Kernels of Truth: A team of Cal scientists came under attack from colleagues and biotech interests after finding modified DNA in native Mexican corn. They may be wrong, but given just how much is at stake, why hasn't anyone else bothered to ask the same question?
By Kara Platoni
May 29, 2002
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CHRIS DUFFEY - They call it maize: Did Ignacio Chapela and David Quist find genetic tinkering in Mexican corn?
David Quist found more than he was looking for. Two autumns ago, the UC Berkeley graduate student was working in Sierra Norte de Oaxaca in southern Mexico, preparing to lead a workshop for local farmers who had set up an agricultural science lab. The next day's lesson was on a technique to test seeds for evidence of genetic modification. For the exercise, workshop attendees were going to test corn purchased from the local government food store, much of which comes from the United States in this post-NAFTA age. To show his students what a positive signal would look like, Quist had brought along some transgenic corn DNA from the United States, where about forty percent of the crop is now genetically modified. To demonstrate a negative signal, he planned to use native corn, or criollo, grown in Oaxaca, the evolutionary cradle of the species. But while prepping for the workshop, Quist kept getting an alarming result: His negative control was testing positive. The native corn, it seemed, showed evidence of genetic modification.
What Quist saw was either inevitable or horrific, depending on whom you ask. Oaxaca is the center of genetic diversity for maize, and diversity is essential to the survival of a species. It's what keeps entire populations from being wiped out by a single blight, pest, or change in climate. But human tinkering has led to some unfavorable trends; 75 percent of the planet's natural genetic crop diversity has been lost over the last century, according to the UN Food and Agriculture Organization. Much of that loss has been attributed to the commercialization and globalization of agriculture. Transgenic crops -- those bearing genes from other species -- are considered a particular threat to diversity because they are engineered for survival, with special traits such as resistance to insects, chemical sprays, or harsh environmental conditions like salinity or drought. Bioengineering's critics say these very advantages could allow transgenic plants to take over and further homogenize the gene pool.
For Mexico, this is of particular concern. The Mexican government outlawed the planting of transgenic maize in 1998 to protect its national crop from cross-pollination, though it allows import of the gene-altered product as food and animal feed. Despite such regulations, environmentalists worry that modified crops could end up dominating the gene pool anyway, especially with a promiscuous, wind-pollinated species such as corn. Evidence of cross-pollination in remote Oaxaca did not augur well for the government's ability to keep transgenes out, and Quist says he fervently hoped what he was seeing was a false positive.
Quist's advisor, microbial ecologist and UC Berkeley associate professor Ignacio Chapela, suggested that he return home to retest his samples. Back in the team's laboratory at the university's Department of Environmental Science, Policy, and Management, the young researcher ran the maize through several more rounds of experimentation. While tests on two of the samples were negative, four of the six native corn samples indicated the presence of transgenes. Quist also tested a sample from the government food store, which came back strongly positive.
Specifically, Quist was finding a gene fragment from the cauliflower mosaic virus that is often used to boost the expression of newly introduced genes in engineered crops. He also believed he'd found other small DNA fragments common to transgenic crops, and evidence of a diversity of sequences flanking the viral DNA, which led him to conclude that the foreign genetic material had moved around to different parts of the genome, and was being passed from one generation of plants to the next via pollination. Quist and Chapela estimated that, based on their data, one to ten percent of native Mexican maize might be similarly affected.
A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces.
-- Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations, by A. PIÑEYRO-NELSON, J. VAN HEERWAARDEN, H. R. PERALES, J. A. SERRATOS-HERNÁNDEZ, A. RANGEL, M. B. HUFFORD, P. GEPTS, A. GARAY-ARROYO, R. RIVERA-BUSTAMANTE, E. R. ÁLVAREZ-BUYLLA
If correct, the team's conclusions could have profound ecological and political implications. Critics of genetic engineering warn that the invasion of transgenes into native varieties could provoke a host of negative effects: Such a crossover, they say, could create new allergens in food and further shrink agricultural gene pools, leaving whole crop populations vulnerable to destruction -- as occurred in the disastrous Irish potato famine of 1845-1851, during which an estimated 1.5 million people starved to death. Furthermore, they say, poor farmers could become even more dependent on multinational corporations for their seeds. In the case of maize, it's feared that transgenic pollen could mingle with corn's inedible Mexican ancestor, teosinte, turning it into a "superweed." Finding transgenic DNA in the hills of Oaxaca, which were supposedly a bastion of genetic purity, suggested to Quist that cross-pollination might be far worse in the valleys, where the country's industrial maize production is based.
