A Herbivore Tag-and-Trace System Reveals Contact- and Density-Dependent Repellence of a Root Toxin

Foraging behavior of root feeding organisms strongly affects plant-environment-interactions and ecosystem processes. However, the impact of plant chemistry on root herbivore movement in the soil is poorly understood. Here, we apply a simple technique to trace the movement of soil-dwelling insects in their habitats without disturbing or restricting their interactions with host plants. We tagged the root feeding larvae of Melolontha melolontha with a copper ring and repeatedly located their position in relation to their preferred host plant, Taraxacum officinale, using a commercial metal detector. This method was validated and used to study the influence of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) on the foraging of M. melolontha. TA-G is stored in the latex of T. officinale and protects the roots from herbivory. Using behavioral arenas with TA-G deficient and control plants, we tested the impact of physical root access and plant distance on the effect of TA-G on M. melolontha. The larvae preferred TA-G deficient plants to control plants, but only when physical root contact was possible and the plants were separated by 5 cm. Melolontha melolontha showed no preference for TA-G deficient plants when the plants were grown 15 cm apart, which may indicate a trade-off between the cost of movement and the benefit of consuming less toxic food. We demonstrate that M. melolontha integrates host plant quality and distance into its foraging patterns and suggest that plant chemistry affects root herbivore behavior in a plant-density dependent manner.     

Visualizing a Plant Defense and Insect Counterploy: Alkaloid Distribution in <Emphasis Type="Italic">Lobelia</Emphasis> Leaves Trenched by a Plusiine Caterpillar

Insects that feed on plants protected by latex canals often sever leaf veins or cut trenches across leaves before feeding distal to the cuts. The insects thereby depressurize the canals and reduce latex exudation at their prospective feeding site. How the cuts affect the distribution and concentration of latex chemicals was not known. We modified a microwave-assisted extraction technique to analyze the spatial distribution of alkaloids in leaves of Lobelia cardinalis (Campanulaceae) that have been trenched by a plusiine caterpillar, Enigmogramma basigera (Lepidoptera: Noctuidae). We produced sharp two dimensional maps of alkaloid distribution by microwaving leaves to transfer alkaloids to TLC plates that were then sprayed with Dragendorff’s reagent to visualize the alkaloids. The leaf prints were photographed and analyzed with image processing software for quantifying alkaloid levels. A comparison of control and trenched leaves documented that trenching reduces alkaloid levels by approximately 50% both distal and proximal to the trench. The trench becomes greatly enriched in alkaloids due to latex draining from surrounding areas. Measurements of exudation from trenched leaves demonstrate that latex pressures are rapidly restored proximal, but not distal to the trench. Thus, the trench serves not only to drain latex with alkaloids from the caterpillar’s prospective feeding site, but also to isolate this section, thereby preventing an influx of latex from an extensive area that likely extends beyond the leaf. Microwave-assisted extraction of leaves has potential for diverse applications that include visualizing the impact of pathogens, leaf miners, sap-sucking insects, and other herbivores on the distribution and abundance of alkaloids and other important defensive compounds.     

Synthesis,SAR and Unanticipated Pharmacological Profiles of Analogues of the mGluR5 Ago‐potentiator ADX‐47273

An iterative analogue library synthesis strategy rapidly developed comprehensive SAR for the mGluR5 ago‐potentiator ADX‐47273. This effort identified key substituents in the 3‐position of oxadiazole that engendered either mGluR5 ago‐potentiation or pure mGluR5 positive allosteric modulation. The mGluR5 positive allosteric modulators identified possessed the largest fold shifts (up to 27.9‐fold) of the glutamate CRC reported to date as well as providing improved physiochemical properties.

     

Investigation of Stainless Steel Corrosion in Ultrahigh-Purity Water and Steam Systems by Surface Analytical Techniques

Stainless steel pipes with different degrees of rouging and a Teflon^®-coated rupture disc with severe corrosion were thoroughly investigated by combining multiple surface analytical techniques. The surface roughness and iron oxide layer thickness increase with increasing rouge severity, and the chromium oxide layer coexists with the iron oxide layer in samples with various degrees of rouging. Unlike the rouging observed for stainless steel pipes, the fast degradation of the rupture disc was caused by a crevice corrosion environment created by perforations in the protective Teflon coating. This failure analysis clearly shows the highly corrosive nature of ultrapure water used in the manufacture of pharmaceutical products, and demonstrates some of the unexpected corrosion mechanisms that can be encountered in these environments.     

