嗜肺军团菌效应蛋白之间的调控机制

嗜肺军团菌(Legionella pneumophila)是一种革兰氏阴性致病菌,它可以引起人类军团病。嗜肺军团菌的Dot/Icm分泌系统在其致病过程中至关重要,其向宿主细胞内转运约330种效应蛋白,通过修饰细胞调节因子、抑制细胞凋亡等一系列措施操纵宿主细胞的多种生命活动,以完成自身的增殖与侵染。为避免对宿主生理造成不必要的破坏,嗜肺军团菌已进化出复杂而精细的调控机制来平衡嗜肺军团菌毒力与宿主细胞的稳态,以确保嗜肺军团菌在宿主细胞内的生存。军团菌效应蛋白的功能及分子机制的研究近几年取得突破性进展,嗜肺军团菌效应蛋白之间的作用机理也成为我们进一步研究的热点。该文主要对嗜肺军团菌的致病机制及其效应蛋白间的调控机制进行了综述,为进一步了解嗜肺军团菌致病机制提供了一定的参考。     

对于军团菌的免疫遏制:宿主能否另辟蹊径?

嗜肺军团菌可引起严重的非典型肺炎,其特殊的Dot/Icm IVB型分泌系统转运近330种效应蛋白(大多数作为蛋白酶发挥功能)至宿主细胞,通过修饰细胞调节因子、抑制细胞凋亡等一系列措施调控宿主免疫应答以逃逸宿主免疫系统的监测,完成自身的增殖与侵染。嗜肺军团菌诱发的病原相关分子模式(pathogen-associated molecular patterns,PAMPs)和效应器触发反应(effector-triggered response,ETR)为探究军团菌与宿主互作提供新思路。该文就军团菌的致病机制、对宿主免疫的应对策略以及宿主的免疫应答等方面进行讨论,旨在探索由军团菌引起的肺部感染的相关免疫机制,利于开发出最优的细菌性肺炎治疗方案。     

一个细菌的致命之旅——嗜肺军团菌分泌系统及效应蛋白的研究进展

嗜肺军团菌是引起军团菌肺炎以及庞蒂亚克热的革兰氏阴性胞内病原细菌,嗜肺军团菌侵染宿主的主要特点是可以通过其IVB型毒力分泌系统,向宿主细胞内分泌超过150种的底物效应蛋白。通过这些效应蛋白的作用,嗜肺军团菌能够调整宿主细胞的胞内运输途径,改变内外环境来伪装自己的吞噬泡,干扰宿主的细胞周期,抑制宿主细胞的凋亡,从而有效逃避宿主细胞的防御功能,创造出理想的胞内增殖环境。最后,效应蛋白还可以帮助军团菌从宿主细胞中逃逸。目前,嗜肺军团菌已经成为"病原菌-宿主相互作用"的重要研究模型,其毒力分泌系统及其底物效应蛋白的功能也成为细胞微生物学的研究热点。对嗜肺军团菌分泌系统及效应蛋白的研究不仅能够帮助阐明病原细菌的致病机理,还有助于推动对宿主免疫机制的更深层次的研究。文章主要针对嗜肺军团菌的毒力分泌系统,尤其是IVB型分泌系统的结构和功能,以及底物效应蛋白的研究进展进行了综述,向读者展示出一个小小的细菌所拥有的那令人惊叹的、如此狡猾的生存策略和它精致的杀伤武器。     

嗜肺军团菌效应蛋白质介导的新型泛素化过程

泛素化是真核细胞特有的蛋白质翻译后修饰方式,调节真核细胞内多种重要生理过程,例如蛋白质稳态、细胞周期、免疫反应、DNA修复以及囊泡转运等。鉴于泛素化对于生命活动的重要性,病原菌在与宿主细胞的长期进化过程中衍生出一系列针对宿主泛素化过程的效应蛋白质,调控宿主体内泛素化过程,从而构建有利于病原菌自身生长繁殖的内环境。嗜肺军团菌是一种革兰氏阴性菌,是军团菌肺炎的致病菌,能够引起发热和肺部感染,重型病死率高达15%~30%。Dot/Icm Ⅳ型分泌系统是嗜肺军团菌侵染过程中最主要的毒力系统。在侵染宿主细胞的过程中,嗜肺军团菌利用该分泌系统,分泌超过330种效应蛋白质,协助细菌在宿主胞内生存、增殖和逃逸。多种嗜肺军团菌效应蛋白质通过直接或者间接的方式对宿主泛素化过程进行调控。近年的研究发现,多种效应蛋白质可以介导不同于真核生物经典泛素化的新型泛素化过程。本文介绍了嗜肺军团菌效应蛋白质介导的新型泛素化过程的最新研究进展,为理解泛素化过程在嗜肺军团菌致病过程中的重要作用提供参考依据。     

