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Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.  相似文献   

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A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.  相似文献   

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The water-insoluble procedures in US Pharmacopeia (USP) General Chapter Residual Solvents <467>, which are based on European Pharmacopoeia procedures, were optimized and modified before their inclusion in the chapter to improve their scope, performance, and ruggedness. The optimized procedures use a static headspace introduction system with a gas chromatograph equipped with a flame ionization detector. This article describes some of the key changes made to the USP published procedures, including use of dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) as the solvent, addition of 5 mL of water and 1 mL of sample (dissolved in DMSO or DMF) to the headspace vial, use of a 3:1 GC split ratio, and use of new matrix-matched system suitability solutions. These procedures were verified with two different active pharmaceutical ingredients—hydroxyzine pamoate and prednisone. In the investigation, the more polar material (hydroxyzine pamoate) showed greater recoveries for the optimized procedures when prepared in DMSO. The less polar material (prednisone) typically had greater recoveries in DMF for the optimized procedures. During experimentation, insights into sample preparation, additional types of headspace instrumentation, solvent purity, and other parameters were also gained.  相似文献   

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A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.  相似文献   

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In Bacillus subtilis, mutant alleles of the genes sms and subA partially suppress the recombination phenotype of recU cells. When present in an otherwise Rec(+) strain, Delta sms and Delta subA alleles render cells slightly sensitive to DNA-damaging agents, and impair chromosomal transformation (3- to 10-fold reduction), but do not affect plasmid transformation (less than 1.5-fold reduction). The Delta sms and Delta subA alleles were introduced into rec-deficient strains representative of the epistatic groups alpha (recF strain), beta (addA addB), gamma (recH), epsilon (recB, Delta recU and recD strains) and zeta (Delta recS). Both the Delta sms and Delta subA mutations were found to increase sensitivity to DNA-damaging agents in recF, Delta recS and addAB cells. In contrast, the Delta sms mutations decreased the sensitivity of recB, Delta recU, recD and recH cells, and the Delta subA mutation decreased the sensitivity of recB and Delta recU cells to DNA-damaging agents. Functions classified within the epistatic groups alpha, epsilon and zeta are required for intramolecular recombination, measured as plasmid transformation. The Delta sms and Delta subA mutations, which partially suppressed the recombinational repair phenotype of mutants for functions within epistatic group epsilon, enhanced plasmid transformation of recU (recB, recD) and recS cells by 10- to 20-fold. In the absence of the proteins Sms and SubA, the recombination machinery is apparently redirected towards (an) alternative pathway(s). Furthermore, the shared ability of the Delta sms and Delta subA mutations to act as indirect suppressors of recB, recU and recD mutations supports the classification of the recBUD genes within epistatic group epsilon.  相似文献   

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There are three most important bacterial causative agents of serious infections that could be misused for warfare purposes: Bacillus anthracis (the causative agent of anthrax) is the most frequently mentioned one; however, Fracisella tularensis (causing tularemia) and Yersinia pestis (the causative agent of plague) are further bacterial agents enlisted by Centers for Disease Control and Prevention into the category A of potential biological weapons. This review intends to summarize basic information about these bacterial agents. Military aspects of their pathogenesis and the detection techniques suitable for field use are discussed.  相似文献   

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Escherichia coliL-asparaginase, an antileukaemic agent in man1, inhibits in vitro mitogen or antigen-induced blastogenesis in man2,3 and in animals (M. Bennett, E. G. Mayhew and T. Han, unpublished data) and suppresses bone-marrow derived antibody precursor cells in the mouse4. We now report that another L-asparaginase preparation—from Erwinia carotovora—also possesses antileukaemic activity5,6 and has a more pronounced immunosuppressive effect on in vitro blastogenesis than the E. coli enzyme.  相似文献   

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The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.  相似文献   

