Genetically-Modified Trout: Bricks or Bouquets?

Do these genes make me look big? The modified rainbow trout boast more flesh per fish. Photograph courtesy: Terry Bradley

Once again mankind has decided to play God and tinker with the building blocks of life. This time, the victims are some very unlucky rainbow trout.

Scientists have created hundreds of mutant fish with "six-pack abs" and bulging "shoulders" by beefing them up (literally) with new genes. (These fish look like they are riddled with gigantic cancerous tumours under their skin, if you ask me.)

Obviously, these fish are not going to make it in the marketplace if good looks is any criteria. Researchers are counting on the fact that these fish will each provide approximately 15% - 20% more flesh than the average, non-tampered with trout to be a huge selling point.

Developed with fish farming in mind, the genetically-modified trout are the result of ten years of experimentation. The team that conducted this experimentation was led by Terry Bradley of the University of Rhode Island's Department of Fisheries, Animal, and Veterinary Sciences.

Twenty thousand rainbow trout eggs were injected with different types of DNA from other species. Animals that have had foreign DNA inserted into them are known as transgenic. The added DNA was intended to suppress a protein called myostatin. Myostatin suppresses muscle growth so the world isn't populated by muscle-bound Green Hulks. They got the results they were looking for in about 300 of the eggs.

Photo courtesy: Wikipedia

These transgenic trout now contain genes modelled on the myostatin-inhibiting proteins in the massive, powerfully-built Belgian Blue cattle. What makes the Belgian Blue so unique is that the amazing muscle structure gives the animal a "double-muscled" appearance. (Note the cesarean scars on the heifer. Sometimes, the intense muscling can interfere with other natural functions, such as birthing.)

Myostatin is what is what prevents all cows from looking like a Belgian Blue. Researchers are now looking at the ability to control myostatin as a possible way to reverse muscle-wasting diseases in humans.

Mutant trout (left) vs. unmodified trout. Photographs courtesy: Terry Bradle

For better or worse, this test is the first piece of evidence researchers have that myostatin inhibition has a similar effect on both fish and mammals.

"Our findings are quite stunning," Bradley said in a statement. "The results have significant implications for commercial aquaculture."

If these fish are given the green light, the modifications could mean cheaper trout for consumers as farmers could grow larger fish on the same amount of food. Sounds good on the surface (if you can get past the unhealthy, lumpy look of the fish). However, danger could loom...

Some trout with altered genes have been approved for release; but, trout with DNA added from another species have not been approved for commercial use yet, says Fredrik Sundström, zoologist with the University of Gothenburg in Sweden.

Other genetically-modified trout soon to make an appearance on a dinner plate near you have been engineered for faster growth; disease resistance; or, survival in frigid waters (the "antifreeze" gene).

Sundström, who has investigated the potential risks of transgenic trout escaping into the wild, said studies suggest not only that the fish can breed in rivers; but, are capable of passing on their lab-altered genes into the natural populations. (Read about threats to freshwater fish.)

"Under certain conditions the transgenic fish do better than the wild types; but, under other conditions we see the opposite," he added.

"If they have a lot of food, transgenic fish can use that food to a greater extent; but, if you have predators nearby they also seem to be more susceptible to predation," Sundström said.

Sundström states that he doubts that this latest transgenic trout would find enough food in the wild to support it's larger body size. (Just a minute...wasn't the whole allure of these trout that you got a bigger fish for the same amount of food?) He also states he wonders whether the bulky fish would be able to maneuver swiftly enough to escape predators. (But wasn't their larger size supposed to reduce predators?)

However, he does go on to admit that if these fish did survive in the wild, they could overturn their ecosystems by out-competing their unaltered cousins leaving them with little food and an uncertain future.

Via National Geographic