Expression profile for metabolic and growth-related genes in domesticated and transgenic coho salmon (Oncorhynchus kisutch) modified for increased growth hormone production

To gain a better understanding of the aspects underlying growth in salmonids, quantitative expression analysis was performed for a number of genes related to muscle growth, metabolism, immunology and energy regulation in the liver and muscle of wild-type coho salmon (Oncorhynchus kisutch), domesticated coho salmon selected for growth, growth hormone-transgenic coho salmon fed to satiation, and growth hormone-transgenic coho salmon reared on restricted rations. In comparisons among these four experimental groups, our findings show a significant and correlative up-regulation in the expression of a number of muscle determination and development factors in full-fed (FF) transgenic and domestic coho salmon. Expression of several metabolic genes involved with amino acid turnover and utilization also was correlated between these two faster-growing groups. However, distinct differences between domesticated and FF-transgenic fish were found for some genes involved with muscle cell differentiation, innate immune system, metabolism, and amino acid regulation. Wild-type and ration-restricted growth hormone-transgenic fish correlated very highly in the expression of most genes tested, suggesting that limiting available energy reduces the effects of elevated growth hormone and down-regulates muscle and metabolic regulatory pathways similarly to the reduced potential for growth hormone production seen in wild-type fish.