The structure of the carbohydrate backbone of the core–lipid A region of the lipopolysaccharide from Proteus penneri strain 40: new Proteus strains containing open-chain acetal-linked N-acetylgalactosamine in the core part of the LPS

Analysis of the core part of the LPS from several strains of Proteus revealed that P. penneri strains 2, 11, 19, 107, and P. vulgaris serotypes O4 and O8 have the same structure with a new type of linkage between monosaccharides–an open-chain acetal — that was previously determined for P. vulgaris OX2 and P. penneri 17. The LPS from P. penneri strain 40 contains the same structure substituted with one additional monosaccharide:

Full-size image (5K)

where (1S)-GalaNAc¹ is a residue of N-acetyl- -galactosamine in the open-chain form. It is connected as a cyclic acetal to positions 4 and 6 of the galactosamine residue having a free amino group. All other sugars are in the pyranose form.     

Characterization and biological activity of the main flavonoids from Swiss Chard (Beta vulgaris subspecies cycla)

The molecular components of a phenolic fraction (P2), obtained from liquid chromatography of a Swiss Chard (Beta vulgaris subsp. cycla) extract, were identified using HPLC-ESI-MS/MS. The primary P2 components were: vitexin-2'O-rhamnoside, its demethylated form 2'-xylosylvitexin, isorhamnetin 3-gentiobioside, and rutin. P2 "in toto" and the single components were characterized for antioxidant capacity, antimitotic activity on MCF-7 human breast cancer cells and for toxicity to human lymphocytes and macrophages. P2 inhibited MCF-7 cell proliferation (IC(50) value = 9 microg/ml) without inducing apoptosis, showed no toxicity to human lymphocytes and slight toxicity to macrophages. Vitexin-2'O-rhamnoside strongly inhibited DNA synthesis in MCF-7 cells, whereas 2'-xylosylvitexin and isorhamnetin 3-gentiobioside were activators; combinations of activators and inhibitors maintained the over-all inhibitory effect.     

奇异变形杆菌毒力因子的研究进展

奇异变形杆菌是革兰阴性细菌,在自然界中广泛存在,具有特殊的群集运动能力,与临床关系密切,可在膀胱和肾脏中形成结石,在尿道留置管外表面、内腔中形成结晶生物膜,是引起复杂尿路感染的主要病原体,主要的毒力因子包括菌毛、黏附素、尿素酶、溶血素、金属摄取和免疫逃避等。综述了近年来有关奇异变形杆菌毒力因子的研究,为相关研究提供参考。     

鸡源奇异变形杆菌分离鉴定及生物学特性

【背景】奇异变形杆菌(Proteusmirabilis,PM)是人畜共患病原菌,在自然界分布广泛。近年来,随着畜禽奇异变形杆菌病发病率上升和耐药性增强,亟需开展对该菌的防控研究。【目的】分离鉴定鸡源奇异变形杆菌,鉴定其耐药性、致病性、生物被膜形成能力等生物学特性。【方法】采用聚合酶链式反应(Polymerase Chain Reaction,PCR)方法鉴定了从2019-2020年病鸡中分离的52株临床奇异变形杆菌。分别采用药敏试验、PCR、结晶紫染色法对临床菌株的耐药性、毒力基因及生物膜的形成进行研究。【结果】选择14株代表性菌株进行16SrRNA基因测序,结果表明所测分离菌株均为奇异变形杆菌。所有分离菌株均对克林霉素、阿奇霉素、红霉素、四环素和利福平耐药,对氯霉素和头孢曲松外的抗生素耐药性均高于50%。对分离的奇异变形杆菌的13个毒力基因检测表明,所有菌株均能检测到hpmA、hpmB、rpoA、mrpA、fliL、zapA、ureC、atfC、atfA、pmfA,而ucaA和rsbA检出率分别为19.23%(10/52)和48.08%(25/52),hlyA未检出。对分离株生物被膜形成能力检测结果表明,所有菌株均能形成生物被膜,19.23%(10/52)的分离菌株形成生物被膜能力强,而且25℃条件下成膜能力比37℃更强。【结论】鸡源奇异变形杆菌携带多种毒力基因,具有较强生物被膜形成能力,耐药模式多样且日趋严重,应进一步加强对奇异变形杆菌在动物致病性和耐药性方面的监控,以降低其感染风险。     

