细菌群体感应淬灭酶的研究进展

细菌的群体感应系统（Quorum sensing,QS）参与许多生物学功能的调控,其中包括动植物病原细菌致病因子的生成以及人类某些病原细菌生物膜的形成。酰基高丝氨酸内酯（N—acylhomoserine laetone,AHL）是调控群体感应系统的关键信号分子。近年的研究表明,不同生物体包括细菌和真核生物中都存在类别不同的能够降解AHL的群体感应淬灭酶（Quorum—quenching enzyme）。在AHL依赖型致病菌和转基因植物中表达AHL降解酶能有效地抑制QS信号分子的积累,从而阻断了病原细菌的发病机制,提高了植物的抗病性。这些新颖的群体感应淬灭酶的发现,不仅为防治细菌侵染提供了可行的途径,也对研究它们在宿主中的功能和对生态系统的潜在影响提出挑战。     

植物病原细菌毒性调控网络的研究进展

植物病原细菌通过复杂和精细的全局性调控网络来协调多个层面的毒性决定因子。在不同的植物病原细菌中,这些全局性的毒性调控网络控制着细菌的侵染策略、存活以及在面临寄主植物防卫系统的互作环境中实现成功侵染的病程。本文详细分析了植物病原细菌4个重要属(假单胞菌属、果胶杆菌属、黄单胞菌属和雷尔氏菌属)的模式病原菌主要的毒性调控系统,包括群体感应系统、双组分调控系统、转录激活调控子以及转录后、翻译后的调控机制。在此基础上,重点评价了一些模式菌株全局性毒性调控机制的异同点,总结了一些最新的研究进展,并绘制了精细的网络调控图。这些分析表明,虽然一些相同的调控系统控制着病原菌的毒性,但是在不同种以及种下的亚种或者致病变种中这些调控机制功能各异,对于病原菌全毒性的贡献也存在着明显的差异。     

病原效应蛋白HopB1抑制植物的天然免疫反应

植物在完成整个生活史的过程中无时无刻不受到环境中各种病原微生物(如细菌,真菌和病毒等)的侵染。这些病原微生物的侵染会引发严重的植物病害,造成世界范围内许多重要经济和粮食作物的大量减产,导致大量的经济损失并严重威胁人类的粮食安全。长期以来,农业育种人员经过不断的尝试和持续的改良大大提高了作物品种的抗病性,但由于病原微生物与植物互作的复杂性,目前人们依然需要面对各种严重的植物病害。因此研究病原微生物的致病机理和植物抗性机制显得尤为重要,通过对病原物和植物互作的研究能够为解决农业生产中农作物病虫害提供强有力的理论支持。     

细菌攻入植物内的新武器

近日,中美科学家联合报道了细菌毒性蛋白HopF2帮助病原细菌侵染植物宿主的机理。HopF2是丁香假单胞菌致病的关键武器,细菌能够将这些蛋白“注射”到植物宿主细胞内,干扰植物的免疫信号通路以及其他细胞活动,使宿主易感。     

植物与病原菌互作的蛋白质组学研究进展

深入认识植物与病原菌的识别方式、亲和性或非亲和性的互作模式,对于揭示植物-病原菌互作机制研究具有重要意义.利用蛋白质组学方法研究病原菌侵染植物过程,分析相关的基因和蛋白,有助于从分子水平上探究植物-病原菌相互作用机制.本文概述了植物-病原菌的互作机制,系统介绍了差异蛋白质组学分析方法在植物-病原真菌、植物-病原细菌两类互作系统中的应用,分析了植物与病原菌互作过程中可能涉及的差异表达功能蛋白,并对当前蛋白质组学技术在植物与病原菌互作研究中存在的诸多问题进行了探讨.     

