When you order sushi, chances are, you are hoping to get what you ordered.
And thanks to some molecular biology students, evidence has surfaced that some sushi restaurants may be scamming us — and it may make your stomach churn to hear what is actually in the food your ordered….
A biology professor at Fanshawe College in London, Ontario, Dr. McDonald, tweeted out about an experiment her students were conducting using fish DNA. They were told to sequence fish DNA from restaurant sushi orders and see if the fish actually matched the ones labeled on the menu.
Dr.McDonald shared with Bored Panda how his students had to perform a process called DNA sequencing on their samples.
“Identifying species by their sequence barcode is almost exactly like going shopping. You pick out the items you want, some of them have price stickers on them, some of them don’t, and you take them to the cash register. As each item’s tag is scanned, the barcode on the item is the identifier: each item has a different barcode.”
“When scanned, the exact item and that item’s price is displayed on the register’s screen as long as it’s in the database. With living organisms, each major group of organisms has a well-established “barcode” in animals we use a gene called co1, in plants we use a gene called rbcL, in fungi we use a gene called ITS, etc.”
“A gene sequencer has the ability to read all of the letters of the genetic code between two primers, that act like target probes. They restrict the region you’re generating the sequence for, instead of getting the entire genome. Once the sequencer has given you all of the letters between your primers, you run that through the barcode database and it will tell you what species that barcode is from. It’s really nice because it can work on a very small piece of tissue, instead of relying on identification based on the entire, intact, organism.”
Through this process, the students discovered multiple abnormalities with the samples, such as “red snapper” and “red tuna” that was actually tilapia while Rainbow Trout was disguised as “Atlantic Salmon.”
The “white tuna” the class had sampled had also not been labeled correctly, as it was actually “escolar” which is dangerous as it can cause extreme gastrointestinal distress.
“Last but not least of successful sample runs, we had one that makes my skin crawl. It was a sequence that came back with a bunch of “unknown bases” (a bit of cleaning up will help immensely) but I worked with what I had and ran it through the database. Was supposed to be Salmon.”
“This salmon was not from a restaurant, but was instead purchased from the seafood department of a local grocery store. Again, to remain nameless. This was purchased from a counter, someone reaches in and grabs the fish, puts it in a bag, sticks a sticker on it, pay by the pound.”
So what was it exactly? Body Louse.
A.k.a body lice.
“This wasn’t a piece of garbage from a market. This was from a “salmon fillet” that someone paid good money for, cut some off before they cooked it, put it in saran wrap & brought it in. BODY LOUSE. Think about how much there must be in that sample to override fish DNA!”
All that to say — maybe next time, skip the sushi and opt for good ole’ pizza.
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