This study shows that the pheromone biosynthesis activating neuropeptide (PBAN) is involved in the regulation of sex pheromone biosynthesis in
Thaumetopoea pityocampa.
In vitro incubation of ...pheromone glands with PBAN resulted in a dose-dependent increase in pheromone titer. The formation of labeled pheromone from deuterated 11-hexadecynoic acid was stimulated in pheromone glands upon
in vitro incubation with PBAN. However, no differences were found between PBAN-treated glands and controls in the amounts of labeled intermediates.
In vivo experiments with deuterated (Z)-11-hexadecenoic acid and 11-hexadecynoic acid showed that 12,13-methylenehexadec-12-enoic acid inhibited both the δ-11 desaturation of (Z)-11-hexadecenoic acid and the Z-13 desaturation of 11-hexadecynoic acid. The amounts of natural pheromone produced by pheromone glands topically treated,
in vivo, with 12,13-methylenehexadec-12-enoic acid and further incubated,
in vitro, with PBAN were similar to those found in glands that had not been administered the inhibitor. Topical application of (Z)-13-hexadecen-11-yn-l-ol to pheromone glands
in vivo resulted in the formation of the corresponding acetate. All these results indicate that PBAN controls pheromone biosynthesis in the processionary moth by regulating a step involved in the transformation of the enyne acyl intermediate into the enynol.
Deuterium-labeled fatty acids have been used to elucidate the sex pheromone biosynthetic pathway in Spodoptera littoralis.
Label from palmitic acid was incorporated during the scotophase into all the ...pheromone acetates and their corresponding fatty
acyl intermediates. (Z,E)-9,11-tetradecadienyl acetate, the major component of the pheromone blend, is synthesized from palmitic
acid via tetradecanoic acid, which, by the action of a specific (E)-11 desaturase and subsequently a (Z)-9 desaturase, is
converted into (Z,E)-9,11-tetradecadienoate. By further reduction and acetylation, this compound leads to the dienne acetate.
Deuterated precursors applied to the pheromone gland during the photophase were also incorporated into the pheromone. The
percentage of labeled (Z,E)-9,11-tetradecadienyl acetate relative to natural compound was significantly higher during the
light period. Label incorporation from different intermediates into the pheromone was stimulated by injection of brain-subesophageal
ganglion extract during the photophase. The influence of the pheromone biosynthesis-activating neuropeptide on the biosynthetic
pathway is discussed.
Inhibition of sex pheromone production has been observed after topical treatment of pheromonal glands with DMSO solutions of 2-bromohexadecanoic acid, in three lepidopteran insects: Spodoptera ...littoralis, Thaumotopoea pityocampa, and Bombyx mori. It has been shown that this effect was brought about by action on the reductases and acetyltransferases of the final steps of the pheromones biosynthesis. Other halofatty acids, such as 2-fluoro- and 2-chlorohexadecanoic acids, were less active than the above bromoderivative whereas 2-bromotetradecanoic acid and 2-bromooctanoic acid exhibited activities quite comparable to the C-16 bromoacid. These results indicate that bromosubstitution is very important for this inhibitory action and chain length is of secondary importance.
Analysis by gas chromatography coupled to mass spectrometry demonstrated that 11,12-methylenehexadec-11-enoic acid and 12,13-methylenehexadec-12-enoic acid are beta-oxidized in Spodoptera littoralis ...sex pheromone gland to 9, 10-methylenetetradec-10-enoic acid and 10,11-methylenetetradec-10-enoic acid, respectively. This result supported our previous hypothesis that inhibition of the (Z)-9 desaturation of (E)-11-tetradecenoic acid by those C-16 fatty acids is actually caused by their corresponding beta-oxidation products. However, although (2,2,3,3-2H4)-11,12-methylenehexadec-11-enoic acid was not chain-shortened to the C-14 derivative, its activity as inhibitor of the (Z)-9 desaturation reaction was similar to that exhibited by 11,12-methylenehexadec-11-enoic acid. Therefore, the C-16 cyclopropene fatty acids may inhibit the (Z)-9 desaturation enzyme by themselves, probably through interaction of the cyclopropene ring with a binding site of the enzyme with the substrate double bond.
A simple enzymatic methodology for the selective monoacetylation of 1,
n-diols (
n=5,8) using immobilised
Thermomyces lanuginosus lipase in different organic media is reported.
A simple enzymatic ...methodology for the selective monoacetylation of 1,
n-diols (
n=5,8) using vinyl acetate is reported. Monoacetylation excesses of 81–87% at 74–90% 1,
n-diol conversions were obtained in toluene and diisopropyl ether using
Thermomyces lanuginosus lipase (TLL) immobilised on polypropylene powder as catalyst.
An improved competitive indirect immunoassay for the detection of 2,4,6-trichlorophenol (2,4,6-TCP) has been developed and optimized by preparing heterologous haptens that have been evaluated as ...coating antigens. The relation between the degree of heterology and immunoassay detectability has been investigated according to the geometric and electronic distribution similarities between the haptens and the analyte using molecular modeling tools. The assay has been characterized according to different physicochemical parameters such as the incubation time, the ionic strength, the effect of detergents and the pH. The resulting assay has an IC
50 of 1.44
μg
l
−1 and a limit of detection (LOD) of 0.2
μg
l
−1 and it shows a good accuracy and suitability to analyze trichlorophenol in drinking water.
Cultured plants of Ajuga nipponensis contained cyasterone (1), ajugasterone C (2), cyasterone-22-acetate (3) and 22-dehydrocyasterone (4) based on HPLC and NMR data, whereas 20-hydroxyecdysone was ...not detectable. The presence of compounds 2-4 is reported for the first time in this species. Compound 1 is the main phytoecdysteroid component found in both preblossom and blossom plants, but the latter contained higher amount than the former. Compared with other parts of the plant, the highest percentage of 1 and 3 occurred in leaves, amounting to 60.1% and 88.0% respectively, whereas the flowers contained mainly 2, which represented 72.8% of the total amount in whole plant. The contents of phytoecdysteroids in stems were very low.
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