Gene Editing of the Follicle-Stimulating Hormone Gene to Sterilize Channel Catfish, Ictalurus punctatus, Using a Modified Transcription Activator-like Effector Nuclease Technology with Electroporation

SIMPLE SUMMARY: Follicle-stimulating hormone (fsh) is crucial to the reproduction of fish. In the current investigation, transcription activator-like effector nuclease (TALEN) plasmids targeting the channel catfish fsh gene were electroporated into fertilized eggs to generate infertile channel catfish (Ictalurus punctatus). Human chorionic gonadotropin (HCG) hormone treatment enhanced the spawning and hatching rates of catfish fsh-knockout mutants when lowered infertility was detected. Gene editing of channel catfish offers promise for reproductive confinement of genetically modified, native, and invasive fish to eliminate genetic drift into external ecosystems. ABSTRACT: Follicle-stimulating hormone (fsh) plays an important role in sexual maturation in catfish. Knocking out the fsh gene in the fish zygote should suppress the reproduction of channel catfish (Ictalurus punctatus). In this study, transcription activator-like effector nuclease (TALEN) plasmids targeting the fsh gene were electroporated into fertilized eggs with the standard double electroporation technique. Targeted fsh cleavage efficiency was 63.2% in P(1) fsh-knockout catfish. Ten of fifteen (66.7%) control pairs spawned, and their eggs had 32.3–74.3% average hatch rates in 2016 and 2017. Without hormone therapy, the spawning rates of P(1) mutants ranged from 33.3 to 40.0%, with an average egg hatching rate of 0.75%. After confirmation of the low fertility of P(1) mutants in 2016, human chorionic gonadotropin (HCG) hormone therapy improved the spawning rates by 80% for female mutants and 88.9% for male mutants, and the mean hatch rate was 35.0% for F(1) embryos, similar to that of the controls (p > 0.05). Polymerase chain reaction (PCR) identification showed no potential TALEN plasmid integration into the P(1) channel catfish genome. Neither the P(1) nor the F(1) mutant fish showed any noticeable changes in in body weight, survival rate, and hatching rate when the reproductive gene was knocked out. F(1) families had a mean inheritance rate of 50.3%. The results brought us one step closer to allowing implementation of certain genetic techniques to aquaculture and fisheries management, while essentially eliminating the potential environment risk posed by transgenic, hybrid, and exotic fish as well as domestic fish.