氟化物对家蚕肠道微生物菌群的影响

摘要:【目的】探讨氟化物对家蚕肠道微生物菌群的影响,开发具有潜在应用价值的益生菌以提高家蚕对氟化物的抗性。【方法】PCR扩增家蚕肠道内细菌16S rRNA基因并构建克隆文库;用核糖体DNA限制性分析(Amplified ribosomal DNA restriction analysis,ARDRA)方法对克隆子进行分型。从家蚕T6和734肠道样品中共获得14种分类操作单元(Operational taxonomic unit,OTUs),以16S rRNA基因为基础构建系统发育树进行分析。再经巢式PCR-DGGE技术检测家蚕肠道内优势菌群的变化。【结果】结果表明:家蚕氟中毒后肠道内肠球菌属Enterococcus和芽孢杆菌属Bacillus细菌菌群减少,而葡萄球菌属Staphylococcus的细菌增多。【结论】氟化物能通过改变家蚕肠道内细菌的多样性和比例,从而破坏家蚕肠道微生物菌群平衡,且对家蚕734的影响作用大于T6。     

规模化牛场犊牛直肠细菌多样性分析

【目的】研究腹泻犊牛直肠细菌多样性,以及与健康犊牛直肠细菌多样性的差异。【方法】通过建立直肠菌群16S rRNA基因克隆文库,分别用限制性内切酶MspⅠ和HhaⅠ对阳性克隆的PCR产物进行限制性酶切片段长度多态性(RFLP)分析,通过测定16S rRNA基因序列,绘制系统发育树,确定犊牛直肠菌群的组成。【结果】腹泻组克隆阳性率达98.75%(474/480),优势菌群以乳杆菌属(14%)、肠球菌属(10%)和埃希菌属(8%)等需氧和兼性厌氧菌为主,健康组克隆阳性率达96.45%(488/506),优势菌群以梭菌属(13%)、双歧杆菌属(8%)和巨型球菌属(5%)等专性厌氧菌为主。【结论】2周龄犊牛直肠菌群复杂多样,并且具有自己的独特性菌群,且腹泻时乳杆菌属、肠球菌属、埃希氏菌属等显著增加。     

九龙江河口区nirS型反硝化细菌多样性及系统发育学分析

【目的】结合16S rRNA基因克隆文库和nirS基因克隆文库的分析,揭示九龙江河口区nirS型反硝化细菌多样性。【方法】选取九龙江河口区一富营养化采样点,分别采集水样及沉积物样品,进行理化因子的测定并提取细菌总DNA。以水样DNA构建16S rRNA基因克隆文库,以沉积物DNA构建nirS基因克隆文库,分析微生物群落结构的多样性并构建系统发育树。【结果】从16S rRNA基因克隆文库中获得86条有效序列,按97%的序列相似性划分为53个OTU,分别属于Proteobacteria门、Planctomycetes门、Bacteroidetes门、Actinobacteria门、Firmicutes门和Chloroflexi门。其中属于Proteobacteria门OTU的克隆子占克隆数的62.9%,是最优势的类群,分属于Alphaproteobacteria、Betaproteobacteria、Gammaproteobacteria和Deltaproteobacteria纲等。从nirS基因克隆文库中获得190条有效序列,翻译为氨基酸序列后,按82%的序列相似性划分为60个OTU,并定位到属的水平。其中Proteobacteria门是最优势的类群,占文库克隆子总数的71.6%,包括Alphaproteobacteria纲(5.8%)、Betaproteobacteria纲(49.0%)和Gammaproteobacteria纲(16.9%)。nirS基因克隆文库中丰度最高的OTU与GenBank中的一株可培养反硝化菌Thauera sp. R-26906具有100%的序列相似性。【结论】九龙江河口区的微生物以及亚硝酸盐还原酶基因(nirS)具有丰富的多样性。大部分NirS序列在GenBank中的最相似序列来源于河口、海湾等相似的环境。     

南美白对虾肠道微生物群落的分子分析

采用分子生物学手段16S rDNA克隆文库方法对实验室养殖条件下的南美白对虾肠道细菌进行了多样性研究。用限制性片段长度多态性(RFLP)方法从文库中筛选出可能不同细菌来源的克隆子12个,测定其16S rDNA片段核甘酸序列,将所获得的序列与GenBank数据库进行BLAST比对,结果表明:南美白对虾肠道的16S rDNA克隆文库中126个克隆子分属2个不同的细菌类群:变形细菌(Proteobacteria)和厚壁细菌(Firmicutes),其中厚壁细菌为优势菌群占到75.4%,且与最相似序列同源性均低于94%;变形细菌占到24.6%,与最相似序列同源性均高于98%,分别为希瓦氏菌属(Shewanella),泛菌属(Pantoea),Aranicola属,假单胞菌属(Pseudomonas)和弧菌属(Vibrio)。     

厦门近海海水中多环芳烃降解菌的原位富集与降解菌多样性

摘要：【目的】为了分析厦门近海原位海水中多环芳烃降解菌的多样性。【方法】将涂有菲的聚氯乙烯（PVC）板悬挂在厦门国际邮轮码头的海水中,进行菲降解菌的原位富集。利用变性梯度凝胶电泳（Denaturing gradient gel electrophoresis,DGGE）和16S rRNA基因文库两种方法分析了在PVC板表面富集微生物的菌群结构。之后,在实验室模拟原位条件下,对PVC板表面富集的菲降解菌群进行进一步富集、分离和初步鉴定。【结果】PVC板在海水中浸没6 d后,16S rRNA基因文库分析表明,在涂菲的PVC板表面富集的菌群中解环菌属（Cycloclasticus）对应的克隆子占文库总克隆子的50%;在未涂菲的PVC板表面吸附的菌群中红杆菌科（Rhodobacteraceae）为优势菌,其对应的克隆子占文库总克隆子的47%;而解环菌属的克隆子只占文库总克隆子的2%。DGGE的分析结果也证明解环菌是菲原位富集降解菌群中的优势菌。实验室进一步富集后,从该菌群中分离鉴定出14株细菌,其中一株新鞘氨醇杆菌B14(Novosphingobium sp.B14)具有菲降解能力。但是,解环菌未能获得纯培养。【结论】菲原位富集发现,厦门近海水体中解环菌是多环芳烃的主要降解菌。     