The discovery that transgene fragments seemed to be appearing at different locations within the genome was perhaps even more significant. It undercut the very premise that genetic engineering is a safe and exact science, that once new DNA is introduced into a species, humans can know and control exactly where the gene goes, how it will be expressed, and if it will be passed on to other plants.
New genetics & hazards of genetic modification
The rationale and impetus for genetic engineering and genetic modification was the "central dogma" of molecular biology that assumed DNA carries all the instructions for making an organism. This is contrary to the reality of the fluid and responsive genome that already has come to light since the early 1980s. Instead of linear causal chains leading from DNA to RNA to protein and downstream biological functions, complex feed-forward and feed-back cycles interconnect organism and environment at all levels, marking and changing RNA and DNA down the generations. In order to survive, the organism needs to engage in natural genetic modification in real time, an exquisitely precise molecular dance of life with RNA and DNA responding to and participating fully in "downstream" biological functions. That is why organisms and ecosystems are particularly vulnerable to the crude, artificial genetically modified RNA and DNA created by human genetic engineers. It is also why genetic modification can probably never be safe.
1. Genetic modification done by human genetic engineers is anything but precise; it is uncontrollable and unpredictable, introducing many collateral damage to the host genome as well as new transcripts, proteins and metabolites that could be harmful.
2. GM feed with very different transgenes have been shown to be harmful to a wide range of species, by farmers in the field and independent scientists working in the lab, indicating that genetic modification itself is unsafe.
3. Genetic modification done by human genetic engineers is different from natural genetic modification done by organisms themselves for the following reasons: it relies on making unnatural GM constructs designed to cross species barriers and jump into genomes; it combines and transfers genes between species that would never have exchanged genes in nature; GM constructs tend to be unstable and hence more prone to further horizontal gene transfer after it has integrated into the genome.
4. Horizontal gene transfer and recombination is a major route for creating new viruses and bacteria that cause diseases and spreading drug and antibiotic resistance. Transgenic DNA is especially dangerous because the GM constructs are already combinations of sequences from diverse bacteria and viruses that cause diseases, and contain antibiotic resistance marker genes.
5. There is experimental evidence that transgenes are much more likely to spread and to transfer horizontally.
6. The instability of the GM construct is reflected in the instability of transgenic varieties due to both transgene silencing and the loss of transgenes, for which abundant evidence exists. Transgenic instability makes a mockery of "event-specific" characterization and risk assessment, because any change in transgene expression, or worse, rearrangement or movement of the transgenic DNA insert(s) would create another transgenic plant different from the one that was characterized and risk assessed. And it matters little how thoroughly the original characterization and risk assessment may have been done. Unstable transgenic lines are illegal, they should not be growing commercially, and they are not eligible for patent protection.
7. There is abundant evidence for horizontal transfer of transgenic DNA from plant to bacteria in the lab and it is well known that transgenic DNA can persist in debris and residue in the soil long after the crops have been cultivated. At least 87 species (2 % of all known species) of bacteria can take up foreign DNA and integrate it into their genome; the frequency of that happening being greatly increased when a short homologous anchor sequence is present.
8. The frequency at which transgenic DNA transfers horizontal has been routinely underestimated because the overwhelming majority of natural bacteria cannot be cultured. Using direct detection methods without the need to culture, substantial gene transfers were observed on the surface of intact leaves as well as on rotting damaged leaves.
