Re: Gene swap claim used to support GM food (19/7/2006)

Recently we commented on the absurdity of claims made by the Australian researcher, Dr Richard Oliver, that evidence from his research showing a single gene had moved in nature between one specific fungal disease and another, suggested not only that all genes had been in flux but that all genes were safely transferable between species. This, according to Oliver, provided a powerful new argument for GM food.

Here Dr Doug Gurian-Sherman, senior scientist at the Center for Food Safety and a former EPA scientist, provides some further - and very telling - points that contradict Oliver's extrapolations.

Hi Jonathan,

You make some very good arguments here. Gene transfer between unrelated species has likely occurred occasionally over evolutionary time scales, and this has already been recognized in the science community for at least a decade or two. But that is very different than the scale of transfer of GE.

So the basic point of this paper is not new (although there has been no evidence before that I am aware of its occurrence in recent times). But the way the occasional historical cases of gene swapping have been detected in the past is in part by the different chemical signatures that DNA from different organisms have (a main one is the GC content of its DNA; or the GC/AT ratio). Each organism has a GC signature, and occasionally, a small area of anomalous GC content is found in an organism. This (along with other data) is an indication of HGT. But if Dr. Oliver's contention that this occurs commonly (let alone that all gene combinations have been tried), these GC anomalies would be common instead of rare.

There are many other reasons that Oliver's extrapolations are off base. One obvious one is, how would organisms that occupy different environments even have the opportunity to exchange genes? For another, most crops are only about ten thousands years old, and the agroecosystems that they occupy exert very different selective pressure (evolutionary selection) than for the wild species that went before. So gene combinations that may have occurred before and failed in the crop's wild progenitor (in the extremely unlikely event that it occurred at all) may find new life in a crop selected and cultivated by humans. As you say, this is really gross extrapolation and wholly unsupportable.

Doug Gurian-Sherman, Ph.D.
Senior Scientist
Center for Food Safety
660 Pennsylvania Avenue, Suite 302
Washington, D.C. 20003
t 202-547-9359
f 202-547-9429
[email protected]

Gene swap claim used to support GM food

The logic of this article, which has been circulating round the pro-GM lists, totally defeats me. On the face of it, it provides one of the wildest cases of overgeneralisation I've ever come across. See what you think.

We are told that research published in the journal Nature Genetics has provided the first evidence of a gene having naturally moved from one fungal disease to another. This, the research leader Professor Richard Oliver tells us, is "the first time that a fungal gene has been shown to move between different fungal species."

So far so good, but on the basis of this initial evidence of this single gene transfer between these two highly specific fungal species, we are told that biology is set to be fundamentally rewritten.

Professor Oliver provides no explanation as to why we should rewrite our understanding of the whole of biological creation on the basis of this one incident. He simply makes a series of assertions:

*genes are probably transferring all the time;

*all the gene combinations that we can think of have probably already been tried in nature;

*biologists need to review their "most cherished notion" that species are distinct entities.

These speculations are then used to assert that this provides "a powerful new argument in favour of genetically modified food"!

We are also told, "There've been... many billions of years to put all these combinations together, and any one that would actually survive and cause an impact in the environment, you could argue has already been tried in the environment and shown (to be) wanting."

So, on the basis of initial evidence of a single gene having moved in nature between one specific fungal disease and another, we can apparently conclude that all genes are safely transferable by humans between all species!!!!!!!

Yet the claim that all possible gene transfers have probably already been tried out and we shouldn't worry about it, is directly contradicted by the researchers' own findings. They tell us that the single gene transfer they have identified took place relatively recently - "in the early 1940s" - and it "created a new, damaging wheat disease" that has caused problems world wide!

Some might think the logical deduction from this research is that gene transfers should be approached with considerable caution, but for Professsor Oliver apparently it means anything goes.

Gene swap find adds support for GM food
AAP, July 10, 2006

The gene swapping antics of two wheat diseases are set to cause upheaval for biologists and deliver a powerful new argument in favour of genetically modified food, researchers say.

The Australian-led research has provided the first evidence of gene transfers between fungal diseases, finding a gene carrying a critical virulence factor moved from one disease to another.

Published in the journal Nature Genetics, the study suggests the gene transfer happened in the early 1940s and created a new, damaging wheat disease.

"In a broader context, it probably means that genes are transferring all the time, that they're very rarely fixed in the new host," said research leader Professor Richard Oliver, who heads Murdoch University's Australian Centre for Necrotrophic Fungal Pathogens.

"In this particular case, getting the new gene gave (the fungus) a whole important

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