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Tuber huidongense and T. liyuanum are common commercial white truffles in China that belong to the Rufum and Puberulum groups of the genus Tuber, respectively. Their mycorrhizae were successfully synthesized with two native trees—Castanea mollissima and Pinus armandii—under greenhouse conditions. The identities of the mycorrhizae were confirmed through internal transcribed spacer (ITS) sequence analyses, and their morphological characteristics were described. All of the obtained mycorrhizae have an interlocking pseudoparenchymatous mantle, which is a typical feature of truffle mycorrhizae. The mycorrhizae of T. huidongense on the two trees have hyaline branched emanating hyphae, similar to the documented mycorrhizae of the Rufum group. The unramified, spiky, and hyaline cystidia on the mycorrhizae of T. liyuanum with both C. mollissima and P. armandii further confirmed that this characteristic is constant for the mycorrhizae of the Puberulum group. The successful mycorrhizal syntheses on the two nut-producing trees will be of economic importance in the cultivation of the two truffles.  相似文献   

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Tropilaelaps mercedesae is a serious ectoparasite of Apis mellifera in China. The aim of this study was to investigate the infestation rates and intensity of T. mercedesae in A. mellifera in China, and to explore the relative importance of climate, district, management practices and beekeeper characteristics that are assumed to be associated with the intensity of T. mercedesae. Of the 410 participating apiaries, 379 apiaries were included in analyses of seasonal infestation rates and 352 apiaries were included in multivariable regression analysis. The highest infestation rate (86.3%) of T. mercedesae was encountered in autumn, followed by summer (66.5%), spring (17.2%) and winter (14.8%). In autumn, 28.9% (93) of the infested apiaries were in the north (including the northeast and northwest of China), 71.1% (229) were in the central and south (including east, southeast and southwest China), and 306 apiaries (82.9%) were co-infested by both T. mercedesae and Varroa. Multivariable regression analysis showed that geographical location, season, royal jelly collection and Varroa infestation were the factors that influence the intensity of T. mercedesae. The influence of beekeeper’s education, time of beekeeping, operation size, and hive migration on the intensity of T. mercedesa was not statistically significant. This study provided information about the establishment of the linkage of the environment and the parasite and could lead to better timing and methods of control.  相似文献   

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Recently, the prenyltransferase SirD was found to be responsible for the O-prenylation of tyrosine in the biosynthesis of sirodesmin PL in Leptosphaeria maculans. In this study, the behavior of SirD towards phenylalanine/tyrosine and tryptophan derivatives was investigated. Product formation has been observed with 12 of 19 phenylalanine/tyrosine derivatives. It was shown that the alanine structure attached to the benzene ring and an electron donor, e.g., OH or NH2, at its para-position are essential for the enzyme activity. Modifications were possible both at the side chain and the benzene ring. Enzyme products from seven phenylalanine/tyrosine derivatives were isolated and characterized by MS and NMR analyses including HSQC and HMBC and proven to be O- or N-prenylated derivatives at position C4 of the benzene rings. K M values of six selected derivatives were found in the range of 0.10–0.68 mM. Catalytic efficiencies (K cat/K M ) were determined in the range of 430–1,110 s−1·M−1 with l-tyrosine as the best substrate. In addition, 7 of 14 tested tryptophan analogs were also accepted by SirD and converted to C7-prenylated derivatives, which was confirmed by comparison with products obtained from enzyme assays using a 7-dimethylallyltryptophan synthase 7-DMATS from Aspergillus fumigatus.  相似文献   

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We conducted a novel non-visual screen for cuticular wax mutants in Arabidopsis thaliana (L.) Heynh. Using gas chromatography we screened over 1,200 ethyl methane sulfonate (EMS)-mutagenized lines for alterations in the major A. thaliana wild-type stem cuticular chemicals. Five lines showed distinct differences from the wild type and were further analyzed by gas chromatography and scanning electron microscopy. The five mutants were mapped to specific chromosome locations and tested for allelism with other wax mutant loci mapping to the same region. Toward this end, the mapping of the cuticular wax (cer) mutants cer10 to cer20 was conducted to allow more efficient allelism tests with newly identified lines. From these five lines, we have identified three mutants defining novel genes that have been designated CER22, CER23, and CER24. Detailed stem and leaf chemistry has allowed us to place these novel mutants in specific steps of the cuticular wax biosynthetic pathway and to make hypotheses about the function of their gene products.Abbreviations EMS Ethyl methane sulfonate - SEM Scanning electron microscopy - SSLP Simple sequence length polymorphism - WT Wild type  相似文献   

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