咖啡摄入量对小鼠肠道微生物及酶活性的影响

目的研究摄入不同咖啡浓度对小鼠酶活性、肠道微生物、体重的影响,从分析肠道四种微生物变化和四种酶的活性变化来讨论摄入咖啡对健康的影响。方法 SPF级昆明小鼠随机分为4组,即低、中、高咖啡浓度组和正常对照组,所有实验组小鼠日常给予蒸馏水饮用,实验低、中、高浓度组每天2次分别灌胃给予0.0045g/mL、0.0090g/mL、0.0180g/mL的咖啡溶液0.4mL/(只·次),对照组给予蒸馏水灌胃,实验时间为1个月,测小鼠体重、肠道微生物和酶活性等指标并进行分析。结果与对照组相比,低浓度咖啡摄入组乳杆菌、双歧杆菌、大肠埃希菌数显著增加(P0.01或P0.05),需氧和厌氧细菌数显著降低(P0.01);中浓度咖啡摄入组乳杆菌、双歧杆菌数显著低于对照组和低浓度组(P0.01),大肠埃希菌显著高于对照组(P0.05);高浓度咖啡摄入组乳杆菌和大肠埃希菌总数显著低于对照组(P0.01或P0.05);低浓度摄入组的木聚糖酶、纤维素酶、淀粉酶、蛋白酶的活性均显著高于(Ps0.01)对照组和中浓度咖啡摄入组;各组小鼠体重差异无统计学意义(P0.05)。结论适当摄入咖啡小鼠肠道双歧杆菌和乳杆菌等益生菌数量增加显著,小鼠肠道中具有代表性的淀粉酶、纤维素酶、蛋白酶、木聚糖酶的活性均显著增加,但咖啡摄入对小鼠体重影响不显著。     

绿茶摄入量对小鼠肠道微生物及酶活性的影响

目的从肠道微生态角度研究绿茶摄入量对小鼠肠道微生物和酶活性的影响,探析饮茶(绿茶)有益健康的机制,为饮茶做出科学指导。方法将SPF级实验小鼠随机分为正常对照组、低浓度绿茶摄入组、中浓度绿茶摄入组和高浓度绿茶摄入组。低、中、高浓度绿茶摄入组分别给予10%、20%和30%(g/g)的茶水溶液,连续灌胃1个月后采集空肠至回肠段内容物进行微生物和酶活性分析,同时观察实验动物体质量变化情况。结果各实验组小鼠体质量增长与对照组相比无明显差异;与对照组相比,低浓度绿茶摄入组小鼠肠道乳酸菌数降低而细菌数升高,中浓度摄入组乳酸菌数、细菌以及双歧杆菌数显著降低,高浓度摄入组细菌数、双歧杆菌数升高而乳酸菌数显降低著,且中浓度摄入组乳酸菌数和细菌数均极显著地低于低浓度摄入组;由酶活性分析可看出,与对照组小鼠相比,各实验组小鼠肠道淀粉酶和蛋白酶活性均升高而木聚糖酶活性显著降低。结论摄入一定量的绿茶对肠道微生物有一定的调节作用,可提高淀粉酶和蛋白酶活性而益于机体健康。     

