A group of scientists inserted an alligator gene into the catfish genome. Alligator genes called cathelicidins are antimicrobial genes that play a role in animal innate immune responses, providing defense against a variety of pathogens, including bacteria and viruses.
The researchers inserted the gene into the part of the catfish genome that codes for important reproductive hormones. The resulting hybrids showed increased disease resistance and sterility.
A healthier and sterile hybrid
Aquaculture not only contributes to climate change but also makes certain animals suffer from its effects. Catfish account for more than 50% of the demand for farmed fish in the US. However, almost 45% of the total population does not survive past the fingerling stage, thus threatening the environment and industry sustainability.
Catfish are not only highly susceptible to bacterial infections and abiotic stresses, but also develop antibiotic resistance. Scientists are trying to give these freshwater fish an edge against the odds by implanting them with disease-fighting genes from alligators.
The CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) system has revolutionized gene modification, making gene editing more precise, efficient and accessible. A team led by Rex Dunham and Baofeng Su at Auburn University, Alabama, used Cas9, one of the enzymes produced by the CRISPR system, to integrate cathelicidin genes from alligators into catfish DNA.
“The survival rate of cathelicidin transgenic fish is 100-400% higher than native fish. The sterility of these hybrids helps prevent their impact on the ecosystem and prevents the establishment of transgenic or domestic genotypes in natural environments,” the team said as quoted by Interesting Engineering.
Survival and ethical issues
While ensuring that these genetically modified fish do not eliminate fears of over-breeding and overpowering native species in the wild, it is hard to ignore the lack of use of farm-produced sterile fish in laboratories.
“The use of CRISPR also casts doubt on the viability of this technique because it may prove too difficult to produce enough of these fish for viable and genetically healthy strains,” said Greg Lutz, an aquaculture geneticist at Louisiana State University.
Also of concern are the uncertainties surrounding the approval of these transgenic fish for human consumption due to the ethical issues surrounding genetic modification, and the potential unintended consequences of using CRISPR.
Finally, even if researchers insist they are willing to eat them, public acceptance of alligator hybrid fish is an inevitable challenge. Please note, this research has not been peer-reviewed and is available as a preprint which can be accessed at bioRxiv.
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