性激素变化对小鼠肠道菌群构成的影响

肠道菌群在维持宿主免疫和消化系统功能方面发挥着重要作用,肠道菌群的多样性和丰富度是衡量宿主健康状况的重要生理指标。性激素对动物生长发育发挥重要作用,但其对肠道菌群构成影响的相关实验研究相对较少。本研究以模式生物小鼠（Mus musculus）为对象,探究性激素的变化对小鼠肠道菌群构成的影响。采用外科手术方式建立小鼠去势模型,通过16S r RNA高通量测序技术,研究性激素对小鼠肠道菌群构成的影响。研究结果表明,雌性小鼠和雄性小鼠去势后,性激素水平显著下降。肠道菌群在门水平上,正常小鼠和去势小鼠肠道细菌群落均由拟杆菌门（Bacteroidetes）、厚壁菌门（Firmicutes）、变形菌门（Proteobacteria）、埃普西隆杆菌门（Epsilonbacteraeota）、髌骨细菌门（Patescibacteria）、放线菌门（Actinobacteria）、软壁菌门（Tenericutes）、脱铁杆菌门（Deferribacteres）、酸杆菌门（Acidobacteria）和蓝藻细菌门（Cyanobacteria）组成,主要菌群为厚壁菌门和拟杆菌门物种,两门占物种相对丰度百分比...     

基于高通量测序的树鼩不同肠道部位菌群结构分析

目的观察树鼩不同肠道部位菌群的多样性及构成。方法采集3只雄性树鼩回肠、盲肠、结肠内容物,提取DNA,利用Illumina PE250高通量测序平台扩增肠道菌16S rDNA V4区域,分析菌群结构和丰富度。结果树鼩回肠、盲肠、结肠菌群的优化序列数差异无统计学意义。α多样性分析,树鼩肠道3个部位菌群的Chao1指数、PD指数、Simpson指数、Shannon-Wiener指数差异无统计学意义,相对于回肠,盲肠与结肠菌群多样性的相似性较高。Rank-Abundance曲线显示,回肠菌群的丰富度较高且分布较均匀。β多样性分析,树鼩回肠菌群结构差异性较小,盲肠与结肠菌群结构差异较大。树鼩肠道菌群共检出26个门,17个门在3个组共存。互养菌门(Synergistetes)、Rokubacteria门、奇古菌门(Thaumarchaeota)、TA06门仅见于回肠;衣原体门(Chlamydiae)为盲肠中特有;迷踪菌门(Elusimicrobia)仅在结肠中发现。共获得414个属,结肠、盲肠、回肠中独有属分别为15个、7个、3个。共发现530个种,其中唾液乳杆菌(Lactobacillus salivarius)丰富度最高。Random Forest分析结果显示,在树鼩回肠、盲肠、结肠中发现7个生物标记物。结论树鼩回肠、盲肠、结肠肠道菌群多样性差异无显著性,但相对于结肠与盲肠,回肠菌群丰富度较高且分布较均匀。树鼩3个肠道部位具有各自独特的菌群。     

高通量测序检测肺炎婴幼儿抗生素治疗前后肠道菌群变化

目的了解抗生素对肺炎婴幼儿肠道菌群多样性和结构的影响。方法选取5例1岁以内因轻度社区获得性肺炎住院的患儿,收集抗生素治疗前及治疗后第3~5天的粪便标本。利用Illumina MiSeq测序平台,对细菌的16SrRNA基因V3~V4区进行高通量测序,并对测序结果进行生物信息学分析。结果抗生素治疗后第3~5天婴幼儿肠道菌群的多样性明显下降。变形菌门的相对丰度在3例婴幼儿的肠道中下降;厚壁菌门的相对丰度在4例婴幼儿的肠道中下降;而拟杆菌门的相对丰度在4例婴幼儿的肠道中上升;厚壁菌门与拟杆菌门的比例下降。肠道内不动杆菌属、喜胆汁菌属、埃格特菌属、肠球菌属、支原体、颤螺菌属、紫单胞菌属、普雷沃菌属和真杆菌属增长1倍以上;奇异菌属、双歧杆菌属、黄杆菌属、乳酸菌属、链球菌属、萨特菌属和韦荣球菌下降超过50%。结论婴幼儿短期使用抗生素治疗肺炎后,肠道菌群的多样性下降,肠道微生态失衡。     