养胃四君子茶对脾虚便秘小鼠肠道微生物、酶活性及胃动力的影响

目的探讨养胃四君子茶对脾虚便秘小鼠肠道微生物及酶活性的影响。方法将40只小鼠随机分为正常对照组、模型组、治疗组[养胃四君子茶(低剂量组、中剂量组、高剂量组)],每组8只。对模型组和治疗组采用灌胃番泻叶水提液7 d后,改用饮食不节+缺水燥结+过度疲劳喂养8 d等方法。造模结束后,模型组和正常对照组采用无菌水灌胃,治疗组用养胃四君子茶灌胃,0.8 mL/d连续6 d。然后采集肠道内容物,分析肠道菌群及酶活性。结果与正常对照组小鼠肠道细菌总数比较,模型组显著上升(P<0.05),治疗组差异无统计学意义(P>0.05);大肠埃希菌数量各组差异无统计学意义(P>0.05);小鼠肠道乳酸菌数量养胃四君子茶低、中剂量组均较正常对照组、模型组显著升高(均P<0.01);双歧杆菌数量养胃四君子茶低、中剂量组与正常对照组、模型组相比均显著升高(均P<0.01);与正常对照组比较,其余各组小鼠肠道酶活总体呈上升趋势,尤其肠道淀粉酶(P<0.01);养胃四君子茶低、中剂量组蛋白酶活性均显著上升(均P<0.05);与正常对照组比较,模型组及养胃四君子茶低、中剂量组木聚糖酶活性显著上升(P<0.01或P<0.05),其余组差异无统计学意义(P>0.05);与正常对照组比较,模型组及养胃四君子茶低、中剂量组纤维素酶活性均显著上升(均P<0.05)。与正常对照组比较,模型组、养胃四君子茶低剂量组的血清D 木糖含量显著下降(均P<0.01)。结论养胃四君子茶可抑制细菌过度增长、扶植有益菌生长,改善肠道酶活性、增强胃肠蠕动,从而改善脾虚便秘。     

铁皮石斛多糖对脾虚便秘小鼠免疫、肠道微生物及酶活性的影响

为了探讨铁皮石斛多糖对脾虚便秘小鼠免疫、肠道微生物及酶活性的影响,明确多糖对脾虚便秘的治疗作用,通过灌胃番泻叶水煎液7 d后控制饮食,饥饱失常8 d,建立小鼠脾虚便秘模型。造模成功后,正常组和模型组灌胃等量无菌水,治疗组灌胃铁皮石斛多糖溶液,分析小鼠体重、脾脏系数、胸腺系数、肠道菌群和酶活性的变化情况。结果表明,模型组的小鼠体重、体重变化率、脾脏指数、胸腺指数、五类可培养微生物(细菌总数、大肠杆菌、乳酸菌、双歧杆菌和真菌)数量与正常组比较差异显著(P0.01或P0.05)。治疗完成后,小鼠体重和体重变化率显著增高,高于正常组(P0.05);小鼠脾脏指数和胸腺指数均有不同程度恢复,接近正常组(P0.05);大肠杆菌大量得到恢复,但远没有达到正常组水平(P0.01);乳酸菌和双歧杆菌明显地减少,但总数显著超过正常组(P0.01);木聚糖酶和蛋白酶接近正常组,淀粉酶显著增加,纤维素酶显著减少(P0.01)。说明铁皮石斛多糖对增强机体免疫力、调控肠道微生态平衡和肠道酶活性方面有一定的促进作用,能优化肠道环境,改善脾虚便秘症状。     

四磨汤口服液对脾虚便秘小鼠肠道微生物及酶活性的影响

目的探讨四磨汤对脾虚便秘疗效、肠道微生物和酶活性的影响。方法将18只实验小鼠随机分成模型组、正常对照组和治疗组,每组6只。对模型组和治疗组采用灌胃番泻叶水煎液7 d后控制饮食,饥饱失常8 d,进行小鼠脾虚便秘造模。造模结束后,模型组和正常对照组均用无菌水灌胃,治疗组用四磨汤口服液灌胃,共7 d,然后采集肠道内容物,分析肠道菌群及酶活性。结果模型组自然恢复后,肠道微生物(细菌总数、大肠埃希菌、乳酸菌、双歧杆菌和真菌)、纤维素酶活性、木聚糖酶活性、淀粉酶活性和蛋白酶活性与正常对照组比较差异有统计学意义(P0.01或P0.05)。治疗组大肠埃希菌数和真菌数与正常对照组比较差异无统计学意义(P0.05),达到正常对照组水平。细菌总数显著增加(P0.01),乳酸菌显著减少(P0.05),双歧杆菌数目显著增加(P0.01),治疗组纤维素酶和木聚糖酶活性极显著低于正常对照组(P0.01),淀粉酶活性极显著高于正常对照组(P0.01),蛋白酶活性与正常对照组比较差异无统计学意义(P0.05)。结论四磨汤通过调控肠道菌群平衡,调整肠道酶活性来治疗脾虚便秘。     