我国典型湿热地区变质烟用香精中腐败微生物的多样性分析

【背景】烟用香精是卷烟生产中的重要辅料,有些香精,特别是剩余的加料香精在运输和储存等过程中可能污染微生物,引起腐败变质发生。【目的】分析变质烟用香精中腐败微生物的群落多样性,确定引起加料香精变质的主要腐败微生物。【方法】采用稀释平板法,对我国典型湿热地区云南、福建和广西三地变质加料香精样品中的污染细菌、霉菌或酵母进行分离,分析其16S rRNA、ITS或26S rRNA基因序列,并通过反证试验确定引起变质的主要腐败微生物。【结果】所考察3个典型湿热地区变质加料香精存在不同程度的细菌、霉菌或酵母污染,其中细菌污染最为普遍。分离的76株污染细菌分布在2门4纲5目10科15属,细菌的群落多样性比较丰富,其中雷尔氏菌属(Ralstonia)、柠檬酸杆菌属(Citrobacter)、肠杆菌属(Enterobacter)及芽孢杆菌属(Bacillus)是优势菌群;9株霉菌分布在子囊菌门(Ascomycota)的3纲6属,每个属分离到1-2株霉菌;42株酵母分布在子囊菌门的6个属,其中毕赤酵母属(Pichia)、细枝钩酵母菌属(Wickerhamomyces)及酵母菌属(Saccharomyces)是优势菌群。云南和福建两地样品的细菌菌群组成明显多于广西,广西样品的霉菌菌群组成以及福建样品的酵母菌群组成均分别多于其余两地。反证试验结果显示,柠檬酸杆菌属、肠杆菌属、芽孢杆菌属、雷尔氏菌属和毕赤酵母属是引起烟用加料香精变质的主要腐败微生物。【结论】变质加料香精中污染微生物菌群组成及腐败微生物确定的研究将有助于我国湿热地区香精香料中污染微生物的控制和腐败变质的预防。     

免培养法研究野生川金丝猴肠道内生细菌多样性

【目的】了解野生川金丝猴(Rhinopithecus roxellana)肠道内生细菌的组成及其多样性。【方法】提取川金丝猴肠道内生细菌总DNA,选用细菌通用引物799F和1492R对总DNA进行16S rRNA基因特异性扩增,构建川金丝猴肠道内生细菌16S rRNA基因克隆文库,对阳性克隆进行限制性内切酶片段长度多态性(PCR-RFLP)分析,并对HaeⅢ酶切带谱菌株进行测序,构建系统发育树。【结果】根据酶切带谱分析和测序结果,将随机挑取的157个阳性克隆归为27个不同的可操作分类单元(OTUs)。系统发育分析表明这些克隆序列有62.10%属于厚壁菌门(Firmicutes),其中包括梭菌属(Clostridium)、Cellulosilyticum属、Robinsoniella属、Anaerofustis属、Blautia属和Anaerovorax属,有37.90%属于未培养细菌。【结论】川金丝猴肠道内生细菌多样性丰富,并且可能存在新的分类单元。     

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。     

感染微生态研究进展——肠道菌群对机体代谢影响

1肠道菌群的组成 在人体,肠道菌群是一个复杂的微生态系统,由于细菌培养手段的局限性,我们对其结构和组成知之甚少。近年来,随着分子生物学技术在感染微生态学上的应用,根据细菌16S rRNA序列的分类,发现肠道内寄住的微生物群的种类超过800种,主要有拟杆菌属、梭菌、乳杆菌、大肠埃希菌属和双歧杆菌属等;     

橘小实蝇成虫肠道可培养细菌群落结构分析

【目的】研究橘小实蝇(Bactrocera dorsalis) 3个种群(实验室正常喂养种群、实验室无菌糖水喂养种群和野生种群)成虫肠道可培养细菌的群落结构组成。【方法】利用16S rRNA基因的聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)分析技术,结合菌落形态观察和生理生化特征鉴定细菌种类。【结果】从橘小实蝇3个种群成虫肠道600株可培养细菌得到53种不同细菌遗传型,分属于肠杆菌科(Enterobacteriaceae)、肠球菌科(Enterococcaceae)和芽孢杆菌科(Bacillaceae)等3个科。其中肠杆菌科是肠道可培养细菌最优势的细菌种类。同样以序列相似性大于97%的菌株归为相同的细菌种类为标准,找到了橘小实蝇3个种群可培养细菌的共有菌种,结合菌落形态观察和生理生化特征鉴定,确定共有菌种为肠杆菌属5株,克雷伯氏菌属2株,柠檬酸杆菌属1株,泛菌属1株,肠球菌属2株,以及芽孢杆菌属4株。【结论】通过研究橘小实蝇成虫肠道可培养细菌群落结构组成,可为探讨肠道菌群对寄主的生理功能和生态学意义奠定基础,最终为利用微生物防治此类害虫提供新思路。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.