Geranyllinalool (Diterpene Alcohol) : An insecticidal component of pine wood and termites (Isoptera: Rhinotermitidae) in four European ecosystems.

Geranyllinalool is an insecticidal component of pine wood and of the defensive secretion ofReticulitermes species. Lethal doses (LD50) were calculated for termites and various ant species. Termite workers were very resistant (10,000 ppm). Ant resistance varies among species according to their trophic strategy and attack mode. The geranyllinalool acts as a natural insecticide against some ant predators (LD50=6 ppm), which use raid or chemical crypsis to invade termite nests. In contrast, predators laying the venom on the cuticle of their termite prey were very resistant (10,000 ppm). Generally, ants acting as space competitors could detoxify the quantity emitted by one termite soldier (18 ppm).

Alkaloid venom of European ants in the genus Monomorium. Site of synthesis, identification and quantification.

The venom of the European Ant Monomorium is composed of five alkaloids: three 2.5 transdialkylpyrrolidines and two 2.5 transdialkylpyrrolines. The venom is synthesized by a glandular complex composed of a biramous external filamentous gland, and a single internal gland invaginated into the reservoir. External glands and the proximal two-thirds of the internal gland are composed of glandular units, with one glandular cell and one associated duct cell. Glandular cells contain numerous giant mitochondria, a well-developed smooth endoplasmic reticulum and enigmatic rod-shaped structures. The secretory product is electron-lucent. The distal third of the internal gland is composed of 38-48 large secretory cells issuing directly into the reservoir. Their secretory product presents the same characteristics as the venom accumulated in the reservoir (opacity, affinity to stains and osmium).

[Not Available]. / Etude analytique des produits lourds du petrole-V Bromation des residus lourds petroliers au moyen d'un reactif original, le tribromure de tetrabutylammonium, et essais preliminaires de determination d'un indice de brome applicable aux fractions lourdes.

A new method of bromine number determination appropriate to heavy-ends petroleum is reported. This method, which uses an electrochemical titration and tetrabutylammonium tribromide as reagent, has been tested on Boscan atmospheric residues. The titration of the unreacted tribromide ions and of the bromide ions produced enables the proportion of the bromine addition to multiple bonds and the proportion of substitution reactions with aromatic compounds (phenols, amines, etc.) to be estimated. The sensitivity and reproducibility of this easy method are both good.

[Assignment, by proton magnetic resonance, of histidines of dihydrofolate reductase from chicken liver]. / Affectation, par résonance magnétique de protons, des histidines de la dihydrofolate réductase de foie de poulet.

The effects of pH and temperature upon C epsilon 1 H resonances of the four histidyl residues of chicken liver dihydrofolate reductase in binary complex with methotrexate were studied by 500-MHz 1H NMR spectroscopy. The four histidines labelled a, b, c, d are distinguishable by their pK values and the chemical shifts of their C epsilon 1H protons. The local electromagnetic environment as deduced from X-ray studies at 2.9 A resolution was used as a basis for proposed assignment of the four histidines. The assignments were a: H42, b: H140, c: H131, d: H87. Furthermore the histidyl residue labelled c was shown to be upfield shifted in its C epsilon 1H proton in the enzyme-methotrexate complex compared to the native enzyme. The hypothesis of a conformational change of the protein is discussed.