Some factors involved in the titration and neutralisation of vaccinia virus

Conclusions If certain virus-serum mixtures containing partinlly neutralised vaccinia are inoculated intradermally in non-resistant rabbits and on the chorio-allantoic membrane of duck embryos, the rabbits' skin may be protected from infection, whereas the membrane is not. With regard to this passive immunisation effect and the great variability of resistance in rabbits, the rabbits' skin is inferior to the chorio-allantoic membrane for neutralisation tests. Purification by tryptic digestion and differential centrifugation renders the virus suspension more suitable for titration tests. Virus titration with purified vaccinia on the chorio-allantoic membrane of selected duck eggs produces consistant results, if confluent reactions three days after the inoculation are read. The virus titres obtained in this way with a sample of purified vaccinia did not differ in ten duplicate titrations. Vaccinia neutralising potency can be measured according to the maximal quantity of virus neutralised by undiluted serum rather than to the minimal quantity of serum with neutralisation effect.     

基于TM影像的白云岩与石灰岩上喀斯特植被时空变化差异研究

喀斯特土壤主要由白云岩和石灰岩风化而来,植被生长及其分布究竟怎样响应这一特殊地质背景?以人为干扰影响较小的喀斯特自然保护区为研究对象,采用监督分类法对1990年和2011年两期TM影像进行植被分类,并利用景观格局分析方法研究两种岩性上植被变化差异。结果表明,1990年和2011年研究区内两种母岩上均以乔木林和乔灌为主,草灌和草丛分布少,白云岩上乔木林的面积比例大于石灰岩上的比例,而草灌和草丛小于石灰岩上的比例;近20年来白云岩与石灰岩上草丛、草灌、灌丛和乔灌均以正向演替为主,但白云岩上正向演替比例大于石灰岩上的比例;两种岩性上植被斑块连接性均增强、破碎程度均降低,白云岩上植被斑块的破碎化程度和多样性指数较石灰岩上低,内部连接性强。由此可见,喀斯特白云岩较石灰岩有利于草丛、草灌的自然恢复,岩性引起的水土资源配置和养分地球化学循环过程差异制约着喀斯特地区植被的时空格局。     

The heparin-accelerated neutralisation of bovine α and β thrombins by antithrombin III

The heparin-accelerated neutralisation of bovine α and β thrombins has been examined using a peptide substrate H-d-phenylalanyl-pipecolyl-arginine-paranitroanilide-HCl to measure thrombin amidase activity. α and β thrombins were both neutralised by antithrombin III and this neutralisation was further accelerated by the presence of small amounts of heparin. Low and high molecular weight heparin and heparins fractionated by their affinity for antithrombin III were all able to accelerate the neutralisation of α and β thrombin. This work is therefore unabel to confirm reports that α and β thrombins have different heparin sensitives.     

Overexpression of plastidic protoporphyrinogen IX oxidase leads to resistance to the diphenyl-ether herbicide acifluorfen

The use of herbicides to control undesirable vegetation has become a universal practice. For the broad application of herbicides the risk of damage to crop plants has to be limited. We introduced a gene into the genome of tobacco (Nicotiana tabacum) plants encoding the plastid-located protoporphyrinogen oxidase of Arabidopsis, the last enzyme of the common tetrapyrrole biosynthetic pathway, under the control of the cauliflower mosaic virus 35S promoter. The transformants were screened for low protoporphyrin IX accumulation upon treatment with the diphenyl ether-type herbicide acifluorfen. Leaf disc incubation and foliar spraying with acifluorfen indicated the lower susceptibility of the transformants against the herbicide. The resistance to acifluorfen is conferred by overexpression of the plastidic isoform of protoporphyrinogen oxidase. The in vitro activity of this enzyme extracted from plastids of selected transgenic lines was at least five times higher than the control activity. Herbicide treatment that is normally inhibitory to protoporphyrinogen IX oxidase did not significantly impair the catalytic reaction in transgenic plants and, therefore, did not cause photodynamic damage in leaves. Therefore, overproduction of protoporphyrinogen oxidase neutralizes the herbicidal action, prevents the accumulation of the substrate protoporphyrinogen IX, and consequently abolishes the light-dependent phytotoxicity of acifluorfen.     