常见SPF级小鼠和大鼠肠道菌群多样性研究

目的研究常见SPF级小鼠和大鼠的肠道菌群多样性。方法分别采集广东地区三家实验动物生产单位的C57BL/6、ICR、BALB/c小鼠和Wistar、SD大鼠的盲肠内容物样品,用细菌16S rDNA通用引物扩增V4-V5区域,采用Illumina Miseq 2×300 bp测序平台进行测序,使用生物信息学方法进行微生物群落分析、Alpha多样性分析与Beta多样性分析。结果对序列去杂优化后OTU聚类分析,稀释性曲线说明本次测序的数据量合理;实验小鼠和大鼠肠道菌群共分成八个门,其中拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)占据主要地位,属水平上主要是拟杆菌属(Bacteroides)、Hungatella、副杆状菌属(Parabacteroides)、乳酸杆菌属(Lactobacillus)等;样品间差异性分析显示相同设施来源动物的菌群组成相似性较高;Alpha分析结果显示来源于同种设施的动物物种丰富度相近;Beta分析显示相同设施动物的肠道菌群差异较小,但品系对肠道菌群差异性有所影响。结论不同来源设施的饲养环境是动物肠道菌群多样性的主要影响因素,不同品系对肠道菌群多样性有一定影响。     

普氏蹄蝠胃肠道菌群的多样性

【目的】研究普氏蹄蝠(Hipposideros pratti)胃肠道菌群多样性及致病菌的种类。【方法】采用Mi Seq高通量测序技术,通过对16S r RNA基因V1-V2区基因进行测序,研究普氏蹄蝠胃肠道细菌的群落组成。应用MG-RAST V3.3.6分析和统计样品序列和操作分类单元(OTU)数目,分析胃肠道菌群物种丰度,并进行聚类分析。【结果】从普氏蹄蝠胃和肠道中分别获得144 998条和275 274条原始序列以及48 332条和91 758条有效序列,分属于894个和756个操作分类单元。胃中菌群丰度指数Chao指数(1 490)和ACE指数(2 221)分别低于肠道菌群的Chao指数(2 051)和ACE指数(3 556);Shannon多样性指数(2.405)低于肠道(2.407);Simpson多样性指数(0.168)高于肠道(0.151)。系统进化分析表明胃肠中的细菌主要分布在6个门,均以变形菌门(Proteobacteria)(胃中占56.4%,肠中占46.0%)和厚壁菌门(Firmicutes)(胃中占40.7%,肠中占49.2%)为优势菌门。胃肠道中丰度在0.1%以上的属有24个,胃中优势类群为乳球菌属(Lactococcus)和哈夫尼菌属(Hafnia),分别占整个菌群的26.1%和21.0%;肠道中优势类群为肠球菌属(Enterococcus)和沙门氏菌属(Salmonella),分别占整个菌群的15.2%和12.7%。普氏蹄蝠胃肠道中的优势菌群均为人类的致病菌或者条件致病菌。【结论】普氏蹄蝠携带有大量人类致病菌。因此,应注意防止向人类传播。     

