24 research outputs found

    Cyanogenesis of Wild Lima Bean (Phaseolus lunatus L.) Is an Efficient Direct Defence in Nature

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    In natural systems plants face a plethora of antagonists and thus have evolved multiple defence strategies. Lima bean (Phaseolus lunatus L.) is a model plant for studies of inducible indirect anti-herbivore defences including the production of volatile organic compounds (VOCs) and extrafloral nectar (EFN). In contrast, studies on direct chemical defence mechanisms as crucial components of lima beans' defence syndrome under natural conditions are nonexistent. In this study, we focus on the cyanogenic potential (HCNp; concentration of cyanogenic glycosides) as a crucial parameter determining lima beans' cyanogenesis, i.e. the release of toxic hydrogen cyanide from preformed precursors. Quantitative variability of cyanogenesis in a natural population of wild lima bean in Mexico was significantly correlated with missing leaf area. Since existing correlations do not by necessity mean causal associations, the function of cyanogenesis as efficient plant defence was subsequently analysed in feeding trials. We used natural chrysomelid herbivores and clonal lima beans with known cyanogenic features produced from field-grown mother plants. We show that in addition to extensively investigated indirect defences, cyanogenesis has to be considered as an important direct defensive trait affecting lima beans' overall defence in nature. Our results indicate the general importance of analysing ‘multiple defence syndromes’ rather than single defence mechanisms in future functional analyses of plant defences

    Vaccine strategies against cystic fibrosis pathogens

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    A great number of cystic fibrosis (CF) pathogens such as Pseudomonas aeruginosa, the Burkholderia cepacia and the Mycobacterium abscessus complex raised difficult therapeutic problems due to their intrinsic multi-resistance to numerous antibiotics. Vaccine strategies represent one of the key weapons against these multi-resistant bacteria in a number of clinical settings like CF. Different strategies are considered in order to develop such vaccines, linked either to priming the host response, or by exploiting genomic data derived from the bacterium. Interestingly, virulence factors synthesized by various pathogens might serve as targets for vaccine development and have been, for example, evaluated in the context of CF

    The KSTAR project: An advanced steady state superconducting tokamak experiment

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    The Korea Superconducting Tokamak Advanced Research (KSTAR) project is the major effort of the national fusion programme of the Republic of Korea. Its aim is to develop a steady state capable advanced superconducting tokamak to establish a scientific and technological basis for an attractive fusion reactor. The major parameters of the tokamak are: major radius 1.8 mi minor radius 0.5 m. toroidal held 3.5 T and plasma current 2 MA, with a strongly shaped plasma cross-section and double null divertor. The initial pulse length provided by the poloidal magnet system is 20 s, but the pulse length can be increased to 300 s through non-inductive current drive. The plasma heating and current drive system consists of neutral beams? ion cyclotron waves, lower hybrid waves and electron cyclotron waves for flexible profile control in advanced tokamak operating modes. A comprehensive set of diagnostics is planned for plasma control, performance evaluation and physics understanding. The project has completed its conceptual design and moved to the engineering design and construction phase. The target date for the first plasma is 2002.

    Present status of Hanbit magnetic mirror device

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    The Hanbit magnetic mirror device, which is operated as a joint plasma research facility, has been constructed at Korea Basic Science Institute for basic study and technology development of high temperature plasma confinement, plasma heating and diagnostics, and plasma applications, such as high-temperature material testing for tokamak diverters. A 500-kW RF transmitter and a 100-kW RF transmitter for ICRF heating are major heating sources in operation, and a few gyrotron-based ECRH systems are in preparation, The target plasma parameters at the central cell are 1-keV ion temperature, 200-eV electron temperature, and 5 x 10(12) cm(-3) electron density with 500-ms plasma duration. The present status of the Hanbit device, which includes the system overview and recent experimental result, is described in this paper, and future plans will be discussed.X1114sciescopu
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