Chemical model for phosphine‐induced lipid peroxidation

Phosphine (PH₃) from hydrolysis of metal phosphides is highly toxic and is important for control of stored‐product insect pests (AlP, Mg₃P₂) and rodents (Zn₃P₂). This fumigant inhibits respiration and induces lipid peroxidation in insects and mammals. PH₃ (from Mg₃P₂) and H₂O₂, acting for 15 min in phosphate buffer (pH 7.4), oxidized cod liver oil (high in unsaturated lipids) to malondialdehyde. Both Mg₃P₂ and H₂O₂ were found to be necessary for this lipid peroxidation, which under optimal conditions produced a seven‐fold increase in malondialdehyde relative to basal levels in cod liver oil with H₂O₂ but no PH₃. Under the same conditions, 15‐, 9‐ and 2‐fold increases in malondialdehyde were obtained from ethyl arachidonate, methyl linoleate and methyl oleate. Small amounts of hydroxyl radical from PH₃/H₂O₂ were trapped with salicylic acid. Reactive oxygen species for lipid peroxidation may therefore be derived from direct reaction of PH₃ with H₂O₂ as an alternative hypothesis to their respiration‐linked formation. © 2000 Society of Chemical Industry     

Discovery of highly insecticidal synthetic spinosyn mimics – CAMD enabled de novo design simplifying a complex natural product

Simplifying complex natural products: Computer modeling‐based design leads to highly insecticidal, chemically simpler synthetic mimics of the spinosyn natural products that are active in the field. © 2018 Society of Chemical Industry     

Intellectual property in entomology: Analysis and perspective on recent trends in global patent publications

Intellectual property (IP) is an important consideration for entomological research and provides a means to capture value from new discoveries. Herein, we describe an analysis of more than 26 000 patent publications from 2007–2017 related to the field of entomology. These patents were divided among 8000 patent assignees; however, only 5% of the assignees had ≥10 patents. Corporations accounted for the largest share of patents (59%), with individuals (20%), academic institutions (17%) and government organizations (4%) making up the remaining segments. From 2007–2017 the number of entomological patents increased by 400%, with the largest number being from China. However, unlike patents from Europe, Japan or the US, which target a range of countries, the Chinese patents almost exclusively focus on China. Among the array of subjects covered are transgenic insects and plants, repellents, recombinant insect cells, with the highest proportion of patents focused on insecticides (39%), followed by insecticide mixtures (27%) and formulations (21%). The top 30 patent assignees included companies/institutions from China (18), Europe (3), Japan (6) and the US (3). Among the top 12 entities, IP from the US assignees was distributed across insecticides, mixtures and insecticidal traits while those from China were more focused on mixtures. However, given expanding IP numbers from China it is expected that in the future there will be a greater impact on new insecticides and related technologies. © 2020 Society of Chemical Industry     

Cover Image,Volume 75, Issue 9

The cover image is based on the Perspective Natural Products: A Strategic Lead Generation Approach in Crop Protection Discovery by Beth A Lorsbach et al., https://doi.org/10.1002/ps.5350 .

     

Trifluoromethylketones as possible transition state analog inhibitors of juvenile hormone esterase

A series of compounds containing the trifluoromethylketone group have been synthesized utilizing either a modified Grignard procedure or by reacting selected aliphatic bromides or tosylates with the Collman reagent [Na₂Fe(CO)₄]. When tested in vitro as inhibitors of crude juvenile hormone esterase from the hemolymph of the cabbage looper, Trichoplusia ni (Noctuidae), the most active compounds were trifluoromethylketones possessing either a juvenoid-like structure or a straight aliphatic chain. The logarithm of the inhibitory potency of the aliphatic compounds was proportional to their chain length, up to 1,1,1-trifluorotetradecan-2-one (I₅₀ = 1 × 10^?7M). This powerful inhibition was found to be highly selective for JHE, reversible, competitive by Lineweaver-Burk analysis, and was characterized by high affinity of the inhibitor for the esterase (K_i = 3.2 × 10^?9M, K_m JH III = 2 × 10^?7M). Other trifluoromethylketones were shown to be inhibitors of T. ni α-naphthylacetate esterase and bovine trypsin. By analogy with the mechanism of trypsin action, trifluoromethylketones are probably potent inhibitors due to their resemblance to a tetrahedral transition state on the reaction coordinate to the acylated enzyme.     

Saccades are spatially, not retinocentrically, coded

Most models of the saccadic eye movement system imply that saccades are programmed for a certain distance and direction. Electrical stimulation of the brain was used to move the eyes of monkeys just before saccades to visual targets. Despite the stimulation-induced perturbation, saccades brought gaze to the target locations. This compensation indicates that saccades are coded to direct the eyes to a certain position in the orbit (or in space).     

When is a habitat not a habitat? Dramatic resource use changes under differing weather conditions for the butterfly Plebejus argus

A key to conserving organisms is identification of the habitat bounds and essential resources within them. In population studies (metapopulations) of phytophagous arthropods it is tacitly assumed that habitat bounds portray short-term stability and that habitat is largely synonymous with hostplant areas or with a single vegetation unit comprising hostplants; structural components are usually ignored. We test these assumptions by monitoring the behaviour and relative abundance of Plebejus argus (L.) (Lepidoptera: Lycaenidae) in relation to changing weather conditions in two patches of a North Wales metapopulation for the butterfly. Our findings confirm the importance of structural habitat components. P. argus density is higher in the vicinity of shrubs which are used for roosting, resting, basking, mate location and shelter. A dominant proportion of the population adopts shrub areas in cooler, cloudy and windy weather. In warmer, sunnier and calmer conditions, the butterfly spends longer in flight and moves out onto calcareous heath dominated by hostplants. In doing so, an increasing, even dominant, proportion of the population occupies exposed slopes adjacent to and above shrub covered areas associated with the hostplant. In effect, the habitat bounds appear to change with conditions on scales of days and hours. What part of a landscape may be defined as a habitat, and what part of it may appear to be most important for an organism, depends on just when and where surveys are carried out. We argue that for correct delineation of habitats attention needs to be given to resource use in different conditions. In the face of enhanced global warming, a broad view should be taken of arthropod habitats that considers the resources required for varying conditions.     

Magma flow instability and cyclic activity at soufriere hills volcano, montserrat, british west indies

Dome growth at the Soufriere Hills volcano (1996 to 1998) was frequently accompanied by repetitive cycles of earthquakes, ground deformation, degassing, and explosive eruptions. The cycles reflected unsteady conduit flow of volatile-charged magma resulting from gas exsolution, rheological stiffening, and pressurization. The cycles, over hours to days, initiated when degassed stiff magma retarded flow in the upper conduit. Conduit pressure built with gas exsolution, causing shallow seismicity and edifice inflation. Magma and gas were then expelled and the edifice deflated. The repeat time-scale is controlled by magma ascent rates, degassing, and microlite crystallization kinetics. Cyclic behavior allows short-term forecasting of timing, and of eruption style related to explosivity potential.