氦氧饱和高气压暴露对铜绿假单胞菌毒力表型的诱导调节

研究氦氧饱和高气压暴露对铜绿假单胞菌与急性侵袭感染相关的主要毒力因子表型的影响。分别检测暴露前后铜绿假单胞菌的生长速度、运动能力,对乙酰胺的分解能力和培养细胞外液中绿脓菌素、弹性蛋白酶的分泌水平和活性。在动物水平验证毒力的变化。结果显示,经4.5 MPa氦氧饱和加压暴露后,与对照组相比铜绿假单胞菌的生长增殖、运动能力和对乙酰胺的分解能力增强,绿脓菌素分泌增加,弹性蛋白酶活性增强;暴露后细菌对实验小鼠的毒性增加。因此氦氧饱和高气压环境对铜绿假单胞菌的毒力表型有正调控作用。     

铜绿假单胞菌Arr基因突变对生物膜和绿脓菌素合成的影响

为了研究铜绿假单胞菌Arr基因对生物膜和绿脓菌素合成的影响,采用抗庆大霉素基因序列(Gentamycin resistance cassette,aacC1)插入失活的策略构建了铜绿假单胞菌Arr基因突变株PA-AG,通过96孔板静止培养、结晶紫染色的方法检测其生物膜的形成量,利用抽提的方法检测绿脓菌素的合成量。结果在KMB或LB培养基中,突变株PA-AG形成生物膜的量均有所减少,野生株约是突变株的2倍,然而突变株合成绿脓菌素的能力却明显加强,约为野生株的2.5倍。由此推测,铜绿假单胞菌Arr基因在一定程度上促进了生物膜的形成,抑制了绿脓菌素的合成。     

植物发酵液提取物对铜绿假单胞菌生物膜的作用

【目的】探讨植物发酵液提取物(plant fermentation extract,PFE)对铜绿假单胞菌生物膜的抑制作用,为临床上铜绿假单胞菌感染相关疾病的治疗提供参考。【方法】通过划线法分离临床标本中的铜绿假单胞菌并进行鉴定,通过报告菌株测定铜绿假单胞菌的毒力因子,采用试管法和激光共聚焦扫描显微镜测定生物膜的形成。【结果】在分离出的16株铜绿假单胞菌中,PFE对PA007菌株的作用效果最好,1%PFE显著降低PA007菌株生物膜、绿脓菌素和N-(3-oxododecanoyl)-HSL(3-oxo-C12-HSL)的产量(P0.05)。同时,也显著降低Las A蛋白酶的活性以及持留菌存活率(P0.05)。荧光定量PCR实验结果表明PFE能显著抑制las I和pqs A基因的表达(P0.05)。【结论】PFE具有抗铜绿假单胞菌感染能力,在临床上铜绿假单胞菌感染疾病的治疗中具有巨大的潜在价值。     

铜绿假单胞菌LasR基因反义核酸原核表达载体的构建及对该菌毒力的影响

PCR扩增LasR基因,用反向克隆法构建LasR基因反义核酸原核表达载体pUCP18/lasRantisense并转化铜绿假单胞菌,经酶切、PCR及测序鉴定重组载体.RT-PCR检测LasB基因和LasI基因mRNA的表达,NAD法测定外毒素A的活性,紫外分光光度计测定绿脓菌素的产生水平.用转化pUCP18/lasRantisense质粒菌株感染大鼠呼吸道并进行病理组织切片检查.PCR扩增出约720bp片段,与GenBank(No:NC_002516)报道的基因片段大小一致,构建了LasR基因反义核酸原核表达载体pUCP18/lasRantisense,并成功转化铜绿假单胞菌,且有效表达,使转化菌的毒力因子弹性蛋白酶、外毒素A和绿脓菌素表达水平均降低.与标准株感染的大鼠比较,转化pUCP18/lasRantisense质粒菌株感染的大鼠支气管炎症明显减轻.上述结果表明,LasR基因反义核酸原核表达载体pUCP18/lasRantisense可以降低铜绿假单胞菌的毒力.     

转录调节因子σ~(38)介导铜绿假单胞菌绿脓菌素合成代谢调控

【目的】为了进一步鉴定铜绿假单胞菌转录调控因子σ~(38)对2个拷贝吩嗪合成基因簇(phz A1-G1和phz A2-G2)的具体调控方式并推定介导绿脓菌素合成代谢的可能调控机制。【方法】根据铜绿假单胞菌基因组信息,利用同源重组原理构建rpo S基因缺失突变株Δrpo S以及克隆全长rpo S基因作互补分析;再以单一吩嗪基因簇缺失突变株Δphz1和Δphz2为出发菌株,分别构建rpo S缺失突变株Δrpo Sphz1和rpo S插入突变株Δrpo Sphz2,测定并比较野生株及相关突变株的绿脓菌素合成量,初步推定σ~(38)因子对2个不同吩嗪基因簇表达的调控方式。【结果】在GA培养基中,突变株Δrpo S的绿脓菌素合成量比野生株显著增加;互补分析证实,σ~(38)可使突变株Δrpo S的绿脓菌素降低并接近野生株PAO1水平;与对照株Δphz1相比,突变株Δrpo Sphz1的绿脓菌素合成量因σ~(38)因子缺失而显著减少;而与对照株Δphz2相比,突变株Δrpo Sphz2的绿脓菌素合成量因σ~(38)因子缺失显著增加。【结论】转录调控因子σ~(38)对铜绿假单胞菌绿脓菌素的合成代谢的确具一定的负调控作用;结合已报道的研究结果,初步推定:σ~(38)因子通过负调控吩嗪基因簇phz1,正调控吩嗪基因簇phz2的表达实现对绿脓菌素合成代谢的调控。     

