基于转录组学研究日粮添加尿素对育肥湖羊肝组织氨代谢的影响

doi:10.11843/j.issn.0366-6964.2023.03.026

摘要/Abstract

摘要： 旨在通过转录组学方法探究日粮添加不同水平尿素对育肥湖羊肝组织氨代谢及相关代谢通路的影响。试验选择42只3月龄体重(24.3±1.7)kg的育肥公湖羊，随机分为3个处理组，即在饲喂基础日粮的基础上分别添加0(U0组)、10(U10组)和30 g·kg^-1(U30组)的尿素。试验预饲期1周，正试期10周。试验结束时每组随机选取6只羊进行屠宰取样，采集肝组织样品测定氨态氮和尿素氮浓度，提取肝组织RNA进行转录组学测序，基于|fold change|>2且P<0.05的筛选标准得到差异表达基因，并针对差异表达基因进行GO功能和KEGG通路富集分析。结果发现，日粮添加尿素提高了肝组织氨态氮浓度，其中U10组氨态氮浓度较U0组显著升高(P<0.05)。与U0和U10组相比，U30组肝组织尿素氮浓度显著升高(P<0.05)。转录组学测序技术结果显示，各组间两两比较获得546个差异表达基因(DEGs)，其中与U0组相比，U10组和U30组分别各有85个上调基因以及95和108个下调基因；与U10组相比，U30组中有58个上调基因和115个下调基因。GO功能注释结果初步揭示，差异表达基因多数被注释到与胺代谢和分解、免疫系统等相关的GO条目上。KEGG富集分析结果显示，与U0组相比，U10组主要富集在脂质代谢、碳水化合物代谢、辅酶因子和维生素代谢、外源物质的生物降解和利用等与能量代谢相关的通路，其中多数基因显著上调。随着尿素剂量的进一步升高，U30组更多的富集到RIG-I型受体信号通路、胞质DNA感应通路、趋化因子信号通路等与免疫系统相关的信号通路。与U0组相比，尿素添加组使肝组织尿素生成和谷氨酰胺合成途径中精氨酸酶(arginase，ARG)和谷氨酰胺合成酶(glutamine synthetase，GLUL)等关键酶基因的表达量显著上调(P<0.05)。以上结果表明，日粮添加尿素通过上调精氨酸生物合成途径中关键酶基因的表达，促进肝组织尿素氮生成，从而影响肝组织氨代谢。

关键词: 尿素, 育肥湖羊, 肝, 转录组

Abstract: The aim of this study was to evaluate the effects of dietary urea supplementation with different levels on liver ammonia metabolism and related metabolic pathways by transcriptomic method in fattening Hu lambs. Forty-two 3-month-old fattening male Hu lambs with similar body weight of (24.3±1.7) kg were selected and randomly assigned to one of three experimental diets, which supplemented with 0 (U0 group), 10 (U10 group) and 30 (U30 group) g·kg^-1 urea on the basis of basal diets, respectively. The experiment consisted of 1 week of adaptation followed by 10 weeks of dietary treatments. At the end of the feeding trial, six animals from each group were harvested. Liver tissues of each lamb were collected to measure the concentration of ammonia-N and urea-N, and the RNA was extracted for liver transcriptome analysis. The differentially expressed genes (DEGs) were identified based on |fold change|>2 and P<0.05, and gene ontology (GO) analysis and kyoto encyclopedia of genes and genomes (KEGG) annotation were conducted. The results showed that urea supplementation increased the ammonia-N concentration in liver, and the ammonia-N concentration in U10 group was significantly higher than that in U0 group (P<0.05). Compared with U0 and U10 groups, the hepatic urea-N concentration was greatly increased in U30 group (P<0.05). Transcriptome sequencing results showed that a total of 546 DEGs were obtained by pairwise comparison among all groups. Compared with U0 group, U10 and U30 group both had 85 up-regulated DEGs, and 95 and 108 down-regulated DEGs, respectively. Compared with U10 group, 58 up-regulated DEGs and 115 down-regulated DEGs were found in U30 group. GO functional annotation results suggested that these DEGs were mainly annotated in GO terms, including amine metabolism and catabolism, regulation of immune system, and so on. Compared with U0 group, KEGG enrichment analysis showed that the energy metabolic pathway of U10 group were mainly enriched in lipid metabolism, carbohydrate metabolism, metabolism of cofactors and vitamins, xenobiotics biodegradation and metabolism, and most of its genes were significantly up-regulated. While with the urea addition to the diet further increased, the metabolic pathway of U30 group were mainly associated with the immune system, including RIG-I like receptor signaling pathway, cytosolic DNA-sensing pathway and chemokine signaling pathway. Compared with U0 group, the expression of key enzyme genes such as arginase (ARG) and glutamine synthetase (GLUL) in urea biosynthesis and glutamine synthesis pathway in liver were significantly up-regulated in the groups with urea addition (P<0.05). In conclusion, dietary urea supplementation increased the concentration of urea-N in liver by up-regulating the expression of key enzyme genes in arginine biosynthesis pathway, thus affecting liver ammonia metabolism.

Key words: urea, fattening Hu lambs, liver, transcriptome

中图分类号:

S826.5

孙美杰, 曹力文, 郑文金, 申军士, 朱伟云. 基于转录组学研究日粮添加尿素对育肥湖羊肝组织氨代谢的影响[J]. 畜牧兽医学报, 2023, 54(3): 1148-1159.

SUN Meijie, CAO Liwen, ZHENG Wenjin, SHEN Junshi, ZHU Weiyun. Effect of Dietary Urea Supplementation on Liver Ammonia Metabolism in Fattening Hu Lambs Based on Transcriptome Sequencing[J]. Acta Veterinaria et Zootechnica Sinica, 2023, 54(3): 1148-1159.

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