By Brian Carnell

Tuesday, April 9, 2002

Several months ago, Nature published a paper by Ignacio Chapela and David Quist claiming that DNA from genetically modified maize had been found in samples taken from maize growing in the wild in Mexico. Proof of cross-contamination from genetically modified plants, right? Not quite.

This month Nature performed a mea culpa and said it should not have published the study, which has been criticized by a number of other researcher. According to Nature,

Nature has concluded that the evidence available is not sufficient to justify the publication of the original paper.

The problem is that the researchers behind the original study used a method known as inverse polymerase chain reaction to look for the rogue DNA segments. Unfortunately, i-PCR is known for producing false positives unless analyzed carefully -- something that other researchers argue the study failed to do.

As Nick Kaplinsky of the University of California-Berkeley pointed out in Nature, the results of the original,

seem to be based on an artefact arising from the i-PCR [technique] used... Transgenic corn may be grown illegally in Mexico, but Quist and Chapela's claim that these transgenes have pervaded the entire native maize genome is unfounded.

Quist and Chapela defend their research, maintaining they controlled for the artefact problem.

Source:

Doubts over Mexican GM maize report. Alex Kirby, The BBC, April 5, 2002.

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