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The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze both hydrolysis at high water contents and transesterification in quasi-anhydrous conditions. Here, we investigated the Thermomyces lanuginosa lipase structure in solution in the presence of a tributyrin aggregate using 30 ns molecular-dynamics simulations. The water content of the active-site groove was modified between the runs to focus on the protein-water molecule interactions and their implications for protein structure and protein-lipid interactions. The simulations confirmed the high plasticity of the lid fragment and showed that lipid molecules also bind to a secondary pocket beside the lid. Together, these results strongly suggest that the lid plays a role in the anchoring of the protein to the aggregate. The simulations also revealed the existence of a polar channel that connects the active-site groove to the outside solvent. At the inner extremity of this channel, a tyrosine makes hydrogen bonds with residues interacting with the catalytic triad. This system could function as a pipe (polar channel) controlled by a valve (the tyrosine) that could regulate the water content of the active site.

Twelve Gossypiumgenotypes (species, fertile interspecific allotetraploid and allohexaploid hybrids, backcross progeny of interspecific hybrids) characterized by drastic differences in their seed gossypol content were used to design a visual quantification method of the gossypol concentration in cotton seeds. After developing an high performance liquid chromatography (HPLC) method that allowed measurement of gossypol content in single seed samples, the results of 123 HPLC analyses carried out seed‐by‐seed were compared with different parameters characterizing the level of gossypol glands in the seed. A significant correlation was found between the gossypol content %Gdetermined on single seeds by HPLC and the number Nof gossypol glands per seed section area (S, expressed in mm2), leading to the establishment of the following model: %G= bi(N/S), where the regression coefficient bidepends on the cotton genotype considered. The estimation of %Gdirectly from N/Sis a rapid and accurate method which can be used in breeding programs to screen the progeny of cotton genotypes showing a high segregation for their seed gossypol content.

Summary. Aphidophagous ladybirds are reluctant to oviposit in patches of prey where conspecific larvae are present. This is adaptive as larval cannibalism is a major threat to egg survival. Ladybirds avoid laying eggs in such patches by responding to a species specific oviposition deterring pheromone present in the tracks of larvae. This study revealed that the oviposition deterring pheromone consists of a mixture of alkanes of which n-pentacosane is the major component (15.1%). These alkanes are likely to spread easily on the hydrophobic cuticle of plants and so leave a large signal. In addition, they are not quickly oxidized and therefore provide a long lasting signal. The latter was confirmed by the observation that 10 day old tracks still deterred oviposition.

Summary.: Young larvae of Adalia bipunctata search an area more intensively when exposed to the odour from other larvae feeding on aphids than when exposed only to the odour of aphids. In an olfactometer young larvae were significantly attracted either to the odour of crushed aphids or larvae feeding on aphids, but not to that of aphids, larvae, larvae plus aphids or larvae feeding on an artificial diet. That is, the change in searching behaviour appears in response to a volatile released by aphids when attacked. The odour released by crushed aphids is made up entirely of aphid alarm pheromone, β-farnesene. It is likely that the adaptive significance of this response is that it increases the ability of larvae to locate larvae that have already caught prey. By sharing the aphid kill of another larva it is likely that a first instar ladybird larva greatly increases its probability of surviving to the next instar. It is suggested that this social feeding is facilitated by egg clustering, which also may additionally account for why aphidophagous ladybirds lay their eggs in clusters.

Summary.: The eggs of some ladybirds are known to be toxic to intraguild ladybird predators. However, this defence is of little value if the eggs are killed before their toxicity becomes apparent. The results presented in this paper indicate that chemicals on the surface of the eggs of two species of ladybirds signal the relative risk of cannibalism and intraguild predation. In Adalia bipunctata and Coccinella septempunctata, 87% of the chemicals are alkanes. Each species of ladybird is less reluctant to eat their own eggs than those of the other species. This asymmetry is to be expected because there is a greater risk to ladybirds from intraguild predation than cannibalism. Similar alkanes to those on the surface of the eggs of A. bipunctata are present in tracks left by larvae and on the elytra of the adults of this species. Those in the larval tracks deter females from ovipositing in patches of prey already being attacked by their larvae and those on the elytra are used in mate recognition. That different context dependent messages could be signalled by similar chemicals is an example of semiochemical parsimony.