铜绿假单胞菌lasI,rhlI基因功能缺陷株的构建和生物学功能验证

构建铜绿假单胞菌lasI,rhlI基因功能缺陷株,为进一步阐明氦氧饱和高气压暴露条件诱导lasI,rhlI基因介导铜绿假单胞菌毒力调节的分子机制研究奠定基础。用双亲株接合转移法删除lasI,rhlI基因ORF编码区,通过RT-PCR方法验证目标基因编码序列mRNA的缺失;通过对细菌生长增殖能力、弹性蛋白酶代谢活性和细菌绿脓菌素分泌能力等表型的测定,验证目标基因编码序列缺失后的基因调节功能的缺陷。结果表明成功构建铜绿假单胞菌lasI,rhlI基因功能缺陷株,可作为进一步研究的基因工程菌。     

谷胱甘肽对铜绿假单胞菌exoS 和exoY基因的影响

摘要: 【目的】研究谷胱甘肽对铜绿假单胞菌exoS和exoY基因表达的影响。【方法】利用丁硫氨酸亚砜胺和马来酸二乙酯同时耗竭细胞内的谷胱甘肽,并构建包含被lacZGm破坏的谷胱甘肽合成酶基因的突变体。通过分别连有exoS 和exoY基因启动子的pMS402质粒上Lux报道子发光值大小检测exoS 和exoY基因表达变化情况。【结果】exoS和exoY基因的表达在用化学药品耗竭的细胞中或是在谷胱甘肽合成酶突变体中都降低。【结论】铜绿假单胞菌细胞内的谷胱甘肽可以促进exoS和exoY的表达。这将为进一步研究铜绿假单胞菌的感染以及致病性机理提供一定的理论基础。     

绿脓菌素分型的研究

早在1925年Gratia发现某些大肠菌具有抑制其它大肠菌生长的物质,命名为大肠菌素。以后Fredericq等人进一步研究又发现了巨形杆菌产生巨杆菌素,鼠疫杆菌产生鼠疫菌素,荧光假单胞菌产生荧光菌素及绿脓假单胞菌产生绿脓菌素。这些物质统称为细菌素。     

铜绿假单胞菌和白假丝酵母的跨界相互作用

铜绿假单胞菌和白假丝酵母(又称白念珠菌)这两种条件致病菌可共存于人体。两者间存在复杂的相互关系,即跨界相互作用。铜绿假单胞菌抑制白念珠菌形态转换,抑制其生物膜形成并毒杀其菌丝;白念珠菌则抑制铜绿假单胞菌绿脓素形成并抑制其丛集运动。跨界相互作用可能存在3种机制:信号转导通路、生物膜和毒力因子。铜绿假单胞菌通过信号分子N-3-氧代十二烷酰-L-同型丝氨酸内酯(3-oxo-C12-HSL)抑制白念珠菌形态转换,而白念珠菌通过信号分子法呢醇抑制铜绿假单胞菌绿脓素生成和丛集运动,即存在信号分子介导的跨界相互作用。跨界相互作用影响铜绿假单胞菌和白念珠菌各自的致病性。如能充分利用跨界相互作用,将有助于优化治疗的选择。     

铜绿假单胞菌检测方法的比较与优化北大核心CSCD

通过铜绿假单胞菌检测方法比较和优化以期获得一种准确度高、操作简单且对实验条件要求不高的检验方法。实验以VITEK 2 Compact全自动细菌鉴定系统鉴定结果为参考,采用GB 8538.57-2016和GB/T7918.4-1987中铜绿假单胞菌的检测方法,对27株试验菌株进行鉴定试验。结果表明,GB 8538.57-2016方法检测结果准确度最低,假阳性检出率为29.6%,GB/T7918.4-1987假阳性检出率为7.4%。以GB 8538.57-2016铜绿假单胞菌的检测方法为例,优化后的检测方法增加了血琼脂平板培养、革兰氏染色及镜检和对血平板所有可疑菌落进行绿脓菌素试验。用改进后的GB 8538-2016铜绿假单胞菌检测方法对27株试验菌株进行验证试验,检验结果与VITEK 2 Compact一致。     

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.     

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     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV