Ottawa Citizen

Susan Burgess The Ottawa Citizen

Canadian researchers are adapting technology created for the Human Genome Project to detect genetic modification in food.

The "DNA chip" is a glass slide spotted with DNA probes designed to recognize other, complementary sequences in the DNA of modified food. The food DNA is treated and reacted with the chip. When the probes recognize and bind to a modification, they appear fluorescent.

A computer analysis of an exposed chip will reveal which modifications are present in the sample.

"It's still very much in its early developmental stages," says Dr. Burton Blais, a research scientist at the Canadian Food Inspection Agency who is helping to develop the chip.

"We hope within two to three years to have the first-generation systems ... that could be actually practical for testing GMOs (genetically modified organisms) in food."

The chips were originally developed to help sort out complex patterns of gene expressions in human cells. Once adapted, the technology could be used, for example, to test whether corn had been modified with a gene to confer insect resistance.

The CFIA now uses a technology known as PCR -- polymerase chain reaction -- to test foods for genetic modification. A different PCR test is needed for each modification.

The advantage of the DNA chip over the older technology is that it can test for all of the modifications at once, says Dr. Blais.

"Right now, if you wanted to identify each of them by PCR, it would be very tedious. If you gave me a food sample, and (said), 'Tell me which GMO is in here, of all the possibilities in the world,' it would take me a long time to go through each one of them and tell you the answer," says Dr. Blais.

Dr. Blais estimates there are several dozen GM traits in the world's food supply. Nearly 50 modifications have been approved in Canada, and tests for those that have not been approved are developed as the need arises.

But with many more food experiments on the horizon, the "shotgun" approach to testing that the chip allows could soon be in high demand.

"There's already talk of a second generation of GMOs enhancing the nutritional qualities of foods. And so we would certainly want to be able to detect those as well," says Dr. Blais.

Now that countries in Europe and elsewhere demand labelling of genetically modified foods, the DNA chip could also come in handy to verify that certain exports from Canada to those countries are GM free.

Japan began enforcing labelling laws just last month, and Korea is planning stiff financial penalties for violations of labelling requirements that take effect in September.

"I'm not sure if that's going to be the CFIA's mandate to (certify exports), but certainly the technologies that we're developing will be useful for that purpose," says Dr. Blais.

"If there are private testing laboratories that set up in Canada, they might be the ones that actually do the testing."

Bart Bilmer, the director of the CFIA's office of biotechnology, says that improvements in testing technology don't mean Canada is likely to start mandatory labelling of GM foods, as has been called for in a recent private member's bill introduced by Liberal MP Charles Caccia.

Because many of the foods Canadians buy in supermarkets are highly processed, even sophisticated tests for GMOs may not be able to verify what's on the label.

Also, because GM and non-GM crops aren't segregated, it's difficult to enforce claims about product ingredients, says Mr. Bilmer.

"These products get mixed together and they travel all over the place," he says.

-- Rachel Gibson (rgibson@hotmail.com), May 13, 2001