The weathering ability of higher plants. The case of Ailanthus altissima (Miller) Swingle

The growth of higher plants on monuments causes weathering of the substrata and can be one of the biggest problems for conservators.Deterioration can be: chemical — acidity of the roots; root exudation of organic acids that decompose the calcium bicarbonate, which is the main component of limestone used as building material. Mechanical — through the growth pressure of the roots, either on or near the monuments. This paper aims to point out the importance of studying the floristic and ecological aspect of higher plants growing on buildings, particularly the Tree of Heaven — Ailanthus altissima (Miller) Swingle, an Asiatic plant, naturalised in Europe. This tree can be found growing both in modern and ancient buildings, and its large root system causes severe damage to the structure of the buildings.The results of a biocide treatment (ammoniacal solution) are described.     

Evaluation of the effect of some biocides against organisms isolated from historic monuments

On the surfaces of monuments and buildings, organic and inorganic pollutants accumulate, as well as various microbial communities which contribute to stone decay. In order to control these organisms, we have tested some chemical products with biocide and water-repellent properties. Some of these products were tested in an agar diffusion test and on limestone slabs. Efficacy of the products and the microbial inhibition were studied with scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) techniques. This revised version was published online in June 2006 with corrections to the Cover Date.     

Deterioration of limestone walls in Jerusalem and marble monuments in Rome caused by cyanobacteria and cyanophilous lichens

Hard limestone walls in Jerusalem and marble monuments in Rome were studied. An attempt was made to classify the principal biodeterioration processes in walls facing the prevailing wind and those which were protected from it. In Jerusalem, those that face the prevailing rain-bearing wind become populated by cyanobacteria and cyanophilous lichens. Within c. 100 years white walls are turned to grey or black colour by these organisms. Rain detaches rock particles from the vicinity of the microorganisms at a rate of 1 mm in 200 years. Dark patches on marble monuments in Rome indicate the presence of cyanobacteria. Such biological activity promotes detachment of particles by rain and accelerates weathering leading to pit formation. The estimated rate of pitting is 1 mm per 40 years in the Forum Traianum. To prevent the biodeterioration of limestone and marble monuments the habitats and ecological demands of the various microorganisms must be considered.     

Ability of human sera to neutralise the activity of Vero cytotoxins VT1, VT2 and variant forms of VT2

Abstract Sera, from 17 patients with diarrhoea or haemolytic uraemic syndrome, and six healthy adults, were tested for neutralisation of Vero cytotoxins (VT). For all 17 patients there was evidence of infection with Escherichia coli O157. Sera from two controls but from none of the patients neutralised VT1, although two patients were infected by strains producing VT1 and VT2. Sera from all six controls and 14 patients neutralised VT2 derived from strains 933 and E32511, but not variant forms of VT2 derived from strains E32511, E57, B2F1 and H.1.8. This neutralising activity warrants further investigation, especially as many 0157 VTEC carry both VT2 and VT2 variant genes.     

The use of the Cole/Hurlbert C8 association coefficient in inverse ecological classification

Abstract. Inverse classification is routinely used in vegetation surveys to produce groups of sociologically similar species. However, no classification methods have been proposed specifically for this purpose, nor has any evaluation been made of the suitability of existing methodsforthe purpose. Anewvariant of Cluster Analysis is introduced, i. e. using the Cole/Hurlbert association measure C₈ as coefficient, and named for convenience Cole Cluster Analysis. This method, and four standard ones, were used on saltmarsh vegetational data from New Zealand. Ecophysiological data were obtained from salt-tolerance experiments. These data, and distributional information, were used as independent criteria against which to compare the inverse vegetation classifications. Information Analysis did not prove suitable for inverse analysis in this test. Nor did Cluster Analysis with the Simple Matching Coefficient or with Jaccard's coefficient. Indicator Species Analysis was more suitable, but the new Cole Cluster Analysis seemed the most effective on these data.     

The chemical control of salvinia molesta (Mitchell) and some related toxicological studies

Laboratory trials were performed to screen the potentials of four herbicides — PARAQUAT, DIQUAT, TOK E-25 and DALAPON — for the chemical control of Salvinia molesta. The herbicides were applied as aerial sprays, and their phytotoxic effects were assessed by visual estimation. Paraquat and Diquat have been found to be the more promising.The toxicities of the four herbicides were tested on three aquatic organisms associated with the plant in the aquatic environment —larva of Nymphula responsalis, Rasbora trilineata and Poecilia reticulata. An attempt was made to correlate the toxicological results with the application rates of the herbicides in terms of safety factors. TOK E-25 has been found to be most toxic, the others being relatively safe.     

Production and characterisation of monoclonal antibodies to ovine interleukin-5

Monoclonal antibodies (MAbs) were developed against recombinant ovine interleukin-5 (IL-5) produced in the baculovirus expression vector system. One MAb, D11 (isotype IgG1), neutralised the activity of both recombinant and native sources of IL-5 in a biological assay (Baf cell assay) but was only weakly reactive in immunocytochemistry. Conversely, a second MAb, A8 (isotype IgA), successfully detected IL-5 in immunocytochemistry but did not display neutralising activity. The development of these MAbs will enable the assay of ovine IL-5 in vitro and permit studies into the role of hypersensitivity reactions in sheep by neutralisation of IL-5 in vivo.     

