Gene Editing of the Catfish Gonadotropin-Releasing Hormone Gene and Hormone Therapy to Control the Reproduction in Channel Catfish, Ictalurus punctatus

Abstract

Transcription activator-like effector nuclease (TALEN) plasmids targeting the channel catfish gonadotropin-releasing hormone (cfGnRH) gene were delivered into fertilized eggs with double electroporation to sterilize channel catfish (Ictalurus punctatus). Targeted cfGnRH fish were sequenced and base deletion, substitution, and insertion were detected. The gene mutagenesis was achieved in 52.9% of P1 fish. P1 mutants (individuals with human-induced sequence changes at the cfGnRH locus) had lower spawning rates (20.0–50.0%) when there was no hormone therapy compared to the control pairs (66.7%) as well as having lower average egg hatch rates (2.0% versus 32.3–74.3%) except for one cfGnRH mutated female that had a 66.0% hatch rate. After low fertility was observed in 2016, application of luteinizing hormone-releasing hormone analog (LHRHa) hormone therapy resulted in good spawning and hatch rates for mutants in 2017, which were not significantly different from the controls (p > 0.05). No exogenous DNA fragments were detected in the genome of mutant P1 fish, indicating no integration of the plasmids. No obvious effects on other economically important traits were observed after the knockout of the reproductive gene in the P1 fish. Growth rates, survival, and appearance between mutant and control individuals were not different. While complete knock-out of reproductive output was not achieved, as these were mosaic P1 brood stock, gene editing of channel catfish for the reproductive confinement of gene-engineered, domestic, and invasive fish to prevent gene flow into the natural environment appears promising.

Generation of eco-friendly channel catfish,Ictalurus punctatus, harboring alligator cathelicidin gene with robust disease resistance by harnessing different CRISPR/Cas9-mediated systems

“…This variation may be due to heterozygous individuals lacking stable genetic traits, or off-target integrations in other regions concealing growth advantages in the P 0 generation [50]. cfGnRH-deficient channel catfish did not show significant effects in growth and survival throughout a four-year culture compared to the WT fish [19]. However, potential pleiotropic effects could exist when the LH gene is replaced by the As-Cath in our cases.…”

“…On the other hand, representative examples have illustrated that reproductive confinement is promising in model and cultured fish by knocking out/disrupting gonadal development-related genes [23,[63][64][65][66]. Recently, Qin et al [19] demonstrated that the reproduction-blocked channel catfish are sterile, and this reproductive confinement can be lifted through hormone therapy with LHRHa. In this study, the dose of 1600 IU/kg HCG coupled with 50 μg/kg LHRHa can restore fecundity at the highest level in comparison to other hormone treatments, but this improvement is not significant from that of 1200 IU/kg HCG.…”

“…Fortunately, numerous genome-editing-based studies have demonstrated that it is possible to render fish reproductively sterile by altering/disrupting key genes involved in reproduction via the NHEJ repair pathway. Thus, potentially reducing negative environmental effects associated with genetically modified fish [17][18][19]. Luteinizing hormone (LH) gene regulates gametogenesis and gestation through binding the receptor [20,21].…”

“…Thus, potentially reducing negative environmental effects associated with genetically modified fish [17][18][19]. Luteinizing hormone (LH) gene regulates gametogenesis and gestation through binding the receptor [20,21].…”

Harnessing antimicrobial peptide genes to expedite disease-resistant enhancement in aquaculture: Transgenesis and genome editing

“…Genes encoding these three key hormones are pivotal in gonadal maturation. Qin et al (2016) and Qin et al (2022) revealed that channel catfish with LH- or GnRH-mutations had a reduced fertility compared to wild-type individuals, indicating that knocking out or disrupting the LH or GnRH gene can induce reproductive confinement. Docosahexaenoic acid (DHA), an omega-3 fatty acid, is essential for the development of human eye and nerve tissues (Judge et al, 2007), and the DHA biosynthesis pathway requires the elongase gene Elovl2 to function (Gregory and James, 2014).…”