绵羊胃肠道游离氨基酸与小肽分布及其转运载体相关基因表达的研究

发布时间：2018-02-24 22:03

本文关键词： 绵羊小肽游离氨基酸转运载体 mRNA表达　出处：《畜牧兽医学报》2017年03期 　论文类型：期刊论文

【摘要】：旨在研究绵羊胃肠道内游离氨基酸(FAA)和小肽(PAA)的数量分布和碱性氨基酸转运载体CAT1、酸性氨基酸转运载体EAAT3、中性氨基酸转运载体y+LAT2和ASCT2、小肽转运载体PepT1、氨基肽酶APN、二肽酶DPEP2mRNA在胃肠道的表达规律。试验选取18月龄健康小尾寒羊6只,屠宰后收集瘤胃、十二指肠、空肠、回肠和盲肠的食糜及对应肠道组织,对食糜上清液的小肽和游离氨基酸进行测定,并用实时定量PCR对基因表达量进行测定。结果显示:1)绵羊食糜多数游离氨基酸浓度从高到低的分布为空肠、十二指肠、回肠、瘤胃和盲肠,前二者显著高于其他部位(P0.05);不同部位游离氨基酸组成比例不同;多数小肽浓度从高到低的分布为十二指肠、空肠、回肠、盲肠和瘤胃,除瘤胃和盲肠外各部位间差异显著(P0.05);不同部位小肽的组成比例不同;小肽占总氨基酸(TAA)的比例在空肠显著低于其他部位(P0.05)。2)CAT1mRNA在空肠表达量最高,但不同部位间差异不显著;EAAT3、y+LAT2、PepT1、APN mRNA表达规律相似,均在回肠表达量最高;ASCT2mRNA在十二指肠表达量最高,DPEP2mRNA在盲肠表达量最高。结果提示,胃肠道不同区段游离氨基酸和小肽的浓度和组成不同;游离氨基酸的主要释放部位是空肠,主要吸收部位是回肠;小肽的主要释放部位是十二指肠,主要消化部位是空肠,在肠系膜系统的主要吸收部位是回肠;瘤胃和小肠各区段吸收碱性氨基酸的能力基本相同;酸性和多数中性氨基酸主要吸收部位是回肠,少数中性氨基酸主要吸收部位是空肠。本研究为绵羊小肠氨基酸营养和蛋白质消化吸收规律的研究提供了理论依据。
[Abstract]:The aim of this study was to study the quantitative distribution of free amino acid (FAA) and small peptide (PAA) in the gastrointestinal tract of sheep and their basic amino acid transport vector CAT1, acid amino acid transport vector EAAT3, neutral amino acid transport vector y LAT2 and ASCT2, small peptide transport vector PepT1, aminopeptidase. The expression of APN, dipeptidase DPEP2mRNA in gastrointestinal tract was studied in 6 healthy 18-month-old small tail Han sheep. The chyme and corresponding intestinal tissue of rumen duodenum jejunum ileum and cecum were collected after slaughter and the small peptides and free amino acids in supernatant of chyme were determined. The gene expression was determined by real-time quantitative PCR. The results showed that the concentration of most free amino acids in chyme of sheep from high to low were jejunum, duodenum, ileum, rumen and cecum. The first two were significantly higher than other parts (P 0.05), the proportion of free amino acids in different parts were different, and the distribution of most small peptides from high to low were duodenum, jejunum, ileum, cecum and rumen. There were significant differences between different parts except rumen and cecum (P 0.05); the proportion of small peptide in different parts was different; the proportion of small peptide to total amino acid (TAA) was significantly lower in jejunum than that in other parts (P 0.05) .2CAT1 mRNA expression was the highest in jejunum. However, there was no significant difference between different sites in the expression of APN mRNA in EAAT3T _ (2) and PepT _ (1) T _ (1), which were the highest in the ileum and the highest in duodenum and the highest in the cecum. The results suggested that the expression of Asct2mRNA was the highest in the duodenum, and the expression of DPEP2mRNA was the highest in the cecum. The concentration and composition of free amino acids and small peptides in different regions of the gastrointestinal tract are different. The main releasing sites of free amino acids are jejunum, the main absorption part is ileum, the main release site of small peptide is duodenum, and the main part of digestion is jejunum. The main absorption site of mesenteric system is ileum; the ability of absorption of basic amino acids in rumen and small intestine is basically the same; the main absorption site of acid and most neutral amino acids is ileum. A few neutral amino acids are mainly absorbed in jejunum. This study provides a theoretical basis for the study of amino acid nutrition and protein digestion and absorption in sheep small intestine.
【作者单位】：西北农林科技大学动物科技学院;
【基金】：基金项目:国家绒毛用羊产业技术体系(CARS-40-13) 北方作物秸秆饲用化利用技术研究与示范(201503134)
【分类号】：S826

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