核盘菌可溶性蛋白质及同工酶电泳研究

为了研究核盘菌的分类和生理分化问题,对供试的28个核盘菌株进行了可溶性蛋白质,芳香基酯酶和酸性磷酸酯酶同工酶电泳谱带以及紫外光吸收峰图形的试验研究,其结果,可分为五种类型。其中属于核盘菌属有四个种,即核盘菌Sclerotinia sclerotiorum(Lib.)de Bary(=Whetzelinia sclerotiorum(Lib.)Korf & Dumont),三叶草核盘菌S.trifoliorum Erikss.,细辛核盘菌(S.asari Wu et C.R.Wang和人参菌核病菌Sclerotinia sp。人参菌核病的另一分离菌和油菜菌核病的一个分离菌其谱带与灰葡萄孢(Botrytis cinerea)谱带相似,应归属于与葡萄孢属(Botrytis)相应的核盘菌。在核盘菌S.sclerotiorum种群中,南方菌系与北方菌系的可溶性蛋白质稍有差异,芳香基酯酶和酸性磷酸酯酶活性强度也稍有不同,可能存在生理分化现象。     

黄连木五倍子的生态研究与利用

一、产地自然概况黄连木五倍子最早发现于河南省南部信阳市郊贤山脚下(东经114°0′,,北纬32°10′)。该地为低山丘陵,海拔90一320m,南部紧连鸡公山厂傍依南湾水库和狮河。     

Influx and efflux of inorganic carbon in Synechococcus UTEX625

The CO₂ and HCO₃^? fluxes in air-grown cells of Synechococcus UTEX 625 al pH 8-0 were measured during dark to light and light to dark transitions using a mass spectrometer and sampling of the reaction medium. The kinetic parameters for initial uptake of CO₂ and HCO₃^? were determined during the initial period of illumination. The development of the internal C_i pool was followed up to steady-state photosynthesis, which occurred when the size of the internal inorganic carbon pool remained apparently constant for a limited period. The experimental procedure confirmed that only CO₂ transport occurred with 100mmolm^?3 Na⁺ and that both CO₂ and HCO^?3 transport occurred with 25molm^?3 Na⁺. The K_1/2 values of initial CO₂ and HCO₃ uptake were 0.7 and 17.2 mmolm^?3respectively and agreed closely with the K_1/2 values of net CO₂ and HCO₃^? transport during steady-state photosynthesis, which were 0.66 and 17.1 mmolm^?3 respectively. Maximum rates of CO₂and HCO₃^? transport were 423 and 219mmolh^?1 g^?1 Chl. Maximum CO₂ efflux observed upon darkening was 118mmolh^?1 g^?1 Chl. A permeability coefficient of the cell for CO₂ of 3 × 10^?8 m s^?1 was determined from the dark CO₂ efflux assuming an internal pH of 7.2 in the dark. Following the initial CO₂ uptake in the light, the extracellular [CO₂] steadily declined when only CO₂ transport was allowed, but an increase in the extracellular [CO₂] when HCO₃^? transport was allowed to proceed suggested that an enhanced CO₂ efflux occurred as a result of the larger size of the intracellular C_i pool.     

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n=172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence=89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.     

