应用PCR-DGGE和Real-Time PCR分析健康与腹泻獭兔盲肠菌群

【目的】研究獭兔腹泻发生后盲肠菌群结构的变化情况,为微生态防治断奶兔腹泻提供理论基础。【方法】分别提取5只健康和腹泻獭兔盲肠内容物总DNA,应用PCR-DGGE及Real-Time PCR技术比较分析獭兔盲肠中菌群结构的差异。【结果】腹泻獭兔PCR-DGGE图谱条带丰富度、均匀度、多样性指数与健康獭兔相比差异均不显著,但聚类分析和主成分分析(PCA)能够将腹泻组和健康组区分开。Real-Time PCR检测显示,腹泻獭兔盲肠正常菌群普雷沃氏菌、梭菌类群Ⅰ数量与健康獭兔相比没有变化(P0.05);链球菌属、梭菌类群Ⅳ和ⅩⅣa、白色瘤胃球菌、溶纤维丁酸弧菌、普拉梭杆菌等有益微生物数量显著降低(P0.01),而埃希氏大肠杆菌数量却显著升高(P0.05)。【结论】獭兔腹泻发生后盲肠有益微生物数量降低,有害微生物数量升高;菌群结构有差异但不显著(P0.05),腹泻獭兔盲肠菌群结构有复杂化的趋势。     

WHBE兔与日本大耳白兔腹泻型肠易激综合征模型的肠道菌群研究

目的比较分析WHBE兔和日本大耳白(Japanese white rabbit,JW)兔腹泻型肠易激综合征(irritable bowel syndrome,IBS)模型肠道菌群的差异性。方法 WHBE兔和JW兔各16只,按品系随机分为两组,即正常对照(NC)组和IBS模型组,每组8只。采用湿热应激复合番泻叶方法建立腹泻型IBS兔模型,观察实验兔的腹围指数、粪便含水量、结肠转运功能,处死后分别取结肠组织和结肠内容物进行病理组织学观察和肠道菌群多样性分析。结果与NC组比,IBS模型兔均出现腹围指数和粪便含水量增加,结肠转运时间缩短,但结肠组织未见病理性改变;同时IBS模型兔Shannon指数和Chao1指数均显著下降(P0.05)。根据OTU分类分析的结果,厚壁菌门和拟杆菌门为兔肠道菌群的绝对优势菌群。与NC组比较,WHBE兔IBS模型组厚壁菌门、疣微菌门、绿弯菌门、Akk菌属、链球菌属均明显下降(P0.05,P0.01),拟杆菌门和rc4-4菌属丰度显著上升(P0.05,P0.01);而JW兔IBS模型组优杆菌属和罕见小球菌属均显著上升(P0.05),乳酸杆菌属、粪杆菌属、韦荣球菌属和链球菌属均显著下降(P0.05)。与JW兔NC组比,WHBE兔NC组厚壁菌门、Odoribacter菌属、韦荣球菌属、链球菌属、颤螺旋菌属、Pseudoflavonifractor菌属较低(P0.05,P0.01),拟杆菌门、疣微菌门、优杆菌属、粪杆菌属、Akk菌属较高(P0.05,P0.01)。与JW兔IBS模型组比,WHBE兔IBS模型rc4-4菌属、粪杆菌属、梭菌属的丰度较高(P0.05,P0.01),而厚壁菌门、多尔氏菌属、粪球菌属和罕见小球菌属的丰度则较低(P0.05,P0.01)。结论 IBS模型兔存在肠道菌群失调,导致菌群多样性降低;WHBE兔和JW兔IBS模型肠道菌群变化均具有其自身的特点,且具有明显的差异性。     

肠道菌群正常参考值的检测

目的定性定量检测并比较杭州地区健康青壮年及老年人群肠道主要菌群(双歧杆菌属、类杆菌属、消化链球菌属、产气荚膜梭菌、乳杆菌属、肠杆菌科、肠球菌属及酵母菌等)的正常参考值,同时计算并比较双歧杆菌属细菌数量与肠杆菌科细菌数量的对数值比值(B/E值).方法采用光冈法 .结果老年组肠道双歧杆菌数量及B/E值较青壮年组均显著减少(P＜0.05, P＜0.001);消化链球菌、肠杆菌科及肠球菌细菌数量显著增加(P＜0.01,P ＜0 .001,P＜0.05).结论在获得肠道菌群正常参考值的同时,发现随着年龄的增加,老年人肠道双歧杆菌数量明显减少,肠杆菌科及肠球菌细菌数量显著增加.     