A method for the isotope dilution-mass spectrometric (ID-MS) determination of butyric acid C4 in butter fat (RM164) was developed in order to support the data gathered from nine experienced European laboratories within the final certification exercise. The ID-MS results (3,46±0,06 g C4/100 g fat) were in very good agreement with those obtained by “classical” GLC and HPLC techniques. (RM164 was finally certified at 3,49±0,06 g C4/100 g fat). This paper reports briefly on a previous preliminary study undertaken to validate a procedure (agreed by the BCR-sterol group) for the isolation of the sterol from fats and oils. By use of labelled sterols and radiometric measurements it was shown that sterol recoveries were superior to 96%.

A methodology for the analysis of dexamethasone and related compounds is proposed. Nine corticoids (corticosteroids) have been separated by TLC and by normalphase HPLC. The optimization of the HPLC separation is performed on a diol column and with a n-hexane/isopropanol (80:20) mobile phase. Mass spectrometry is used to elucidate the nature of the compounds isolated from illicit drug formulations and to confirm the structure of synthesised derivatives from the parent dexamethasone.

Biological activity of leaves, fruits and extract of the African shrubBoscia senegalensis (PERS.) LAM. ex Poir. was evaluated against five stored-grain insects. When added to cowpeas at 2–4% (w/w), fresh ground fruits and leaves caused 80–100% mortality inCallosobruchus maculants (F.) adults and significantly reduced both emergence and damage of the F1 progeny. Acetone fruit extract exhibited a potent fumigant effect onProstephanus truncatusHorn, C.maculatus, andSitotroga cerealella OLIV.; with LT50 values of 3.8, 2.3, and below 1.5 hr, respectively. LC50 determination forB. senegalensis fruits and leaves as well as pure methylisothiocyanate (MITC) onTribolium castaneum HERBST,Sitophilus zeamais MOTSCH. andC. maculatus showed a differential response of the insects to plant parts or MITC. Quantitative dosage ofBoscia active components and LC50 values obtained for the plant tissues, compared to those of pure molecules, indicate that the biological activity ofB. senegalensis is due to the liberation of MITC from a glucosinolate precursor glucocapparin contained inBoscia fruits and leaves.

Citronellol esterification catalyzed byCandida antarcticalipase is performed with high yields (74%) in a solvent-free medium. The use of dessicants gives a 10% yield enhancement and substrate excess consumption by adding calculated amounts of acetic acid lead to a 80% pure citronellyl acetate. Quantities up to 100 ml are treated with success.

Six sterols were extracted from lipids produced by Candida curvata yeast. Ergosterol (main component) and five minor compounds: ergosta-7, 24(28)-dien-3 β-ol, ergosta-5, 7-dien-3 β-ol, ergosta-5, 7, 9, (11), 22-tetraen-3 β-ol, ergosta 7, 22-dien-3 β-ol, ergost-7-en-3 β-ol were identified by gas chromafography/mass spectrometry (GCMS) and quantitated by GLC.

Despite the general high sensitivity of protozoa to shearing effects,Tetrahymena rostratawas cultivated using a controlled fed batch fermentor; the feeding medium contained 15 % skimmed milk. With an unchanged growth rate, final cell concentration (14.105cell/ml) was 4 times higher than in simple batch culture. γ-Linolenic acid (16 % of the total fatty acids) reached 0.5 gr/l medium.

The synthesis of symmetrical and asymmetrical palmito- and stearo-elaidic triglycerides (PEP, SES, EPP, PEE, ESS, and SEE, in which P=palmitic, S=stearic, and E=elaidic acid) was undertaken to investigate their polymorphism. The chemical pathways and the purification steps, including crystallization and adsorption chromatography, are described. The different chromatographic analyses (gas-liquid chromatography: carbon number profile and fatty acid methyl ester profile, and high-performance liquid chromatography) revealed that the purity of the synthesized products was superior to 99% except for SES (>96%). The thermal behavior, as well as the polymorphism of these triglycerides, has been investigated by means of differential scanning calorimetry and powder X-ray diffraction spectroscopy at variable temperatures. The six compounds crystallize according to a double chainlength packing. The most stable polymorphic form of palmito-elaidic triglycerides belongs to the ß' variety, whereas the stearo-elaidic triglycerides are ß stable.

