河北九莲城淖尔可培养放线菌多样性及抗菌活性筛选

【目的】勘探干涸的九莲城淖尔土壤放线菌多样性并进行活性筛选,以期发现药用微生物资源,为新抗生素的发现奠定基础。【方法】采用15种分离培养基,以稀释涂布法分离放线菌;根据分离菌株的16S rRNA基因序列同源性分析放线菌多样性;发酵液经乙酸乙酯萃取,菌丝体经丙酮浸提,获得提取浓缩物样品;样品通过纸片扩散法进行抗菌活性初筛;抗菌阳性菌株采用PCR技术进行Ⅰ型聚酮合酶(PKS I)KS域、Ⅱ型聚酮合酶(PKS II)KS域和非核糖体多肽合成酶(NRPS)A结构域抗生素生物合成基因的检测。【结果】从11份盐湖土壤样品中分离纯化到251株放线菌,其分布于放线菌纲的10个目15个科31个属,其中优势菌属为链霉菌属和拟诺卡氏菌属;251株放线菌中包括57株耐(嗜)盐放线菌,其优势菌属为拟诺卡氏菌属(22株)和涅斯捷连科氏菌属(15株)。基于16S r RNA基因序列的系统发育分析显示,菌株J11Y309为糖霉菌科潜在新属,菌株J12GA03为分枝杆菌科潜在新种。96株放线菌活性检测结果显示,56株至少对1株检定菌具有抗菌活性,阳性率为58.3%;56株有活性的放线菌中,47株至少含有1种抗生素生物合成基因,其中17株同时具有3种抗生素生物合成基因。【结论】干涸的九莲城淖尔土壤中含有较为丰富的药用放线菌资源,具有从中发现放线菌新物种和新抗生素的潜力。     

海南东寨港真红树植物内生放线菌多样性及其抗菌活性

【目的】勘探海南东寨港真红树植物内生放线菌多样性,为发现放线菌新物种和新抗生素奠定基础。【方法】样品经表面消毒后粉碎,用10种不同培养基分离放线菌;通过PCR扩增、测定并比对16S r RNA基因序列,开展放线菌多样性分析;通过发酵、萃取等处理方法得到四类样品,包括发酵原液、乙酸乙酯提取液及水层和菌体的丙酮浸泡提取液;采用纸片扩散法对样品进行抗菌活性筛选;基于PCR的基因筛选技术探测活性菌株可能存在的NRPS、PKS I、PKS II抗生素生物合成基因。【结果】经形态特征排重,从14种真红树植物样品中共得到放线菌146株,16S r RNA基因序列比对表明它们分布于13个科18个属,其中链霉菌属为优势菌属,菌株S3Cf-2和S3Af-1的16S r RNA基因序列分别与有效发表菌株Couchioplanes caeruleus DSM44103T(X93202)和Microlunatus terrae BS6T(JF806519)的相似率最高,分别为97.45%和97.43%,可能为新物种。对其中46株放线菌发酵样品的抗菌活性检测表明,40株具有抗菌活性,总阳性率为86.96%;活性菌株中,38株菌存在至少一种所探测的生物合成基因簇,阳性率为95%,其中14株同时具有所探测的3种抗生素生物合成基因簇。【结论】海南东寨港真红树植物中存在多样性丰富的药用放线菌资源,具有从中发现放线菌新物种及新抗生素的潜力。     

塔里木盆地胀果甘草内生放线菌多样性及抗菌活性分析

【目的】发掘具有开发前景的放线菌资源,对分离自新疆胀果甘草的内生放线菌的多样性、抗菌活性和次级代谢产物合成相关基因进行研究。【方法】采用5种培养基和3种前处理方法,从胀果甘草中分离获得80株放线菌。基于菌株形态学特征,对36株代表菌株进行抗菌活性检测,通过特异性引物扩增方法,检测了PKS I、PKS II、NPRS和卤化酶基因,探究其合成天然产物的潜在能力。结合筛选结果,选取其中20株代表菌,经16S r RNA基因测序,对其进行系统发育分析。【结果】培养基E2和E3结合热处理的分离效果较好;86.1%的代表菌株对供试的细菌、病原真菌表现出了不同程度的抗菌活性,PKS I、PKS II、NRPS基因和卤化酶基因阳性检出率分别为16.7%、72.2%、25.0%和11.1%。具有活性功能的代表菌株经16S r RNA基因测序分析,分别属于链霉菌属(Streptomyces)、小单胞菌属(Micromonospora)、红球菌属(Rhodococcus)和游动放线菌属(Actinoplanes)4个属,其中链霉菌属(Streptomyces)为优势菌属,占60%以上。【结论】胀果甘草是我国传统的药用植物,其植株内部蕴藏着丰富的放线菌资源,并在次生代谢产物合成方面拥有巨大潜力,具有进一步开发的价值。     

