塔里木盆地荒漠盐碱生境土壤放线菌的初步研究

采用常规方法研究了新疆塔里木盆地荒漠盐碱生境土壤放线菌区系、放线菌的耐盐、碱性及对植物病原真菌的拮抗性。结果表明:土壤放线菌区系较单一,仅分离到链霉菌属和拟诺卡氏菌属,其中以链霉菌属为主(98.57%),链霉菌可分10个类群,以白孢类群为优势类群。土壤含盐量愈高,链霉菌组成愈简单。放线菌的最适生长盐浓度多集中在6%~8%,最适生长pH集中在7~8。24株供试放线菌中,有4株中度嗜盐放线菌对供试靶标菌有拮抗性,占供试菌的16.67%。     

拉鲁湿地自然保护区放线菌组成分析及生物活性测定

探究拉鲁湿地自然保护区的放线菌组成及其抑菌和酶活性,为放线菌新药物先导化合物和高活性酶的筛选提供资源。从拉鲁湿地自然保护区不同土壤类型、不同优势植被采集25份土样。用分散差速离心法分离了拉鲁湿地中温放线菌和低温放线菌。从中温放线菌中选择15株代表菌株进行了初步分类鉴定。采用打孔法检测了其对2株细菌和4株病原真菌的抑菌活性。结果表明：（1）拉鲁湿地放线菌数量从水生环境向陆地生态系统递增,中温放线菌数量显著多于低温放线菌;（2）拉鲁湿地土壤中分离到链霉菌属、小单孢菌属、诺卡氏菌属、马杜拉菌属、小链孢菌属5个放线菌属。其中以链霉菌属和小单孢菌属为优势属。链霉菌属以金色类群、白孢类群和粉红孢类群为主,小单孢菌分离到黄橙类群和黑褐类群;（3）供试菌株分解纤维素能力较强,分解蛋白质活性较低,具有抗菌活性的菌株很少,且抗菌活性较弱;（4）供试菌株耐毒性物质的能力较强。这些菌可用于毒害有机物污染物的处理。     

一株拮抗可可球二孢菌放线菌的分离及鉴定

目的:筛选具有拮抗植物病原真菌可可球二孢菌活性的放线菌.方法:选择高氏一号培养基分离放线菌,以可可球二孢菌为指示菌进行抑菌活性筛选,通过形态学特征、生理生化特征、培养特征以及16S rRNA基因序列分析等研究对筛选得到的高活性菌株进行菌种鉴定.结果:从南方红豆杉根际土壤中筛选得到一株高活性菌株KLBMP 2284,16S rRNA基因序列比对结果显示其与弗吉尼亚链霉菌(Streptomyces virginiae)相似性98.963％,发酵液稀释300倍后抑制率为41.64％.结论:KLBMP 2284为弗吉尼亚链霉菌的一个菌株.     

丹参植株内生菌的分离纯化及其抗病性研究

为探明丹参(Salvia miltiorrhiza Bge)内生菌的种类,筛选拮抗农作物病害菌的生防菌株,从健康丹参植株中进行内生菌分离,依照形态特征以及16SrDNA序列对菌株进行初步分类鉴定,采用琼脂块法进行拮抗菌株筛选,并选取拮抗活性较强的菌株液体发酵进行体外抑菌试验。结果表明:(1)从丹参植株中共分离得到69株内生菌(真菌62株、放线菌7株),其中23株内生真菌属于无孢类群或现有条件不适合产孢,其余真菌菌株中串珠镰孢菌属(Fusarium moniliforme Sheld.)和交链孢菌属(Alternaria sp)为优势菌群;7株内生放线菌均为链霉菌属。(2)病原菌拮抗性实验表明,有44株内生菌对病原菌具有不同程度的拮抗活性,其中12株内生菌对2种及以上靶标病原菌具有拮抗活性,表明丹参内生菌具有一定的广谱抗菌性。(3)放线菌菌株A232的次级代谢产物对白色假丝酵母(Canidia albicans)和苹果腐烂菌(Valsa mali)都表现出较强的拮抗活性,通过形态、培养特征以及16SrDNA序列分析,鉴定其为Streptomyces luteoverticillatus。     

青海高寒草甸土壤放线菌区系研究

2001～2002年从海北高寒草甸生态系统采集土样,用不同方法从中分离放线菌300余株,根据其形态和分类特征,分别归入小单孢菌属(Micromonospora)、诺卡氏菌属(Nocardia)、糖多孢菌属(Saccharopolyspora)、原小单孢菌属(Promicromonospora)和链霉菌属(Streptomyces),并将链霉菌归入7个类群。同时对230株中温菌和110株低温菌的部分酶活性及其对真菌和细菌的拮抗性进行了测定,发现链霉菌不仅具有许多酶活性,而且对真菌和细菌有拮抗性。     

假橐吾内生菌分离及其拮抗菌的筛选与鉴定

从菊科植物假橐吾(Ligulariopsis shichuana Y.L.Chen)中分离得到110株内生真菌和26株内生放线菌,依照形态培养特征对菌株进行初步分类鉴定,采用琼脂块法进行拮抗菌株筛选,并对拮抗性最好的2株内生放线菌进行分子鉴定.结果表明:(1)经初步鉴定,将分离到的假橐吾内生真菌合并为86种,分为10个属,其中交链孢霉属和丝核菌属占优势(分别为41.9%和16.3%);内生放线菌分为3个属,其中链霉菌属占优势(92.3%).(2)抗菌活性试验表明,有31株内生真菌分别对细菌、植物病原真菌具有显著抑制作用,全部内生放线菌对靶标菌有抗性,其中菌株wz57和wz01拮抗性最强.(3)根据16S rDNA序列比对结果,菌株wz57和wz01与链霉菌属(Streptomyces griseoplanus)相似性最高,分别达到99.3%和99.5%,初步归为Streptomyces griseoplanus.     