肺炎克雷伯菌噬菌体解聚酶的研究进展

肺炎克雷伯菌(Klebsiella pneumoniae)是在临床引起多种感染的常见条件致病菌之一。多重耐药肺炎克雷伯菌株的出现,给防控细菌感染带来了巨大阻力。肺炎克雷伯菌噬菌体编码的解聚酶是一种稳定性高、特异性强的生物酶,具有分解细菌胞外多糖、限制细菌生长等多种功能。解聚酶可为防控肺炎克雷伯菌感染提供新思路,在抗菌应用中具有广阔前景。本文就肺炎克雷伯菌噬菌体解聚酶的研究进展进行综述。     

铜绿假单胞菌群体感应系统介导的呼吸道病原菌种间互作研究进展

细菌性慢性呼吸道感染是严重威胁人类健康和制约社会经济发展的常见疾病。呼吸道环境和结构的复杂性导致慢性感染病灶常常定植着多种病原菌,如铜绿假单胞菌Pseudomonas aeruginosa、金黄色葡萄球菌Staphylococcus aureus、大肠埃希氏菌Escherichia coli、肺炎克雷伯氏菌Klebsiella pneumoniae、鲍曼不动杆菌Acinetobacter baumannii和白色念珠菌Candida albicans等。这些病原菌在慢性呼吸道感染的发展过程中进化出了合作、竞争、共生等复杂的种间关系,通过形成相对稳定的群落系统使多种病原菌成为一个整体来应对呼吸道各种苛刻的生存条件,从而导致呼吸道感染针对性治疗的失败或病情反复。目前国际上关于病原菌种间互作关系的研究正处于起步阶段,临床证据表明铜绿假单胞菌的定植与慢性呼吸道感染的发生、发展息息相关,并且该菌可以利用群体感应系统来主导与其他病原菌的互作与共存。因此,本文围绕群体感应系统综述了铜绿假单胞菌与其他常见呼吸道感染病原菌的种间关系和互作机理,可加深人们对病原菌种间互作与慢性呼吸道感染相关疾病关联性的认识,并为进一步临床治疗方案的改进、疾病控制和新型抗感染药物的研发提供新视角、新方向。     

植物与微生物之间的跨界信号调控

依靠信号分子的交流方式广泛存在于原核生物和真核生物之间,在此交流过程中,相互联络的生物之间产生并释放小分子化合物,从而建立原核生物和真核生物交流的通道,影响彼此基因的表达,这个过程即为跨界信号交流.跨界信号交流广泛发生在病原菌或益生菌与其宿主之间,其产生的生理效应主要取决于特异信号在生物个体中所激发的信号通路.揭示跨界信号调控的信号分子或语言,并阐明其作用机理具有很大的挑战性.已有研究表明,细菌和植物能产生多种多样的信号分子,解析这些信号分子并探讨其作用机理逐渐成为该领域研究热点,其研究成果将有助于发掘新的植物抗病策略,例如,通过干扰跨界信号调控途径而不是直接杀死病原细菌达到抗病的效果;而益生菌中的信号分子的作用机理的研究,也利于农业上的应用.这篇综述总结了植物与细菌之间跨界信号调控的最新研究进展,以及植物相关细菌群体感应系统的LuxR类的转录调控因子在跨界信号调控过程中的作用机制.     

从野栖小家鼠中分离克雷伯氏菌的报告

克雷伯氏菌属(Klebsiella)的细菌在自然界中的存在较为广泛,常见于人的呼吸道和泌尿系统的感染中,它可引起人的大叶性肺炎或偶尔的败血症,对家畜及实验动物等具有强毒性。但从野栖小家鼠的病鼠中分离到肺炎克雷伯氏菌(K.pneumoniae)和臭鼻克雷伯氏菌(K.ozaenae)的报道迄今未曾见到。1978年8月从捕获的104只小家鼠中发     

病原弧菌的致病机理

由弧菌属细菌 (Vibriospp.)引起的弧菌病 (Vibriosis)是在世界各地海水养殖鱼、虾、贝类等动物中普遍流行、危害最大的细菌性疾病。在已知的弧菌中,有 10多种是海洋养殖动物的病原菌。长期以来,人们对病原弧菌的致病性研究一直是利用分离菌株对养殖动物进行各种方式的人工感染,通过观察实验动物是否发病来判断病原弧菌的致病性,而对弧菌病的发生、发展等过程缺乏深入的了解。由于对病原弧菌致病机理的研究最终将会为弧菌病的防治提供可靠的科学依据,近十年来,对病原弧菌的致病机理研究已成为对弧菌病研究的重点和最活跃的研究领域,研究工作主要包括对常见的病原弧菌在养殖动物体内外环境中的生       