THE LASER TOMOGRAPHICAL METHOD USINGMINIMUM OF PROJECTION FOR BIOLOGICAL OBJECT STRUCTURE STUDY

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Results and recommendations

In the first phase of a collaborative study by the International Programme on Chemical Safety (PRCS), four coded chemicals, i.e. azidoglycerol (AG, 3-azido-1,2-propanediol), methyl nitrosurea (MNU), sodium azide (NaN₃) and maleic hydrazide (MH), and ethyl methanesulfonate (EMS) as a positive control were tested in four plant bioassays, namely the Arabidopsis embryo and chlorophyll mutation assay, the Tradescantia stamen hair assay (Trad-SH assay), the Tradescantia micronucleus assay (Trade-MCN), and the Vicia faba root tip assay. Seventeen laboratories from diverse regions of the world participated with four to six laboratories each using one plant assay. For the Arabidopsis assay, laboratories were in agreement with MNU and AG giving positive responses and NaN₃ giving a negative response. With the exception of one laboratory which reported MH as weakly mutagenic, no mutagenic response was reported for MH by the other laboratories. For the Vicia faba assay, all laboratories reported a positive response for MNU, AG, and MH, whereas two of the six laboratories reported a negative response for NaN₃. For the Trad-SH assay, MH was reported as giving a positive response and a positive response was also observed for MNU with the exception of one laboratory. NaN₃, which exhibited a relatively high degree of toxicity, elicited a positive response in three of the five laboratories. AG was found positive in only one of the two laboratories which tested this chemical. For the Trad-MCN assay, MNU and MH were reported as positive by all laboratories, while four out of five laboratories reported NaN₃ to be positive. Only one of three laboratories reported AG to be positive. The major sources of variability were identified and considered to be in the same range as found in similar studies on other test systems. Recommendations were made for minor changes in methodology and for initiating the second phase of this study.     

Evidence for the role of glycoprotein G of respiratory syncytial virus in binding of Neisseria meningitidis to HEp-2 cells

Abstract Viral glycoproteins G and F are expressed on the surface of cells infected with respiratory syncytial virus (RSV). We investigated the role of these proteins in the previously reported enhanced binding of Neisseria meningitidis to RSV-infected HEp-2 cells. Virus particles attached to bacteria were detected by immunofluorescence with flow cytometry. Binding of FITC-labelled bacteria to RSV-infected cells was significantly inhibited by monoclonal antibody against glycoprotein G. Unlabelled bacteria interfered with binding of the anti-G monoclonal antibody to these cells. These interactions were not found with a monoclonal antibody against glycoprotein F. We propose that glycoprotein G of RSV expressed on the surface of infected cells might act as an additional receptor for meningococci.     

A Novel Method for Generating Nested Deletions Using the in Vitro Bacteriophage T3 DNA Packaging System

To sequence a DNA segment inserted into a cosmid vector underthe directed sequencing strategy, we established a simple andrapid method for generating nested deletions which uses thein vitro packaging system of bacteriophage T3 DNA. The principleis based on the previous finding that this system can translocateany linear double-stranded DNA up to 40 kb into the phage capsidin a time-dependent manner and the encapsulated DNA becomesDNase-resistant. For this purpose, we constructed a cosmid vectorthat carries two different antibiotic selection markers at bothsides of the multiple cloning site, and after insertion of aDNA segment, the clone was linearized by -terminase at the cossite. After the packaging reaction in vitro followed by DNasetreatment, the encapsulated DNA was introduced into Escherichiacoli cells to give clones with unidirectional deletions by differentialantibiotic selection. Restriction and sequence analyses of deletionclones demonstrated that an ordered set of clones with nesteddeletions, ranging from less than 1 kb to 25 kb, was createdfrom either the end of the DNA segment. Thus, nested deletionclones that cover the entire region of a 40-kb cosmid insertcan be obtained by a single packaging reaction, and its restrictionmap can be simultaneously obtained.     

Stability of bilirubin oxidase in organic solvent media: a comparative study on two low-water systems

The storage stability of bilirubin oxidase was studied in water-in-oil CTAB microemulsions with a chloroformrich continuous organic phase. The kinetics of the inactivation process were best described by a double exponential equation. Approximately half of enzymatic activity was lost during a "fast" phase with a half life of ca. 50 min, whereas the remaining activity was lost much more slowly (half life ca. 1000 min). Rates of inactivation were not affected significantly by variation of either solvent composition or concentration of water droplets, but inactivation was more rapid when droplet size was very small. Steady-state enzyme kinetics were studied at various stages in the inactivation process, and it was shown that inactivation occurred without change in the K(m) of the enzyme for bilirubin. Stability was also studied in a liquid/solid two-phase system; it was found that the inactivation process in this system; it was found that the inactivation process in this system was best described by a single exponential term. The rate was similar to the "fast" phase rate observed in the water-in-oil microemulsion system. Inactivation of the enzyme slow. Addition of the surfactant CTAB to the aqueous environment increased the rate of inactivation to levels comparable to those of the "slow" phase observed in water-in-oil microemulsions. (c) 1993 Wiley & Sons, Inc.