药用植物内生放线菌的分离、筛选及活性菌株YIM 61470鉴定

从云南西双版纳热带雨林多种药用植物中分离到272株内生放线菌,活性筛选表明 146株菌的发酵产物具有抗菌活性,其中94株菌具有拮抗病原细菌活性,127株菌具有抑制病原真菌的功能.分离菌株YIM 61470具有广谱抗菌活性,通过形态特征、培养特征、生理生化特征、细胞化学分类特征和基于16S rRNA基因序列的相似性分析等研究,菌株YIM 61470被鉴定为链霉菌属(Streptomyces)氢化链霉菌(S.llydrogenans)的一个菌株.     

南方红豆杉内生及根际放线菌多样性及其生物活性

【目的】研究药用植物南方红豆杉内生及根际土壤放线菌的多样性及其抑菌、抗肿瘤等重要生物活性并获得一些具有强抑制植物病原真菌以及抗肿瘤等重要生物活性的菌株。【方法】选择7种培养基从南方红豆杉及其根际土壤中分离放线菌,对链霉菌进行形态学分类,去重复后对其进行抑制植物病原真菌以及抗肿瘤活性的筛选并对高活性菌株进行初步鉴定。对部分菌株进行16S rRNA基因测序分析研究其多样性。【结果】研究共分离得到277株放线菌,经去重复后剩余111株放线菌,可归类到6个亚目、7个科、8个属。其中链霉菌可分为10个类群。生物活性研究结果显示:30.9%的菌株具有抑制植物病原真菌活性,其中6株放线菌对多种植物病原真菌显示了强的抑菌活性。分别有44.1%和33.3%的菌株对胃癌肿瘤细胞株SGC-7901和肺癌肿瘤细胞株NCI-H460的抑制率在40%以上。【结论】药用植物南方红豆杉及其根际土壤蕴含种类丰富的放线菌资源,具有良好的生物学活性。菌株KLBMP 2170具有显著的抑菌以及抗肿瘤活性,值得我们去进一步研究。     

油松菌根根际放线菌的分离与鉴定

为了探讨油松菌根根际放线菌与菌根真菌及油松猝倒病的关系,该实验从油松菌根根际土中分离、纯化得到170株放线菌,采用平板对峙培养法对油松猝倒病病原真菌立枯丝核菌(Rhizoctonia solani)和茄腐皮镰孢霉(Fusarium solani)进行生防放线菌的初筛,得到7株对病原真菌抑制效果较好的放线菌.用初筛选的7株放线菌菌株分别与外生菌根真菌灰鹅膏菌(Amanita vatinata)、灰环粘盖牛肝菌(Suillus laricinus)和血红铆钉菇(Gomphidius viscidus)进行纯培养互作复筛,得到2株放线菌(菌株19#、菌株110#)对外生菌根真菌灰鹅膏菌和血红铆钉菇均具有促生作用.将菌根真菌灰鹅膏菌、放线菌菌株19#、病原真菌立枯丝核菌进行纯培养互作试验表明,菌株19#能协同灰鹅膏菌拮抗立枯丝核菌.经形态特征、培养特征、生理生化特性测定和16SrDNA序列分析,确定菌株19#为苯胺紫链霉菌(Streptomyces mauvecolor).     

大花黄牡丹内生菌的分离鉴定及其抗菌活性菌株的筛选

采用研磨法从健康大花黄牡丹的根、茎、叶柄、叶和种子中进行菌种分离,依据其形态、培养特征及其他生物学特性对菌株进行初步鉴定;采用平板对峙法对分离的内生菌进行拮抗试验研究,并对强活性菌株进行16S rD-NA序列鉴定,以明确大花黄牡丹内生菌的种类,筛选对农作物病害有抑制作用的菌株.结果表明:(1)获得内生真菌188株,鉴定为10个属,以短蠕孢属(50％)、青霉孢属(18.6％)和曲霉孢属(12.3％)为优势种群.获得内生放线菌145株,以链霉菌属(98.6％)为优势种群.表明大花黄牡丹内生菌在数量和种类上存在极丰富的多样性,同时在不同组织存在一定的差异性.(2)抑菌试验结果显示,21.6％真菌对指示菌有抑菌作用,抑菌圈直径最大为10mm;27.8％放线菌对指示菌有抑菌作用,其中菌株PND31的抑菌活性较强,抑菌谱较广.(3)16S rDNA序列鉴定显示,菌株PND31与链霉菌属聚在一起,初步归为链霉菌属一个种.     

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.