Isolation and characterization of brassinosteroids from algal cultures of Chlorella vulgaris Beijerinck (Trebouxiophyceae)

The brassinosteroids (BRs) occur ubiquitously in the plant kingdom. The occurrence of BRs has been demonstrated in almost every part of higher plants, such as pollen, flower buds, fruits, seeds, vascular cambium, leaves, shoots and roots. In this study, BRs were isolated and identified in the culture of wild-type Chlorella vulgaris. Seven BRs, including teasterone, typhasterol, 6-deoxoteasterone, 6-deoxotyphasterol, 6-deoxocastasterone, castasterone and brassinolide, were identified by GC–MS. All compounds belong to the BR biosynthetic pathway. The results suggest that early and late C6 oxidation pathways are operating in C. vulgaris. This study represents the first isolation of BRs from C. vulgaris cultures.     

Heterologous Expression and Characterization of L-Amino Acid Deaminase from Proteus mirabilis in Escherichia coli

We expressed an L-amino acid deaminase (Pma) from Proteus mirabilis (P. mirabilis) in Escherichia coli and characterized the kinetics of phenylpyruvic acid production. P. mirabilis Pma was well expressed in E. coli in an active state and was found to be associated with membranes. The association of Pma with cellular membranes is likely to be necessary for its enzymatic activity.     

有机栽培龙脑百里香精油对白色念珠菌体外抑菌活性的研究

【背景】白色念珠菌(Candidaalbicans)属于条件致病性真菌,可引起严重的黏膜真菌感染及全身系统性真菌感染,是导致患者高发病率和高死亡率的主要菌群之一。【目的】探究百里香精油对白色念珠菌的抑菌活性及抑制机理。【方法】测定5种百里香精油对白色念珠菌的抑菌圈直径,分析具有高抑菌活性的精油成分。在此基础上,通过扫描电子显微镜(scanning electron microscope, SEM)观察精油对白色念珠菌菌体细胞形态的影响。测定碱性磷酸酶(alkaline phosphatase, AKP)含量、胞外溶液电导率并进行碘化丙啶(propidium iodide, PI)染色分析,探究精油对白色念珠菌生物膜的形成与黏附及磷脂酶活性的影响,并通过实时荧光定量PCR法分析与白色念珠菌生物膜形成相关基因(凝集素样序列基因ALS4,从酵母型向菌丝型细胞的形态转变基因HWP1、磷脂酶基因PLB1)的表达水平,探究该精油对白色念珠菌的抑菌机制。【结果】筛选出了对白色念珠菌高度敏感的有机栽培龙脑百里香精油(Thymus vulgaris CT borneol essential oil, T...     

Structure of the neutral O-polysaccharide and biological activities of the lipopolysaccharide of Proteus mirabilis O20

Mild acid degradation of the lipopolysaccharide (LPS) of Proteus mirabilis O20 resulted in depolymerisation of the O-polysaccharide to give a repeating-unit pentasaccharide. A polysaccharide was obtained by O-deacylation of the LPS followed by nitrous acid deamination. The derived pentasaccharide and polysaccharide were studied by NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, ROESY, 1H,13C HMQC and HMQC-TOSCY experiments, along with chemical methods, and the following structure of the repeating unit of the O-polysaccharide was established: [Carbohydrate structure: see text]. As opposite to most other P. mirabilis O-polysaccharides studied, that of P. mirabilis O20 is neutral. A week serological cross-reactivity was observed between anti-P. mirabilis O20 serum and LPS of a number of Proteus serogroups with known O-polysaccharide structure. The ability of LPS of P. mirabilis O20 to activate the serine protease cascade was tested in Limulus amoebocyte lysate and in human blood plasma and compared with that of P. mirabilis O14a,14c having an acidic O-polysaccharide. The LPS of P. mirabilis O20 was found to be less active in both assays than the LPS of P. mirabilis O14a,14c and, therefore, the structurally variable O-polysaccharide may influenced the biological activity of the conserved lipid A moiety of the LPS.     

