Effects Of De Novo Lipogenesis (DNL)on Fat Deposition In Subcutaneous And Abdominal Adipose Tissues Of Duck

Liver and adipose tissues are the primary positions for animal De novo lipogenesis (DNL), but it’s of great difference in different adipose tissues between species. In order to compare the difference of DNL in subcutaneous and abdominal adipose tissues, partial sequences of ACC, SCDl, ELOVL6, FAS, SREBP-lc and GPAT were cloned and the mRNA expression of these genes in the liver and subcutaneous and abdominal adipose tissues per week were detected for eight weeks posthatch using Real-Time RT-PCR. Meanwhile, the total lipid contents of the three tissues and the plasma triacylglycerol (TG), Very low density lipoprotein (VLDL), Glucose and Insulin concentrations were tested every week. The results were as follows:(1)Partial sequences of ACC, FAS, SCDl, ELOVL6, SREBP-lc and GPAT were cloned, the sequences lengths were163bp,109bp,101bp,99bp,92bp and128bp respectively.(2)In hepatocytes, FAS, ACC, GPAT, SCDland ELOVL6expressed largest at the3rd,5th,5th,1st and1st week respectively, but SCDl, ELOVL6, FAS, ACC, GPAT and SREBP-lc got similar expression levels at the1st week.(3)In subcutaneous adipocytes, FAS, ELOVL6, SCDl, SREBP-lc expressed the largest at the1st week, and got similar expression levels with ACC and GPAT at1st week. Both expression levels of ACC and GPAT increased with time and got the highest at the5th week.(4)In abdominal adipocytes, ACC, SCDl, ELOVL6, SREBP-lc and GPAT expressed the largest at the4l week, and the second largest at the1st week. Expression of FAS decreased first and increased later, and got valley at the41week, but got similar expression level with others at the1st week.(5) Comparing the relative expression levels of the three tissues, FAS, ACC, ELOVL6and GPAT expressed mainly in hepatocytes, SCDl had a certain high level of expression in two adipose tissues, and SREBP-lc shared similar expression levels in three tissues.(6)The total lipid contents in subcutaneous and abdominal adipose tissues first increased and slightly reduced then, and got peak at the5th and4th week respectively, and the liver kept relative constant content.(7) Plama TG and VLDL contents both first increased and then reduced, and got peak at the4th week. Either of Insulin and glucose concentration reduced with time, and insulin got peak at the2n week, glucose at the1st week.(8)Total lipid content in liver did not correlate with plasma TG or VLDL concentration, but positively correlated with expression level of ACC (p<0.01), GPAT (p<0.01) and SREBP-1c (p<0.05) respectively. Total lipid content in subcutaneous adipose tissue positively correlated with plasma TG (p<0.05) and VLDL (p<0.01) content, and positively correlated with ACC (p<0.01) and GPAT (p<0.01) expression level, but negatively correlated with ELOVL6expression. Total lipid content in abdominal adipose tissue positively correlated with plasma TG (p<0.05) and VLDL (p<0.05) content, but had no significant correlation with expression level of any other genes.(9)Plasma glucose contents only positively correlated with SCD1’s (p<0.05) expression in hepatocytes, and positively correlated with expression level of ELOVL6(p<0.01) and SREBP-1c (p<0.01) respectively, but negatively correlation with GPAT (P<0.05) in subcutaneous adipocytes, and negatively correlation with ACC (p<0.01), and GPAT (P<0.05) in abdominal adipocytes. Interestedly, plasma insulin contents neither correlated with expression of any genes in any tissues. Both plasma TG and VLDL contents negatively correlated with expression level of SCD1(p<0.05) in hepatocytes, and had no correlation with any genes in subcutaneous adipocytes, but positively correlated with ACC, GPAT, SCD1, ELOVL6and SREBP-1c (p<0.01) respectively in abdominal adipocytes.