Marble stone processing powder residue as chemical adjuvant for the biologic treatment of acid mine drainage

Marble stone powder (calcite tailing) is a residual material resulting from the cutting and polishing of marble stone. Its use as adjuvant for the biologic treatment of acid mine drainage is studied. The performance of a combined chemical/biologic packed bed reactor containing a sulphate-reducing bacteria inoculum and calcite tailing as neutralising agent was compared with the individual neutralisation and biologic steps. Unlike the individual steps, the combined column is efficient in terms of metals and sulphate removal and acidity neutralisation, producing treated water suitable for irrigation. This work emphasizes on the key role played by waste calcite tailing in the inlet of the reactor. By thus adjusting pH to values adequate for sulphate-reducing bacteria water suitable for irrigation can be obtained in a single equipment with low energy demand. This goal would be impossible without the neutralisation action.     

Production of monoclonal antibody to Clostridium difficile toxin A which neutralises enterotoxicity but not haemagglutination activity

Nine monoclonal antibodies (mAb) to Clostridium difficile toxin A were produced. The isotype of one mAb (37B5) was IgG2b, kappa, and that of the other eight mAbs was IgM, kappa. Immunoblot analysis after non-denatured PAGE showed that with the exception of one mAb (112G6) all mAbs gave a positive reaction with the 540 kDa band of toxin A. Immunoblot analysis showed that four mAbs (2E15, 3B4, 37B5 and 49C4) gave a positive reaction with the 240 kDa major band of toxin A. In neutralisation tests with these mAbs for enterotoxicity, mouse lethality, haemagglutination activity and cytotoxicity, 37B5 neutralised enterotoxicity in a rabbit ileal loop response test but did not neutralise any other biological activities. None of the other eight mAbs showed any neutralising activities at all.     

Detection of Clostridium novyi type B α toxin by cell culture systems

Ten permanent cell lines were examined for their reaction to the Clostridium novyi alpha toxin. The action of the toxin was determined after 3 days by microscopic examination and the MTT assay. The alpha toxin exhibited the strongest effect on ESH-L cells rather than other cell lines. Vero and SFT-R cells reacted in a comparable way, but less sensitively. We were able to show that the cytopathic effect on the three types of cells was neutralised by the international standard for gas gangrene antitoxin (C. novyi) but in no case by heterologous antisera. Our results have shown that the three cell lines were specific indicators for the detection of the cytopathic effect of alpha toxin. The cytopathic effect can be measured reproducibly by the cell culture assay used. These results are suitable as the starting point for the development of the neutralisation test using cell cultures.     

Long-term monitoring of the restoration and development of limestone grasslands in north western Germany: Vegetation screening and soil seed bank analysis

We analysed the long-term development of limestone grasslands in West- and Central Europe (Mesobromion: Gentiano-Koelerietum) under conditions of restoration comparing vegetation changes with the composition of its corresponding soil seed bank over a time period from 1992 to 2005. Because of optimal climatic, edaphic and geomorphologic conditions restoration of vegetation developed gradually into the optimal phase of the typical limestone grassland vegetation type. However, the development of the soil seed bank compared to that of the actual vegetation cover is much slower, and even after 13 years all three study plots did not reach the optimal phase compared to soil seed bank composition from well-developed control vegetation nearby. This finding agrees with the assumption that after changes of management limestone grasslands need decades or even centuries to develop into self-sustaining species-rich habitats. We also monitored the orchid Ophrys insectifera as target species and characteristic species of this type of plant association over the last 27 years. Here, population density increased continuously over time indicating that vegetation restoration efforts of the last decades have had a positive effect.We further documented that the data obtained for the soil seed bank largely depend on the applied method used for the characterization of the soil seed bank. The seedling emergence and the rinsing method provided different results, and in case of our study area the rinsing method was mostly superior. The rinsing method detected up to 20fold higher total seed numbers.     