Prevalence of tick-borne pathogens in ixodid ticks (Acari: Ixodidae) collected from European wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis>) and Iberian red deer (<Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis>) in central Spain

Emerging tick-borne diseases of humans and animals have occurred frequently during the past 30 years. These disease outbreaks appear to result from changes in the distribution of tick and vertebrate hosts, and the introduction of humans and domestic animals into tick–pathogen–wildlife cycles. Use of molecular technologies now available for identification of pathogens in ticks can provide valuable information that allows for risk analysis of emerging tick-borne diseases. In this study, the prevalence of selected pathogens in ticks collected in six locations in central Spain from the major wild ungulate species, European wild boar (Sus scrofa) and Iberian red deer (Cervus elaphus hispanicus), was determined by PCR. Tick species collected included Ixodes ricinus, Dermacentor marginatus, Rhipicephalus bursa and Hyalomma m. marginatum. Pathogens identified in ticks included piroplasmids, Anaplasma spp., Ehrlichia spp. and Rickettsia spp. Piroplasmids were identified in all tick species except I. ricinus. Ehrlichia spp. were detected in all tick species and collection locations, while Rickettsia spp., which proved to be R. slovaca and a recently identified Rickettsia sp. DnS28, were identified only in D. marginatus. A. marginale and A. phagocytophilum were detected in D. marginatus, R. bursa and Hy. m. marginatum. Concurrent infections of these pathogens were frequently observed in ticks. Notably, A. phagocytophilum, which is infective for a broad host range that includes humans and domestic and wild animals, was identified in ticks from all collection locations. The variety of ticks and tick-borne pathogens demonstrated in this study suggests a risk in central Spain for the emergence of tick-borne diseases in humans and domestic animals.     

GyrB sequence analysis and MALDI-TOF MS as identification tools for plant pathogenic Clavibacter

The bacterial genus Clavibacter has only one species, Clavibacter michiganensis, containing five subspecies. All five are plant pathogens, among which three are recognized as quarantine pests (mentioned on the EPPO A2 list). Prevention of their introduction and epidemic outbreaks requires a reliable and accurate identification. Currently, identification of these bacteria is time consuming and often problematic, mainly because of cross-reactions with other plant-associated bacteria in immunological tests and false-negative results in PCR detection methods. Furthermore, distinguishing closely related subspecies is not straightforward. This study aimed at evaluating the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and a fragment of the gyrB sequence for the reliable and fast identification of the Clavibacter subspecies. Amplification and sequencing of gyrB using a single primer set had sufficient resolution and specificity to identify each subspecies based on both sequence similarities in cluster analyses and specific signatures within the sequences. All five subspecies also generated distinct and reproducible MALDI-TOF MS profiles, with unique and specific ion peaks for each subspecies, which could be used as biomarkers for identification. Results from both methods were in agreement and were able to distinguish the five Clavibacter subspecies from each other and from representatives of closely related Rathayibacter, Leifsonia or Curtobacterium species. Our study suggests that proteomic analysis using MALDI-TOF MS and gyrB sequence are powerful diagnostic tools for the accurate identification of Clavibacter plant pathogens.     

芽胞杆菌BJ-6的鉴定及对甜瓜细菌性果斑病的防治

芽胞杆菌是目前植物病害生物防治研究最多的一类微生物,其在自然界中分布广泛,开发潜力大。【目的】为了探究从杏树根际土壤分离的芽胞杆菌BJ-6的分类地位及其防病促生作用。【方法】本研究测定了芽胞杆菌BJ-6的形态和生理生化特征,通过PCR扩增了该菌的16S rRNA、gyrA和gyrB基因并进行了序列测定,通过多基因聚类分析确定其分类地位,平板对峙法测定抗菌谱,盆栽幼苗实验验证其对甜瓜细菌性果斑病的防治效果和对甜瓜的促生作用。【结果】结合形态特征、生理生化特性及多基因序列分析建立的系统进化树,确定菌株BJ-6为解淀粉芽胞杆菌(B. amyloliquefaciens),抑菌实验发现该菌株对15种植物病原菌均有不同程度的抑菌活性,盆栽实验结果发现该菌株发酵液对甜瓜细菌性果斑病有很好的防治效果,并对甜瓜苗有很好的促生作用。【结论】BJ-6属于解淀粉芽胞杆菌,抑菌谱广,且具有防病促生作用,具有进一步开发为生防制剂的前景。     

