热应激对蛋鸡肠道菌群结构、碱性磷酸酶活性及氨基酸转运载体mRNA表达丰度的影响

摘要

[目的]揭示热应激环境下蛋鸡肠道菌群结构、肠黏膜碱性磷酸酶活性和氨基酸转运载体mRNA表达量的变化机理。[方法]试验选择16周龄济宁百日鸡96只，随机分成对照组（（24±1）℃；Ⅰ）和热应激（（38±1）℃）组，各组设6个重复，每个重复8只，试验持续14 d。采用16S rDNA的PCR-DGGE技术和实时荧光定量PCR等手段，分析热应激2（Ⅱ）、7（Ⅲ）、14 d（Ⅳ）时，对十二指肠、空肠及回肠内容物菌群多样性和肠黏膜碱性磷酸酶活性以及氨基酸转运载体rBAT、y+LAT 1、CAT l mRNA基因表达的相对丰度变化规律。[结果]热应激7 d开始各肠段菌群多样性较为丰富，热应激7、14 d时空肠和回肠部位敏感乳杆菌（Lactobacillus agilis），回肠部位约氏乳杆菌（Lactobacillus johnsonii）、不可培养细菌（uncultured bacterium）和不可培养的拟杆菌属（uncultured Bacteroidalesbacterium）均末检测到；而热应激不同时间段空肠和回肠部位可检测到不可培养细菌、溃疡拟杆菌（Bacteroides helcogenes）、卵形拟杆菌（Bacteroides ovatus）、索氏志贺氏菌（Shigella sonnei）；空肠和回肠部位黏膜上皮细胞表面的碱性磷酸酶活性与Ⅰ组比较显著下降（P＜0.05）；而空肠和回肠Ⅲ组的rBAT、y+LAT 1 mRNA表达丰度均最低，空肠在各热应激时段表达丰度变化幅度最大（P＜0.05），回肠的CAT 1 mRNA表达丰度在Ⅲ、Ⅳ组与Ⅰ组比较影响更明显（P＜0.01）。[结论]热应激对空肠和回肠部位微生物菌群影响较为明显，肠道微生物群落改变可导致肠道的消化吸收功能发生改变。%[Objective] The objective of this study is to reveal the influence mechanisms of heat stress affecting the intestinal flora structure of layer, the alkaline phosphatase activities of intestinal mucosa and the mRNA expression of amino acid transporters.[Method]A total of 96 Jining Bairi chicken aged at 16 weeks were chosen and randomly divided into control group (group I, (24±1)℃) and heat stress group ((38±1)℃). six replicates were desighed for each group with 8 individuals for each replicate, and the duration sustained for 14 days. PCR-DGGE and RT-PCR of 16S rDNA were used. The bacterial diversity of the contents in dodecadactylon, jejunum and ileum, alkaline phosphatase activities of intestinal mucosa and the mRNA expression of amino acid transporters e.g. rBAT, y+LAT1, and CATl were analyzed when the layers were under the heat stress on 2nd day (group II), 7th day (group III) and 14th day(group IV), respectively.[Result]The bacterial diversities of each intestinal segments showed relatively abundant from the 7th day after heat stress. On the 7th and 14th days, no sensitive lactobacillus in jejunum and ileum was detected, and so were the L. johnsonii, nonculturable bacteria and Bacteroides in ileum. While the nonculturable bacteria, ulcer Bacteroides, ulcer Bacteroides, and Shigella sonnei were detected at every phase of heat stress. The alkaline phosphatase activities of mucosal epithelial cells in jejunum and ileum decreased significantly compared to the control group (P<0.05). The mRNA expressions of rBAT, y+LAT1 of the group III in jejunum and ileum were the lowest. The variation extent of the mRNA expression in jejunum at each phase of heat stress was the greatest (P<0.05). The mRNA expressions of CAT1 in ileum of groups III and IV were affected more greatly by the heat stress compared to that of group I (P<0.01).[Conclusion]The influence on the intestinal flora in jejunum and ileum by heat stress is more evidently and the intestinal function of digestion and absorption can be changed by the variation of the intestinal flora..