9. In the only monitoring experiment carried out with appropriate molecular probes so far, China has detected the spread of a GM antibiotic resistance gene to bacteria in all of its major rivers; suggesting that horizontal gene transfer has contributed to the recent rise in antibiotic resistance in animals and humans in the country.
10. GM DNA has been found to survive digestion in the gut of mice, the rumen of sheep and duodenum of cattle and to enter the blood stream.
11. In the only feeding trial carried out on humans, the complete 2,266 bp of the epsps transgene in Roundup Ready soybean flour was recovered from the colostomy bag in 6 out of 7 ileostomy subjects. In 3 out of 7 subjects, bacteria cultured from the contents of the colostomy bag were positive for the GM soya transgene, showing that horizontal transfer of the transgene had occurred; but no bacteria were positive for any natural soybean genes.
12. The gastrointestinal tract of mammals is a hotspot for horizontal gene transfer between bacteria, transfer beginning in the mouth.
13. Evidence is emerging that genomes of higher plants and animals may be even softer targets for horizontal gene transfer than genomes of bacteria.
14. The CaMV 35S promoter, most widely used in commercial GM crops, is known to have a fragmentation hotspot, which makes it prone to horizontal gene transfer; in addition. it is promiscuously active in bacteria, fungi, as well as human cells. Recent evidence also suggests that the promoter may enhance multiplication of disease-associated viruses including HIV and cytomegalovirus through the induction of proteins required for transcription of the viruses. It also overlaps with a viral gene that interferes with gene silencing, an essential function in plants and animals that protects them against viruses.
15. The Agrobacterium vector, most widely used for creating GM plants is now known to transfer genes also to fungi and human cells, and to share genetic signals for gene transfer with common bacteria in the environment. In addition, the Agrobacterium bacteria as well as its gene transfer vector tend to remain in the GM crops created, thereby constituting a ready route for horizontal gene transfer to all organisms interacting with the GM crops, or come into contact with the soil on which GM crops are growing or have been grown.
16. In 2008, Agrobacterium was linked to the outbreak of Morgellons disease. The Centers for Disease Control in the US launched an investigation, which concluded in 2012, with the finding: "no common underlying medical condition or infection source was identified". But they had failed to investigate the involvement of Agrobacterium.
17. New GM crops that produce double-stranded RNA (dsRNA) for specific gene-silencing are hazardous because many off-target effects in the RNA interference process are now known, and cannot be controlled. Furthermore, small dsRNA in food plants were found to survive digestion in the human gut and to enter the bloodstream where they are transported to different tissues and cells to silence genes.
18. Evidence accumulated over the past 50 years have revealed nucleic acids (both DNA and RNA) circulating in the bloodstream of humans and other animals that are actively secreted by cells for intercommunication. The nucleic acids are taken up by target cells to silence genes in the case of double-stranded microRNA (miRNA), and may be integrated into the cells' genome, in the case of DNA. The profile of the circulating nucleic acids change according to states of health and disease. Cancer cells use the system to spread cancer around the body. This nucleic acid intercom leaves the body very vulnerable to genetically modified nucleic acids that can take over the system to do considerable harm.
-- Ban GMOs Now: Especially in the Light of the New Genetics, by Dr Mae-Wan Ho and Dr Eva Sirinathsinghji
The researchers knew their claims would be scrutinized closely when they published their results in the British journal Nature last November. After all, Quist says, the peer-review process had consisted of four rigorous reviews over an eight-month period by a team of anonymous experts. But no one could have predicted the magnitude of the controversy to come.
Over the past seven months, publication of the team's results has led to what some now call the "Mexican maize scandal." It has prompted Greenpeace to call for an investigation by the international Commission for Environmental Cooperation set up under NAFTA. It has left the Mexican government scrambling to confirm or deny the conclusions, and forced a prominent Mexico-based research center to defend the integrity of its gene bank. And it has fomented a contentious battle between prominent scientists and environmentalists, between those who would dismiss the study as junk science or defend Quist and Chapela as public-interest researchers victimized by an industry-led smear campaign to discredit them.