Mixtures of plant growth-promoting rhizobacteria for induction of systemic resistance against multiple plant diseases

Studies of induced systemic resistance using strains of plant growth-promoting rhizobacteria (PGPR) have concentrated on the use of individual PGPR as inducers against multiple diseases of a single crop. To date, few reports have examined the potential of PGPR strain mixtures to induce systemic resistance against diseases of several different plant hosts. The objective of this study was to select mixtures of compatible PGPR strains with the capacity to elicit induced systemic resistance in four hosts. The specific diseases and hosts tested in this study included: bacterial wilt of tomato (Lycopersicon esculentum) caused by Ralstonia solanacearum, anthracnose of long cayenne pepper (Capsicum annuum var. acuminatum) caused by Colletotrichum gloeosporioides, damping off of green kuang futsoi (Brassica chinensis var. parachinensis) caused by Rhizoctonia solani, and cucumber mosaic virus (CMV) on cucumber (Cucumis sativus). To examine compatibility, seven selected PGPR strains were individually tested for in vitro antibiosis against all other PGPR strains and against three of the tested pathogens (R. solanacearum, C. gloeosporioides, and R. solani). No in vitro antibiosis was observed among PGPR strains or against pathogens. Twenty-one combinations of PGPR and seven individual PGPR were tested in the greenhouse for induced resistance activity. Results indicated that four mixtures of PGPR and one individual strain treatment significantly reduced the severity of all four diseases compared to the nonbacterized control: 11 mixtures reduced CMV of cucumber, 16 mixtures reduced bacterial wilt of tomato, 18 mixtures reduced anthracnose of long cayenne pepper, and 7 mixtures reduced damping off of green kuang futsoi. Most mixtures of PGPR provided a greater disease suppression than individual PGPR strains. These results suggest that mixtures of PGPR can elicit induced systemic resistance to fungal, bacterial, and viral diseases in the four hosts tested.     

黄病毒科和冠状病毒科病毒侵染中的外泌体研究进展

外泌体是一种在细胞间信息传递和物质运输中起重要作用的细胞外囊泡,它携带来源于宿主细胞的蛋白质、脂质和RNA等物质,并对受体细胞的生理状态产生重要影响.黄病毒科病毒如丙型肝炎病毒和冠状病毒科病毒如新型冠状病毒导致的疾病严重威胁人类健康,深入了解黄病毒科和冠状病毒科病毒与宿主的相互作用,对于筛选治疗的细胞靶点以及外泌体疫苗...     

整合子系统介导沙门菌耐药性的研究进展

沙门菌(Salmonella spp.)是公共卫生学上具有重要意义的人畜共患病病原菌。人、畜感染沙门菌后会引起伤寒、副伤寒、胃肠炎、败血症和肠外局灶性感染等疾病。抗生素是治疗沙门菌严重感染的有效手段,随着临床和畜牧业中抗生素的大量使用,使得沙门菌的耐药情况日益严重。整合子是普遍存在于细菌中的一种可移动基因元件,可有效捕获外源基因确保其表达,并复合于转座子、质粒等,使多种耐药基因在细菌种内或者种间进行传播。在过去的二十年中,随着新基因盒和复杂整合子的不断出现,导致整合子系统迅速进化。整合子在沙门菌耐药性传播过程中具有非常重要的作用,因此,本文对整合子系统的分子结构、分类、作用机制,以及沙门菌中存在的Ⅰ、Ⅱ、Ⅲ类整合子介导的耐药性及现有检测方法的研究进展进行综述,以期为沙门菌耐药性研究提供参考。     

Chlamydial endocytobionts of free-living amoebae differentially affect the growth rate of their hosts

Bacteria closely related to chlamydiae live and multiply as endocytobionts within free-living amoebae, making these amoebae potential vehicles of new emerging bacterial pathogens of humans. Hartmannella vermiformis containing endobiotic Neochlamydia hartmannellae grew more rapidly than those without endobionts, whilst Acanthamoeba sp. harbouring the Parachlamydia-related endocytobiont UWE25 multiplied more slowly than those without endobionts. The cause for the opposite effect of chlamydial endocytobionts on the growth of their host cells remains unknown.     

