Deep sequencing of the tilapia (Oreochromis niloticus) liver transcriptome response to dietary protein to starch ratio

To comprehensively understand the effects of dietary protein to starch ratio on alternations in physiologic status of tilapia, fish were fed with high protein to starch ratio (HP, 33.5% protein and 16.62% starch content) and low protein to starch ratio isoenergetic diets (LP, 25.2% protein and 26.82% starch content) for 8 weeks. Our results indicated that the fish fed with LP diet had a significantly poor growth performance and feed utilization. Lower dietary protein to starch ratio also resulted in markedly higher plasma cholesterol, plasma triacylglycerol, liver lipid and muscle lipid content, which indicated more fat deposition in fish. RNA-seq was employed to evaluate the tilapia hepatic transcriptome response to LP diet. RNA-seq data showed that 71 genes were significantly up-regulated and 26 genes were significantly down-regulated by LP diet. Different expression genes were mapped to 47 signaling pathways including glycolysis, gluconeogenesis, biosynthesis of amino acids, lipogenesis and lipolysis etc. The present study gains a comprehensive understanding of the molecular mechanisms underlying the effects of dietary protein and starch ratio on alternations in physiologic of tilapia. (C) 2014 Elsevier B.V. All rights reserved.