西农萨能奶山羊脂肪酸合酶（FASN）和硬脂酰CoA去饱和酶1（SCD1）基因多态性与乳脂肪酸成分的关联分析

发布时间：2018-03-10 19:04

本文选题：FASN　切入点：SCD1　出处：《西北农林科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：脂肪酸合酶(Fatty acid synthase, FASN)是哺乳动物脂肪酸从头合成的关键酶,催化短中链饱和脂肪酸的形成。硬脂酰辅酶A去饱和酶(Stearoyl-CoAdesaturase-1, SCD1)是催化形成单不饱和脂肪酸的关键酶,通过对饱和脂肪酸第9位碳链增加一个不饱和双键而形成单不饱和脂肪酸,催化底物主要以棕榈酸(C16：0)及硬脂酸(C18：0)为主,是乳腺自身进行脂肪酸去饱和作用的关键酶。反刍动物乳脂的遗传力较高,并且在乳腺组织中FASN和SCD1基因的mRNA表达量较高,因此本试验选取以上两个基因作为候选基因。采集母羊分娩后4个月内的奶样(泌乳30天,60天,90天,120天),分析主要乳成分和脂肪酸组成,并与候选基因筛选出的多态位点进行关联分析。主要结果如下：1)通过DNA池测序技术,分析得到FASN基因的3个多态位点(内含子1的SNP C-911-T,内含子2的SNP A-852-G,外显子37的SNP T-14420-C)和SCD1基因的2个多态位点(外显子3的SNP A-5205-G,内含子3的SNP C-5311-T),并检测到FASN基因存在两个单倍型,H1 (C1-A2-T3)和H2 (T1-G2-C3)。所有突变位点中,除SNP A-5205-G外其他突变位点均符合哈代温伯格平衡定律。利用线性混合模型,对FASN和SCD1基因的SNPs以及FASN基因的单倍型与产奶性状进行相关性分析。模型中涉及到种群效应、检测天数效应、泌乳时间效应、胎次效应、个体效应、公畜效应、等位基因效应和单倍型效应以及泌乳时间内等位基因与单倍型之间的互作效应。FASN基因的3个SNP在不同泌乳时间均显著影响了C6：0,C8：0,C10：0和C14：0脂肪酸的含量,并且主要等位基因均显著下调了从头合成的脂肪酸含量。单倍型H1(C1A2T3)也显著下调了从头合成的脂肪酸含量,但是单倍型H2(T1G2C3)对从头合成脂肪酸的影响与之相反。此外,单倍型H2显著性影响了C18:1 n9 trans和CLA cis9, tran11的含量。SCD1基因的SNP位点C-5311-T在不同泌乳时间均显著影响了C16：1,C13：0,C14：1脂肪酸的含量。尽管SCD1基因的SNP A-5205-G不符合哈代温伯格平衡定量,但是其对C4：0,C11：0,C12：0,C16：1,C17：1,C18：0脂肪酸的含量具有显著性影响。以上结果表明,这些多态位点可以作为改善山羊奶品质的分子标记。2)利用线性混合模型分析泌乳时间、胎次、种群采样时间等因素对羊奶成分以及脂肪酸组成的影响。模型分析过程中涉及的随机效应包括公畜和羊只个体的效应。采样时间和种群因素显著影响乳中脂肪酸的组成,表明饲养管理水平和环境因素对乳成分以及乳中脂肪酸组成具有重要的影响。随着泌乳时间的延长以及胎次的增加,羊奶中饱和脂肪酸含量增加,与其相反,单不饱和脂肪酸和多不饱和脂肪酸含量降低。结果表明,山羊乳腺组织的发育随着年龄的增长趋向完善。随着泌乳时间的延长,脂肪与蛋白的校正比值出现显著下调。表明在奶山羊泌乳早期脂解作用的存在。在早期泌乳阶段,奶中多不饱和脂肪酸含量更为丰富,而饱和脂肪酸含量较少。随着泌乳时间的延长,CLA cis9,trins11的含量增加,推测随着泌乳时间的延长,SCD1的活性及表达水平不断升高。相关性分析表明,从头合成的饱和脂肪酸与C18类多不饱和脂肪酸存在负相关,这可能是由于多不饱和脂肪酸对脂肪酸从头合成的抑制作用所致。尽管C4：0脂肪酸被认定是从头合成而来,但是其与中链脂肪酸存在负相关,说明C4：0脂肪酸的来源不止一条途径。奶中的奇数链脂肪酸主要来源于瘤胃中的微生物,因此其含量以及与其他脂肪酸的相关性反应了瘤胃微生物群落的活性。奇数链脂肪酸与CLA cis9, trans 11以及其他反式脂肪酸存在正相关,说明奇数链脂肪酸与反式脂肪酸的相关性可以作为诊断奶山羊瘤胃微生物活性的一种生物学标记。本试验首次分析了影响奶中脂肪酸变化的因素,为日后改善羊奶品质提供了理论依据。
[Abstract]:Fatty acid synthase (Fatty acid, synthase, FASN) is a key enzyme in mammalian fatty acid biosynthesis, the formation of short chain saturated fatty acid catalysis. Stearoyl coenzyme A desaturase (Stearoyl-CoAdesaturase-1, SCD1) is the key enzyme catalyzing the formation of monounsaturated fatty acids and saturated fatty acids by ninth carbon chain add an unsaturated double bond and the formation of monounsaturated fatty acids catalyzed mainly by palmitic acid (C16:0) and stearic acid (C18:0), is a key enzyme in breast self fatty acid desaturation. Fat of ruminant animal genetic capacity is high, and FASN in breast tissue and SCD1 gene mRNA the expression level is high, so this experiment selected above two gene as candidate gene. The milk samples within 4 months after birth (lactation ewes collected 30 days, 60 days, 90 days, 120 days), the main composition analysis of milk composition and fatty acid, and the candidate base Polymorphic loci were screened by correlation analysis. The main results are as follows: 1) by DNA sequencing technology, analysis of 3 polymorphisms of FASN gene (SNP, C-911-T, SNP in intron 1 A-852-G and intron 2 and exon 37 of SNP T-14420-C) 2 polymorphic sites and SCD1 gene (the exon 3 of SNP A-5205-G, SNP C-5311-T), and intron 3 of FASN gene was detected in two haplotypes, H1 (C1-A2-T3) and H2 (T1-G2-C3). All mutations, in addition to SNP A-5205-G the other mutations are in line with the Hardy Weinberg equilibrium. Using linear mixed model, correlation analysis the SNPs of FASN and SCD1 gene and FASN gene haplotypes and milk production traits. Related to the population effect model, testing days effect, lactation