There certainly are huge sums at stake -- current industry estimates value the global commercial seed market at around $30 billion, and the market share for genetically modified seeds has grown exponentially. In 1996, just 1.7 million hectares of genetically modified (GM) crops were planted worldwide. In the past year alone, the figure jumped nineteen percent to nearly 53 million hectares, according to a report from ISAAA, a pro-biotech advocacy group.
But the biotech foods industry still has plenty of room for expansion. At present, nearly all GM crops are engineered for just a few traits: herbicide and pesticide tolerance, resistance to insects, or both, and 99 percent of all transgenic crops, the group reports, are grown in just four countries -- Argentina, Canada, China, and the United States, which alone accounts for 68 percent of the world's GM crops.
Consequently, much of the world is still an untapped market. This year, the industry is expected to seek removal of embargoes on genetically engineered seeds in Mexico, Brazil, and Europe. But growing public skepticism about the safety of genetically modified foods could cost industry leaders Pharmacia, DuPont, and Syngenta billions in potential earnings.
Supporters of this market tout bioengineering's equally vast potential benefits, saying it can boost the agricultural yields of Third World nations or help solve world hunger. As proof, they point to benevolent uses of genetically modified foods such as the "golden rice" project, in which the seeds for Vitamin A-enriched rice were given away to help combat malnutrition in developing countries. They also say genetically modified crops can have positive environmental effects by reducing the need for chemical pesticides, since insect resistance is built right into a plant's genetic code.
1. Bt crops claim to reduce pesticide use is based on excluding the Bt produced in the crops in total "pesticides applied"; but the Bt toxins leach from the plants and persist in soil and water, with negative impacts on health and the ecosystem comparable to conventional pesticides.The Bt toxins manufactured within the cells of Bt crops are not counted as insecticides “applied” on Bt-crop acres.
Clearly, this assumption underestimates the pounds of insecticidal compounds required to manage insects on Bt crop acres. Opinions differ among entomologists, the industry, and other experts on whether it is appropriate to count Bt toxins manufactured inside GE plants as equivalent to a liquid Bt insecticide sprayed on the outside of the plant. Uncertainty over the exact mode of action of Bt insecticides and GE toxins is part of the reason for differing opinions.
Those who argue that plant-manufactured Bt toxins should not count as equivalent to an applied insecticide assert that a Bt variety is just like any other new plant variety that has been bred to express some plant protein or phytochemical useful in combating insect-feeding damage.
Those skeptical of this position point to major differences in the two Bt delivery systems and in the source of the Bt toxin. Bt liquid sprays are applied only when and as needed, consistent with the core principles of IPM. Liquid sprays expose pest populations to short-lived selection pressure, thereby reducing the risk of resistance.
Bt plants, however, produce the toxin continuously during the growing season, not just when needed, and in nearly all plant tissues, not just where the toxins are needed to control attacking insects. In a year with low pest pressure, farmers can decide not to spray insecticides on a corn field, but they cannot stop Bt hybrids from manufacturing Bt toxins in nearly all plant cells.29
-- Impacts of Genetically Engineered Crops on Pesticide Use In the United States: The First Thirteen Years, by Charles Benbrook
-- Ban GMOs Now: Especially in the Light of the New Genetics, By Dr Mae-Wan Ho and Dr Eva Sirinathsinghji
While the Nature paper added fuel to an already hot global debate, it also had a deep local impact. The controversy renewed scrutiny of a 1998 decision by UC Berkeley's Department of Plant and Microbial Biology to sign a five-year, $25 million alliance with bioengineering giant Syngenta, then called Novartis. The deal granted the corporation first dibs on negotiating patent licenses on one-third of the department's discoveries regardless of whether or not those projects were financed with Novartis funds, and it gave the corporation two out of five seats on the department's research committee, leaving some researchers concerned that the university would be encouraged to produce research that favored genetic engineering and squelch studies that didn't. Although both sides of debate claim that their interest is in science and not politics, it's no secret that Chapela and Quist opposed the Syngenta deal, nor that some of their most vociferous critics have been their own colleagues from the Plant and Microbial Biology department located just across the campus in Koshland Hall.
