Evaluation of entomopathogenic nematodes and their combined application against Curculio elephas and Polyphylla fullo larvae

Journal of Pest Science - The larvae of Curculio elephas (Coleoptera: Curculionidae) and Polyphylla fullo (Coleoptera: Scarabaeidae) are major agricultural pests of chestnut and roots of cultivated...     

RNA structure: reading the ribosome

The crystal structures of the ribosome and its subunits have increased the amount of information about RNA structure by about two orders of magnitude. This is leading to an understanding of the principles of RNA folding and of the molecular interactions that underlie the functional capabilities of the ribosome and other RNA systems. Nearly all of the possible types of RNA tertiary interactions have been found in ribosomal RNA. One of these, an abundant tertiary structural motif called the A-minor interaction, has been shown to participate in both aminoacyl-transfer RNA selection and in peptidyl transferase; it may also play an important role in the structural dynamics of the ribosome.     

Molecular confinement accelerates deformation of entangled polymers during squeeze flow

The squeezing of polymers in narrow gaps is important for the dynamics of nanostructure fabrication by nanoimprint embossing and the operation of polymer boundary lubricants. We measured stress versus strain behavior while squeezing entangled polystyrene films to large strains. In confined conditions where films were prepared to a thickness less than the size of the bulk macromolecule, resistance to deformation was markedly reduced for both solid-glass forging and liquid-melt molding. For melt flow, we further observed a complete inversion of conventional polymer viscosity scaling with molecular weight. Our results show that squeeze flow is accelerated at small scales by an unexpected influence of film thickness in polymer materials.     

Negative refraction at visible frequencies

Nanofabricated photonic materials offer opportunities for crafting the propagation and dispersion of light in matter. We demonstrate an experimental realization of a two-dimensional negative-index material in the blue-green region of the visible spectrum, substantiated by direct geometric visualization of negative refraction. Negative indices were achieved with the use of an ultrathin Au-Si3N4-Ag waveguide sustaining a surface plasmon polariton mode with antiparallel group and phase velocities. All-angle negative refraction was observed at the interface between this bimetal waveguide and a conventional Ag-Si3N4-Ag slot waveguide. The results may enable the development of practical negative-index optical designs in the visible regime.     

Production of complex human glycoproteins in yeast

We report the humanization of the glycosylation pathway in the yeast Pichia pastoris to secrete a human glycoprotein with uniform complex N-glycosylation. The process involved eliminating endogenous yeast glycosylation pathways, while properly localizing five active eukaryotic proteins, including mannosidases I and II, N-acetylglucosaminyl transferases I and II, and uridine 5'-diphosphate (UDP)-N-acetylglucosamine transporter. Targeted localization of the enzymes enabled the generation of a synthetic in vivo glycosylation pathway, which produced the complex human N-glycan N-acetylglucosamine2-mannose3-N-acetylglucosamine2 (GlcNAc2Man3GlcNAc2). The ability to generate human glycoproteins with homogeneous N-glycan structures in a fungal host is a step toward producing therapeutic glycoproteins and could become a tool for elucidating the structure-function relation of glycoproteins.     

Noncanonical TGFβ signaling contributes to aortic aneurysm progression in Marfan syndrome mice

Transforming growth factor-β (TGFβ) signaling drives aneurysm progression in multiple disorders, including Marfan syndrome (MFS), and therapies that inhibit this signaling cascade are in clinical trials. TGFβ can stimulate multiple intracellular signaling pathways, but it is unclear which of these pathways drives aortic disease and, when inhibited, which result in disease amelioration. Here we show that extracellular signal-regulated kinase (ERK) 1 and 2 and Smad2 are activated in a mouse model of MFS, and both are inhibited by therapies directed against TGFβ. Whereas selective inhibition of ERK1/2 activation ameliorated aortic growth, Smad4 deficiency exacerbated aortic disease and caused premature death in MFS mice. Smad4-deficient MFS mice uniquely showed activation of Jun N-terminal kinase-1 (JNK1), and a JNK antagonist ameliorated aortic growth in MFS mice that lacked or retained full Smad4 expression. Thus, noncanonical (Smad-independent) TGFβ signaling is a prominent driver of aortic disease in MFS mice, and inhibition of the ERK1/2 or JNK1 pathways is a potential therapeutic strategy for the disease.     

Impact of heavy metal amended sewage sludge on forest soils as assessed by bacterial and fungal biosensors

Bacterial and fungal bioluminescence-based biosensors were used as indicators of potential heavy metal toxicity to microorganisms in the needle litter of a mature Pinus radiata forest under heavy metal contaminated sewage sludge. Sewage sludge was amended with increasing concentrations of Cu, Ni and Zn and applied to the surface of a mature P. radiata forest. The response of the bacterial and fungal biosensors to soluble Cu, Ni and Zn in needle litter extracts was investigated. The bioluminescence response of the bacterial biosensor Escherichia coli HB101 pUCD607 declined as water-soluble Zn concentrations increased. The effective concentrations that gave a 50% reduction in bioluminescence (EC₅₀ values) for water-soluble Zn and total litter Zn were 1.3 mg l⁻¹ and 3700 mg kg⁻¹, respectively. The bioluminescence response of the fungal biosensor Armillaria mellea declined as soluble Cu concentrations increased. The EC₅₀ values for water-soluble Cu and total litter Cu were 0.12 mg l⁻¹ and 540 mg kg⁻¹, respectively. No decline in bioluminescence was noted for either the bacterial or fungal biosensor on exposure to increasing concentrations of water-soluble Ni. The use of a combination of bacterial and fungal biosensors offers a rapid and sensitive tool for assessing toxicity of heavy metals to microorganisms and, thus, elucidating the environmental impact of contaminants in sewage sludge on litter dwelling microorganisms.