The influence of soil moisture and temperature on the survival, aestivation, growth and development of juvenile Aporrectodea tuberculata (Eisen) (Lumbricidae)     

Linda A. Wever  Timothy J. Lysyk  M.Jill Clapperton   《Pedobiologia》2001,45(2):121

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The after-hours mutant reveals a role for Fbxl3 in determining mammalian circadian period     

Godinho SI  Maywood ES  Shaw L  Tucci V  Barnard AR  Busino L  Pagano M  Kendall R  Quwailid MM  Romero MR  O'neill J  Chesham JE  Brooker D  Lalanne Z  Hastings MH  Nolan PM 《Science (New York, N.Y.)》2007,316(5826):897-900

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Discovery and directed evolution of a glyphosate tolerance gene   总被引：2，自引：0，他引：2  

Castle LA  Siehl DL  Gorton R  Patten PA  Chen YH  Bertain S  Cho HJ  Duck N  Wong J  Liu D  Lassner MW 《Science (New York, N.Y.)》2004,304(5674):1151-1154

The herbicide glyphosate is effectively detoxified by N-acetylation. We screened a collection of microbial isolates and discovered enzymes exhibiting glyphosate N-acetyltransferase (GAT) activity. Kinetic properties of the discovered enzymes were insufficient to confer glyphosate tolerance to transgenic organisms. Eleven iterations of DNA shuffling improved enzyme efficiency by nearly four orders of magnitude from 0.87 mM-1 min-1 to 8320 mM-1 min-1. From the fifth iteration and beyond, GAT enzymes conferred increasing glyphosate tolerance to Escherichia coli, Arabidopsis, tobacco, and maize. Glyphosate acetylation provides an alternative strategy for supporting glyphosate use on crops.  相似文献   

NIH Molecular Libraries Initiative     

Austin CP  Brady LS  Insel TR  Collins FS 《Science (New York, N.Y.)》2004,306(5699):1138-1139

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CD46 in meningococcal disease     

Johansson L  Rytkonen A  Bergman P  Albiger B  Källström H  Hökfelt T  Agerberth B  Cattaneo R  Jonsson AB 《Science (New York, N.Y.)》2003,301(5631):373-375

The human-specific bacterial pathogen Neisseria meningitidis is a major cause of sepsis and/or meningitis. The pili of N. meningitidis interact with CD46, a human cell-surface protein involved in regulation of complement activation. Transgenic mice expressing human CD46 were susceptible to meningococcal disease, because bacteria crossed the blood-brain barrier in these mice. Development of disease was more efficient with piliated bacteria after intranasal, but not intraperitoneal, challenge of CD46 transgenic mice, suggesting that human CD46 facilitates pilus-dependent interactions at the epithelial mucosa. Hence, the human CD46 transgenic mice model is a potentially useful tool for studying pathogenesis and for vaccine development against meningococcal disease.  相似文献   

NIOSH and the CDC reorganization     

Key MM  Robbins A  Millar JD  Rosenstock L 《Science (New York, N.Y.)》2004,305(5684):607

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Biological control of take-all by fluorescent Pseudomonas spp. from Chinese wheat fields     

Yang MM  Mavrodi DV  Mavrodi OV  Bonsall RF  Parejko JA  Paulitz TC  Thomashow LS  Yang HT  Weller DM  Guo JH 《Phytopathology》2011,101(12):1481-1491

Take-all disease of wheat caused by the soilborne fungus Gaeumannomyces graminis var. tritici is one of the most important root diseases of wheat worldwide. Bacteria were isolated from winter wheat from irrigated and rainfed fields in Hebei and Jiangsu provinces in China, respectively. Samples from rhizosphere soil, roots, stems, and leaves were plated onto King's medium B agar and 553 isolates were selected. On the basis of in vitro tests, 105 isolates (19% of the total) inhibited G. graminis var. tritici and all were identified as Pseudomonas spp. by amplified ribosomal DNA restriction analysis. Based on biocontrol assays, 13 strains were selected for further analysis. All of them aggressively colonized the rhizosphere of wheat and suppressed take-all. Of the 13 strains, 3 (HC9-07, HC13-07, and JC14-07, all stem endophytes) had genes for the biosynthesis of phenazine-1-carboxylic acid (PCA) but none had genes for the production of 2,4-diacetylphloroglucinol, pyoluteorin, or pyrrolnitrin. High-pressure liquid chromatography (HPLC) analysis of 2-day-old cultures confirmed that HC9-07, HC13-07, and JC14-07 produced PCA but no other phenazines were detected. HPLC quantitative time-of-flight 2 mass-spectrometry analysis of extracts from roots of spring wheat colonized by HC9-07, HC13-07, or Pseudomonas fluorescens 2-79 demonstrated that all three strains produced PCA in the rhizosphere. Loss of PCA production by strain HC9-07 resulted in a loss of biocontrol activity. Analysis of DNA sequences within the key phenazine biosynthesis gene phzF and of 16S rDNA indicated that strains HC9-07, HC13-07, and JC14-07 were similar to the well-described PCA producer P. fluorescens 2-79. This is the first report of 2-79-like bacteria being isolated from Asia.  相似文献   

Gene amplification and insecticide resistance   总被引：1，自引：0，他引：1  

Bass C  Field LM 《Pest management science》2011,67(8):886-890

Pesticide resistance in arthropods has been shown to evolve by two main mechanisms, the enhanced production of metabolic enzymes, which bind to and/or detoxify the pesticide, and mutation of the target protein, which makes it less sensitive to the pesticide. One route that leads to enhanced metabolism is the duplication or amplification of the structural gene(s) encoding the detoxifying enzyme, and this has now been described for the three main families (esterases, glutathione S-transferases and cytochrome P450 monooxygenases) implicated in resistance. More recently, a direct or indirect role for gene duplication or amplification has been described for target-site resistance in several arthropod species. This mini-review summarises the involvement of gene duplication/amplification in the insecticide/acaricide resistance of insect and mite pests and highlights recent developments in this area in relation to P450-mediated and target-site resistance.  相似文献   

Biological control of Rhizoctonia root rot on bean by phenazine- and cyclic lipopeptide-producing Pseudomonas CMR12a     

D'aes J  Hua GK  De Maeyer K  Pannecoucque J  Forrez I  Ongena M  Dietrich LE  Thomashow LS  Mavrodi DV  Höfte M 《Phytopathology》2011,101(8):996-1004

Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia solani, the intermediately aggressive AG 2-2 and the highly aggressive AG 4 HGI, were included in growth-chamber experiments with bean plants. The wild-type strain CMR12a dramatically reduced disease severity caused by both R. solani AGs. A CLP-deficient and a phenazine-deficient mutant of CMR12a still protected bean plants, albeit to a lesser extent compared with the wild type. Two mutants deficient in both phenazine and CLP production completely lost their biocontrol activity. Disease-suppressive capacity of CMR12a decreased after washing bacteria before application to soil and thereby removing metabolites produced during growth on plate. In addition, microscopic observations revealed pronounced branching of hyphal tips of both R. solani AGs in the presence of CMR12a. More branched and denser mycelium was also observed for the phenazine-deficient mutant; however, neither the CLP-deficient mutant nor the mutants deficient in both CLPs and phenazines influenced hyphal growth. Together, results demonstrate the involvement of phenazines and CLPs during Pseudomonas CMR12a-mediated biocontrol of Rhizoctonia root rot of bean.  相似文献   

Discussion     

Linda J. Young 《Journal of Agricultural, Biological & Environmental Statistics》2002,7(3):320-323

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