Study On The Expression Of NELL1 And FMO3 In Tail Fat, Subcutaneous Fat, Perirenal Fat And Liverinsheep

The position and the way of fat deposition in sheep had a significant influence on meat quality and economic benefit.Thus, revealing the effect of gene function, dietary and growth stage on fat deposition is important to improve the meat quality in sheep. In this study, we selected fat deposition related genes NELL1 and FMO3, and investigated their expression differences in tail fat tissues among fat-tailed and thin-tailed sheep(Tong sheep, Tan sheep, Kazakh and Tibetan). This experiment was aimed to explore the effect of different nutrition levels and growth stage on NELL1 and FMO3 expression in fat tissue of Tan sheep, and discover the tissue specificity and express profiles of these two genes in fat-tailed sheep under different nutrition levels and in different growth periods, so as to provide theoretical basis for the nutritional regulation of fat deposition in fat-tailed sheep breeds.Experiment 1:Study on the expression of NELL1 and FMO3 mRNA in tail adipose tissue of different breeds of sheep.Nine-month Tan sheep, Tong sheep, Kazakh and Tibetan sheep which had the similar body weight were selected for adipose tissue collection, three individuals were used for each breed. The total RNA was extracted from adipose tissues of sheep tails, and the expression level of FMO3 and NELL1 were analyzed by quantitative PCR.The results showed:1. the expression level of FMO3 was the highest in the Kazakh breed(fat-tailed)(P<0.05), right after with Tong, Tan, Tibetan sheep(short-tail)(P<0.05)2. NELL1 is highly expressed in the tails of Tibetan sheep(P<0.05), declined in turn with Tan sheep, Tong sheep, and Kazakh breed.Experiment 2:The effect of different nutrientlevels on the mRNA express of NELL1 and FMO3 in adipose tissues of Tan-sheepunderdifferent stagesA total of 112 healthy Tan sheep were randomly divided into 4 groups(according to a completely random experiment design) with 4 replicates per group(2 males and 2 females), each replicate comprises 7 animals. This experiment was divided into 3 periods according to weight gain target: 22-28 kg,28-35 kg,35-40 kg,at the every time we feed different nutrient levels of diet which were assigned to four treatments(group T1, group T2, group T3, group T4) from low to high. At the end of each stage, the liver fat, perineal fat, tail fat and subcutaneous fat were collected. The total RNA was extracted from adipose tissues, and the expression level of FMO3 and NELL1 were analyzed by quantitative PCR. The results showed:1. In the first stage, the mRNA expression of NELL in tail fat was highest in T4 group(P<0.05). There was no significant difference of that among other three groups.In the second and third stage, it was also the highest in T4 group(P<0.05). There were some subtle changes in TI, T2 and T3 group..2. In the first and the second stage, there were no significant differences on mRNA expression of NELL1 in subcutaneous fat among four nutrient level groups(P>0.05). In the third stage, it was the highest in T4 group(P<0.05), and then T2, T3 and T1 in turn. The mRNA expression of NELL1 in subcutaneous fat was the highest in the first stage(P<0.05).3. In the same period, the nutrient levels had no significant influence on mRNA expression of NELL1 in perineal fat(P>0.05). The mRNA expression of NELL1 in perineal fat in different growth stage had significant difference(P<0.05) at the same nutrition levels.4. In the first stage, the nutrition levels had no significant effect on mRNA expression of NELL1 in liver(P>0.05); In the second stage, it was the highest in T4 group, and then T3, T1 and T2 group in turn(P<0.05); In the third stage, it was the highest in T1 group(P<0.05), and then T2, T3 and T4 group in turn. The mRNA expression of NELL1 in liver increased significantly in whole period(P<0.05).5. The mRNA expression of FMO3 in tail fat was the highest in T2 group, and it showed a trend of rising firstly then declining in every stage. For the mRNA expression of FMO3 in subcutaneous fat, perineal fat and liver, that was the highest in T3, T1 and T4, respectively. There was a significant difference between the highest and lowest group for the mRNA expression of FMO3 in the same stage(P<0.05).Experiment 3: Study on the expression of NELL1 and FMO3 mRNA in different tissues of Tan sheepAt the end of the experiment, four sheep in T2 group were slaughtered and were used to collect the tissues of liver, perineal fat, tail fat and subcutaneous fat.The mRNA expression of NELL1andFMO3 were determined by real-time PCR. The results showed as follows:1. For the mRNA expression of NELL1, that in liver was the highest and that in liver was notably higher than tail fat, subcutaneous fat and perineal fat(P<0.05), and that in tail fat was markedly higher than subcutaneous fat and perineal fat(P<0.05), and there was no significantly difference between these two tissues(P>0.05).2. The mRNA expression of FMO3 was the highest in liver and that in liver was significantly higher than tail fat, subcutaneous fat and perineal fat(P<0.05), and that in tail fat was remarkably higher than subcutaneous fat and perineal fat(P<0.05) There was no significantly difference between subcutaneous fat and perineal fat(P>0.05).In conclusion, there were many factors such as breeds, positions, growth stage and nutrient levels which could have an influence on the expression of NELL1 and FMO3. The expression of NELL1 and FMO3 are related to fat deposition.