猪不同肠段微生物体外培养对蛋氨酸的代谢特性

【目的】旨在通过微生物体外发酵技术,以回肠微生物为参照,研究猪盲肠及结肠微生物对在小肠微生物中代谢率较低的蛋氨酸的代谢特性。【方法】采集4头健康100 kg左右杜×长×大杂交猪的盲肠、结肠与回肠食糜作为接种物,分别接种于10 mmol/L蛋氨酸的培养基中,37°C体外培养24 h。分别设含蛋基酸溶液和含各肠段食糜接种物的空白对照组。【结果】(1)不同肠段微生物以蛋氨酸为底物体外发酵,盲肠组蛋氨酸消失率(21.9%)显著高于结肠组(16.7%)与回肠组(16.3%)(P0.05)。盲肠组总SCFA量显著高于结肠与回肠组(P0.05),伴随着p H值下降程度最高;盲肠组MCP产量也显著高于结肠与回肠组(P0.05);在产气量与NH3-N浓度上,盲肠组与结肠组均显著低于回肠组(P0.05)。(2)以蛋氨酸为底物体外发酵,门水平上,总菌、厚壁菌门含量在各肠段组间无显著差异(P0.05),拟杆菌门含量在盲肠组最高;与不加蛋氨酸底物的对照组比较,三个肠段试验组总菌、厚壁菌门含量均显著高于对照组(P0.05),而拟杆菌门含量在试验组与对照组间差异不显著(P0.05)。属水平上,盲肠组和结肠组大肠杆菌属数量显著低于回肠组(P0.05),而柔嫩梭菌属和梭菌XIV属数量在盲肠组和结肠组均高于回肠组;各肠段组间双歧杆菌数量无显著差异(P0.05)。【结论】以蛋氨酸为底物,体外培养猪盲肠微生物对蛋氨酸代谢率高于回肠微生物,伴随着其他发酵参数的变化,并且发酵产生更多的菌体蛋白。相比于回肠微生物发酵,大肠微生物发酵后,柔嫩梭菌属和梭菌XIV属数量较高,而大肠杆菌属数量较低。     

基于概率话题模型的轻微型肝性脑病患者肠道菌群结构研究

【目的】利用LDA(Latent Dirichlet Allocation)概率话题模型分析轻微型肝性脑病(MHE)患者服用利福昔明联合益生菌对其肠道菌群结构异质性和临床疗效的影响。【方法】采用R语言包中的LDA概率话题模型的折叠Gibbs抽样蒙特卡洛算法,对MHE患者肠道菌群结构的时间异质性OTUs(operational taxonomic unit)数据集进行分析。【结果】LDA模型将MHE患者的42份粪便样本分成3个主题(topic),并能鉴定出影响MHE患者肠道菌群异质性结构最大的OTUs菌属,分别为埃希菌属(Escherichia)、类杆菌属(Bacteroides)和链球菌属(Streptococcus)。对比治疗前后,这3种菌属在组内的变异模式为同类型菌属的转变次数和频率均高于不同类型的菌属。利福昔明联合益生菌治疗组和单独利福昔明治疗组治疗后,MHE患者的肠道菌群结构均有所改变(P0.05)。此外,根据临床疗效指标,对比两组患者治疗后血清IL-2、IL-4、IL-6、IL-10、TNF-α、TBIL、ALT、CRP、NCT-A、γ-GGT及血氨水平,观察组明显优于对照组,差异显著,有统计学意义(P0.05)。治疗组总有效率88.8%,不良反应总发生率22.2%,对照组总有效率75%,不良反应总发生率38.5%(P0.05)。【结论】LDA模型不仅能有效地量化菌群结构的异质性,还能鉴定出相对应影响异质性最大的OTUs。利福昔明联合益生菌疗法能明显改善MHE患者的血氨水平和血清炎性因子水平,且对MHE患者的肠道菌群结构也有一定的改变,具体表现为致病菌数量减少,有益菌数量增加,具有较好的临床应用价值。     