Tissue-Specific Fatty Acid Composition of Glandular Trichomes of Mite-Resistant and -Susceptible Pelargonium xhortorum

Anacardic acids, alkyl phenolic acids excreted by tall glandular trichomes of the garden geranium, Pelargonium xhortorum, confer small-pest resistance. Up to 90% of the trichome exudate from mite-resistant P. xhortorum inbreds consists of an unusual anacardic acid with an unsaturated omega-5 (⁵) alkyl chain. As fatty acids are biochemical precursors to anacardic acids, we examined by GC the fatty acid composition of leaves, pedicels, petals, sepals, mature seeds, and glandular trichomes from pest-resistant and pest-susceptible Pelargonium inbred lines to determine the localization of ⁵-fatty acids within plant tissues. The fatty acid composition of lipid classes (galactolipids, phospholipids, and neutral lipids) extracted from glandular trichomes from mite-resistant pedicels were also examined. ⁵-Fatty acids (16:111 and 18:113) were found only in the glandular trichomes from pest-resistant geraniums (27.2% in trichomes of pedicels) and were localized predominantly in the phospho- and galactolipids (phosphatidylinositol, 25.9%; phosphatidylcholine, 18.2%; monogalactosyldiglyceride, 15.5%; and diglactosyldiglyceride, 14.0%).     

High-strength all-solid lithium ion electrodes based on Li4Ti5O12

A Li₄Ti₅O₁₂-Li_0.29La_0.57TiO₃-Ag electrode composite was fabricated via sintering the corresponding powder mixture. The process achieved a final relative density of 97% the theoretical. Relatively thick, ∼100 μm, electrodes were fabricated to enhance the energy density relatively to the traditional solid-state thin film battery electrodes. The sintered electrode composite delivered full capacity in the first discharge at C/40 discharge rate. Full capacity utilization resulted from the 3D percolated network of both solid electrolyte and metal, which provide paths for ionic and electronic transport, respectively. The electrodes retained 85% of the theoretical capacity after 10 cycles at C/40 discharge rate. The tensile strength and the Young's modulus of the sintered electrode composite are the highest reported values to date, and are at least an order of magnitude higher than the corresponding value of traditional tapecast “composite electrodes”. The results demonstrate the concept of utilizing thick all-solid electrodes for high-strength batteries, which might be used as multifunctional structural and energy storage materials.     

A preliminary assessment of the potential for “team science” in DOE Energy Innovation Hubs and Energy Frontier Research Centers

President Obama has called for the development of new energy technologies to address our national energy needs and restore US economic competitiveness. In response, the Department of Energy has established new R&D modalities for energy research and development designed to facilitate collaboration across disciplinary, institutional, and sectoral boundaries. In this research note, we provide a preliminary assessment of the potential for essential mechanisms for coordinated problem solving among diverse actors within two new modalities at the DOE: Energy Innovation Hubs and Energy Frontier Research Centers.     

NMR spectroscopic and thermodynamic studies of the etherate and the α, α′, and γ phases of AlH3

Aluminum hydride (alane; AlH₃) has been identified as a leading hydrogen storage material by the US Department of Energy. With a high gravimetric hydrogen capacity of 10.1 wt.%, and a hydrogen density of 1.48 g/cm³, AlH₃ decomposes cleanly to its elements above 60 °C with no side reactions. This study explores in detail the thermodynamic and spectroscopic properties of AlH₃; in particular the α, α′ and γ polymorphs, of which α′-AlH₃ is reported for the first time, free from traces of other polymorphs or side products. Thermal analysis of α-, α′-, and γ-AlH₃ has been conducted, using DSC and TGA methods, and the results obtained compared with each other and with literature data. All three polymorphs were investigated by ¹H MAS-NMR spectroscopy for the first time, and their ²⁷Al MAS-NMR spectra were also measured and compared with literature values. AlH₃·nEt₂O has also been studied by ¹H and ²⁷Al MAS-NMR spectroscopy and DSC and TGA methods, and an accurate decomposition pathway has been established for this adduct.