Salt Sensitive Tet-Off-Like Systems to Knockdown Primordial Germ Cell Genes for Repressible Transgenic Sterilization in Channel Catfish, Ictalurus punctatus

Abstract

Repressible knockdown approaches were investigated for transgenic sterilization in channel catfish, Ictalurus punctatus. Two primordial germ cell (PGC) marker genes, nanos and dead end, were targeted for knockdown, and an off-target gene, vasa, was monitored. Two potentially salt sensitive repressible promoters, zebrafish adenylosuccinate synthase 2 (ADSS) and zebrafish racemase (Rm), were each coupled with four knockdown strategies: ds-sh RNA targeting the 5 end (N1) or 3 end (N2) of channel catfish nanos, full-length cDNA sequence of channel catfish nanos for overexpression (cDNA) and ds-sh RNA targeting channel catfish dead end (DND). Each construct had an untreated group and treated group with sodium chloride as the repressor compound. Spawning rates of full-sibling P 1 fish exposed or not exposed to the constructs as treated and untreated embryos were 93% and 59%, respectively, indicating potential sterilization of fish and repression of the constructs. Although the mRNA expression data of PGC marker genes were inconsistent in P 1 fish, most F 1 individuals were able to downregulate the target genes in untreated groups and repress the knockdown process in treated groups. The results indicate that repressible transgenic sterilization is feasible for reproductive control of fish, but more data from F 2 or F 3 are needed for evaluation.

Effectiveness of Cathelicidin Antimicrobial Peptide against Ictalurid Catfish Bacterial Pathogens

“…Repressible primordial germ cell knockout would be one option to accomplish this goal of absolute reproductive control to eliminate virtually all environmental risk of transgenic fish, and this has been accomplished in Channel Catfish (Li et al. 2017, 2018).…”

“…However, for any transgenic approach to be implemented commercially, government regulatory approval will be needed, and that approval is more likely if the fish are reproductively confined. Repressible primordial germ cell knockout would be one option to accomplish this goal of absolute reproductive control to eliminate virtually all environmental risk of transgenic fish, and this has been accomplished in Channel Catfish (Li et al 2017(Li et al , 2018.…”

Comparison of growth performance among channel-blue hybrid catfish, ccGH transgenic channel catfish, and channel catfish in a tank culture system

“…The P 1 transgenic and control broodstock used for this study were from the Catfish Genetics Research Unit, School of Fisheries Aquaculture and Aquatic Sciences, Auburn University, AL, USA. The P 1 transgenic fish were produced via electroporation 63 , 64 . Broodstock were tested to determine if they were transgenic prior to spawning 18 , 27 .…”