罗布泊盐湖可培养放线菌多样性及PKS Ⅱ功能基因筛选

目的:挖掘新疆罗布泊盐湖可培养放线菌的资源和探索该环境放线菌产生Ⅱ型聚酮合成酶(PKS)基因的潜能。方法:从新疆罗布泊盐湖采集到10份样品,采用不同盐浓度的9种选择性培养基分离放线菌,并通过PCR技术扩增其16S r DNA序列、聚酮合成酶(PKS)基因分子筛选,测序后进行系统发育分析和BLAST比较研究。结果:试验结果共得42株放线菌,包括6个属,链霉菌属(Streptomyces)和拟诺卡氏菌属(Nocardiopsis)的类群最多,糖霉菌属(Glycomyces)、放线多孢菌属(Actinopolyspora)、微球菌(Micrococcus)和栖白蚁菌属(Isoptericola)的菌株相对较少。研究获得新的放线菌分类单元,其16S r DNA基因序列与已知菌株的序列相似性低于97%。42株放线菌中共有29株产生PKSⅡ基因,主要是链霉菌属和拟诺卡氏菌属。结论:研究结果表明罗布泊盐湖放线菌具有丰富的资源多样性和较强合成抗生素的潜在能力。     

川楝内生放线菌多样性及抗菌活性筛选

【目的】探究药用植物川楝内生放线菌多样性,从中挖掘出新的放线菌菌株,发现新的潜在农业生防和医药先导化合物。【方法】从四川境内的资阳、遂宁以及重庆万州采集川楝的根、茎、叶、果、皮,采用纯培养方法,用4种培养基共分离获得148株放线菌。通过形态学观察筛选出60株放线菌进行RFLP分析,选出代表菌株进行16S r RNA基因序列分析。以3株细菌和6株病原真菌作为指示菌株,检测初筛出的60株菌株的抗菌活性以及聚酮合酶(PKSⅠ、PKSⅡ)基因、非核糖体多肽合成酶(NRPS)基因和卤化酶(Halo)基因。【结果】基于16S r RNA-RFLP分析,60株放线菌被分成10簇,筛选出25株代表菌株分别属于7个属,包括Streptomyces、Micromonospora、Planotetraspora、Streptosporangium、Nocardiopsis、Prauseria、Microbispora,其中链霉菌占73.3%。供试的川楝内生放线菌对细菌、真菌有不同程度的抗菌活性;其中含有4类化合物合成基因的菌株占10%-55%。【结论】药用植物川楝内生放线菌具有丰富的多样性,且不同地区不同部位川楝组织中放线菌的种群存在差异;分离菌株广谱的抗菌活性证明,川楝内生放线菌在次生代谢产物合成方面具有巨大潜力,这为进一步的药物开发提供了丰富的菌种资源。     

贵州兴义喀斯特洞穴可培养放线菌多样性及抗菌活性初筛

【目的】进一步了解兴义喀斯特洞穴可培养放线菌资源及产活性代谢产物的能力。【方法】选取多种分离培养基,利用稀释直接涂布平板法对贵州黔西南兴义市多个喀斯特洞穴的土壤和岩石进行可培养放线菌资源分离;利用三种发酵培养基对相关放线菌进行生物产物初筛。【结果】根据16S rRNA基因序列的比对分析,将分离得到的251株放线菌分别归类到44个属,其中链霉菌属(Streptomyces)占分离菌株的比例为24.30%,小单孢菌属(Micromonospora)占比11.95%,红球菌属(Rhodococcus)占比9.16%,微杆菌属(Microbacterium)占比7.17%,诺卡氏菌属(Nocardia)占比6.37%,该五类放线菌为该地区可培养放线菌的优势菌群。对70株细菌进行活性次级代谢产物筛选,其中35株放线菌对指示菌具有抑制活性,且主要类群为链霉菌属和小单孢菌属。【结论】贵州兴义喀斯特洞穴中存在丰富多样的放线菌类群,且蕴藏大量具有产生活性次级代谢产物能力的菌株,为医药产业提供潜力菌株资源,极具进一步发掘和研究的价值。     

西藏仲巴五彩沙漠放线菌资源勘探及生物活性筛选

【背景】细菌耐药性问题日益严峻,新抗生素的研发速度远远落后于临床需要,从特殊生境中挖掘微生物药物资源有望解决以上问题。【目的】勘探西藏仲巴五彩沙漠土壤放线菌多样性并进行生物活性筛选,为发现药用放线菌资源、开发新型抗生素奠定基础。【方法】采用8种分离培养基,通过平板稀释涂布法分离放线菌;根据分离菌株的16S r RNA基因序列同源性分析放线菌多样性;采用PCR技术对分离的放线菌菌株进行II型聚酮合酶(PKS-II)酮缩酶结构域KS、非核糖体多肽合成酶(NRPS)腺苷酸化结构域A、安莎类抗生素生物合成前体3-氨基-5-羟基-苯甲酸合酶(AHBA)保守区、黄素腺嘌呤二核苷酸卤化酶(Halo)保守区抗生素生物合成基因检测;对生物合成基因检测阳性的菌株进行液体发酵,发酵液经乙酸乙酯萃取、菌体经丙酮浸提,获得提取浓缩物样品进行抑菌活性和抗氧化活性筛选。【结果】从4份土样中分离纯化到231株放线菌,分布于7个属,其中链霉菌为优势菌属。68株放线菌的生物合成基因分析显示至少具有1种生物合成基因簇,其中6株同时具有4种生物合成基因簇;进一步的抑菌活性检测显示所有检测的菌株至少表现为对1株检定菌具有抑菌活性,其中8株具有广谱抗菌活性;抗氧化活性筛选结果为13株显示总抗氧化能力阳性,10株具有较好的羟自由基清除能力,3株显示较强的氧自由基清除能力。【结论】西藏仲巴五彩沙漠土壤中含有较丰富的放线菌药用资源,具有从中发现放线菌新菌种和开发新抗生素的潜力。     