北京地区四个豹猫亚种群肠道菌群的组成

野生动物的肠道微生物组成受食物资源和遗传属性的影响较大, 为了解北京地区小型猫科动物肠道菌群组成特点及其影响因素, 本研究通过扩增细菌16S rRNA的V3‒V4高变区进行高通量测序, 对云蒙山、云峰山、松山、百花山4个区域的豹猫(Prionailurus bengalensis)亚种群进行肠道菌群组成分析。结果表明, 在门水平上, 豹猫的肠道优势菌群主要由厚壁菌门(相对多度52.40%)、变形菌门(25.18%)、放线菌门(9.07%)、拟杆菌门(8.17%)和梭杆菌门(4.74%)组成。在属水平上, 相对多度最高的前5个属为假单胞菌属(Pseudomonas, 13.37%)、布劳特氏菌属(Blautia, 11.20%)、梭菌属(Clostridium_sensu_stricto_1, 9.10%)、消化梭菌属(Peptoclostridium, 8.62%)、乳杆菌属(Lactobacillus, 6.08%), 共约占总多度的50%。各区域豹猫亚种群的肠道菌群β多样性不存在显著差异, 松山区域的ACE指数和Chao 1指数与云蒙山和云峰山存在显著差异。鉴于松山亚种群的遗传结构与其他区域有所不同, 而4个区域的气候类型和豹猫食物构成相似性高, 推测该亚种群的肠道菌群主要受遗传结构分化的影响, 对此还需进一步研究。     

基于性别二分类的青海天峻藏民肠道菌群差异分析

目的对青海省天峻县的藏族牧民健康志愿者肠道菌群进行研究,探讨青海藏民肠道菌群结构及性别对肠道菌群组成的影响。方法以28例藏族牧民志愿者的粪便样品作为研究对象,应用基于16SrDNA V3+V4可变区的高通量测序技术测定肠道菌群组成及核心菌群;通过db-RDA和菌群多样性分析,探索性别因素对肠道菌群结构的影响。结果在门水平上,厚壁菌门和拟杆菌门是青海藏族志愿者的优势菌群。在属水平上,优势菌属是普氏菌属、Lachnospiracea_incertae_sedis、Faecalibacterium和拟杆菌属;特有优势菌属是Lachnospiracea_incertae_sedis。db-RDA结果显示性别因素对肠道微生物群结构有一定分离趋势,多样性结果进一步证实性别差异显著影响菌群结构。男性和女性存在12种差异菌群,包括普氏菌属、Acidaminobacter属等。结论性别差异对青海藏民肠道菌群影响显著。     

不同地理纬度笼养狼肠道菌群多样性比较研究

动物肠道菌群关系其健康状态,而菌群组成受到生活环境等因素的影响,探究其中关系有利于更好地进行物种保护。本研究基于非损伤性取样,利用16S rDNA高通量测序技术,开展不同地理纬度笼养国家二级重点保护野生动物狼（Canis lupus）的肠道菌群结构比较和初步功能预测。针对取自天津市动物园（38°88′N）和南京市红山森林动物园（31°14′N）两地饲养的狼粪便样本（分别简称为天津样本和南京样本）进行高通量测序,利用生物信息学比较分析两组样本的微生物组成和多样性差异。结果表明：Student’s t和Welch’s t检验显示南京样本的α多样性显著高于天津样本。在门水平上,厚壁菌门（Firmicutes）和放线菌门（Actinobacteria）是两组样本中的优势菌门,天津样本中弯曲杆菌门（Campilobacterota）的丰度显著高于南京样本。在属水平上,两组样本的肠道菌群中优势菌属均包括艰难梭菌属（Peptoclostridium）、柯林斯菌属（Collinsella）和狭义梭菌属（Clostridium＿sensu＿stricto＿1）。基于Unweighted UniFrac距...     

喂养方式对西安地区0～2个月婴儿肠道菌群的影响

目的 探讨母乳和混合喂养方式对西安地区婴儿肠道菌群的影响。方法 收集24例0～2月龄西安地区健康婴儿粪便样本,根据婴儿的喂养方式,将样本分为母乳喂养组（17例）和以奶粉为主的混合喂养组（7例）。利用16S rRNA基因测序技术对不同喂养方式的婴儿肠道菌群进行测序,比较不同喂养方式对婴儿肠道菌群多样性和菌群差异的影响。结果 母乳喂养组婴儿粪便样本Ace指数和Chao1指数显著高于混合喂养组（t=4.886, P<0.05; t=6.855, P<0.05）, Shannon指数显著低于混合喂养组（t=2.126,P<0.05）。门水平上,2组样本均以放线菌门、厚壁菌门、变形菌门和拟杆菌门为主,但比例存在差异。相比混合喂养组,母乳喂养组婴儿粪便样本放线菌门和拟杆菌门丰度显著升高（U=6,P<0.05;U=0,P<0.05）,厚壁菌门和变形菌门丰度显著降低（U=24,P<0.05;U=16,P<0.05）。属水平上,母乳喂养组婴儿粪便样本双歧杆菌相对丰度（72.04%）显著升高,同时发现罗氏菌属和葡萄球菌属相对丰度也高于混合喂养组（U=17,P<...     