After Nature published Quist and Chapela's study, it received four letters strongly criticizing the work. A team of referees vetted the letters, and Nature published two in April. One, drafted by Cal graduate student Nick Kaplinsky, was co-signed by a group of students and faculty primarily from the Plant and Microbial Biology Department. The second was drafted by postdoctoral fellow Matthew Metz, a recent Cal graduate now at the University of Washington, and signed by a colleague in Switzerland. Both letters claimed that Quist and Chapela mistook meaningless strings of DNA for transgenes and that their results were merely false positives, probably stemming from lab contamination. They accused the researchers of running afoul of scientific principles by failing to double-check their results and, more pointedly, accused them of allowing political convictions to sway their research conclusions. The study, Metz told The Washington Post, was nothing more than "mysticism masquerading as science."
Black Africans have paid a high price for the private paradises built by the whites on their homeland. The parks and reserves always lay claim to traditional tribal areas; they are never set up where whites have settled. Undeterred, Rob Soutter continued his lecture on the WWF's wondrous conservation projects and the "integration" of the blacks. In my mind's eye I pictured long columns of refugees. In Africa alone, 14 million people have been forcibly relocated to make room for wild animals: they are called "conservation refugees".
By that time my patience was running thin; I had enough of the small talk at WWF HQ on glittering Lake Geneva, with its yacht harbors and green wetlands, so I interrupted Rob's flow with a provocative request: "Could we film at the next Panda Ball?" Soutter's self-satisfied smile collapsed into a lopsided grin: "I think not. The guests appreciate discretion."
The Panda Ball is an annual event often held at Buckingham Palace in London, or some other royal venue. Attendance is restricted to the elite membership of The 1001 Club, a sort of WWF secret society. After Rob had regained his countenance, he simply shrugged off the subject: "The Club no longer has any significance -- we've only kept it going out of respect for the late Prince Bernhard of The Netherlands. It doesn't bring in as much money as some might think, either." As soon as the words had left his mouth, his eyes seemed to flash annoyance -- perhaps he was regretting his statement already.
The 1001 Club was founded in 1971 by then-President of WWF International Prince Bernhard of the Netherlands. The German-born prince recruited powerful businessmen worldwide to join the club, but also a few old comrades, whom he knew from his time in the elite Nazi Reiter-SS equestrian unit, and from his post at the Paris branch of the notorious IG Farben. To this day, the secretive WWF order numbers exactly 1001 "initiates" from across the globe. They generally maintain lifelong membership; when a vacancy arises, a select applicant is appointed to fill it.
Prince Bernhard himself remained member No. 1 until his death, aged 93, in 2004. The identities of the other 1000 have remained secret -- until the present day. Only a few names have slipped out over the years: Henry Ford, Baron von Thyssen, billionaire Muslim spiritual leader Prince Aga Khan, Prof. Bernhard Grzimek, US Secretary of Defense Robert McNamara, Fiat boss Agnelli, and various members of European royal families: an alliance of money, bloodlines, and the political elite.
The 1001 Club pays the salaries to maintain the WWF International central secretariat in Gland on Lake Geneva. That allows the international leadership to operate independently of the now 90 national WWF sections. The Panda Ball and other discreet get-togethers also offer a good opportunity for discussing the strategic focus of the world's largest conservation organization. The 1001 Club is no sub rosa WWF command center, to be sure. However it most definitely is an old boys' network with significant influence in the corridors of global corporate and policy-making power.
Rob Soutter wanted to know if I had a list of club members, and seemed relieved to hear that I did not. I knew then that I had to get ahold of that list. It could be the key to the inner sanctum of the WWF, and would also provide insight for the five million WWF members worldwide who still have no idea who really pulls the strings in the organization, and why. Their faith in the beneficent panda is, for the most part, unwavering....