丝核菌的分类系统：现状及存在问题

以重要植物病原菌为特征的丝核菌是一类在土壤中广泛分布的丝状真菌,通常不产孢,以菌丝或菌核的形式存在,多样性非常丰富。本文基于国内外最新研究进展,对依据菌丝体的细胞核数目、菌丝融合、有性生殖和系统进化等方面的基本特征展开的丝核菌分类体系及分类现状进行了综述。基于菌丝的细胞核数目,丝核菌被分为单核、双核和多核丝核菌三大类群。自然界中单核丝核菌数量极少,多核和双核丝核菌在全球分布广泛,占丝核菌的绝大多数。基于菌丝融合试验的结果,目前多核丝核菌被分为13个菌丝融合群,双核丝核菌被分为18个菌丝融合群。部分融合群内又根据一些稳定的特征分了亚群,但亚群的建立标准并不统一。目前的分子系统学研究结果基本支持丝核菌的菌丝融合群及亚群的分类。基于部分有性世代被发现的菌株的形态特征,多核和双核丝核菌分别被鉴定为亡革菌属和角担菌属。此外,目前已有分属重要植物病原菌和兰科菌根菌类群的至少9个融合群或亚群的17个菌株完成了基因组测序,比较基因组学和线粒体组学开始在丝核菌分类和进化研究中发挥作用。丝核菌分类系统特殊且复杂,作者在文末提出了目前丝核菌分类学研究面临的问题和今后研究的趋势,期待更多的学者参与到这个重要菌...     

Seeds as Vehicles for Pathogen Importation

Since the 1900s, consumer demand for new plant products gave opportunity for many plant pathogens to disseminate to new areas on imported seeds. New markets for plant commodities encouraged plant breeders to begin collecting seed stocks from abroad. The birth of new seed companies extend their markets to new area. These events began the global dissemination of many seedborne pathogens. Many seedborne pathogens gained entry and escaped detection by specific traits that favored their dissemination. Three recent case scenarios are presented that illustrate how plant pathogens that passively employ the seed coats of their host achieved global dissemination and permanence in each patho-system. Evidence is presented to show that asparagus (Asparagus officinalis) seed produced in the US acted as a vehicle for disseminating one vegetatively compatible group (VCG) of a pathogenic fungus on asparagus called Fusarium proliferatum throughout new plantings in Australia. Similarly, public demand for Mediterranean cuisine in the US and abroad during the last 20 years led to an increase in the importation of basil (Ocimum basilicum) seed along with an inconspicuous fungus called Fusarium oxysporum. The fungus caused a destructive disease called Fusarium wilt of basil that appeared in over 25 separate locals spanning three continents. The third example demonstrated how new developments in lupine (Lupinus spp.) cultivars and increased public demand led to the global dispersal of a seedborne pathogen called Colletotrichum gloeosporioides. Each case highlights how these pathogens use seeds, humans, and particular traits to disperse globally in short period of time.     

中药抑制嗜水气单胞菌、副溶血弧菌和溶藻弧菌的分子机制研究进展

嗜水气单胞菌（Aeromonas hydrophila）、副溶血弧菌（Vibrio parahaemolyticus）和溶藻弧菌（Vibrio alginolyticus）是常见的鱼类致病菌,导致鱼类患出血性败血症、溃疡等疾病。大黄、金银花、甘草等中药因具有天然活性、不易产生细菌耐药性而有望替代抗生素抑制这些鱼类致病菌。回顾细菌的致病性和中药的药理活性,从蛋白质组学和基因转录水平阐述了中药抑制嗜水气单胞菌、副溶血弧菌和溶藻弧菌的分子机制。这些研究对人类了解和控制致病菌的感染、提高鱼类免疫力以及推广应用中药作为饲料添加剂具有重要的指导意义。