来自西双版纳3种有毒植物的免培养与纯培养放线菌多样性及生物活性

【背景】由于土壤放线菌中获得新化合物日益困难,抗生素滥用使致病菌耐药性不断增加,人们转向研究植物内生放线菌以期发现新化合物。【目的】探究西双版纳热带雨林有毒植物内生放线菌的多样性,为开发新药提供具有潜在生物活性的菌株。【方法】通过Illumina Hi Seq高通量测序和纯培养方法分析箭毒木、八角枫、马缨丹3种有毒植物的内生放线菌群落结构组成,利用纸片扩散法筛选抑菌活性,通过PCR扩增检测7类化合物合成基因。【结果】高通量测序的多样性分析和群落结构分析得出:3种有毒植物在门分类水平检测出古菌域的2个门、细菌域的18个门和暂定的Rsa HF231、WD272门;在属分类水平检测出30个属的放线菌,八角枫和马缨丹的微生物群落结构比箭毒木更丰富。纯培养分离获得11个属34株菌,分离自箭毒木的菌株比八角枫和马缨丹的菌株更多,而且大多数高通量检测出的菌种不能通过纯培养获得。抑菌活性检测结果显示:抗菌活性作用明显的菌株以链霉菌属为主。链霉菌属的NRPS和PKS基因的检出率明显高于其他化合物合成基因。【结论】有毒植物内生放线菌多样性非常丰富。有毒植物内生放线菌具有合成次生代谢产物的潜力,可以为生物农药及抗生素开发提供丰富的菌种资源。     

百部内生放线菌的分离、分类及次级代谢潜力

【目的】以对叶百部块根为材料分离内生放线菌,并对分离菌株进行分类、抗菌活性和次级代谢产物合成基因研究。【方法】样品经过严格的表面消毒,选用4种培养基分离百部内生放线菌;分离菌株通过形态观察和16S rRNA序列分析进行分类鉴定;采用琼脂移块法测试分离菌株的抗菌活性;通过PCR检测分离菌株的PKS/NPRS和卤化酶基因;使用HPLC-UV/VIS-ESI-MS/MS分析发酵产物。【结果】从6个样品中获得18株内生放线菌,分属链霉菌属(Streptomyces)、小单孢菌属(Micromonospora)、假诺卡氏菌属(Pseudonocardia)和甲基杆菌属(Methylobacterium)。分离菌株绝大部分具有抗菌活性和次级代谢产物合成基因,其中13株对耐药金黄色葡萄球菌和/或绿脓杆菌有拮抗活性,17株具有PKS/NRPS基因,8株菌具有卤化酶基因,且卤化酶阳性代表菌株的发酵产物具有抗细菌活性和卤代化合物特征。【结论】百部作为一种传统中药,其内生放线菌以链霉菌和小单孢菌为主,在次级代谢产物合成方面具有很好的潜力,可作为一类重要微生物资源进行活性产物开发。     

西双版纳、白茫雪山、波罗的海南岸地衣纯培养放线菌多样性

【背景】在地衣共生系统中除了共生真菌、藻类以外,还蕴藏着丰富的放线菌资源。【目的】采集来自云南西双版纳、白茫雪山、德国波罗的海南岸3个地区的地衣,对获得的地衣纯培养放线菌进行多样性分析。【方法】采用3种放线菌选择分离培养基,通过平板稀释涂布法分离放线菌。通过比较16S rRNA基因序列相似性以及构建系统发育树,确定纯培养放线菌的分类地位。【结果】共分离菌株1 123株,鉴定417株。其中从西双版纳17份地衣样品中分离纯化到107株放线菌,分布在7个目14个科33个属,潜在新种18株,其中链霉菌为优势菌属;从白茫雪山7份地衣样品中分离纯化到103株放线菌,分布在4个目5个科9个属,潜在新种16株。其中链霉菌为优势菌属,占比39%;从波罗的海南岸5份地衣样品中分离纯化到65株放线菌,分布在4个目8个科18个属,潜在新种5株,潜在新种菌和链霉菌为优势菌属。【结论】在本研究条件下,西双版纳可培养地衣放线菌多样性较白茫雪山和波罗的海南岸丰富。白茫雪山地衣链霉菌居多,潜在新种占比15.5%。3个地区地衣放线菌的区系组成各不相同,这与3个地区地衣所处地理环境、完全不同的气候密切相关。     

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.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.