更年期综合征人体肠道微生物群落结构研究

目的定性定量检测更年期综合征个体肠道微生物群落,探讨该状态中的人群肠道内微生态平衡状态及其特点,从而为研究更年期综合征人群的防治新策略提供数据资料。方法设患更年期综合征妇女研究组和相近年龄同性别的健康妇女对照组,采用光冈法检测相关肠道菌群(双歧杆菌属、乳杆菌属、类杆菌属、产气荚膜梭菌、消化链球菌属、肠杆菌科、肠球菌属及酵母菌)的菌群值,同时计算和比较双歧杆菌属细菌数量与肠杆菌科细菌数量的对数值比值(B/E值)。结果与相似年龄同性别的健康人群对照组比较,更年期综合征人群研究组肠道双歧杆菌数量显著降低(P0.01);B/E值较显著减少(P0.01);肠杆菌科细菌、消化链球菌、肠球菌数量显著增加(P0.01,P0.01,P0.05)。结论更年期综合征人群肠道双歧杆菌数量显著减少,肠杆菌科及肠球菌细菌数量显著增加,益生菌群与肠杆菌科结构发生改变,可能更年期综合征人群由于神经内分泌失调等健康状态的下降,引起肠道有益菌群与腐败菌比例发生变化,从而引起肠道微生态失调。     

16s rRNA基因克隆文库分析比较牙周炎患者和健康人口腔唾液微生物多样性

【目的】通过对同一地区、同一民族牙周炎患者和健康人的唾液微生物群落结构的分析,探寻牙周炎患者口腔微生物的多样性。【方法】采集甘肃东乡族自治县的东乡族牙周炎患者和健康人唾液各5例,分别记作DP(东乡牙周)和DH(东乡健康),提取细菌总DNA,构建16S r RNA基因克隆文库,测序后利用MOTHUR、MEGA 4.0、Clustal X 3.0等软件对测序结果进行分析。【结果】所有样本共检测出115个OTUs(DP 60,DH 75),归属于6个门,27个属。TM7是DP组特有的优势菌门。仅在DP组中检测到的优势菌属是梭菌属(Fusobacterium)、卟啉单胞菌属(Porphyromonas)、消化链球菌属(Peptostreptococcus)和TM7_genera。【结论】发现牙周炎患者与健康人口腔唾液微生物存在一定差异。其中,TM7、梭菌属和消化链球菌属在牙周病中的作用值得进一步研究。     

低聚果糖联合锌制剂对小儿迁延性腹泻的治疗效果及对其肠道菌群结构的影响

目的观察低聚果糖联合锌制剂对小儿迁延性腹泻的治疗效果,并探讨其对肠道菌群结构的影响。方法回顾102例小儿迁延性腹泻的临床资料,均接受常规治疗,其中有48例接受锌制剂治疗,标记为A组;余54例接受低聚果糖联合锌制剂治疗,标记为B组。比较排便次数、大便性状、饮食/母乳喂养恢复正常的时间,治疗效果,治疗前后肠道菌群结构及药物安全性。结果 B组排便次数恢复正常、大便性状恢复正常、饮食/母乳喂养恢复正常时间均短于A组(均P0.05);两组疗效等级差异具有统计学意义(P0.05),B组总有效率明显高于A组(P0.01);治疗后两组肠道微生态Chao1指数、Shannon指数均较治疗前升高(均P0.05),治疗后B组肠道微生态Chao1指数、Shannon指数均高于A组(均P0.05);2组治疗后双歧杆菌属、乳杆菌属、肠杆菌属水平相对丰度均增加,且B组均高于A组,2组治疗后梭菌属、漫游球菌属、乳球菌属、链球菌属、拟杆菌属、希瓦菌属、冷杆菌属、葡萄球菌属水平相对丰度均下降,且B组均低于A组,差异均有统计学意义(均P0.05);两组不良反应发生率接近(P0.05)。结论对小儿迁延性腹泻予以低聚果糖联合锌制剂可促进症状消失,增强疗效,还可调节肠道菌群结构,安全可靠。     