~(137)Cs辐照对橘小实蝇雄虫肠道菌群多样性的影响

【目的】为研究137Cs辐照前后橘小实蝇雄虫肠道菌群多样性和丰度的变化及其肠道菌群在不同分类阶元上的显著差异物种。【方法】本研究利用IlluminaHiSeq高通量测序技术对辐照组和对照组共6个样品进行测序分析。【结果】变形菌门和厚壁菌门分别以60.38%、24.33%的比例作为橘小实蝇肠道中的优势菌门和次优势菌门,肠杆菌科和肠球菌科分别以60.38%和15.69%作为优势菌科和次优势菌科。米勒氏菌属(Moellerella)、摩根氏菌属(Morganella)、Cosenzaea属、链球菌科未知属和酸热菌属(Acidothermus)是组间显著差异的菌属。【结论】本研究发现橘小实蝇在辐照后的肠道菌群多样性和丰度均有显著性降低,并在目至属等3个分类阶元上找到辐照后具有显著差异的物种,为后期利用差异菌群来改善辐照对橘小实蝇的消极影响及修复辐照损伤提供理论基础。     

人工饲养恒河猴幼猴不同肠段微生物宏基因组学研究

目的以恒河猴幼猴为模型,采用16S rRNA宏基因组方法探讨十二指肠、盲肠、直肠的菌群组成。方法收集4例健康幼猴十二指肠、盲肠、直肠样本,提取细菌总DNA,采用新一代高通量测序技术对16S rRNA基因的V3-V4高变区测序,分析比较菌群结构及多样性。结果 (1)门水平各肠段微生物优势菌群主要为硬壁菌门、变形菌门及拟杆菌门,在各肠段中的占比总和超过88%;(2)属水平,十二指肠中以芽胞杆菌属等为优势菌属,盲肠中以螺杆菌属、颤杆菌属、孢杆菌属等为优势菌属,直肠中以乳酸菌属、链球菌属、颤杆菌属等为优势菌属;(3)各肠段微生物功能差异较大,十二指肠主要承担营养物质的消化吸收,盲肠主要承担细胞及遗传物质的合成,直肠主要承担调节机体免疫力、抗感染等功能。结论各肠段菌群组成差异较大;各肠段细菌功能差异较大,且与其生理功能有一定关联;在肠道菌群研究中,应充分考虑粪便样品微生物的组成是否能够完全代表肠道微生物的组成。     

不同品种、日龄和饲养方式对肉鸡肠道菌群的影响

目的研究品种、日龄和饲养方式对肉鸡肠道菌群的影响。方法选择北京油鸡和AA肉鸡各120只,分笼养和地面平养两种饲养方式,每种饲养方式60只鸡(5个重复,每个重复12只),于7、14、21和42日龄无菌收集十二指肠、回肠和盲肠内容物,分析各肠段肠道菌群变化。结果 (1)从十二指肠、回肠到盲肠微生物种类越来越丰富,相同肠段不同处理间随日龄的增加微生物种类也不断增加,十二指肠、回肠主要菌是植物乳酸杆菌和双歧杆菌,盲肠主要菌是拟杆菌和梭菌,且AA肉鸡拟杆菌数量大于北京油鸡;(2)品种对十二指肠和回肠条带数影响不显著,但北京油鸡大于AA肉鸡,日龄对回肠条带数的影响显著。品种与日龄的互作对盲肠的影响显著,品种、日龄和饲养方式三个处理的互作对回肠条带数的影响显著。(3)十二指肠各处理间肠道菌群的相似性在42日龄达到稳定,回肠在21日龄稳定,盲肠从7日龄到42日龄各处理间肠道菌群相似性变化不大。结论不同肠段的微生物区系有明显差异,品种、日龄和饲养方式对肉鸡肠道微生物区系有不同影响,但微生物区系会随着肉鸡日龄的增加趋于稳定。     

