousands incorporate the "foreigner" with the gene gun technique.

Per the book analogy, a single, intact, foreign page (gene) is inserted. That‘s the intention anyway.

In reality, most transformed DNA end up with many copies of foreign genes, or partial genes and/or gene fragments. Sections of inserted genes are commonly changed, rearranged, or deleted in the insertion process. Plus, extraneous pieces of plasmid DNA sometimes intermingle in and around the inserted gene, or scatter throughout the genome.

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Mutations Near the Site of Insertion

Besides changes made in the inserted material, sections of the plant‘s DNA near the insertion site are frequently messed up in some way. This effect, called insertional mutagenesis or insertion mutation, has been known for years. But it wasn‘t until 2003 that a large-scale systematic analysis was conducted.

Researchers looked at insertions into 112 Arabidopsis thaliana plants-a species used often in plant research. [2] Although the study may not accurately reflect what happens in edible crop plants, it is the only large study at this point.

Selected plants had single copies of the foreign gene, inserted with Agrobacterium.

Eighty of the 112 plants (71%) developed small mutations near the insertion site. Mutations included deletions of 1-100 base pairs and/or insertions of 1-100 extraneous base pairs. Inserted sequences came from the foreign gene, extraneous parts of the plasmid, or other parts of the plant‘s DNA.

The remaining 32 plants (29%) acquired large scale insertions, rearrangements, duplications and/or deletions. In two plants, parts of whole chromosomes broke off and translocated into another section of the DNA.

Another study using the same plant species also found that a section of DNA at least 40,000 base pairs long translocated from one chromosome to another. That long section actually duplicated itself, since it was also found intact in its original position. [3] A third study identified a deletion of 75,800 base pairs, which probably contained 13 genes. [4]

As stated, the above studies used the Agrobacterium insertion method. Astoundingly few studies analyze insertion mutations with the gene gun method. But the conducted research consistently demonstrates large scale disruptions of the DNA.

According to the Econexus report, "The vast majority of insertion events created via particle bombardment [gene gun] are extremely complex, with multiple copies of transgenic DNA inserted at a single insertion-site."1 They contain large amounts of extraneous DNA, multiple fragments of the foreign gene, and/or small or large fragments of plant DNA interspersed with the inserted genes. In one study, scientists found 155 separate breaks indicating recombinations of the inserted genetic material. [5]

As per the Econexus report, in rare cases where only a single copy of the foreign gene is inserted, they still "turn out to contain fragments of superfluous DNA and/or they appear to be associated with large deletions and/or rearrangements of the target plant DNA."

One study on gene gun insertion revealed that DNA of an oat plant contained:

Analysis also indicated that the plant‘s DNA on either side of the insertion contained rearrangements or deletions. And, there were two other insertions elsewhere in the DNA. One contained a rearranged section of the plasmid (296 base pairs), scrambled plant DNA on either side, and the deletion of 845 base pairs.

The study employed DNA sequence analysis, the most thorough method for evaluating insertion mutations. In practice, it is rarely used.

Instead, genetic engineers traditionally rely on the less precise Southern blot test, which picks up only major changes in DNA sequence. When this test was applied to the oat DNA above, it indicated the presence of only a single intact inserted gene, and failed to identify two other insertions and all the mutations and fragments.

So on the whole, biologists who create GM plants have no idea of the extent to which their creations may produce unintended side effects due to scrambled DNA.

"Location, Location, Location" -- Not Just True in Real Estate

Neither gene insertion method is able to "aim" the foreign gene into a particular location in the DNA. Furthermore, scientists rarely conduct experiments to find out where exactly the inserted genes end up.

But in the real estate of the DNA, location is vital. The functioning of the foreign gene can change dramatically depending on where in the genome it is located. The side effects of gene insertion can be significantly influenced by location as well.

Although only an estimated 1-10% of plant DNA makes up the genes, Agrobacterium insertions end up inside functioning gene sequences 35%-58% of the time. (The percentage for gene guns is unknown.) Genes are also inserted in other areas that influence gene expression. In either case, insertions can significantly disrupt the normal functioning of the plant‘s genes.

One reason insertions end up inside genes so often is that for the foreign genes to function, they need to locate in the regions of the host DNA that are "active," that allow for gene expression. To learn which inserted genes end up in active portions, scientists typically add an antibiotic resistant marker (ARM) gene to the genetic cassette.