嗜肺军团菌调控宿主囊泡转运的效应因子及其分子机制

嗜肺军团菌通过其特有的Dot/Icm type-IVB分泌系统向宿主胞内分泌多种效应因子,有效俘获了宿主胞内参与囊泡转运的重要蛋白,从而"绑架"了宿主细胞的囊泡运输过程,达到逃避宿主清除机制并大量增殖的目的。这些效应因子包括Sid M、Lid A、Lep B、Ank X、Lem3、Sid D、Ral F、Vip D等,通过对这些效应因子的鉴定、功能试验和结构生物学研究,逐渐揭示了它们较为完整深入的分子作用机制。本文综述了目前已知的参与调控宿主囊泡转运过程的重要效应因子及其空间结构和分子机制,有助于综合了解这种复杂的病原微生物与宿主相互作用的过程。     

嗜肺军团菌调节宿主泛素化途径的效应因子及其分子机制研究进展

嗜肺军团菌是一种胞内寄生菌,其通过特有的Dot/Icm Type-IVB分泌系统向胞浆内分泌大量效应因子,其中已知参与宿主泛素化调控的效应因子有十多种。这些效应因子通过对宿主泛素化途径进行调控来达到逃避宿主免疫系统"监视"并大量增殖的目的。参与调控宿主泛素化途径的效应因子包括AnkB、SidC、LubX、SidH、LegU1、GobX、RavD、DupA、DupB、SidJ、Ceg23、MvcA、MavC及SidE家族蛋白等。随着对嗜肺军团菌效应因子功能及结构研究的深入,它们的作用机制逐渐被揭示。本文对其中几种重要嗜肺军团菌效应因子的生物学结构和分子机制进行系统总结,有利于综合了解嗜肺军团菌参与调控宿主泛素化系统的复杂过程。     

乙酰化修饰在嗜肺军团菌致病过程中的作用

乙酰化修饰是由乙酰基转移酶、去乙酰化酶介导的可逆的蛋白质翻译后修饰。其中,乙酰基转移酶将乙酰辅酶A的乙酰基团转移至底物蛋白的氨基酸残基,而乙酰基团的去除由去乙酰化酶完成。乙酰化修饰参与许多基本生物学过程的调节作用,越来越多的研究表明,蛋白质乙酰化修饰在病原菌的致病过程中具有重要作用。病原菌,如引起非典型性肺炎的嗜肺军团菌,可以通过分泌具有乙酰基转移酶活性的效应蛋白靶向宿主细胞信号通路的关键蛋白质因子,干扰宿主细胞信号通路及免疫反应。本文主要从嗜肺军团菌的致病机制、乙酰化修饰及乙酰化修饰在病原体致病过程中的调控作用进行综述,突出已知的乙酰化毒力蛋白的例子,并讨论它们如何影响与宿主的相互作用,为理解乙酰化修饰在嗜肺军团菌致病过程中的作用机制提供参考。     

磷脂酰肌醇信号在GLUT4囊泡转运中的调控作用

葡萄糖转运蛋白4(glucose transporter 4,GLUT4)参与胰岛素敏感的脂肪细胞和肌肉细胞中的葡萄糖转运,对机体葡萄糖代谢至关重要。磷脂酰肌醇作为各种蛋白质的定位信号,参与调控细胞生长和新陈代谢,在胰岛素信号转导过程中起着关键作用。在过去的几十年里,关于磷脂酰肌醇信号调控GLUT4囊泡转运方面已有了很大的进展。该文总结了磷脂酰肌醇在GLUT4囊泡转运中的调控作用。     

嗜肺军团菌毒力基因、致病性及实验诊断研究进展

嗜肺军团菌是引起军团菌肺炎的重要病原体,关于军团菌感染的致病机制目前尚不十分清楚。近来研究发现,军团菌的致病性与其毒力因子和铁代谢等相关,本文对嗜肺军团菌的毒力因子及其作用。致病机制和实验室诊断方法研究进展作一综述。     