The synthesis of symmetrical and asymmetrical palmito- and stearo-elaidic triglycerides (PEP, SES, EPP, PEE, ESS, and SEE, in which P=palmitic, S=stearic, and E=elaidic acid) was undertaken to investigate their polymorphism. The chemical pathways and the purification steps, including crystallization and adsorption chromatography, are described. The different chromatographic analyses (gas-liquid chromatography: carbon number profile and fatty acid methyl ester profile, and high-performance liquid chromatography) revealed that the purity of the synthesized products was superior to 99% except for SES (>96%). The thermal behavior, as well as the polymorphism of these triglycerides, has been investigated by means of differential scanning calorimetry and powder X-ray diffraction spectroscopy at variable temperatures. The six compounds crystallize according to a double chainlength packing. The most stable polymorphic form of palmito-elaidic triglycerides belongs to the β′ variety, whereas the stearo-elaidic triglycerides are β stable.

The oxidative stability of borage (Borago officinalisL.) oils from commercial origin or extracted by different methods (with solvents and supercritical CO2) was determined by the Rancimat method. To delay the oxidative degradation with the aim of preserving the nutritional characteristics of borage oil, several borage—virgin olive oil blends were prepared and submitted to analysis. The results indicated that the incorporation of borage in virgin olive oil (to a level not exceeding 50 g/kg) while modifying the fatty acid profile of the resulting blends had a limited effect on the oxidative stability provided that the blends were maintained in the absence of light.

Myrtus communisL. essential oils were obtained by hydrodistillation, and the yields were 0.3% (w/w) and 0.1% for leaves and berries, respectively. Using gas chromatography (GC) and gas chromatography/mass spectometry (GC/MS), 25 components were identified in berry oil representing 89.5% of the oil composition. Linalool was the major compound in berry oil (36.2%) followed by estragole (18.4%) and 1,8-cineole (11.4%). Leaf oil was composed of 28 compounds representing 95.4% of the total composition of the oil. α-pinene was the major constituent of leaf oil at a concentration of (46.9%), followed by 1,8-cineole (25.2%). The two Algerian oils were characterized by the lack of myrtenyl acetate.

Mycotoxins are naturally occurring toxic chemical compounds produced by fungi infesting agricultural crops both during their growth and storage. Such secondary metabolites, when ingested, can produce toxic syndromes in humans. As it has been suggested that mycotoxins might be involved in the development of Kashin-Beck disease (KBD), we undertook a survey of barley grains of KBD-affected families and non-affected families in that country. We found, by thin layer chromatography, a hitherto unknown metabolite of Alternariasp. This was especially common on the barley grains of KBD-affected families. Les mycotoxines sont des métabolites secondaires produits des champignons infestant les céréales au cours de la période culturale ou durant le stockage des grains. De telles substances chimiques peuvent être toxiques vis-à-vis de l'homme lorsqu'elle sont ingérées. La contamination des grains de céréales par des mycotoxines constitue toutefois une piste sérieuse pour la compréhension de l'étiologie de la maladie de Kashin-Beck. Nous avons entrepris des analyses de plusieurs mycotoxines sur des échantillons de grains d'orge provenant de familles malades et de familles non malades au Tibet. Un métabolite, encore inconnu, produit par Alternariaspp. a été détecté dans les échantillons de grains provenant des familles malades.

Adalinine (2), a new piperidine alkaloid, has been isolated from the European two-spotted ladybird beetle Adalia bipunctata, and its structure has been determined by spectroscopic methods. This alkaloid was also shown to be present in all the life cycle stages of Adalia bipunctata as well as in the adults of a related species, A. decempunctata.

The essential oil of Deverra scoparia Coss. &; Durieu was investigated for its acaricidal activity against the worldwide pest twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). The essential oil was analyzed by fast gas chromatography (GC) and GC-mass spectrometry. The activities of its individual and blended constituents were determined. Our study showed that female mortality increased with increasing D. scoparia oil concentrations, with LD50 and LD90 values at 1.79 and 3.2 mg liter−1, respectively. A reduction in fecundity had already been observed for concentrations of 0.064, 0.08, and 0.26 mg liter−1 D. scoparia essential oil. Ten major components, comprising 98.52% of the total weight, were identified; α-pinene was the most abundant constituent (31.95%) followed by sabinene (17.24%) and &incrmnt;3-carene (16.85%). The 10 major constituents of D. scoparia oil were individually tested against T. urticae females. The most potent toxicity was found with α-pinene, &incrmnt;3-carene, and terpinen-4-ol. The presence of all constituents together in the artificial mixture caused a significant decrease in the number of eggs laid by females, at 0.26 mg liter−1 (11 eggs), compared with the control (50 eggs). The toxicity of blends of selected constituents indicated that the presence of all constituents was necessary to reproduce the toxicity level of the natural oil.