20,353 research outputs found

    Studies on Resistance to Vegetative (Vip3A) and Crystal (Cry1A) Insecticidal Toxins of Bacillus thuringiensis in Heliothis virescens (Fabricius)

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    Bacillus thuringiensis (Bt) toxins expressed in commercial transgenic crop varieties are all δ-endotoxins (Cry toxins) but the identification of novel vegetative insecticidal proteins (Vip toxins) has extended the range of insecticidal proteins derived from Bt. One such Vip toxin, Vip3A, primarily targets the midgut epithelium cells of susceptible insects as Cry toxins do, although they appear to have different binding sites. The present study investigated the comparative toxicity of Vip3A, Cry1Ab and Cry1Ac against Heliothis virescens (tobacco budworm) and the impact of antibiotics on Bt insecticidal activity. The selection of a resistant Vip3A population led to the determination of cross-resistance, the genetics of resistance and fitness effects. There was very little variability in the natural susceptibility to Vip3A, Cry1Ab and Cry1Ac in the populations tested, although the toxicity of Vip3A was much lower compared to the Cry1A toxins. A Vip3A resistant population was successfully established within 13 selected generations, with little or no cross-resistance to Cry1Ab or Cry1Ac. The inheritance of resistance ranged from almost completely recessive to incompletely dominant with a possible paternal influence, was polygenic and relatively stable. Vip3A resistance showed a fitness benefit, reduced larval development time, and fitness costs, including survival to adult eclosion, reduced egg viability and reduced male mating success. The effects of antibiotics on H. virescens larval susceptibility to Bt toxins varied depending on antibiotic treatment, the Bt toxin used and the larval instar tested. Bt cotton expressing both Vip3A and Cry1Ab to provide activity against a wide range of pest Lepidoptera, including H. virescens, a major cotton pest in the USA is in the process of commercialisation. The present work will help to support a suitable insecticide resistance management strategy for continued use of Bt toxin in transgenic crops

    Military Programs Effects on Couples’ During Long Separations

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    Graduate Theoretical Proposa

    Conflicts among Civilizations: The Influence behind War and Art

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    Why war or conflicts are fought between civilizations is a subject that could be debated with no end. The complexity of how our species reacts with each other and generates conflict exceeds the limitations of a single concept. There is not one answer to the question, but often the combination of the need for economic and political authority along with the thrill of victory, power, and nationalism joining together to create the motivation to fight and conquer

    Making the H-Cluster from Scratch

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    Spectroscopic data begin to elucidate the initial steps in the biosynthesis of the hydrogenase active site. [Also see Report by Kuchenreuther et al. ] </jats:p

    High resolution spectroscopy in the microwave and far infrared

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    High resolution rotational spectroscopy has long been central to remote sensing techniques in atmospheric sciences and astronomy. As such, laboratory measurements must supply the required data to make direct interpretation of data for instruments which sense atmospheres using rotational spectra. Spectral measurements in the microwave and far infrared regions are also very powerful tools when combined with infrared measurements for characterizing the rotational structure of vibrational spectra. In the past decade new techniques were developed which have pushed high resolution spectroscopy into the wavelength region between 25 micrometers and 2 mm. Techniques to be described include: (1) harmonic generation of microwave sources, (2) infrared laser difference frequency generation, (3) laser sideband generation, and (4) ultrahigh resolution interferometers

    Explicit Construction of Self-Dual Integral Normal Bases for the Square-Root of the Inverse Different

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    Let KK be a finite extension of \Q_p, let L/KL/K be a finite abelian Galois extension of odd degree and let \bo_L be the valuation ring of LL. We define AL/KA_{L/K} to be the unique fractional \bo_L-ideal with square equal to the inverse different of L/KL/K. For pp an odd prime and L/\Q_p contained in certain cyclotomic extensions, Erez has described integral normal bases for A_{L/\Q_p} that are self-dual with respect to the trace form. Assuming K/\Q_p to be unramified we generate odd abelian weakly ramified extensions of KK using Lubin-Tate formal groups. We then use Dwork's exponential power series to explicitly construct self-dual integral normal bases for the square-root of the inverse different in these extensions
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