Swarming Characteristics of Proteus mirabilis Under Anaerobic and Aerobic Conditions

Nutrients have a pronounced effect on the growth and swarming behaviour of Proteus mirabilis 7002. Iron, zinc, amino acids, and dioxygen are important for rapid growth and normal swarming. Anaerobically grown cultures of P. mirabilis 7002 were unable to swarm on anaerobically maintained rich nutrient agar. Upon exposure to aerobic conditions, P. mirabilis 7002 resumed swarming behaviour. Scanning electron microscopy was used to demonstrate the presence of community organization and mature rafts during normal swarming. These results support the importance of dioxygen and redox status in cell differentiation.     

Monitored releases of Rhinoncomimus latipes (Coleoptera: Curculionidae), a biological control agent of mile-a-minute weed (Persicaria perfoliata), 2004–2008

Mile-a-minute weed, Persicaria perfoliata (L.) H. Gross, is an invasive annual vine of Asian origin that has developed extensive monocultures, especially in disturbed open areas in the Mid-Atlantic region of the United States. A host-specific Asian weevil, Rhinoncomimus latipes Korotyaev, was approved for release in North America in 2004, and weevils have been reared at the New Jersey Department of Agriculture Beneficial Insect Laboratory since then. By the end of 2007 more than 53,000 weevils had been reared and released, mostly in New Jersey, but also in Delaware, Maryland, Pennsylvania, and West Virginia. The beetles established at 63 out of 65 sites (96.9%) where they were released between 2004 and 2007, with successful releases consisting of as few as 200 weevils. Weevils were recorded at 30 additional non-release sites in New Jersey, where they had dispersed at an average rate of 4.3 km/year. Standardized monitoring of fixed quadrats was conducted in paired release and control sites at eight locations. Significant differences in mile-a-minute weed populations in the presence and absence of weevils were found at three locations, with reduction in spring densities to 25% or less of what they had been at the start within 2–3 years at release sites, while weed densities at control sites were largely unchanged. Mile-a-minute weed populations at a fourth site were similarly reduced at the release site, but without control data for comparison due to rapid colonization of the paired control site. At the other four locations, all on islands, mile-a-minute weed populations were reduced at both release and control sites without large weevil populations developing, apparently due to environmental conditions such as late frost and extreme drought.     

长春地区鸡源奇异变形杆菌的分离鉴定及毒力分析

【背景】奇异变形杆菌(Proteus mirabilis)是一种机会致病菌,广泛存在于周围环境中,常导致动物和人类感染。【目的】探究吉林省长春地区某养鸡场病鸡死亡原因,为疾病防控提供参考。【方法】从病死青年鸡脏器分离到病原菌TSA-1,通过革兰氏染色、生化试验和16S rRNA基因序列鉴定,并进行药敏试验、毒力基因检测、细胞毒性和黏附性试验、大蜡螟攻毒试验研究。【结果】分离株TSA-1在镜下呈短杆状、球状的革兰氏阴性菌,生化特性与奇异变形杆菌相一致,16S rRNA基因序列比对显示与奇异变形杆菌相似度为100%;药敏试验结果显示分离株TSA-1对氨苄西林、四环素、卡那霉素、头孢唑林等14种药物耐药,对环丙沙星、恩诺沙星等7种药物敏感;分离株还具有较强的生物被膜形成能力,携带ireA、ucaA、pmfA、atfA、ptA、zapA、hpmA和flhC这8种毒力基因,并对巨噬细胞RAW264.7表现出细胞毒性,而且对Caco-2细胞具有很强的黏附作用;同时对大蜡螟幼虫表现出比禽致病性大肠杆菌(avian pathogenic Escherichia coliO78,APEC-O78)更强的致死作用。【结论】从病死鸡脏器分离得到的奇异变形杆菌TSA-1具有多重耐药性,并携带多种毒力基因,对细胞和大蜡螟幼虫表现出强毒性作用,说明该菌是引起病鸡死亡的主要致病菌之一,应引起重视。     