Once a year the 1001 Club invites its members to the exclusive Panda Ball. One dines and discusses the future of the world in select company. Is the Club just a sentimental relict of the founding era with no significance for current WWF policy, as Rob Soutter tried to convince me in our meeting at WWF headquarters in Gland, Switzerland? If it really is just a harmless group of aging nature-loving aristocrats, why are their gatherings as secretive as the Cosa Nostra? Why do members pay a 25,000-dollar initiation fee? What unseen bonds exist amongst the elite 1001?
I knew that if I could get a look at the secret membership list it would help shed light on these matters. It wasn't easy, but after several months of patient research I finally held two editions of the mystery list in my hand -- one from 1978, the other from 1987. Both of them came from the estate of British journalist Kevin Dowling, whose early film about the African misadventures of the WWF was never aired. The two lists can now be found on the Internet.
The cover page of the membership list reads simply: The 1001 Members. Some of the names I was seeing for the first time, but most of them sounded familiar, because they were prominent amongst the world's political and financial elite. They included: billionaire Muslim spiritual leader Karim Aga Khan IV; Fiat boss Giovanni Agnelli; Lord Astor of Hever (president of The Times of London); Henry Ford II; Stephen Bechtel (Bechtel Group, USA); Berthold Beitz (Krupp); Martine Cartier-Bresson; Joseph Cullman III (CEO Philip Morris); Charles de Chambrun; H.R.H. Prince Philip, the Duke of Edinburgh; Sir Eric Drake (General Director of British Petroleum); Friedrich Karl Flick (Germany); Manuel Fraga-Iribarne (Franco's Minister of Information); C. Gerald Goldsmith; Ferdinand H.M. Grapperhaus (Dutch Undersecretary); Max Grundig (Germany); beer baron Alfred Heineken; Lukas Hoffmann (Hoffmann-La Roche); Lord John King (British Airways); Daniel K. Ludwig (USA); Sheikh Salim Bin Laden (elder brother of Osama Bin Laden); John H. Loudon (CEO Shell); Daniel K. Ludwig; Robert McNamara (Vietnam-era US Secretary of Defense); Maersk Mc-Kinney Moller (shipping magnate); Queen Juliana of the Netherlands; Keshub Mahindra (India); Harry Oppenheimer (Anglo American Corporation); David Rockefeller (Chase Manhattan Bank); Agha Hasan Abedi (President of BCCI Bank); Tibor Rosenbaum (Banque de Credit International, Geneva); Baron Edmond Adolphe de Rothschild (France); Juan Antonio Samaranch (Spain); Peter von Siemens (Germany); Baron Hans Heinrich Thyssen-Bornemisza (Switzerland); Dr. Joachim Zahn (Daimler Benz).
The 1001 Club membership lists available included a remarkably large share of South Africans. In addition to Anton Rupert, owner of Rothmans International and Cartier, a few dozen other leading lights of the apartheid regime -- almost all of them were former or present members of the white-supremacist group Broederbund. The only black African to have found his way into the elite white brotherhood was the Dictator of Zaire, Mobutu Sese Seko.
Most club members were previous or present top dogs in the oil or mining industries, banking or shipping.
-- Panda Leaks: The Dark Side of the WWF, by Wilfried Huismann
The criticism was so strong that Nature's editors asked Quist and Chapela to retest their samples by another method. It was an unusual request, but not unreasonable, says editor-in-chief Philip Campbell in an interview conducted by e-mail. "We believed it possible that such data were promptly obtainable and might resolve the fundamental issue, which was: Were the claims able to be substantiated?" he says. The researchers saw it differently, especially since Nature gave them just four weeks to produce new results -- a short time in the scientific realm -- and 300 words to respond to roughly 1,500 words of criticism. Chapela describes the exchange as "total bullying by Nature." Quist complains that the timetable was "unreasonably short." The new tests validated his original claims, Quist says, but since complete results weren't available by the magazine's deadline, he was forced to respond with a preliminary report.