脂蛋白脂酶调控因子研究进展

脂蛋白脂酶(Lipoprotein lipase, LPL)是脂质代谢的关键酶, 其正常调控对于机体向组织提供脂质营养至关重要。作为LPL重要的调控因子, 糖基化磷脂酰肌醇锚定高密度脂蛋白结合蛋白1(Glycosylphosphatidylinositol- anchored high density lipoprotein-binding protein 1, GPIHBP1)能与LPL结合起脂解平台的作用, 并作为载体参与LPL向毛细血管内皮细胞的转运。另外, 近年来也鉴定出其他几个LPL活性调控因子, 包括microRNAs、A型重复排序蛋白相关受体(Sortilin-related receptor with A-type repeats, SorLA)和载脂蛋白(Apolipoproteins, apo)。这些LPL调控因子的成功鉴定, 有助于人们深入认识机体脂解代谢和乳糜微粒血症发生的内在机制。文章重点综述了LPL的调控因子GPIHBP1的研究进展, 同时也对其他几个调控因子的研究进展进行了讨论。     

Vermicomposting in the management of pig-waste in Hong Kong

The treatment and disposal of pig-waste in Hong Kong has received much attention in recent years but, following any of the presently used treatment processes, solids remain to be further stabilized. Vermicomposting is a waste stabilization technique which converts waste into potentially recyclable materials such as worm protein and worm casts. The earthworm, Pheretima asiatica, can stabilize most of the solids arising from the treatment of pig-waste, including raw pig manure, suggesting that vermicomposting has a high potential as a unit process in the management of pig-waste in Hong Kong.S.H. Wong is with the Environmental Protection Department, Hong Kong; and D.A. Griffiths is with the Department of Botany, University of Hong Kong, Hong Kong.     

Removal of wastewater pathogen indicators in a constructed wetland in Leon, Spain

This paper studies the seasonal presence and removal of the pathogenous micro-organisms Escherichia coli, total coliforms (TC), Clostridium perfringens (Cp), faecal streptococci (FS), Giardia cysts, Cryptosporidium oocysts and helminth eggs, in a constructed wetland treatment system. The removal efficiency of this system with respect to the indicator micro-organisms achieved maximum values in spring and autumn at 99.9% for E. coli and TC, respectively, in winter at 97.0% for FS, in summer at 100% for Clostridium and throughout the year, also at 100%, in the case of Giardia cysts, Cryptosporidium oocysts and helminth eggs. In general, very low protozoan and helminth egg counts were found, and the system demonstrated efficient reduction of the wastewater indicator pathogens.     

Phylogenetic relationships in theCampanulales based onrbcL sequences

Phylogenetic relationships within the angiosperm orderCampanulales were investigated by comparative sequencing of the chloroplast generbcL. CompleterbcL sequences were obtained for ten species in six families within the order. These data were analyzed along with previously publishedrbcL sequences from other taxa (for a total of 117 species) within the subclassAsteridae and outgroups, producing 32 equally parsimonious trees. A subset consisting of 44 of these taxa was then chosen and more rigorous analyses performed, resulting in four equally parsimonious trees. Results indicate that two major clades roughly corresponding to traditionally circumscribedAsterales andCampanulales exist as sister taxa. In particular, therbcL trees indicate thatSphenoclea is not a member ofCampanulales orAsterales, thatPentaphragma is more closely allied toAsterales thanCampanulales, that theCyphiaceae are not monophyletic, thatCampanulaceae andLobeliaceae are not sister taxa, and thatStylidiaceae are correctly placed withinCampanulales.     

Inbreeding in a french peasant population

Genealogical pedigrees were collected from 976 farming couples who lived in a canton of central France in the XIXth and XXth century. Several methods (genealogical, isonymic and probability of origin of genes) were used to appraise the evolution of the biological structure of this population, which has gone through two phases. The first phase from 1800 to the World War I, shows gene flows between the farming population of the canton and those of neighbouring rural districts which are linked to an increase in consanguineous marriages. The second phase, from 1920 onwards, shows important gene flow from distant areas. This trend implies a decrease in consanguineous marriages.     

Lactic acid bacteria in fermented foods in Thailand

Traditional fermented foods (fish, meat and vegetable products), produced by many different processes, are eaten in many parts of Thailand. Lactic acid bacteria are responsible for the souring and ripening of these foods. Homofermentative strains of Lactobacillus pentosus, L. plantarum and Pediococcus pentosaceus are dominant in foods with low salt concentrations whereas P. halophilus strains are present in foods containing high salt. Strains of Lactobacillus sake, other Lactobacillus spp., P. acidilactici and P. urinaeequi are frequently found. Heterofermentative strains of L. brevis, L. confusus, L. fermentum, L. vaccinostercus, other Lactobacillus spp., and of Leuconostoc spp. are distributed as minor bacteria and strains of Staphylococcus, Enterococcus and Halobacterium are occasionally isolated.S. Tanasupawat is with the Department of Microbiology, Faculty of Pharmaceutical Sciences. Chulalongkorn University, Bangkok 10330, Thailand; K. Komagata is with the Department of Agricultural Chemistry, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya-ku, Tokyo 156, Japan.     