长江下游地区中国荷斯坦奶牛生乳中菌落总数的影响因素分析

【背景】随着人们生活水平和健康意识的提高,作为部分乳制品的原料,生乳的质量安全问题显得尤为重要。【目的】检测长江下游地区某集约化牧场中国荷斯坦奶牛生乳中菌落总数、总大肠菌群数的真实水平,同时对影响其变化的生理因素和环境因素进行探讨。【方法】以中国荷斯坦奶牛生乳为研究对象,用乳房炎快速诊断剂检测乳房炎感染情况,菌落总数、总大肠菌群数和环境细菌数的检测方法参照国家标准。对采集的生乳样本进行细菌常规分离鉴定,同时收集乳成分变化数据。【结果】多因素方差分析结果表明,不同泌乳阶段和不同产奶量对荷斯坦奶牛生乳中菌落总数的影响显著(P0.05)和极显著(P0.01);体况、泌乳阶段、胎次、产奶量及乳区对大肠菌群数均无显著影响(P0.05)。夏季生乳的菌落总数、大肠菌群数均极显著地高于其他季节(P0.01);场区内各牛舍的不同卫生环境及细菌数对菌落总数、大肠菌群数的影响均在显著以上(P0.05)。不同乳房炎的感染程度对菌落总数影响极显著(P0.01)。细菌鉴定结果是葡萄球菌属和杆菌属感染居多,链球菌属感染几乎没有。菌落总数的变化对乳蛋白率影响不显著(P0.05),对乳脂率的影响极显著(P0.01)。【结论】随机采样泌乳牛群的不同生理和病理状况、外界不同饲养条件及卫生环境对生乳中菌落总数和大肠菌群数有不同程度的影响,生乳的乳脂率与细菌总数变化负相关。     

抑郁症人群肠道微生物群落结构与功能探讨

目的了解抑郁症人群肠道主要微生物群落情况,探讨在机体精神心理异常状态下肠道内微生态平衡特点,从而为研究抑郁症人群及相关精神心理疾患人群的防治新策略提供数据资料。方法设抑郁症患者研究组和健康对照组,采用日本光冈法定性定量检测肠道乳杆菌属、双歧杆菌属、类杆菌属、消化链球菌属、肠球菌属、产气荚膜梭菌、肠杆菌科及酵母菌的菌群值,计算和比较双歧杆菌属细菌数量与肠杆菌科细菌数量的对数值比值(B/E值)。结果与健康人对照组比较,抑郁症人群研究组肠道乳杆菌和双歧杆菌数量显著降低(P0.01);B/E值显著减少(P0.01);肠杆菌科细菌、肠球菌数量显著增加(P0.01,P0.05)。结论抑郁症人群肠道乳杆菌和双歧杆菌数量显著减少,肠杆菌科及肠球菌细菌数量显著增加,益生菌群与肠杆菌科结构发生改变,推测抑郁症的发生,有可能通过肠-脑轴的联系,使大脑情感中枢功能紊乱与肠道菌群微生态平衡失调的相互作用有关。     

Synthesis of 3′-Deoxy-3′ and 5′-Deoxy-5′-[4-(Purin-9-yl/Pyrimidin-1-yl) methyl-1,2,3-Triazol-1-yl]thymidine via 1,3-Dipolar Cycloaddition

Abstract

Synthesis of new 3′-deoxy-3′ and 5′-deoxy-5′-[(4-(purin-9-yl/pyrimidin-1-yl)methyl-1,2,3-Triazol-1-yl]thymidine 8a-g 10a-g from 3′-azido-3′-deoxy-5′-O-monomethoxytrityl-thymidine and 5′-azido-5′deoxythymidine respectively are described. The key step is the 1,3-dipolar cycloaddition between the azido group and N-9/N-1-propargylpurine/pyrimidine derivatives.     