time effect, birth order effect, individual effect, sire effect, allele effect and haplotypic effect and time of lactation In between the allele and haplotype interaction of 3 SNP effect of.FASN gene in different lactation time had significant effects on C6:0, C8:0, C10:0 and C14:0 fatty acid content, and the main allele were significantly reduced the fatty acid content of de novo synthesized. Haplotype H1 (C1A2T3) also significantly lowered the fatty acid the content of de novo synthesized, but the haplotype of H2 (T1G2C3) on the de novo synthesis of fatty acids on the contrary. In addition, the haplotype of H2 significantly affected C18:1 N9 trans and CLA cis9, the content of.SCD1 tran11 gene SNP locus C-5311-T in different lactation time were significantly affected by C16:1, C13:0, the content of fatty acid C14:1 although the SCD1 gene SNP. A-5205-G does not comply with the Hardy Weinberg equilibrium quantity, but the C4:0, C11:0, C12:0, C16:1, C17:1, significantly influenced the fatty acid content of C18:0. The above results suggest that this Some polymorphic loci can be used as a molecular marker of.2 improve the goat milk quality) of lactation time, using linear mixed model parity, sampling time and other factors on the impact of population goats'milk composition and fatty acid composition. The random effects model analysis involving process including the effect of sire and sheep. The individual sampling time and significantly influence the composition of population the fatty acids in milk, feeding management and environmental factors that have important influence on milk composition and fatty acid composition in milk. With prolonged lactation time and increased parity, increase in saturated fatty acid content of goats' milk instead, monounsaturated fatty acid and polyunsaturated fatty acid content decreased. Show that the goat mammary tissue development along with the age growth tendency to improve. With prolonged lactation time, ratio of fat and protein correction was reduced. In that Early lactation dairy goat lipolysis exists. In the early stage of lactation, milk polyunsaturated fatty acid content is more abundant, and the saturated fatty acid content is low. With prolonged lactation time, CLA cis9, trins11 content increased, presumably with prolonged lactation time, the activity and the expression of SCD1 increased. The correlation analysis shows that the de novo synthesis of acid saturated fat and C18 polyunsaturated fatty acids are negatively correlated, this may be due to polyunsaturated fatty acids on inhibition of fatty acid induced de novo synthesis of fatty acids were identified. Although C4:0 is from the head to the synthesis, but with medium chain fatty acids are negatively correlated. Explain the source of C4:0 fatty acids in more than one way. The odd chain fatty acids in milk from the main source of rumen microorganisms, so the correlation between the contents and fatty acid reaction of rumen microbial communities The activity of odd chain fatty acid and CLA cis9, trans 11 and other trans fatty acids were positively correlated, indicating the correlation of odd chain fatty acids and trans fatty acids can be used as a biomarker for the diagnosis of dairy goat rumen microbial activity. This is the first analysis of factors influencing changes in milk fatty acids, provide the theoretical basis for improving the quality of goats'milk day.

【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S827

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