Isolation of spore-forming bacilli from mosquitoes in natural breeding habitats in Iraq

New isolates of spore-forming bacilli from larvae and pupae of 3 species of mosquitoes are recorded in central Iraq.Bacillus sphaericus Meyer and Neide was isolated fromCulex pipiens (L.) larva.Bacillus carotarum Koch andBacillus cereus Frankland & Frankland were isolated fromTheobaldia longiareolata (Macquart) pupae.Bacillus laterosporus Laubach andBacillus thuringiensis (H 18) were isolated fromAedes caspius (Pallas) larvae. In addition, unidentifiedBacillus spp. were isolated fromCx. pipiens, T. longiareolata andAe. caspius larvae. Examination of soil samples collected from mosquito natural breeding habitats revealed isolates ofB. cereus, Bacillus thuringiensis H4a 4b; H 12 and H 16 and an unidentifiedBacillus sp.

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Résumé Des souches bactériennes sporogènes sont isolées de moustiques qui se trouvent dans la région centrale de l'Irak. Les résultats obtenus sont les suivants:Bacillus sphaericus Meyer & Neide [Culex pipiens (L.), larve],Bacillus carotarum Koch etBacillus cereus Frankland & Frankland [Theobaldia longiareolata (Macquart), nymphe],Bacillus laterosporus Laubach etBacillus thuringiensis (H 18) [Aedes caspius (Pallas), larvel]. L'examen des larves deCulex pipiens. T. longiareolata etAe. caspius, ainsi que l'analyse des échantillons du sol prélevés dans la région montrent la présence deBacillus cereus, Bacillus thuringiensis H4a 4b; H12 plus H16 et d'autresBacillus non identifiés.

     

New species and new combinations in Peruvian Orchidaceae

seventeen new species and combinations are proposed in the generaChondrorhyncha, Cischweinfia, Cochlioda, Eloyella, Encyclia, Kefersteinia, Koellensteinia, Macroclinium, Rodriguezia, Solenidiopsis, andStenia. All new species are illustrated. A key is provided for 2-flowered species ofMacroclinium, PeruvianSigmatostalix, and PeruvianStenia. Solenidium (Solenidiopsis) peruvianum Schltr. is lectotypified.     

Comparison between the allergenic airborne pollen in Trieste and at Lozzo di Cadore (Italy) in 1989

Summary A comparative study was carried out between aeroallergenic pollen spectra in Trieste and at Lozzo di Cadore. The two localities were found to be different on a five-day running mean basis as to the 8 pollen taxa monitored by the National Aerobiological Monitoring Network managed by the Italian Association of Aerobiology (AIA). In the zone of Lozzo the pollination curve of the spring flowering taxa showed a lag of about one month due to the colder climate. Lozzo di Cadore showed a poor airborne pollen content,Corylus and Graminaceae being prevailing. Trieste has a higher airborne pollen diversity and longer pollination times because of its higher floristic and vegetational complexity. In Trieste the allergenic pollen spectrum showed great quantities ofOstrya, Quercus, Oleaceae, Graminaceae and of ruderal taxa, widespread over the area, due to man's influence.     

Incubation temperature critical to successful stimulation of in vitro zygotic embryo growth in four Australian native Cyperaceae species

Many species of Western Australian Cyperaceae (sedges) are vital components of the indigenous flora but commonly display low seed set, poor seed quality and intractable seed dormancy. We report the effects of incubation temperature and in vitro growth media on whole seed germination compared with extracted zygotic embryo growth in Tetraria capillaris, T. octandra, Lepidosperma drummondii and L. tenue. No germination was observed from intact whole seeds of all test species regardless of the treatment evaluated. In contrast, excised zygotic embryos of all study species exhibited significant increases in growth when cultured at 15°C compared to embryos incubated at 25°C; however, optimal media for embryo growth were genera specific. Extracted embryos of T. capillaris and T. octandra exhibited maximum percentage growth (30 and 40%, respectively) at 15°C on ½ MS medium with no plant growth regulators required. In the case of L. drummondii and L. tenue 1 μM thidiazuron was a necessary addition to the ½ MS medium resulting in 40 and 77% growth of embryos (at 15°C), respectively. Incubation of extracted embryos at 25°C (regardless of medium treatment) resulted in <10% embryo growth for T. octandra and L. tenue, while the remaining two species (L. drummondii, T. capillaris) showed no embryo growth at 25°C on any medium treatment.