How AquAdvantage transgenic salmon is made.
To make the AquAdvantage transgenic salmon, scientists select two sequences of DNA—one from a Pacific chinook salmon, the
other from an eel-like fish called the ocean pout, which has antifreeze proteins in its blood that help it live in
near-freezing waters. The genes are chemically knit together and injected into fertilized Atlantic salmon eggs, some of which
incorporate them into their genetic makeup. But that’s only the beginning: in additional steps, eggs from those transgenic
fish are isolated and biochemically “tricked” into developing without fertilization, a procedure known as “gynogenesis.” The
resulting all-female fish—still carrying the new genes—are then treated with a hormone that turns them into males, and their
sperm is used to fertilize ordinary salmon eggs. It’s these offspring that are intended for the dinner plate.
In an elegant feat of genetic engineering, the foreign DNA strands reprogram the salmon’s metabolism: the chinook gene
signals the manufacture of extra growth hormones, while the ocean pout gene (which normally signals the production of
antifreeze proteins when the temperature drops) keeps that internal hormone factory switched to “on” during the winter
months, when ordinary salmon stop growing. As the embryos mature, the foreign genes accelerate their growth: a tiny fry grows
to a 13-pound adult in two years—twice as fast as an ordinary farm-raised fish. Thus the fish can be farmed year-round, in
any climate, and more production cycles squeezed into less time.