The polar-lipid composition of the sphingolipid-producing bacterium Flectobacillus major

Polar lipids comprise about 90% of the total chloroform-methanol extractable lipids of the Gram-negative, fresh-water, ring-forming bacterium Flectobacillus major FM and consist of at least 10 constituents. These are aminophosphosphingolipids, 2-N-(2'-D-hydroxy-13'-methyltetradecanoyl)-15-methyl-4(E)-hexad ecasph ingenyl-1-phosphoethanolamine (36.8% of the total polar lipids) and its 2'-deoxy derivative (3.7%); sulfonic-acid analogues of ceramide, 2-D-(2'-D-hydroxy-13'-methyltetradecanoyl)amino-3-D-hydroxy-15-met hyl hexadecane-1-sulfonic acid (18.1%) and its 2'-deoxy derivative (3. 5%); a lipoamino acid, N-[3-D-(15'-methylhexadecanoyloxy)-15-methylhexadecanoyl]-gl ycine (3. 7%); a lipodipeptide, N-?N'-[3"-D-(15"'-methylhexadecanoyloxy)-15"-methylhexadecanoyl ]glycy l?-L-serine (7.8%); 1,2-diacyl-sn-glycero-3-phosphoethanolamine (7. 7%), 1,2-diacyl-3-alpha-D-galactopyranosyl-sn-glycerol (2.9%); ceramide phospho-myo-inositol (4.9%), and a previously described unusual glycosphingolipid, 7-deoxy-7-amino-D-manno-heptulosonopyranosyl (1-hydroxycarbonyl-6-deoxy-6-amino-alpha-D-mannopyranosyl) ceramide (10.9%); the last two lipids contain only 15-methyl-4(E)-hexadecasphingenine as a long-chain base. The sole structural type of amide-bound fatty acids in the sphingolipids, including the sulfonic-acid analogues, is iso-15:0, either non-hydroxylated or hydroxylated at 2-C, whereas 15-methylhexadecanoic acid is the major ester-bound fatty acid in the remaining lipids.     

不同生长性能苏姜猪保育猪肠道菌群差异分析

【背景】苏姜猪是优质瘦肉型新品种猪,断奶仔猪受到多方面应激影响会出现生长性能差异。【目的】研究不同生长性能的苏姜猪保育猪肠道菌群结构的异同。【方法】试验选取了同日龄、体重相近、健康情况良好的的保育仔猪100头,在相同的饲养条件下饲养42 d,试验结束选取体重较轻的为弱仔猪,3头弱仔猪体重为18.43±2.37kg;体重较大的为健康仔猪,3头健康仔猪体重为27.37±1.36 kg。屠宰后,采集其空肠和盲肠内容物,提取微生物基因组DNA进行高通量测序分析其菌群结构。【结果】苏姜猪仔猪空肠和盲肠在菌群丰度、多样性上有极显著的差异(P<0.01)。苏姜猪仔猪空肠菌群优势菌群为变形菌门(Proteobacteria)假单胞菌属(Pseudomonas)的非致病性菌株,占比超过90%。苏姜猪仔猪盲肠优势菌门依次为拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)。门水平组成结构存在差异,弱仔猪厚壁菌门丰度低于健康仔猪、变形菌门丰度高于健康仔猪。苏姜猪盲肠中普雷沃氏菌属(Prevotella)、疣微菌科UCG-005 (Rumi...     

Preparative route to N-glycolylneuraminic acid phenyl 2-thioglycoside donor and synthesis of Neu5Gc-alpha-(2-->3')-lactosamine 3-aminopropyl glycoside

The spacer-armed trisaccharide, Neu5Gc-alpha-(2-->3')-lactosamine 3-aminopropyl glycoside, was synthesized by regio- and stereoselective sialylation of the suitably protected triol acceptor, 3-trifluoroacetamidopropyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-(6-O-benzyl-beta-D-galactopyranosyl)-beta-D-glucopyranoside, with the donor methyl [phenyl 5-acetoxyacetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-alpha,beta-D-galacto-2-nonulopyranosid]onate. The donor was obtained, in turn, from methyl [phenyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-alpha,beta-D-galacto-2-nonulopyranosid]onate by N-tert-butoxycarbonylation of the acetamido group followed by total N- and O-deacetylation, per-O-acetylation, subsequent Boc group removal, and N-acetoxyacetylation.     

