新疆断裂带泉水中细菌群落结构的PCR-DGGE分析

乌鲁木齐10号泉起源于天山山脉博格达峰,地下径流于地震断裂带,泉水中硫化氢、甲烷等地球化学元素迁移活跃,为 揭示水文地球化学变化对地震断裂带泉水细菌群落结构的影响,本研究对该泉水样品定期采样,以微孔滤膜收集菌体,使用SDS-酶解法提取总DNA,对细菌16S rDNA V 3区进行PCR-DGGE分析并对条带测序,条带的光密度信息与监测的地球化学指标进行典型相关分析(CCA)。结果表明B16(Uncultured bacterium)和ε-变性菌纲 (epsilon proteobacterium)与氟含量成正相关;黄杆菌B1 (Flavobacterium)、绿脓假单胞菌(Pseudomonas aeruginosa)、B10(Uncultured bacterium)和腐生性葡萄球菌(Staphylococcus saprophyticus)与硫化物呈正相关;硫微螺菌(Thiomicrospira arctica) 、黄杆菌B3(Flavobacterium)及阿尔莱葡萄球菌(Staphylococcus arlettae)与氢气呈正相关。断裂带泉水细菌能够对地层深处渗透出的地球化学元素产生灵敏的应答。     

乌鲁木齐10号泉泉水细菌群落对有感地震的响应

摘要:【目的】为了从细胞水平上了解泉水细菌群落对有感地震的映震规律及敏感菌群的代谢特征。【方法】基于2012年1月31日至12月31日,震中距乌鲁木齐10号泉100公里范围内的5次有感地震,利用平板培养计数和BIOLOG GEN III细菌板监测地震前后泉水中细菌群落活性及代谢功能多样性变化。【结果】泉水细菌群落全年呈现随机动态变化,震后可培养细菌菌落数目和细菌群落碳源利用的平均颜色(Average well color development,AWCD)变化高于震前,且表现与震级具有一定相关性;泉水中对有感地震有响应的灵 敏细菌群以糖醇类碳源为主要代谢碳源。【结论】本研究初步证实了GEN III 细菌板能用于泉水细菌群落代谢功能多样性的研究。细菌群落的碳源利用及可培养菌落数目具有一定映震规律。     

海南东寨港红树林不同植被土壤微生物群落结构比较

【目的】比较不同植被下红树林土壤细菌和古菌的多样性及群落结构,认识红树林土壤微生物资源多样性。【方法】直接提取红树林土壤总DNA,采用细菌通用引物27F/1492R和古菌通用引物Arch21F/Arch958R进行PCR扩增,构建细菌和古菌16S rRNA基因文库,对海南东寨港自然保护区秋茄林、无瓣海桑林和无红树林裸滩土壤的细菌和古菌多样性和群落结构进行分析和比较。【结果】3种土壤样品的细菌类群包括变形细菌门(Proteobacteria)等16个类群,其中变形细菌门(Proteobacteria)与绿屈挠菌门(Chloroflexi)是优势类群;古菌包括6个嗜泉古菌界(Crenarchaeota)类群和7个广域古菌界(Euryarchaeota)类群,分别以Marine Benthic Group C、Marine Benthic Group D为优势类群。多样性指数(H’)和物种丰富度指数(Schao1)表明,本地种秋茄林下土壤细菌和古菌的多样性指数最高,外来种无瓣海桑显著低于秋茄林,甚至明显低于相邻无红树林裸滩沉积物;不同植被下土壤细菌和古菌群落结构存在显著差异,秋茄林土壤微生物群落结构和无红树林裸滩沉积物更相似。【结论】红树林土壤微生物类群丰富,不同植被下土壤细菌和古菌多样性和群落结构存在显著差异。     

