Scientists inject Chinese alligator genes into American catfish to create 'super fish'

But what special abilities do these super fish have?

This is an American catfish (Ictalurus punctatus), a catfish related to the catfish and tra fish in Vietnam. It still looks like a catfish, with a smooth, scaleless body and a protruding mouth covered with whiskers.

But don't let what you see fool you. Inside this catfish's genome is a gene that belongs to an alligator. Scientists used CRISPR, the most advanced gene-editing technique available, to inject genes from the Chinese alligator (Alligator sinensis) into this American catfish.

The question is: Why do they do it?

This is an American catfish (Ictalurus punctatus) with alligator genes.

In fact, scientists did not intend to create a school of catfish with sharp teeth or the hunting skills of an alligator, which could terrify any American who went on a picnic in a river, lake or open water.

According to new research published on the pre-peer-review scientific publishing platform biorxiv, these catfish were injected with crocodile genes to enhance their resistance to disease.

Out of every 10 catfish born, 4 will die from infection.

The United States is famous for being a country that eats a lot of fish, especially catfish such as pangasius, basa, and catfish. In 2021, statistics show that US farms raised up to 139 million kg of catfish and still had to import more fish from other countries.

' By weight, 60 to 70 percent of aquaculture in the United States is for catfish production ,' said Rex Dunham, PhD, a zoological geneticist at Auburn University in Alabama.

" Millions of catfish are raised in the United States each year, but of those, millions also die from disease, primarily infections ."

The catfish died white bronze.

Scientists estimate that only 60 percent of catfish eggs survive to maturity and reach harvest size, meaning the remaining 40 percent of fish will die at some point before reaching adulthood.

Catfish often die from infections , because wet fish ponds are also conditions for many pathogenic bacteria to develop. And when fish are raised in high density, they are very susceptible to transmitting pathogens to each other.

One dead fish floating on the surface of a lake means all the other catfish below are in danger.

To limit this, many farm owners have recklessly mixed high concentrations of antibiotics into fish feed. However, this can leave drug residues on the product, while also promoting bacteria to become resistant to antibiotics.

Many farm owners have recklessly mixed high concentrations of antibiotics into fish feed.

So a team of scientists at Auburn University thought: Why don't they genetically modify catfish to make them resistant to disease?

But how?

The logic was to find an extremely hardy freshwater fish and transfer its genes to a weak catfish. What better fish than an alligator!

Inject crocodile genes into catfish, but don't let them lay eggs

" Theoretically, genetically modifying catfish with genes that protect them from disease could reduce waste and help limit the environmental impact of fish farming. We have attempted to do just that - by inserting alligator genes into the genome of a catfish, in this case the channel catfish ," said Dr Dunham.

The alligator gene Dr. Dunham used was obtained from the Chinese alligator, and it codes for a special protein called cathelicidin. Dr. Dunham says this protein has antibacterial properties—it's thought to help protect alligators from infection after they bite each other and get injured.

So he and his colleagues tried introducing this gene into catfish to see if it would make them resistant to infections caused by bacteria.

The cathelicidin gene has antibacterial properties that help protect crocodiles from infection during fierce fights with each other.

However, for this experiment to be approved, Dr. Dunham and his colleagues will have to ensure one condition from the US Department of Agriculture: that the genetically modified catfish will not be allowed to lay eggs.

That's right, they're not allowed to breed. Officials at the U.S. Department of Agriculture fear that if scientists create a mutant catfish, it could become a super fish once it escapes into the wild.

These super fish have the potential to cause disaster from their competitive advantage over other fish. They will multiply to such a huge number that no species can control, not even humans.

To avoid that possibility, Dr. Dunham consulted Associate Professor Baofeng Su, also a geneticist at Auburn University. Baofeng came up with the idea of ​​using the CRISPR editing tool to insert the Chinese alligator cathelicidin gene into the part of the genome that codes for an important reproductive hormone in American catfish.

What would happen if crocodile genes were transferred into catfish?

This would turn off the gene that codes for the hormone. ' We're trying to kill two birds with one stone. Without the hormone, the catfish won't be able to reproduce ,' says Dr. Dunham.

What the hell is this?

Dr. Greg Lutz, a geneticist at Louisiana State University, said when he first heard the idea from scientists at Auburn University, he exclaimed, " What the hell? Who would think of injecting alligator genes into catfish?"

Dr. Lutz himself has many years of experience working in the aquaculture industry. But after reading the paper on biorxiv, he understood why the scientists at Auburn did it.

According to Dr. Dunham's team's report, after receiving the cathelicidin gene from Chinese alligators, American catfish actually developed a higher resistance to disease.

When scientists released these catfish into a tank of water containing two pathogens, bacteria that normally infect and kill catfish, the survival rate of the genetically modified catfish increased fivefold compared to the unmodified fish.

The survival rate of genetically modified catfish was five times higher than that of unedited fish.

Dr Dunham said the transgenic fish were also sterile when their hormone-producing genes were turned off, ensuring they would only survive one generation, even if they escaped from the lab.

Commenting on this result, Dr. Lutz said that transgenic catfish have great potential for application.

' Creating fish that are highly resistant to disease has long been a goal of the aquaculture industry. Gene editing to achieve this goal would have a major impact on the amount of waste produced by fish farms ,' he said.

'Theoretically, raising disease-resistant fish would require fewer resources and produce less waste.'

Are genetically modified fish edible?

That's clearly the end goal of this research. Scientists are creating a catfish with disease-resistant genes from alligators, just to increase the production of the fish for human consumption.

But getting a genetically modified catfish approved for food in the United States could be a long road.

Currently, the only genetically modified fish approved by the Food and Drug Administration (FDA) in the United States is the AquAdvantage salmon . These fish have a gene from another salmon species added to them, making them larger and meatier than regular salmon.

Genetically modified super salmon.

AquAdvantage salmon was approved for the US market in 2021. But that was the result of 26 years of filing and repeatedly proving the safety of AquaBounty, the company that genetically engineered the fish.

But even if catfish and other catfish injected with crocodile genes were licensed for sale, the question is: Would anyone eat them?

Dr. Dunham thinks so. Once the fish is cooked, the protein produced by the alligator gene loses its biological activity. Therefore, it is unlikely to cause any harm to people who eat the fish.

' A lot of people are still eating alligators anyway ,' said Dr. Dunham. 'I would eat those fish right away ,' said Dunham.

Still, Dr. Lutz worries that others might be uncomfortable with the idea of ​​eating a catfish with alligator genes. " I can assure you, there are people who are afraid that this fish will grow big teeth and a long mouth like an alligator and bite humans, let alone eat it ," he said.

However, since the gene transferred from the Chinese alligator does not encode for the catfish phenotype, it is only a relatively interesting fantasy.