Characterization and comparisons of microbiota in different intestinal segments between adult Chinese Shanxi Black Pigs and Large White Pigs

The carcass weight of Chinese Shanxi Black Pigs is relatively lower in comparison with that of the counterparts, i.e., Large White Pigs, although the former are resistant to harsh conditions. Since gut microflora has been recognized to play a key role in pork production, it is of interest to explore the microbial communities in different intestinal segments of pigs and its potential relatedness with host features. In this study, 16S rRNA gene amplicon sequencing, accompanied by the inter- and intra-group comparisons, was implemented to investigate the structure composition and potential functions of microbial communities of four distinct intestinal segments [duodenum (D), jejunum (J), ileum (I), and cecum (C)] between adult Chinese Shanxi Black Pigs and Large White Pigs. Comparative survey revealed that the dominant phylum in both breeds was Firmicutes, followed by Proteobacteria, and Bacteroidetes. At the genus level, Lactobacillus was predominant in all samples, and Prevotella was specifically prevalent in the cecum. Further inspection showed the differences of dominant species in the same segments between these two groups. Notably, unique taxa in C and D segments were more than that in I and J segments. Additionally, each segment was characterized by specifically enriched genera, and distinctive pathways were predicted in certain intestinal segments. In short, the findings presented a coherent picture of structure composition and predicted functionalities of gut microbiota in diverse intestinal segments of adult Chinese Shanxi Black Pigs and Large White Pigs, and extend the understanding of potential link between intestinal microbiota and their hosts.     

Comparison of bacterial diversity along the human intestinal tract by direct cloning and sequencing of 16S rRNA genes

Bacterial diversity of the mucosal biopsies from human jejunum, distal ileum, ascending colon and rectum were compared by analysis of PCR-amplified 16S rDNA clone libraries. A total of 347 clones from the mucosal biopsies were partially sequenced and assigned to six phylogenetic phyla of the domain Bacteria: Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, Verrucomicrobia, and Actinobacteria. The jejunum sample had least microbial diversity compared to the other samples and a trend towards highest diversity in ascending colon was observed. The clone libraries of distal ileum, ascending colon and rectum were not significantly different from each other (P>0.0043), but they differed significantly from the jejunum library (P=0.001). The population of sequences retrieved from jejunal biopsies was dominated by sequences closely related to Streptococcus (67%), while the population of sequences derived from distal ileum, ascending colon and rectum were dominated by sequences affiliated with Bacteroidetes (27-49%), and Clostridium clusters XIVa (20-34%) and IV (7-13%). The results indicate that the microbial community in jejunum is different from those in distal ileum, ascending colon and rectum, and that the major phylogenetic groups are similar from distal ileum to rectum.     

Spatial dynamics of the bacterial community structure in the gastrointestinal tract of red kangaroo (<Emphasis Type="Italic">Macropus rufus</Emphasis>)