Nucleosides and Nucleotides. 104. Radical and Palladium-Catalyzed Deoxygenation of the Allylic Alcohol Systems in the Sugar Moiety of Pyrimidine Nucleosides§,1

Abstract

New methods for the synthesis of 2′,3′-didehydro-2′,3′-dideoxy-2′ (and 3′)-methyl-5-methyluridines and 2′,3′-dideoxy-2′ (and 3′)-methylidene pyrimidine nucleosides have been developed from the corresponding 2′ (and 3′)-deoxy-2′ (and 3′)-methylidene pyrimidine nucleosides. Treatment of a 3′-deoxy-3′-methylidene-5-methyluridine derivative 8 with 1,1′-thiocarbonyldiimidazole gave the allylic rearranged 2′,3′-didehydro-2′,3′-dideoxy-3′-[(imidazol-1-yl)carbonylthiomethyl] derivative 24. On the other hand, reaction of 8 with methyloxalyl chloride afforded 2′-O-methyloxalyl ester 25. Radical deoxygenation of both 24 and 25 gave 26 exclusively. Palladium-catalyzed reduction of 2′,5′-di-O-acetyl-3′-deoxy-3′-methylidene-5-methyluridine (32) with triethylammonium formate as a hydride donor regioselectively afforded the 2′,3′-dideoxy-3′-methylidene derivative 35 and 2′,3′-didehydro-2′,3′-dideoxy-3′-methyl derivative 34 in a ratio of 95:5 in 78% yield. These reactions were used on the corresponding 2′-deoxy-2′-methylidene derivatives. An alternative synthesis of 2′,3′-dideoxy-2′-methylidene pyrimidine nucleosides (43, 52, and 54) was achieved from the corresponding 1-(3-deoxy-β-D-thero-pentofuranosyl)pyrimidines (44 and 45). The cytotoxicity against L1210 and KB cells and inhibitory activity of the pathogenicity of HIV-1 are also described     

Preparation, single-crystal X-ray diffraction and high-resolution NMR spectroscopic analyses of N-[(1,4-anhydro-5-deoxy-2,3-O-isopropylidene-D,L-ribitol)-5-yl]trimethylammonium iodide

The synthesis and isolation of 1,4-anhydro-5-deoxy-5-iodo-2,3-O-isopropylidene-D,L-ribitol and N-[(1,4-anhydro-5-deoxy-2,3-O-isopropylidene-D,L-ribitol)-5-yl]trimethylammonium iodide are described. The products were examined by (1)H, (13)C NMR spectroscopy, and N-[(1,4-anhydro-5-deoxy-2,3-O-isopropylidene-D,L-ribitol)-5-yl]trimethylammonium iodide was additionally analyzed by X-ray crystallography.     

Synthesis of Glucopyranosyl Schiff Base Zinc(II) Complexes Capable of Interacting with Mononucleotides, and Their DNA-Cleavage Activities

New glucopyranosyl Schiff base zinc complexes, [Zn(GlcSal)(2) ] (1; GlcSalH=N-(2-deoxy-β-D-glucopyranos-2-yl-salicylaldimine) and [Zn(AcOGlcSal)(2) ] (2; AcOGlcSalH=N-(2-deoxy-β-D-1,3,4,6-tetraacetylglucopyranos-2-yl-salicylaldimine) were synthesized, and characterized by spectral and analytical methods. The interaction between the Zn complexes and mononucleotides was investigated by (1) H-NMR, (31) P-NMR and UV/VIS spectroscopies. Mononucleotides, cytidine 5'-monophosphate (CMP) and uridyl 5'-monophosphate (UMP), interacted with these complexes to form a 1?:?1 complex with 1 and a 1?:?2 complex with 2, depending on the presence of the OH group of glucopyranosyl substituents. The DNA-cleavage activities of 1 and 2 were studied using plasmid DNA (pBR322) in a medium of 5?mM Tris?HCl/50?mM NaCl buffer in the presence of H(2) O(2) . The DNA-cleavage activity decreased in the order of 2>1>Zn(OAc)(2) , indicating the significant promoting effect of the glucopyranosyl Schiff base ligand and the participation of the glucopyranosyl OH groups in the cleavage mechanism. The mechanism of the DNA cleavage by 1 and 2 was investigated by evaluation of the effect of a HO(.) radical scavenger and a singlet-oxygen ((1) O(2) ) quencher under aerobic conditions. The former exhibited little effect, excluding the HO(.) radical as an active species and supporting the hydrolysis mechanism for the main process of the DNA cleavage. The latter quencher somewhat hindered the cleavage, indicating the partial participation of a (1) O(2) as a competitive active species in the present system.     