Growth stimulation in bean (Phaseolus vulgaris L.) by Trichoderma

Trichoderma species are commonly used as biological control agents against phytopathogenic fungi and some strains are able to produce metabolites that enhance plant growth. In the current study we evaluated the production of potential growth-promoting metabolites, rhizosphere competence and endophytism for 101 isolates of Trichoderma from Colombia, and assessed the relationship of these factors to the enhancement of early stages of growth on bean seedlings. Twenty percent of these Trichoderma strains were able to produce soluble forms of phosphate from phosphoric rock. Only 8% of the assessed strains showed consistent ability to produce siderophores to convert ferric iron to soluble forms by chelation. Sixty percent of isolates produced indole-3-acetic acid (IAA) or auxin analogues. The production of any of these metabolites was a characteristic of specific strains, as the ability to produce these metabolites varied greatly within species. Moreover, the production of these substances did not correlate with enhanced growth on bean seedlings, measured as the combined increase in length of roots and aerial parts in the V3 stage of growth. Seven Trichoderma isolates significantly improved the growth of bean seedlings. However, metabolite production varied widely in these seven strains, and some isolates did not produce any of the assessed growth-promoting metabolites. Results indicated that growth was enhanced in the presence of rhizosphere competent and endophytic strains of Trichoderma, and these characteristics were strain-specific and not characteristic for species.     

夏枯草PvGGPPS基因的克隆和诱导表达分析

为探究夏枯草中GGPPS基因的生物学特性及功能,该文在夏枯草转录组测序的基础上设计特异性引物,采用逆转录PCR技术获得夏枯草中GGPPS基因的全长核苷酸序列,并进行生物信息学分析;采用qPCR法分析PvGGPPS基因在不同外源性物质诱导下在夏枯草果穗中的表达量以及该基因在夏枯草不同组织中的表达量。结果表明:PvGGPPS基因开放阅读框1 092 bp,编码363个氨基酸,理论分子量为38 815.68 D,等电点为5.69。PvGGPPS蛋白具有异戊烯基焦磷酸合酶家族的特征结构域。系统进化树表明PvGGPPS蛋白与丹参、毛喉鞘蕊花GGPPS蛋白具有较高的亲缘关系。qPCR分析表明,PvGGPPS基因在叶中表达量高于果穗及茎。对果穗施加7种外源性物质处理24 h后,GA3处理组该基因表达量升高。PvGGPPS基因在夏枯草不同组织中表达量差异较大,且受外源物质诱导表达。该研究结果为进一步研究PvGGPPS基因对夏枯草萜类成分合成途径中的功能及表达调控奠定基础。     

Proline metabolism in response to highest nitrogen dosages in green bean plants (Phaseolus vulgaris L. cv. Strike)

The objective of the present work was to determine what impact extremely high nitrogen dosages would have on proline metabolism in order to use this amino acid as a bioindicator of N status of green bean plants (Phaseolus vulgaris L. cv. Strike). In this effort, we identified the most favourable pathway of proline synthesis under our experimental conditions. The N was applied to the nutrient solution in the form of NH₄NO₃ at 5.4 mmol/L (N1, optimal level), 11.6 mmol/L (N2), 17.4 mmol/L (N3), and 23.2 mmol/L (N4). Our results indicate that the application of high N dosages inPhaseolus is characterized by the accumulation of NO₃⁻, NH₄⁺ and proline in root and foliar organs. However, although the enzymes in charge of proline biosynthesis, ornithine-δ-aminotransferase (OAT, EC 2.6.1.13) and Δ¹-pyrroline-5-carboxylate synthetase (P5CS, EC 2.7.2.11/1.2.2.41) vary in behaviour depending on the N status, in our experiment, this amino acid appears to be synthesized mainly by the enzyme ornithine-δ-aminotransferase. This suggests predominance of the ornithine pathway over the glutamine pathway. Finally, under our experimental conditions, proline can be defined as a good indicator of N excess of green bean plants.     

