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Would you know if you ate poisonous puffer fish?

A new DNA test offers commercial applications including correctly labeling fish and helping air safety investigators.

A pufferfish at Japanese restaurant Chikubu in New York, Dec. 30, 2001. (Stringer/Reuters)

SAN FRANCISCO — When a Chicago couple grew dangerously ill two years ago after eating a home-cooked fish dinner, Canadian scientists figured out what had sickened them by using a new genetic test.

The test is designed to identify animal species based on subtle variations in a single gene. Dubbed the “barcode of life,” it provides a fast, cheap alternative to sequencing the entire genome.

By applying this technique to a remnant of the dinner, scientists at the University of Guelph in Ontario discovered that the Chicago couple — who recovered — had dined on poisonous puffer fish that had been mistakenly labeled as a safe monkfish, according to a report in a scientific journal.

“The incident showed regulatory authorities, especially the U.S. Food & Drug Administration, that DNA barcoding could be useful in food safety investigations,” said Robert Hanner, a biology professor at the Biodiversity Institute of Ontario at the University of Guelph, where the test was performed. “Now we are trying to make barcoding easier to use in the field, so fish inspectors and buyers can catch such errors in advance,” Hanner said.

Guelph has been a leader in the Consortium for the Barcodes of Life, an international effort to develop this quick, precise way to differentiate species. Formed in 2004, the consortium includes hundreds of scientists from 43 nations.

The barcoding technique targets a single gene located in the mitochondria, the energy-producing region of the cell. This gene appears to be active in all living things and consists of 648 base pairs of DNA. Each species arranges that short snippet of DNA differently, which makes it a useful genetic marker to identify “birds, butterflies, fish, flies and many other animal groups,” as scientists explain on a website about DNA barcoding.

The consortium has been gathering tissue samples and doing the laboratory work to isolate and sequence this barcode gene and match it to various animal species. So far, genetic tags for more than 60,000 species have been deposited in the Barcodes of Life database that serves as the consortium's global repository.

Though barcoding is primarily a research tool, Hanner said it has started to find real-world applications such as helping air safety investigators identify birds that collide with jets during take offs and landings.