生长猪结肠乳酸菌菌群的昼夜节律性变化

【目的】本文旨在研究生长猪在24 h内结肠乳酸菌的多样性变化、丰富度变化与节律性变化。【方法】选取6头装有结肠瘘管的“杜×长×大”三元杂交生长猪,于清晨6:00开始,每隔3 h连续采集一天内生长猪的结肠食糜,提取DNA,用乳酸菌特异性引物进行高通量测序,在属和种水平上分析结肠乳酸菌菌群丰度与节律性变化。【结果】生长猪结肠乳酸菌在24 h内Chao1和Simpson指数发生显著性变化(P<0.05);属水平上Lactobacillus相对丰度最高,一天内在6:00时相对丰度最低,为94.15%,18:00时相对丰度最高,为97.46%;种水平上Lactobacillus johnsonii相对丰度最高,一天内在3:00时相对丰度最低,为47.66%,18:00时相对丰度最高,为71.59%,Lactobacillus reuteri丰度次之。生长猪结肠乳酸菌中46个核心OTU具有节律性,均为Lactobacillus;而在种水平上Lactobacillus gasseri、Lactobacillus johnsonii、Lactobacillus sp. KC45a和Lactobacillus reuteri显现出节律性(P<0.05)。【结论】生长猪结肠乳酸菌在24 h内多样性发生显著性变化,在种水平上显现出节律性,丰富了我们对猪肠道微生物昼夜节律的了解。     

Effect of dietary calcium and phosphorus depletion on vitamin D metabolism and calcium binding protein in the growing pig

Twenty-four young pigs were divided into three groups and each fed a replete, low calcium (Ca) or low phosphorus (P) diet. It was found that the deficient diets induced rises in renal 25 hydroxy-vitamin D 1,hydroxylase (1-hydroxylase) activity, circulating 1,25 dihydroxy-vitamin D3 (1,25 (OH)2-D3) and Ca binding protein (CaBP) and intestinal 1,25(OH)2D3 and CaBP. All these rises were statistically significant in the low Ca group but only the rises in the 1-hydroxylase activity and intestinal 1,25(OH)2D3 were significant in the low P group. A high degree of correlation existed between the parameters. There was no enhancement of intestinal 1,25(OH)2D3 or CaBP concentration relative to the 1-hydroxylase activity in the low P pigs as occurs in the chick. The low-P-induced rise in 1-hydroxylase activity was independent of parathyroid hormone.     

Effect of crude protein and phosphorus level on growth performance,bone mineralisation and phosphorus,calcium and nitrogen utilisation in grower-finisher pigs

Two experiments in a 2?×?2 factorial arrangement were conducted to evaluate the effect of crude protein (CP) (130 vs. 200 g/kg) and phosphorus (P) (4.0 vs. 6.0 g total P/kg) level in a phytase supplemented diet (500 FTU [phytase units]/kg) in grower-finisher pigs. Owing to the design of the experiment, as dietary P level increased, there was also an increase in dietary calcium (Ca) level in order to maintain a dietary Ca to P ratio of 1.6:1. In Experiment 1, four diets were fed to 56 pigs (n?=?14, initial body weight [BW] 36.7?±?4.2 kg) to investigate the interaction between CP and P on growth performance, bone mineralisation and digesta pH. Experiment 2 consisted of 16 entire male pigs (n?=?4; offered identical diets to that offered in Experiment 1) for the determination of total tract apparent digestibility and nitrogen (N), P and Ca utilisation. There was an interaction between CP and P level on bone ash, bone P and bone Ca concentrations (p?<?0.05). Pigs offered low CP–low P diets had a higher bone ash, P and Ca concentrations than pigs offered high CP–low P diets. However, there was no effect of CP level at high P levels on bone ash, P and Ca concentrations. Pigs offered low P diets had a lower ileal pH compared with pigs offered high P diets (p?<?0.05). In conclusion, offering pigs a high CP–low P, phytase-supplemented diet resulted in a decrease in bone mineralisation.