Targeted Gene Insertion and the Effect of Random Insertion of the Masou Salmon Delta5-Desaturase Transgene on n-3 Fatty Acid Production and Culture Traits of Channel Catfish (Ictalurus punctatus)

Abstract

Channel catfish (Ictalurus punctatus) is one of the most abundant catfish species in North America. The objectives of this study were to determine the effectiveness of the Masou salmon delta5-desaturase transgene driven by a beta-actin promoter for improving n-3 fatty acid production in F1 transgenic channel catfish, Ictalurus punctatus together with proximate analysis, as well as to determine pleiotropic effects of disease resistance. Additionally, a novel approach of using multiple transgenes to alter multiple steps in a pathway, which has not been previously reported in aquaculture species was utilized. As a result, Apo14-Masousalmon_Elovl2 gene was successfully inserted on chromosome 1 in one channel catfish utilizing microinjection and CRISPR/Cas9 mediated knockin. Transgenic fish showed a 33% increase in n-3 fatty acid level, and a 15% decrease in n-6 fatty acids level. Masou salmon delta5-desaturase transgene driven by a beta-actin promoter affected n-3 fatty acid production in a positive direction. Insertion of the masou salmon delta5-desaturase transgene into channel catfish had major effects on metabolism, physiology, body composition, and growth of channel catfish. A major goal of increasing the percentage of n-3 fatty acids was achieved, but the objective of increasing total n-3 fatty acids was not. Body composition was altered, pleiotropic effects on performance traits were observed and the transgene appeared to increase uniformity of these traits.