Effect Of Dietary Lipids Source On The Lipoprotein Lipase And Fatty Acid Synthase Gene Expression Of Common Carp(Cyprinus Carpio)

Fatty acids are essential dietary components for fish, as they are precursors to hormones related to growth and development. Moreover, high level of dietary lipids may lead to increased fat deposition in fish, depending upon species and age. It modifies flesh quality in terms of storage stability, transformation yield and organoleptic and physical properties. There are two important enzymes related with the synthesis and release of fatty acids, Fatty Acid Synthase (FASN) and Lipoprotein Lipase (LPL), respectively. FASN catalyzes the synthesis of long-chain fatty acids (FA) and LPL acts on plasma lipoproteins to hydrolyzing triglycerides and generate non-esterified fatty acids. The purpose of this study was to analyze the effect of five dietary lipids sources (fish oil-FO, soybean oil-SO, rapeseed oil-RO, linseed oil-LO and pig oil-PO) in common carp (Cyprinus carpio) on the expression of lipoprotein lipase (LPL) and fatty acid synthase (FASN) genes through the semiquantitative RT-PCR method. The expression of FASN mRNA in liver tissue of carp was higher and significantly (P<0.05) than that of the other tissues; the graded tissue expression for FASN was:liver tissue> brain tissue> muscle tissue. Also the expression of LPL in liver tissue of carp was higher and significantly (P<0.05) and showed the same graded tissue expression:liver tissue> brain tissue> muscle tissue. In the intestine tissue of carp no amount of FASN and LPL mRNA was detected. The dietary lipids sources (fish oil, soybean oil, rapeseed oil, linseed oil and pig oil) had not an effect significantly (P>0.05) on the FASN mRNA abundances in the studied tissues (liver tissue, brain tissue and muscle tissue). The effect of the dietary lipids sources on the LPL mRNA expression was site-specific. In carp, PO diet increased significantly (P<0.05) the LPL mRNA level in liver and muscle tissue. However, in brain tissue the PO diet down-regulated significantly (P<0.05) the expression of LPL mRNA. The FO, SO, LO, and RO diets contained higher and relatively similar quantities of unsaturated fatty acids (ranged about72to92%) were not significantly (P>0.05) different from each other; specifically in liver and muscle tissue. In brain the SO diet increased significantly (P<0.05) the LPL mRNA level and increased FASN mRNAs levels. The LPL mRNA abundances in liver were not congruent with LPL enzyme activity in liver showed in a parallel and complementary study with the same dietary lipid source in carp (Cyprinus carpio). This is one of the examples of disparity between mRNA abundance and enzyme activity. It is clear that in this case quantitative transcriptome data is not indicating directly enzyme activity, therefore more studies are needed to clarify this relation.