After insertion, scientists apply antibiotics to all the cells to kill those without a functioning ARM gene in their DNA. Since the active region of the DNA is also where the plant‘s functioning genes are located, those that survive this selection process are more likely to have foreign genes lodged inside the host genes.

Mutations All Over the DNA Landscape

Once genes are inserted into a plant cell‘s DNA, scientists typically grow the cell into a fully functioning plant using a method called tissue culture. Unfortunately, this artificial method of plant propagation results in widespread mutations throughout the genome.

In fact, tissue culture is sometimes used specifically to create mutations in plant DNA. These mutations can influence the crops‘ height, resistance to disease, oil content, number of seeds, and many other traits. [7],

Genetically modified cells that undergo tissue culture can have even more mutations throughout the genome than cultured non-GM cells. It is unclear why gene insertion has this effect, but scientists speculate that it may, in part, come from unsuccessful insertions or insertions of small fragments.

The process of gene insertion combined with tissue culture typically results in hundreds or thousands of mutations, including small deletions, substitutions, or insertions in the genetic code. The changes are vast. Two studies suggested that 2-4% of the genome of a GM plant was different than non-GM controls.[9],[10]

Furthermore, estimates are based on detection methods that miss many mutations such as short deletions and insertions and most base pair substitutions. Thus, the actual degree of gene disruption is probably greater.

These genome-wide mutations are found in every GM plant analyzed. Astoundingly, these types of mutations are not even evaluated in commercially released GM food crops.

If the original GM plant is crossed (mated) with other lines repeatedly, many of these small, genome-wide mutations are corrected. It is unknown, however, how many mutations still persist in food crops. And the propagation of certain species, like the GM potato that was on the market years ago, probably did not undergo any outcrossing. So it is likely to contain all of the mutations created during insertion and tissue culture.

The Serious Consequences of Mutations

Mutations and extraneous insertions carry risk. They can permanently turn genes on or off, alter their function, and/or change the structure or function of the protein that they create.

A single mutation can influence many genes simultaneously. The insertion process might:

Because of our limited understanding of DNA, even if we knew which parts were disrupted, we don‘t necessarily know the consequences.

In addition, the insertion of bacterial plasmid DNA into plant DNA creates another serious risk.

Similarities in the genetic sequence between the plasmid and the DNA of human or animal gut bacteria or soil bacteria might significantly increase the likelihood of horizontal gene transfer -- meaning that plant genes may transfer into the DNA of the soil or gut bacteria.

The only human feeding study on genetic engineering confirmed that the genes inserted into GM soybeans do transfer into the bacteria inside human intestines.

Advocates of biotechnology often defend the safety of their products by claiming that modern methods of plant breeding other than genetic engineering are used on a wide scale, have a history of safe use and create comparable mutations.

The Econexus report reveals that everything about this argument is pure speculation and is not supported by scientific literature. There is no evidence that these modern methods are used widely, are consistently safe, or create mutations of the same kind or frequency as genetic engineering.

In reality, many biotech scientists are unaware of the massive quantity of mutations that are generated by the GM transformation process (gene insertion and tissue culture).

In fact, the regulatory agencies that approve GM foods operate as if the insertion process has no impact on safety. [11],[12] They don‘t require extensive evaluation of the mutations. Therefore the extent of these in approved GM food crops has not been identified.

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The few studies that were conducted revealed many significant problems. GM varieties contain truncated or multiple fragments of the inserted gene and extraneous or scrambled DNA. The protein produced by the foreign genes can also be truncated, altered, or fragmented.

Many significant differences between GM and non-GM crops have been observed, which may result from the insertion process.

But GM crops are tested for only a handful of nutrients or known toxins, and therefore the true impact of gene mutations is not known.

Furthermore, GM plants are grown in huge quantities. Undetected alterations may result in harm to the environment or human health on an unprecedented scale. With so little known about the impact of gene insertion and with so much at risk, applying genetic engineering to food and crops is a huge gamble.

Let‘s Revise That Book Analogy, Shall We?

With genome scrambling in mind, let‘s revise the book analogy as follows:

The DNA is like a large book with the letters consisting of the four molecules that make up the genetic code. Located throughout the book are special one- to two-page passages, called genes, which describe characters called proteins (including enzymes). The book is divided into chapters called chromosomes.