新疆特殊生境岩石内生细菌末端限制性片段长度多态性技术分析

【目的】了解新疆特殊生境不同类型岩石内生细菌的组成及多样性。【方法】采用末端限制性片段长度多态性技术(Terminal Restriction Fragment Length Polymorphism,T-RFLP),分析新疆乌苏花岗岩(1号样)、一号冰川和木垒变质岩(2,3号样)、裕民和托克逊岩石漆(4,5号样)内生细菌群落。【结果】样品间多样性指数变化不大;聚类分析表明岩石类型相同,其相似性较高,2号样和3号样聚为一支并与1号样再聚为一支,4号样与5号样聚为一支;各样品共有种群为厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes),1号样存在酸杆菌门(Acidobacteria),2号样存在浮霉菌门(Planctomycetes);除5号样优势类群为放线菌门(29.3%),其它4个样品均为变形菌门,只是所占比例略有不同。【结论】生境不同的同类型岩石的内生细菌群落组成存在差异,各类岩石中可能存在大量未知细菌新种。     

新疆乌恰泉华地震前后泉水细菌群落的变化

为了解新疆乌恰泉华地震前后泉水细菌群落的变化,采用微生物纯培养方法结合16S rRNA基因序列系统发育分析法对地震前后泉水样品进行研究。结果表明,地震前和地震后可培养菌落的数目、菌群结构和优势菌都存在差异。地震前,25株菌分属于11个科12个属17个种,多数菌落归属于变形菌门γ亚群(Gammaproteobacteria)(82.63%),其中优势菌株为窄食单胞菌属某种\.RB25(Stenotrophomonas sp. RB25)(56.86%)和不动杆菌属某种.RB11(Acinetobacter sp. RB11)(24.31%);地震后,27株菌分属于14个科17个属21个种,总细菌数量减少,但生物多样性提高,变形菌门α亚群(Alphaproteobacteria)(49.64%)上升为优势类群,优势菌株为根瘤菌属某种.RA42(Rhizobium sp. RA42)(28.21%)。该研究为泉水微生物的映震研究积累了资料。     

日偏食对乌鲁木齐空气可培养细菌群落的影响

利用自然沉降法采集2009年7月19日至24日日偏食前后乌鲁木齐空气微生物,以可培养法分析日偏食对其细菌群落组成的影响。结果如下：（1）细菌数量和种类均随日偏食临近而增多,当天达到峰值,随后减少。（2）所获81株细菌经测序及系统发育分析将其归为四个门,分别为放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes),其中放线菌门为优势类群,占细菌总数的54%。（3）不同采样时间细菌群落组成的聚类分析显示,日偏食发生前日（21日）和当日（22日）空气细菌组成较为相似聚为一类,其余日期的聚为一类。（4）典型相关分析(Canonical Correlation Analysis, CCA)发现,放线菌门中菌株与绝大多数大气环境因子呈正相关性;变形菌门和厚壁菌门与大多数大气环境因子呈正相关性;而拟杆菌门中的菌株只与温度、风速和太阳风速度呈正相关。结果表明,日偏食会增加乌鲁木齐空气可培养细菌的数量和种类。     

放牧对贝加尔针茅草原土壤细菌群落结构的影响

利用变性梯度凝胶电泳(PCR-DGGE)技术,研究了放牧对贝加尔针茅(Stipa baicalensis)草原土壤细菌群落结构的影响。结果表明,放牧条件下,贝加尔针茅草原0～20cm土壤中细菌类群包括变形菌门(Proteobacteria)的α、β、γ、δ变形菌纲,放线菌门(Actinobacteria)、芽单胞菌门(Gemmatimonadetes)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)、酸杆菌门(Acidobacteria)、疣微菌门(Verrucomicrobia)、拟杆菌门(Bacteroidetes)、硝化螺旋菌门(Nitrospirae)等,其中变形菌门、放线菌门属优势类群,疣微菌门细菌是中度放牧样地仅有的类群;典型对应分析表明,土壤细菌群落与放牧强度、土壤理化性状密切相关。轻度放牧样地土壤细菌群落与有机碳、C/N比有较为密切的关系,中度放牧样地土壤细菌群落则与全N有较密切的关系,重度放牧样地土壤细菌群落与土壤pH有关。     

