Molecular Cloning And Tissue Expression Analysis Of FAS, LEPR, JAK2 And STAT3 From Grass Carp (Ctenopharyngodon Idella) And The Regulation Of FAS Gene Expression By Dietary Fat Level

Exp.1 Molecular cloning and tissue expression analysis of FAS(Fatty Acid Synthetase), LEPR(Leptin Receptor), JAK2( Janus Kinase 2) and STAT3(Signal Transducer and Activator of Transcription 3)from grass carp, Ctenopharyngodon idellaThe FAS, LEPR, JAK2 and STAT3 gene fragments were amplified from liver of grass carp (Ctenopharyngodon idella) by degenerate oligonucleotide primed RT-PCR. The obtained nucleotide fragment sequences of the FAS, LEPR, JAK2 and STAT3 gene were analyzed by SMS online software and BioEidt software, and the tissue expressions of the FAS, LEPR, JAK2 and STAT3 gene were analyzed by quantitative real-time PCR.The results were showed as follow: (1) The obtained nucleotide fragment of FAS gene was 683bp, which encoded 227 amino acids. Compard with other species FAS, the grass carp FAS shard 95%-66% identities; The obtained nucleotide fragment of LEPR gene was 713bp, which encoded 237amino acids. Compard with other species LEPR, the grass carp LEPR shard 86%-35% identities. The obtained nucleotide fragment of JAK2 gene was 671bp, which encoded 223 amino acids. Compard with other species JAK2, the grass carp JAK2 shard 91%-70% identities. The obtained nucleotide fragment of STAT3 gene was 770bp, which encoded 256 amino acids. Compard with other species FAS, the grass carp FAS shard 100%-96% identities. (2) Quantitative real-time PCR analysis demonstrated that the FAS, Leptin, LEPR, JAK2 and STAT3 genes of grass carp expressed in all tissues including liver, muscle, brain, heart, spleen and mesentery fat tissue. The FAS gene expresses highest in liver, lower in heart, brain and fat tissue, and lowest in spleen. The leptin gene expresses highest in fat tissue, lower in liver, brain and heart, lowest in muscle and spleen. The LEPR gene expresses highest in spleen and heart, lower in brain, muscle and fat tissue, lowest in liver. The JAK2 gene expresses highest in liver, lower in muscle, brain, spleen and fat tissue, lowest in heart. The STAT3 gene expresses highest in liver, lower in muscle, brain, spleen and fat tissue, lowest in heart.Exp.2 The regulation of FAS expression of grass carp (Ctenopharyngodon idella ) by dietary fat levelTo study the FAS activity and gene expression affected by different dietary lipid levels, grass carps with initial average weight of (134.3±12.1)g were fed with diet supplemented with 0%, 2%,4% fat for 8 weeks. After 24 h of fasting, compared with the control group (0% fat), the liver FAS activity of 2% and 4% fat groups reduced by 33% and 64% (P<0.05), and FAS mRNA expression level reduced by 18% and 74%. The results showed that dietary fat inhibited FAS activity and mRNA expression, with stronger inhibitory effects on higher fat level.