The quantification and community of bacteria in the gastrointestinal (GI) tract (stomach, jejunum, ileum, cecum, colon and rectum) of red kangaroos (Macropus rufus) were examined by using real-time PCR and paired-end Illumina sequencing. The quantification of bacteria showed that the number of bacteria in jejunum and rectum was significantly lower than that in colon and cecum (P < 0.05). A total of 1,872,590 sequences was remained after quality-filtering and 50,948 OTUs were identified at the 97 % similarity level. The dominant phyla in the GI tract of red kangaroos were identified as Actinobacteria, Bacteroidetes and Firmicutes. At the level of genus, the samples from different parts of GI tract clustered into three groups: stomach, small intestine (jejunum and ileum) and large intestine (cecum and rectum). Prevotella (29.81 %) was the most dominant genus in the stomach and significantly (P < 0.05) higher than that in other parts of GI tract. In the small intestine, Bifidobacterium (33.04, 12.14 %) and Streptococcus (22.90, 19.16 %) were dominant genera. Unclassified Ruminococcaceae was the most dominant family in large intestine and the total relative abundance of unclassified bacteria was above 50 %. In identified genera, Dorea was the most important variable to discriminate large intestine and it was significantly higher in cecum than in stomach, small intestine and colon (P < 0.05). Bifidobacterium (21.89 %) was the only dominant genus in colon. Future work on culture in vitro and genome sequencing of those unidentified bacteria might give us insight into the function of these microorganisms in the GI tract. In addition, the comparison of the bacterial community in the foregut of kangaroos and other herbivores and the rumen might give us insight into the mechanism of fiber degradation and help us exploit approaches to improve the feed efficiency and subsequently, reduce the methane emission from herbivores.     

Effects of heat stress on the antimicrobial drug resistance of Escherichia coli of the intestinal flora of swine

The effects of heat stress on the antimicrobial drug resistance of Escherichia coli of the intestinal tract of swine were studied in animals from a farm that had not been supplementing antimicrobials in feed for the past 10 years. In one study, 10 finisher hogs were heat stressed (34 degrees C) for 24 h. Antimicrobial resistance levels after stress were significantly higher (P < 0.05) when compared with pre-stress levels for amikacin, ampicillin, cephalothin, neomycin and tetracycline from faecal samples. This high level of resistance persisted to slaughter that occurred at 10 days post-stress for most of the antimicrobials mentioned. In a second study, samples of different sections of the gastrointestinal tract were collected after heat stress and compared with control, non-stressed animals. Results indicated that E. coli which colonized the ileum and caecum had a higher level of resistance to ampicillin and tetracycline than the E. coli which colonized the colon and rectum. When animals were exposed to heat stress, resistance to ampicillin and tetracycline of E. coli in the lower digestive tract increased (P < 0.05) to a level similar to that observed in the ileum and caecum. Based on these findings, an investigation was made to test the hypothesis that (a) an increase in intestinal motility increases shedding of resistant E. coli and (b) heat stress induces a reduction in intestinal transit time in swine. For each study, two groups of three, randomly selected finisher hogs each were formed (treated and control groups). In study (a), induction of increased motility and peristalsis was obtained using an intramuscular injection of the cholinergic drug neostigmine methylsulphate. Escherichia coli isolates were obtained from the ileum, caecum, colon and rectum after animals were slaughtered. A higher level of ampicillin-resistant E. coli was found in the caecum (40%) than in other segments of the intestinal tract. In treated animals, level of resistance increased for organisms from the colon and rectum. Similar results were obtained for tetracycline resistance. In study (b), intestinal transit time was measured using chromium-EDTA as a marker. Swine were euthanized and samples were collected throughout the intestinal tract (duodenum to rectum) 8 h after administration of the marker to control and heat-stressed animals. Results indicated a reduced transit time for the stressed group. These findings corroborate the initial hypothesis that an outflow of resistant organisms moves from the upper tract (ileum and caecum) to the lower tract (colon and rectum).     

冬季清凉峰山区小麂和野猪的生境选择及差异

从2005 年11 月5 日至2006 年1 月21 日,为了评估小麂和野猪的生境选择及其差异,我们在浙江清凉峰国家级自然保护区核心区共设置了248 个样方群。研究发现,两者都选择平缓坡的灌丛植被、草本密度小、离住宅较近和离隐蔽物距离适中的生境,表现了它们的生境选择有一定的重叠性。但是它们也表现出生境选择的一些差异,小麂选择乔木密度适中、灌丛密度大和郁闭度适中的生境,而野猪选择乔木密度小的生境,随机地使用各类灌丛密度和郁闭度的生境。小麂还选择北坡、离水源距离较远的生境,野猪只是随机地使用不同的坡向和离水源距离的生境。分析两者共存的机制,我们发现小麂采取隐藏策略而野猪采取逃跑策略来避敌和利用资源,即它们之间存在与反捕食策略相关的生境选择差异。
     