宜春温泉水体与泉底沉积物细菌多样性分析

研究宜春富硒温泉水体与泉底沉积物的细菌群落多样性。利用高通量测序技术分析泉水与沉积物中细菌群落结构与多样性。温泉水中主要的细菌类群为变形菌门和拟杆菌门,而在沉积物样品中的主要优势菌群为OP1、蓝细菌、浮霉菌门和绿弯菌门。细菌在属分类水平上,温泉水中优势菌群为不动杆菌属、假单胞菌属、水栖菌属、Thermosynechococcus、鞘脂杆菌属和金黄杆菌属等。沉积物样品细菌中优势菌群属于未知物种,在数据库中并没有相关的注释信息;其中已知的优势菌属为Candidatus acetothermum、Thermosynechococcus、亚热栖菌属、不动杆菌属。宜春温汤富硒温泉水体与沉积物中存在着丰富的微生物群落且组成差异性很大,该研究为了解与发掘温泉微生物菌种资源具有重要价值。     

宋代海底沉船“南海Ⅰ号”出水木质文物中细菌类群

【目的】通过对"南海Ⅰ号"沉船出水木质文物标本中细菌类群的分析,了解饱水木质文物中的细菌类群并推测细菌对木质文物损害的机制。【方法】应用Illumina Mi Seq测序平台对采自该沉船的10份木质文物标本中细菌V3–V4序列进行测序与分析,比较各标本中细菌群落的组成差异。【结果】根据97%序列相似性得到3 780不同的细菌OTUs,分属34目、35科的187个属;多数细菌OTU属于变形菌门(Proteobacteria)细菌,占全部细菌OTU的52.9%,在细菌纲水平上γ-变形菌纲(γ-Proteobacteria)(占17.9%)是丰度最高的细菌纲。德沃氏菌属(Devosia)(3.5%)是"南海一号"沉船样品丰度最高的属,其他分别属于甲基娇养杆菌属(Methylotenera)(2.4%)、鼠尾菌属(Muricauda)(1.2%)。其中氢噬胞菌属(Hydrogenophaga)、中国农大湖积物杆菌(Lacibacter cauensis)、德氏食酸菌(Acidovorax delafieldii)、德沃斯氏菌属(Devosia)、沉积物杆状菌属(Sediminibacterium)、缺陷短孢单胞菌(Brevundimonas diminuta)和门多萨假单胞菌(Pseudomonas mendocina)在所有样品中均可检测到。【结论】"南海Ⅰ号"沉船出水木质文物存在着种类丰富的好氧与厌氧细菌种类,多种细菌类群具有较好的纤维素降解能力与铁硫元素转化能力,控制细菌群落中参与分解纤维素的细菌与铁硫循环菌活性对于保护木质文物有重要作用。     

保安湖水体细菌群落结构时空变化特征及驱动因子

为了探究保安湖水体细菌群落结构时空变化特征及驱动因子,研究于2019年春、夏、秋、冬四季采集保安湖水样,使用宏基因组测序技术对保安湖水体细菌群落的组成及多样性变化进行了研究。结果表明:(1)保安湖不同湖区细菌群落组成无显著差异(P>0.05);夏、秋季细菌丰富度、均匀度、香农及辛普森多样性指数均显著高于春、冬季(P<0.05),夏、秋季优势类群为变形菌门(Proteobacteria)、放线菌门(Actinobactetiota)、蓝藻门(Cyanobacteria),而春、冬季变形菌门(Proteobacteria)和放线菌门(Actinobactetiota)占主导地位;(2)温度、透明度、pH、溶解氧、高锰酸盐指数、叶绿素a及总磷等因素是保安湖水体细菌群落结构变化的重要驱动因子;(3)保安湖细菌群落构建过程在春、夏、秋季由随机性过程主导,在冬季由确定性过程主导;(4)保安湖细菌网络互作具有明显的季节特征,从春季到冬季,保安湖细菌种间相互作用逐渐紧密复杂。综上所述,保安湖水体细菌群落结构具有明显的季节变化特征,温度、透明度、pH、溶解氧、高锰酸盐指数等因素具有驱动水体细...     

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.