One of Nature's peer reviewers was unconvinced. In the same issue that featured the critical letters from Kaplinsky and Metz, the magazine ran an editorial rescinding its support for the original paper. "In light of these discussions and the diverse advice received, Nature has concluded that the evidence available is not sufficient to justify the publication of the original paper," the editors wrote. "As the authors nevertheless wish to stand by the available evidence for their conclusions, we feel it best simply to make these circumstances clear, to publish the criticisms, the authors' response and new data, and to allow our readers to judge the science for themselves." It was an unprecedented move; for the first time in Nature's 133-year history, the journal had withdrawn support for an article without first calling for a retraction.
With all of the politics surrounding the study, it's easy to lose sight of the actual science. Quist and Chapela's experiment hinged on two main points: have transgenes crossed into native corn, and if so, do they fragment and move about the genome?
Although the latter point has been heavily attacked, there is little disagreement about the study's first conclusion. The United States ships six million tons of corn to Mexico every year, and despite Mexico's desire to preserve its strains of native maize, just about everyone agrees that some of it is bound to get planted and then cross-pollinate with its native neighbors. "That's kind of an obvious no-brainer," says Kaplinsky, noting that farmers often have an economic motivation to plant unsanctioned seeds. "In India, even though it's illegal, farmers there have been planting transgenic cotton, and in Brazil they've been planting transgenic soybeans," he says. "Farmers will plant the best seed they can get, especially if they're subsistence farmers. If you're surviving on a harvest and you have a choice between corn that will give you one kilo per plant or two kilos per plant, you'll take the two-kilo-per-plant seed, presumably."
Even the study's toughest critics agree that the appearance of transgenes in Mexico is not only likely, but desirable. Last February, Kaplinsky and Metz joined dozens of other biologists in signing a statement circulated by the AgBioWorld Foundation, a pro-biotech advocacy organization, noting that farmers have deliberately crossbred new and old maize varieties for thousands of years in order to select the most advantageous offspring. "The kind of gene flow alleged in the Nature paper is both inevitable and welcome," the statement said.
Metz and others argue, rather, that Quist and Chapela's study does nothing to prove the presence of transgenes in Oaxaca. "There's a difference between making a bet and presenting solid scientific evidence," Metz says. In fact, he and some other scientists think that Quist and Chapela's research might even be useful in making the case that transgenes from commercially grown corn won't lead to the displacement of native criollo. If the transgenic DNA was truly taking over, he says, "They would have seen something that did not look like criollo -- it would have looked like the conventional breed of corn that the transgenic material came from."
For his part, Chapela expresses surprise that his critics now call this gene flow "inevitable." He interprets this concession as evidence that pro-industry forces were so blindsided by the study that they didn't have a ready response. "Anyone who was prepared would not be so stupid as to say, 'I knew it was going to happen,' " Chapela says. "I think you make yourself liable to go to jail for making a statement like that. There are international treaties trying to prevent it, and there is national legislation trying to prevent it, and everybody agrees that this could be a problem."
In January, Quist and Chapela gained some support when a study jointly prepared by three branches of the Mexican environmental ministry found transgenic contamination rates in Oaxaca and nearby Puebla that were much higher than the Berkeley study claimed. The government announced transgenic contamination of between 3 and 13 percent in eleven communities, between 20 and 60 percent in four others, and 37 percent in government food stores.
Quist and Chapela's second major point is far more contentious because it suggests that a gene transfer can occur through other means than pollination. If so, the genes would be less stable than previously believed and their behavior would be less predictable, as would their effects on human welfare, crop diversity, and the environment. The idea that artificially introduced genes may be unstable is relatively recent and quite threatening to an industry that tries to reassure its customers that planting modified seeds won't have any unexpected results. UC Berkeley genetics professor Michael Freeling, Kaplinsky's lab advisor and a co-signer of his critical letter, says that Quist and Chapela's claim that, as he puts it, "the transgene popped out and, like Frankenstein's monster, jumped all over the genome," would be a "totally unanticipated" result. Likewise, Metz cautions that transgenic DNA is governed by the same constraints as normal DNA, and "does not behave like an infectious agent, leaping around genomes."