Biochemical characterization of a novel lysine racemase from Proteus mirabilis BCRC10725

A lysine racemase gene (lyr) that consisted of an open reading frame of 1224-bp and encoded a protein with a calculated molecular mass of 45 kDa was cloned from the Proteus mirabilis BCRC10725 and expressed in Escherichia coli BL21(DE3). The purified His₆-tagged Lyr was most active towards lysine, exhibiting a specific activity of 2828 ± 97 U/mg. This enzyme also racemized arginine with a specific activity of 568 ± 28 U/mg but not other amino acids. The optimal conditions for Lyr activity to l-lysine were pH 8.0–9.0 and 50 °C. The racemization activity of Lyr was completely inhibited by 5 mM hydroxylamine and was partially restored by the addition of pyridoxal 5′-phosphate. The S394 residue of Lyr was subjected to site-directed mutagenesis. The arginine racemization activities of the S394Y, S394N, S394C and S394T variant proteins were increased by 1.5–1.8 fold compared to the wild-type Lyr, indicating that the S394 residue played a crucial role in determining the preference of Lyr to lysine and arginine.     

Oxidative stress reactions induced in beans (Phaseolus vulgaris) following exposure to uranium

The present study aimed to analyze the biological effects induced by bioaccumulation of uranium in Phaseolus vulgaris. Ten-day-old seedlings were exposed to 0, 0.1, 1, 10, 100 and 1000 microM U in diluted Hoagland solution. Following 1, 2, 4 and 7 days' exposure, plants were monitored for uranium uptake, biometric parameters, capacities of enzymes involved in the anti-oxidative defense mechanisms (GPOD, SPOD, GLUR, SOD, ICDH, G-6P-DH), glutathione (GSH) pool and DNA integrity. Uranium contents were up to 900-fold higher in roots (31-14,916 mg kg(-1) FW following 7 days' exposure to 0.1 and 1000 microM U, respectively) as compared to primary leaves (1-16 mg kg(-1) FW following 7 days' exposure to 0.1 and 1000 microM U, respectively). Uranium exposure did not significantly affect plant growth compared to the control. For all enzymes studied, except SOD, enzyme capacities in roots were slightly stimulated with increasing contaminant concentrations (though not significantly). For roots exposed to 1000 microM U, enzyme capacities were significantly reduced. Enzyme capacities in leaves were not affected by uranium treatment. Total and reduced GSH levels were higher in primary leaves of uranium (相似文献   

基于多重计算设计策略提高奇异变形杆菌脂肪酶的热稳定性

来自奇异变形杆菌的脂肪酶(Proteus mirabilis lipase,PML)具有较好的有机溶剂耐受性,在生产生物柴油等领域有广泛的应用潜力.然而,其热稳定性仍有待提高以更好地适应工业生产.近年来,基于计算机辅助的多种计算设计策略的发展为酶的热稳定性改造提供了更多的思路.文中首先选择了 3种基于互补算法的软件AB...     

In vitro evaluation of combination of Trichoderma harzianum and chitosan for the control of sapstain fungi

In vitro assays were undertaken to evaluate the control of two sapstain fungi, Leptographium procerum and Sphaeropsis sapinea by a combination of chitosan or chitosan oligomer and an albino strain of Trichoderma harzianum. Spore germination and hyphal growth of the test fungi were assessed on media amended with chitosan or chitosan oligomer with and without T. harzianum using either simultaneous inoculation with test fungus or inoculation 1, 2, or 3 days after pre-infection with test fungus.There was no mycelial growth of the test fungi regardless of chitosan concentrations used when either L. procerum or S. sapinea was simultaneously inoculated with T. harzianum. However, the dose–response of chitosan or chitosan oligomer on the test fungi was apparent when T. harzianum was not simultaneously inoculated with test fungus but introduced later. There was a greater growth reduction at higher concentrations (0.075–0.1% v/v) of chitosan, and overall chitosan oligomer was more effective than chitosan aqueous solution.Chitosan alone was able to restrict or delay the germination of spores but the combination of chitosan and T. harzianum inhibited spore germination and hence colony formation of test fungi regardless of time delay.