超微七味白术散对肠道微生物及酶活性的影响

肠道微生物与人体多项生理功能密切相关,为探讨超微七味白术散疗效与肠道微生物及酶活性的关系,为中药复方超微饮片临床应用提供科学依据,运用抗生素建立菌群失调小鼠模型,分别灌胃给药七味白术散传统汤剂、超微全量汤剂、超微1/2量汤剂、超微1/4量汤剂、超微1/8量汤剂,分析肠道菌群数及酶活性。结果表明,模型组的肠道微生物(细菌、大肠杆菌、酵母菌、霉菌、乳酸菌及双歧杆菌)数量、木聚糖酶活、蛋白酶活及淀粉酶活均低于对照组(P＜0.05),纤维素酶活性高于对照组P＜0.01)。传统汤剂组的细菌及酵母菌数均高于对照组,但霉菌数明显下降(P＜0.05)。酵母菌数随超微药物浓度的升高而增多,细菌及霉菌数在超微1/2量时最多,与传统汤剂相比,超微1/2组的三类菌均显著增加(P＜0.01)。大肠杆菌在七味白术散传统汤剂和超微1/2量的作用下达到了正常水平(P＞0.05);经超微全量治疗后,大肠杆菌增长十分迅速,远高于其余各组(P＜0.01);七味白术散能促进肠道乳酸菌和双歧杆菌的增殖(P＜0.05),恢复肠道菌群平衡。肠道乳酸菌和双歧杆菌的变化趋势一致,传统药物组的数量比对照组明显增加(P＜0.01),超微药物组超过了传统汤剂组的数量(P＜0.05),超微1/2剂量组的数量最大,远高于其它各组(P＜0.01)。肠道内纤维素酶、木聚糖酶、蛋白酶及淀粉酶活性与超微饮片浓度有一定相关性,但肠道酶活性未达到对照组水平(P＜0.05)。超微七味白术散1/2量治疗肠道菌群失调小鼠的效果与传统汤剂相当。     

参豉对气虚血瘀模型大鼠肠道微生物及其代谢多样性的影响

【背景】参豉为人参与大豆采用自淡豆豉中分离获得的优势益生菌株共同发酵而成。已证明对气虚血瘀模型大鼠血液指标具有明显的调节作用,但对肠道微生态作用尚不明确。【目的】以气虚血瘀模型大鼠为材料,探讨参豉对肠道微生态是否具有调节作用。【方法】采用长期"力竭游泳+饥饿"方法建立大鼠气虚血瘀模型,造模同时分别灌胃给药参豉高、中、低剂量(每日6、3、1.5 g/kg体重)及补阳还五汤剂60d后,分析肠道6种常驻菌群数量变化;并采用Biolog-ECO自动微生物鉴定系统研究大鼠肠道微生物的代谢情况。【结果】参豉能够促进气虚血瘀模型大鼠肠道中有益菌脆弱拟杆菌、乳酸菌及双歧杆菌的增殖,调节肠杆菌及肠球菌数量使其趋于正常水平,并抑制有害菌产气荚膜梭菌的增殖。Biolog结果显示参豉高剂量组AWCD值与空白组接近;培养48 h时,模型组Shannon指数、Shannon均匀度、Simpson指数以及Mclntosh指数均显著高于空白组,差异显著(P0.05或P0.01),而参豉高剂量组Shannon指数、Shannon均匀度、Simpson指数与空白组相接近,差异无统计学意义(P0.05),与模型组相比差异极显著(P0.01);聚类分析与主成分分析显示参豉各剂量组与空白组、模型组、补阳还五汤组差异明显,可能与不同剂量参豉对气虚血瘀模型大鼠肠道微生态的调节作用相关。【结论】参豉对气虚血瘀模型大鼠肠道菌群具有明显的改善作用。     