维吾尔族结肠癌患者肠道菌群的分布情况研究

目的:检测新疆维吾尔族结肠癌人群肠道菌群结构,探讨维吾尔族结肠癌患者肠道菌群结构差异,以求找到肠内与结肠癌有关系的菌群。方法:使用16Sr DNA-PCR-DGGE技术对维吾尔族结肠癌患者肠道菌群分布情况制作肠道菌群指纹图谱,从图谱中的条带进行切胶回收、进行克隆、测序,与Genebank数据库提供的序列进行比对做树状图分析,对新疆维吾尔族结肠癌患者肠道细菌种群多样性进行探讨。结果:通过实验得到了维吾尔族结肠癌患者肠道菌群结构特征的DNA指纹图谱、基因序列及树状图。测序结果显示,维吾尔族结肠癌患者肠道菌群中主要分布乳酸杆菌属,拟杆菌属和梭杆菌属以及很多差异性细菌的分布情况。从维吾尔族结肠癌患者肠道菌群的分布情况来看,优势菌乳酸杆菌量甚少,拟杆菌属,梭杆菌属数量较多。结论:肠道乳酸杆菌优势菌量的减少及拟杆菌属,梭杆菌属比例的改变可能与结肠癌患者发病有一定的关系。     

Influence of Cereal Non-Starch Polysaccharides on Ileo-Caecal and Rectal Microbial Populations in Growing Pigs

The effect of cereal non-starch polysaccharides (NSP) on the gut microbial populations was studied in 5 growing pigs between 39–116 kg body weight according to a Latin square design. The diets were composed to contain different NSP levels. The control diet had a normal NSP content (139 g/kg dry matter (DM)), 2 diets had a low total amount of NSP (95 and 107 g/kg DM) and 2 diets had a high amount of total NSP (191 and 199 g/kg DM). Furthermore, one of the diets within each category had a content of insoluble NSP similar to the control diet and one had a high content of insoluble NSP. Samples were collected from the ileum, via intestinal post valve T-caecum (PVTC) cannulas surgically inserted at the ileo-caecal ostium, and from the rectum. The total microbial flora of the ileal samples were analysed for by defining base pair length with terminal restriction fraction length polymorphism (T-RFLP). The microbial diversity of the coliform flora of the ileal and rectal samples were defined by biochemical fingerprinting. It was observed that many terminal restriction fragments (TRFs) disappeared when new diets were introduced and that some characteristic TRFs were found in the high and low NSP diets, respectively. Both the total gut microflora and the coliform flora were influenced by the dietary NSP content.     

The thickness of the mucus layer in different segments of the rat intestine

Summary The thickness of the pre-epithelial mucus layer has been measured in different gut segments of rats kept under normal (ad libitum) feeding conditions, and after 48 h of fasting, using cryostat sections and celloidin stabilization from samples containing luminal contents. The mucus layer of the stomach, duodenum, jejunum, ileum, caecum, proximal colon, colon transversum, distal colon and rectum was studied in five groups of male rats (10, 40, 70 and 150 days of age, and older). Underad libitum feeding conditions, a distinct and continuous mucus layer, with a thickness of more than 3 μm, was only observed in the colon transversum, in the distal colon, in the rectum and in the stomach. No pre-epithelial mucus layer was observed in the duodenum and jejunum where the glycocalix from the apical membrane of the superficial cells appeared to be in a direct contact with the luminal ingesta. In the ileum, caecum and the proximal colon, the surface epithelium of the mucosa was only partly covered by a mucus layer of highly variable thickness. After 48 h of fasting, a mucus layer of 28.8 ± 25.6 μm and 93.3 ± 59.4 μm thickness, respectively, was found in the duodenum and jejunum of adult rats, but no increase in the thickness of the mucus layer was observed in the rat hind gut.