When a single foreign page (gene) is inserted through the process called genetic engineering, the book goes through a profound transformation.

As a result of changes in the story line throughout the book, several characters (proteins) act differently, sometimes switching roles from heroes to villains, or vice versa. It all makes you wonder about the comment made by the biotech advocate as he handed you the volume, "It‘s just the same old book, only with a single page added."

CLICK HERE to help write a "book" that‘s worth reading - for the sake of your health and everything you put in your mouth.

You can help by making a donation today to the Institute for Responsible Technology (IRT). Donations support vitally-needed campaign efforts to create GM-free schools, GM-free communities, and GM-free manufacturers by providing written and audio-visual materials, web support, and guidance to local campaigns.

Spilling the Beans is a monthly column available at Publishers and webmasters may offer this article or monthly series to your readers at no charge, by emailing Individuals may read the column each month by subscribing to a free newsletter at

Jeffrey M. Smith is the author of the new publication Genetic Roulette: The Documented Health Risks of Genetically Engineered Foods, which presents 65 risks in easy-to-read two-page spreads. His first book, Seeds of Deception, is the top rated and #1 selling book on GM foods in the world.

He is the Executive Director of the Institute for Responsible Technology, which is spearheading the Campaign for Healthier Eating in America. Go to to learn more about how to avoid GM foods.

[1] Allison Wilson, et. al., "Transformation-induced mutations in transgenic plants:
Analysis and biosafety implications," Biotechnology and Genetic Engineering Reviews - Vol. 23, December 2006.

[2] Forsbach A, Shubert D, Lechtenberg B, Gils M, Schmidt R (2003) A comprehensive characterisation of single-copy T-DNA insertions in the Arabidopsis thaliana genome. Plant Mol Biol 52: 161-176.

[3] Tax FE, Vernon DM (2001) T-DNA-associated duplication/translocations in Arabidopsis. Implications for mutant analysis and functional genomics. Plant Physiol 126: 1527-1538.

[4] Kaya H, Sato S, Tabata S, Kobayashi Y, Iwabuchi M, Araki T (2000) hosoba toge toge, a syndrome caused by a large chromosomal deletion associated with a T-DNA insertion in Arabidopsis. Plant Cell Physiol 41(9): 1055-1066.

[5] Svitashev SK, Pawlowski WP, Makarevitch I, Plank DW, Somers DA (2002) Complex transgene locus structures implicate multiple mechanisms for plant transgene rearrangement. Plant J 32: 433-445.

Makarevitch I, Svitashev SK, Somers DA (2003) Complete sequence analysis of transgene loci from plants transformed via microprojectile bombardment. Plant Mol Biol 52: 421-432.

[7] Dennis ES, Brettell RIS, Peacock WJ (1987) A tissue culture induced Adh2 null mutant of maize results from a single base change. Mol Gen Genet 210: 181-183.

Brettell RIS, Dennis ES, Scowcroft WR, Peacock WJ (1986) Molecular analysis of a somaclonal mutant of maize alcohol dehydrogenase. Mol Gen Genet 202:235-239.

[9] Bao PH, Granata S, Castiglione S, Wang G, Giordani C,Cuzzoni E, Damiani G, Bandi C, Datta SK, Datta K, Potrykus I, Callegarin A, Sala F (1996) Evidence for genomic changes in transgenic rice (Oryza sativa L.) recovered from protoplasts. Transgen Res 5: 97-103.

[10] Labra M, Savini C, Bracale M, Pelucchi N, Colombo L, Bardini M, Sala F (2001) Genomic changes in transgenic rice (Oryza sativa L.) plants produced by infecting calli with Agrobacterium tumefaciens. Plant Cell Rep 20: 325-330.

[11] NRC/IOM: Committee on Identifying and Assessing Unintended Effects of Genetically Engineered Foods on Human Health (2004) Safety of Genetically Engineered Foods: Approaches to assessing unintended health effects. The National Academies Press, Washington, DC.

[12] Kessler DA, Taylor MR, Maryanski JH, Flamm EL, Kahl LS (1992) The safety of foods developed by biotechnology. Science 256: 1747-1832.

© Copyright 2005 by Jeffrey M. Smith. Permission is granted to reproduce this in whole or in part.