小鼠脾虚便秘造模对肠道微生物及酶活性的影响

目的研究小鼠脾虚便秘造模对肠道微生物及酶活性的影响,为脾虚便秘的治疗提供基础。方法采用灌胃番泻叶水煎液7 d,然后控制饮食,饥饱失常;正常组灌胃等量的无菌水7 d后正常喂养,共15 d,制备小鼠脾虚便秘模型。分析小鼠体重、肠道菌群和酶活性的变化情况。结果模型组小鼠体重、体重变化率均显著小于正常组(P<0.05或P<0.01);肠道细菌总数显著小于正常组(P<0.01),大肠埃希菌、乳酸菌、双歧杆菌数和真菌均显著大于正常组(P<0.05或P<0.01);肠道淀粉酶和蛋白酶活性显著低于正常组(P<0.05或P<0.01),木聚糖酶和纤维素酶则显著高于正常组(P<0.01)。结论小鼠脾虚便秘造模影响小鼠的体重,破坏了肠道微生物的平衡,并影响肠道酶活性。     

针刺应激对小鼠肠道微生物、酶活性及血常规的影响

目的探究针刺应激对小鼠肠道微生物、酶活性及血常规的影响。方法设正常组和针刺组,针刺组用银针扎小鼠尾部,使其疼痛、紧张,共21d;所有小鼠均自由采食饮水。分析小鼠肠道菌群、酶活性及血常规的变化情况。结果针刺组小鼠肠道木聚糖酶和纤维素酶活性显著低于正常组(t=17.8470,P=0.0000;t=67.3900,P=0.0000),淀粉酶和蛋白酶则显著高于正常组(t=-33.4280,P=0.0000;t=-6.9810,P=0.0020)。针刺组四类可培养微生物(细菌总数、乳酸菌、大肠埃希菌和双歧杆菌)(t=2.3580,P=0.1420;t=-0.4350,P=0.6860;t=-0.5300,P=0.6470;t=-1.3640,P=0.3040)以及血常规各项指标与正常组比较差异均无统计学意义(P0.05)。结论 21d的针刺应激能显著提高肠道淀粉酶和蛋白酶的活性,降低木聚糖酶和纤维素酶的活性,而对小鼠肠道微生物和血常规无明显影响。     

复方薏苡仁方对小鼠肠道菌群及 微环境的调节作用研究

目的观察复方薏苡仁方调节小鼠肠道菌群功能及胃肠运动的效果,并考察复方薏苡仁方对小鼠盲肠内容物pH及肠黏膜结构等肠道内环境的影响。方法参照《保健食品检验与评价技术规范》(2003版)的规定进行调节肠道菌群实验和小肠墨汁推进试验,检测小鼠盲肠内容物pH,并对肠道黏膜结构进行病理形态学观察。结果 (1)与给样前相比,复方薏苡仁方中、高剂量组肠杆菌数和低、高剂量组肠球菌数均明显减少(P0.05),中、高剂量组乳杆菌数和双歧杆菌数均明显或显著增加(P0.05或P0.01),且高剂量组乳杆菌数和中、高剂量组双歧杆菌数明显高于阳性对照组(P0.05);(2)复方薏苡仁方各剂量组小鼠盲肠内容物pH值均显著降低(P0.01),且均低于阳性对照组,其中低、高剂量组差异有统计学意义(P0.05或P0.01);(3)与正常对照组相比,复方薏苡仁方低、中、高剂量组小鼠十二指肠、空肠、回肠绒毛长度/隐窝深度比值(A/V)均明显或显著增加(P0.05或P0.01),且中、高剂量组十二指肠、空肠及回肠A/V比值明显或显著高于阳性对照组(P0.05或P0.01);(4)与模型对照组相比,复方薏苡仁方各剂量组小鼠小肠推进率均显著增加(P0.01),且均高于阳性对照组(P0.01)。结论复方薏苡仁方对调节肠道菌群及改善肠道微环境具有一定的促进作用。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关.     

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。