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

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

Conflicts among Civilizations: The Influence behind War and Art

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

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

Let $K$ be a finite extension of \Q_p, let $L/K$ be a finite abelian Galois extension of odd degree and let \bo_L be the valuation ring of $L$. We define $A_{L/K}$ to be the unique fractional \bo_L-ideal with square equal to the inverse different of $L/K$. For $p$ 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 $K$ 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

Novel structural determinants of the human neutrophil chemotactic activity of leukotriene B.

A specific 5(S),12(R)-dihydroxy-eicosa-6,8,10(trans/trans/cis), 14(cis)-tetraenoic acid, designated leukotriene B, is generated by the lipoxygenation and subsequent enzymatic hydration of arachidonic acid in a variety of leukocytes. Leukotriene B elicits a maximal human neutrophil chemotactic response in vitro which is similar in magnitude to those evoked by the chemotactic fragment of the fifth component of complement, C5a, synthetic formyl-methionyl peptides, and 5-hydroxy-eicosatetraenoic acid (5-HETE). The neutrophil chemotactic potency of purified leukotriene B, assessed by the 50% effective concentration of 6 x 10(-9) M, is equivalent to that of C5a, but is up to 100-fold greater than that of 5-HETE and of other natural di-HETE isomers. 5(S),12(R)-di-hydroxy-eicosa-6,8,10(all-trans),14(cis)-tetraenoic acid, which differs from leukotriene B only in having a trans-double bond in place of a cis-double bond in the triene portion of the molecule, and acetyl-leukotriene B are significantly less potent neutrophil chemotactic factors than leukotriene B, which indicates that both the conjugated double bonds and the free hydroxyl-group(s) are functionally critical determinants. The capacity of acetyl-leukotriene B to inhibit competitively and selectively the human neutrophil chemotactic response to equimolar concentrations of leukotriene B suggests the existence of a specific subset of receptors for this potent lipid mediator

The Josephson Effect in Single Spin Superconductors

The Josephson Effect provides a primary signature of single spin superconductivity (SSS), the as yet unobserved superconducting state which was proposed recently as a low temperature phase of half-metallic antiferromagnets. These materials are insulating in the spin-down channel but are metallic in the spin-up channel. The SSS state is characterized by a unique form of p-wave pairing within a single spin channel. We develop the theory of a rich variety of Josephson effects that arise due to the form of the SSS order parameter. Tunneling is allowed at a SSS-SSS' junction but of course depends on the relative orientation of their order parameters. No current flows between an SSS and an s-wave BCS system due to their orthogonal symmetries, which potentially can be used to distinguish SSS from other superconducting states. Single spin superconductors also offer a means to probe other materials, where tunneling is a litmus test for any form of ``triplet'' order parameter.Comment: 4 pages, RevTeX, 2 PostScript figures included, to appear in J. Phys. and Chem. of Solid