Matrix-assisted laser desorption/ionization analysis of lipids and high molecular weight hydrocarbons with lithium 2,5-dihydroxybenzoate matrix

Lithium 2,5-dihydroxybenzoate (LiDHB) is shown to be a very effective matrix for matrix-assisted laser desorption/ionization (MALDI) analysis of nonpolar long-chain lipids, hydrocarbons and polymers. Under standard desorption and ionization conditions

MALDI imaging of neutral cuticular lipids in insects and plants

The spatial distribution of neutral lipids and hydrocarbons has been imaged using MALDI-TOF mass spectrometry on intact plant and insect surfaces, namely wings and legs of the gray flesh fly (Neobellieria bullata), wings of common fruit fly (Drosophila melanogaster), leaves of thale cress (Arabidopsis thaliana), and leaves of date palm tree (Phoenix sp.). The distribution of wax esters (WEs) and saturated and unsaturated hydrocarbons (HCs) was visualized. The samples were attached on a target and multiply sprayed with lithium or sodium 2,5-dihydroxybenzoate. The deposits were homogenous, consisting of small islands (50–150 μm) of matrix crystals separated by small areas (10 μm) of uncovered cuticle. Samples of N. bullata wings were found to contain HCs and WEs distributed close to their basal parts. The distribution of sodium and potassium ions was visualized on samples prepared by sublimation of 2,5-dihydroxybenzoic acid. Pheromonal dienes were detected on D. melanogaster female wings. A homogenous distribution of saturated WEs was observed on A. thaliana and Phoenix sp. leaf samples. The optimum number of laser shots per pixel was found to be higher than for polar compounds imaging

Structural identification of an anthrasteroid hydrocarbon from the sheep tick Ixodes ricinus

A new anthrasteroid hydrocarbon was isolated from cuticular integument of engorged female Ixodes ricinus, and its structure was determined by interpretation of spectroscopic and nuclear magnetic resonance data as 14 alpha(H)- 1(10 -> 6)-abeo- cholesta-

Explosive behaviour in workers of the snapping termite Neocapritermes taracua: Is there anything ordinary ?

info:eu-repo/semantics/publishe

Residues of diflubenzuron on horse chestnut (Aesculus hippocastanum) leaves and their efficacy against the horse chestnut leafminer, Cameraria ohridella

Residues of the insect growth regulator diflubenzuron were quantified on horse chestnut (Aesculus hippocastanum L.) leaves treated with a diflubenzuron 480 g litre(-1) SC, Dimilin. To analyse the samples, an analytical procedure was developed involvin

Chemical and vibratory signals used in alarm communication in the termite Reticulitermes flavipes (Rhinotermitidae)

Termites have evolved diverse defence strategies to protect themselves against predators, including a complex alarm communication system based on vibroacoustic and/or chemical signals. In reaction to alarm signals, workers and other vulnerable castes flee away while soldiers, the specialized colony defenders, actively move toward the alarm source. In this study, we investigated the nature of alarm communication in the pest Reticulitermes flavipes. We found that workers and soldiers of R. flavipes respond to various danger stimuli using both vibroacoustic and chemical alarm signals. Among the danger stimuli, the blow of air triggered the strongest response, followed by crushed soldier head and light flash. The crushed soldier heads, which implied the alarm pheromone release, had the longest-lasting effect on the group behaviour, while the responses to other stimuli decreased quickly. We also found evidence of a positive feedback, as the release of alarm pheromones increased the vibratory communication among workers and soldiers. Our study demonstrates that alarm modalities are differentially expressed between castes, and that the response varies according to the nature of stimuli

New diterpenoid glucoside and flavonoids from Plectranthus scutellarioides (L.) R. Br

Three new compounds, diterpenoid glucoside (13S,15S)-6\u3b2,7\u3b1,12\u3b1-trihydroxy-13\u3b2,16-cyclo-8-abietene-11,14-dione 7-O-\u3b2-D-glucoside 1, flavonoids apigenin 7-O-(3\u2032\u2032-O-acetyl)-\u3b2-D-glucuronide 2 and apigenin 5-O-(3\u2032\u2032-O-acetyl)-\u3b2-D-glucuronide 3, together with known compounds caffeic acid 4, luteolin 5-O-\u3b2-D-glucoside 5 and rosmarinic acid 6 were isolated from the aerial parts of Plectranthus scutellarioides (L.) R. Br. The structures of the new compounds were elucidated by spectroscopic and mass-spectrometric analyses, including 1D- and 2D-NMR. Compound 1 inhibited hyaluronidase by 25% at the concentration of 200 \u3bcM, compounds 2 and 3 showed inhibitory activity on butyrylcholinesterase better than standard galanthamine at the concentration of 100 \u3bcM, and compound 6 is a potent antioxidant with an ORAC value of 2.15 \ub1 0.12