入侵种薇甘菊防治措施及策略评估

薇甘菊Mikania micrantha H.B.K.是入侵中国南部地区的一种危害极大的外来入侵种。防治薇甘菊的措施和策略,应根据薇甘菊的物种特性及所能支配的防除资源,综合考虑、统筹安排。薇甘菊能快速生长覆盖其他植物,其残株断枝易成为独立生长的新个体、种子量巨大且极易扩散,喜入侵次生植被。物理清除适用于小面积,对大面积出现的薇甘菊不应采用。化学防除主要用于应急,但未能改变适于薇甘菊生长的生境,薇甘菊仍可能在数年后再次为害。田野菟丝子Cuscuta campestris控制薇甘菊适用于大面积危害区域,当只以控制而不以根除自然群落的薇甘菊为目标时效果很好。群落改造能一劳永逸地解除薇甘菊的危害,但只适用于宜林地,且成本较高。天敌控制和植物化感防治都尚在探索阶段。未来还应发掘有效天敌,研发综合防治措施,揭示宏观分布规律。薇甘菊防治的正确策略是:对于已形成区域性危害的薇甘菊,根除已经不可能,应采取持久战而非速决战,防止薇甘菊入侵新区域是防治的重中之重,必须优先治理轻度入侵地和能向周边区域甚至是遥远区域扩散的传播源,建立防治示范区或样地。     

Microbial communities on the monuments of Moscow and St. Petersburg: biodiversity and trophic relations

Stone monuments situated in the Alexander Nevsky Abbey, the Summer Garden, and the Smolenskoe Cemetery, St. Petersburg, and marble and limestone sculptures and tombstones situated in the Novodevichy Convent and the Donskoy Monastery, Moscow, were investigated for their microbial contamination. The architectural objects studied date to the 12th century. The monuments in the Alexander Nevsky Abbey were found to be severely contaminated with micromycetes belonging to 24 genera (primarily of the class Deuteromycetes). The analysis of the samples taken from the monuments of the Donskoy Monastery by the serial dilution technique showed that they were contaminated with bacteria at a density of (1-1.7) x 10(5) cells/g. This value, however, turned out to be 1 to 2 orders greater when the bacterial population was evaluated by the luciferin-luciferase method. We succeeded in identifying 12 bacterial genera; however, this number may be increased in the course of further studies. Some preventive measures to control the biodeterioration of stone heritage are discussed.     

Expression of a major bovine rotavirus neutralisation antigen (VP7c) in Escherichia coli

Sequences from genomic RNA segment 8 of the United Kingdom tissue-culture (t.c.)-adapted bovine rotavirus encoding a major viral neutralisation antigen VP7c have been expressed in Escherichia coli. Expression under the regulated control of the bacteriophage lambda pR promoter was as a C-terminal extension to E. coli beta-galactosidase (beta Gal). Following temperature induction, high levels of the fusion protein were synthesised and accumulated in induced cells, making up 5%-15% of total bacterial cell protein after 2 h of induction. Immunisation of sero-negative rabbits and mice with gel-purified fusion-protein raised antibodies, which gave specific immunofluorescence with virus-infected cells and were able to immunoprecipitate proteins of the VP7 complex from such cells. Hyperimmune sera also gave a virus-type-specific reaction in a solid-phase enzyme-linked immunoabsorbant assay and neutralised virus infectivity in standard plaque-reduction assays.     

Deterioration of limestone structures associated with copper staining

Sixty limestone monuments in Central London, UK, with copper staining from brass or bronze attachments, were surveyed. Severe spalling was noted at some copper-stained sites. The survey suggests that copper initially protects the surface, but causes stone deterioration after around 70 years. Samples from four limestone monuments were analysed microbiologically and using ESEM/EDX. EDX analyses suggested the build-up of salts below a basic copper carbonate skin (salting) as the most probable explanation of the observed deterioration. Copper-stained stone was free of photosynthetic microorganisms and yielded relatively few other microorganisms. ESEM and EDX analyses of a well-conserved limestone monument surface free of copper showed the almost complete conversion of surface limestone to gypsum. The grey/brown biofilms consisted of actinomycetes and filamentous fungi. The results indicate that copper initially prevents and then enhances limestone deterioration, and that atmospheric pollutants are far less harmful than phototrophic biofilms, since surface areas completely converted to gypsum are well preserved after more than 100 years.     

Monitoring the colonization of monuments by bacteria: cultivation versus molecular methods

Building materials commonly used in wall paintings and monuments (mortar, limestone and sandstone) were inoculated with an artificial consortium composed of 14 microorganisms and incubated for 6 months at 28 degrees C. The colonization of the different materials by the consortium was investigated. Culture-independent techniques revealed the presence of a diversity of bacteria, whereas culture-dependent techniques yielded mainly spore-forming bacteria. The data suggest that plating leads to an overestimation of the number of spore-forming bacteria with respect to quiescent vegetative forms; the latter are less easily cultured, but are readily detected by culture-independent techniques.