Post link 02 December 2015, 17:09
Big russia fresh salmon fishing


FROM THEIR BIRTH in freshwater lakes to getting caught in a fisherman’s net, it can take years for a wild salmon to wind up filleted and garnished with a lemon on your dinner plate. But for the Frankenfish that the FDA approved yesterday—the very first genetically modified organism declared safe to eat—the journey took more than 20 years.

It didn’t take that long because the science was hard. Researchers had already nailed down the genetic tweaks to bulk up the fish—technically called the AquAdvantage salmon—by the early 1990s. Starting with the genome of the Atlantic salmon, a heavily farmed species that’s nearly extinct in the wild, scientists made two changes. They took the gene for a growth hormone from the Chinook (or king) salmon, the largest of the Pacific salmon species, and kicked that hormone into overdrive with a promoter gene taken from ocean pout, an eel-like fish that can survive and grow in near-freezing waters. “Usually the salmon’s growth hormone gets turned off during colder months,” says Eric Hallerman, fish conservation scientist at Virginia Tech University. The pout’s promoter gene basically makes sure the Chinook growth gene never gets shut off. Voila: a mega-fish.

So why did AquAdvantage take so long getting to market? In part, because the government didn’t have a regulatory pathway for GM animals to become food at that time. Fish become food, which goes in your mouth, and the Reagan administration decided that modified animal foods fall under the FDA. That makes sense, because a modified animal could trigger some peoples’ allergies, and there have also been (mostly debunked) claims about GM organisms causing cancer. Those concerns have all been cleared up to the FDA’s satisfaction.

But the AquAdvantage also stoked environmental worries. For instance, what if this super fast-growing, fast-eating fish escapes and starts competing for resources with its wild cousins? Do you want extinction? Because that’s how you get extinction. You also don’t want GM fish and wild fish interbreeding, polluting the wild genomes with engineered sequences.

Traditionally, environmental concerns haven’t been the FDA’s problem. Which is why they sought out the expertise of people like Hallerman, who investigated the fish’s environmental risks for the agency. “The key issue is fitness of the organism,” he says. Fitness, as in Darwinian survival. Hallerman and his co-investigators looked at how well these fish competed for mates and created spawn relative to their wild counterparts. “We found that they are more stressed than non-GMO fish, which makes sense because they are putting all their energy into growth,” he says. But even though the fish’s fitness levels were low, they weren’t zero. “Their traces could still be passed along to another generation.”

The solution was to put the AquAdvantage in species-wide solitary confinement. Currently, the only place the FDA allows the company to grow fish are in aboveground freshwater tanks high in the Panamanian mountains. In order for a Frankenfish to compete or interbreed with wild salmon, it would have to escape the tanks1, somehow make it to a river, and swim down that river into the ocean. Salmon are cold water species, so it’d be tough to survive in the warm equatorial waters. Then the fish would have to swim thousands of miles to either North Atlantic or North Pacific. Not impossible, but in my book any fish that pulls off a feat like that deserves whatever food or sex it can get.

Not that the sex would lead to anything, because the AquAdvantage salmon’s genetic engineers made the fish sterile (also, all the fish are female). You know how when you look at a chromosome, it looks like an X? Each half of that X is called a chromatid, and is inherited from a parent. But AquAdvantage salmon chromosomes look like an XXX2. Triploid chromosomes can’t replicate like normal cells, and the baby fish is doomed to die. The scientists also made every AquAdvantage salmon female, further limiting the engineered species to petri dish procreation.

The FDA decision has implications beyond fast-growing fish. Researchers elsewhere have developed GM critters they hope will address food problems where traditional breeding has fallen short. For instance, goats with milk that doesn’t spoil so easy in warm weather. These are intended for poor countries, where refrigeration and pasteurization are scarce. Other examples include hornless cattle (for less-ouchy wranglin’) and pigs with extra-thick backsides.

How long? “Um, you would hope it’s shorter than 20 years,” says Alison Van Eenennaam, animal geneticist at UC Davis. “Otherwise I’ll be dead before it gets approved.” Unsurprisingly, she sees the FDA’s announcement as a boon to GM researchers. In fact, you could say it was downright benefishial.

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