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File Under: Fiction Is Good for You. I was reading Peter May’s crime novel The Critic, which took as a dramatic starting point the murder of a famous wine critic, one Gil Petty. The hero, forensics expert Enzo Macleod, had recovered Petty’s laptop and had even managed to break into his files. There, he found Petty’s final, unpublished editorial, “revealing for the first time the widespread use of genetically modified yeast in the production of California wines.” Wait, what? Who would invent such a notion?

Of course, it was only a novel. But then it went on to discuss “using a shuttle vector containing a chromosome integration cassette with genes for malolactic enzyme…and a sequence directing homologous recombination…” Mighty technical stuff — based on something real? The (fictional) editorial concluded: “The Food and Drug Administration in the United States alone approves GM microbes such as yeasts used in food products. But international faith in the FDA is fast eroding because approvals are frequently influenced by political pressure, and the approval of wine yeast leaves fundamental questions to be answered. It is certainly premature to market GM wine yeast, and since the wines produced using GM yeast are not labeled in the marketplace, it is only prudent to avoid all U.S. wines.” Petty claimed that the FDA’s tests of the yeast were “based on faith rather than science.”

“This is dynamite,” marveled Macleod, turning to Petty’s daughter. “A man of your father’s influence. If he had published this stuff, it could have caused catastrophic damage to the California wine industry.” Hello, motive for murder.

Knowing that May was a novelist who enjoyed the research end of his work, I couldn’t help asking him — was that stuff about GM yeast true? “It’s absolutely true,” said May. “My genetics man in Canada — Joe Cummins, professor emeritus at the University of Western Ontario — had actually written a report on it.” Indeed, Petty’s editorial comments are taken largely from that report and include both Cummins’ comments and those he cites from the British medical journal The Lancet.

Cummins’ principal concern in the report, as far as I can tell, is that “the FDA letter designating wine yeast ML01 to be Generally Regarded As Safe (GRAS) indicated that the distributor of GM yeast believed that final wines were free of yeast and yeast DNA, but there was no indication that data had been gathered to support that conclusion…The view that yeast and its autolysis products including DNA, RNA, proteins and carbohydrates were somehow lost from the wine was not supported by scientific evidence, only by the unsupported beliefs of the promoters and reviewers.”

He has some case. The FDA’s letter cites the promoter’s account of clarification, stabilization, and filtration as evidence that the yeast cells are removed from the finished wine. Further, the “cellular material” released by autolysis while the wine is aging on the lees (i.e., dead yeast cells) “is degraded through the action of enzymes such as proteases.” But Cummins cited a study claiming that “autolysis of wine yeast leads to ribonucleotides that persist in the wine for at least nine years.”

So — there may be some quantity of genetically modified material in wine produced using GM yeasts. So? The problem, says May, is that “it’s not there on the label. There’s no specific problem that’s been identified with it. It’s a question of simply letting people know. There are a lot of people who will not touch food or drink that’s been genetically modified, and there’s plenty of research to show that they have a reason to be concerned about it in a general sense.”

Here it’s easy for a wine lover to get on his high horse. “You mean to tell me that the U.S. Government, which is so zealous in making sure that every wine label warns, ‘According to the Surgeon General…consumption of alcoholic beverages…may cause health problems,’ isn’t bothering to make sure I know whether or not a wine was made with Frankenyeast? (Or, if it came to it, Frankengrapes?) Even when there was a report back in ’95 in The International Journal of Food Science and Technology that concluded, ‘In genetically engineered yeast cells, the metabolism is significantly disturbed by the introduced genes…and the disturbance brings about the accumulation of the unwanted toxic compound methylglyoxal’?” Apparently so. (Yes, the report is old and examines only one type of GM yeast. And yes, the producers of the GM wine yeast in question assured the FDA that “there should be no concern” because the potentially produced “additional proteins” will have similar amino acid sequences to the commercial yeast strain Davis 522. I’m not pretending that I’m qualified to go ringing any alarm bells. But I’d still like to be told.)

Oddly enough, the Wine Institute seems more concerned about the matter than the FDA. “The wine community is dedicated to only using practices that are beneficial and acceptable to consumers,” reads a 2006 position statement from the Institute. “Wine Institute has reviewed its position on gene technology and affirms as follows: The position of the Wine Institute is that no genetically modified materials be used in the production of California wine.” It’s not a binding statement — the Wine Institute doesn’t have much in the way of police powers — but it’s still a statement.

Or maybe it isn’t so odd. As the statement notes, the Institute considers not only what is beneficial to consumers, but also what is acceptable. Image counts. A study in a recent issue of AgBioForum concluded that “existing evidence from developed countries shows that…mandatory labeling regulations…have contributed to the disappearance of GM food ingredients in targeted products.” Those developed countries include the entire European Union and Australia. A 2001 Greenpeace report made the case that no major wine retailer in the U.K. would sell wines made from GM grapes (they weren’t asked about GM yeasts). At the time, California was sending about $112 million worth of wine to the U.K. annually.

And even in the U.S., where there is no mandatory labeling with regard to GM foods, the times may be a-changing. A 2006 report from the Mellman Group to the Pew Initiative on Food and Biotechnology showed that “pluralities of voters favor increased regulation of GM foods,” with 41 percent of those claiming basic awareness of such regulation saying that there was too little. “It is clear,” concluded the report, “that public opinion remains largely up for grabs. How the next generation of biotech products is introduced — and their perceived benefits and risks — will be critical in solidifying U.S. consumer attitudes.”

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DrJoe April 6, 2008 @ 5:26 a.m.

Notes on the self cloned wine yeast debate: The debate about self cloned wine yeast seemed to centered on one individual who believed that the carcinogen ethyl carbamate (urethane) should not be left in the wine and that people cannot be tested to identify human carcinogens. As one reader commented the urethane in wine is less cancer causing in wine than out of it. That is a well supported observation.

The International Agency for Research on Cancer (a United Nations Agency) is probably the best authority on cancer causing chemicals. Their report is summarized as follows: http://monographs.iarc.fr/ENG/Meetings/96-ethylcarbamate.pdf IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Ethylcarbamate (urethane) Carcinogenicity in experimental animals There is sufficient evidence in experimental animals for the carcinogenicity of ethyl carbamate. Overall evaluation Ethyl carbamate is probably carcinogenic to humans (Group 2A). The groups are as follows: Group 1 carcinogenic to humans (87 chemicals ); Group 2A probably carcinogenic to humans (63); Group 2B possibly carcinogenicto humans (234);Group 3 not classifiable as to carcinogenicity to humans (493); Group 4 probably not carcinogenic to humans (1).There is little question that urethane is hazardous to humans. However, urethane in wine is mitigated by the well known anti cancer chemicals in wine. My main objection to self cloned yeast is as follows: ISIS Press Release 08/01/07 Self-Cloned' Wine Yeasts Not Necessarily Safe by Prof. Joe Cummins “Nevertheless, even self-cloned yeasts must be subject to rigorous and comprehensive safety tests, as it has already been demonstrated that changing the expression of a single gene in yeast can have unexpected effects. In 1995, Japanese researchers reported that a transgenic yeast engineered for increased rate of fermentation with multiple copies of one of its own genes ended up accumulating the metabolite methylglyoxal at toxic, mutagenic levels to humans (1).”My main objection to self cloned yeast is that they must be tested carefully changes to a single gene can lead to unexpected and dangerous consequences.**

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