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Gas Chromatography-mass Spectrometry Analysis (gas + chromatography-mass_spectrometry_analysis)
Selected AbstractsSynergistic sex pheromone components of the grey-spotted tussock moth, Orgyia ericaeENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2010Guo-Fa Chen Abstract The grey-spotted tussock moth, Orgyia ericae Germar (Lepidoptera: Lymantriidae), is an important pest of deciduous trees and woody scrublands in northern China. In a field trapping experiment conducted during the flight of the first generation of 2009, synthetic (Z)-6-heneicosen-11-one, a common Orgyia spp. sex pheromone component, attracted O. ericae males. Gas chromatography-mass spectrometry analyses (full scan or selected ion-monitoring mode) of pheromone gland extracts from females revealed the presence of a major, a minor, and a trace component, i.e., (6Z,9Z)-heneicosa-6,9-diene, (6Z,9Z)-tricosa-6,9-diene, and (Z)-6-heneicosen-11-one, respectively. Field experiments during the flight of the second generation showed that (6Z,9Z)-tricosa-6,9-diene, the minor component, was inactive alone or in any combination with the other two components, whereas (6Z,9Z)-heneicosa-6,9-diene and (Z)-6-heneicosen-11-one were weakly attractive when tested individually. However, traps baited with a binary blend of (6Z,9Z)-heneicosa-6,9-diene and (Z)-6-heneicosen-11-one caught seven-fold more moths than any other treatment (except the ternary blend), indicating a strong synergistic interaction between the two components. The analytical and field trapping data suggested that (6Z,9Z)-heneicosa-6,9-diene and (Z)-6-heneicosen-11-one are likely the key sex pheromone components of female O. ericae. This synergistic blend will be useful as an efficient monitoring tool, and possible control tool, to combat this economically and ecologically important forest defoliator. [source] Oxidative transformation of tetrachlorophenols and trichlorophenols by manganese dioxideENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2009Ling Zhao Abstract This study examined the transformation kinetics of three tetrachlorophenols (TeCPs) and three trichlorophenols (TCPs) in the presence of MnO2 under different solution chemistry conditions. The reaction rate measured for each CP decreased as a function of solution pH, and under the same solution chemistry conditions, the measured rates may depend primarily on both the adsorbability at the MnO2 surfaces and the isomeric structures of the CPs. Isomeric effects indicated that chloro substituent on ortho or para positions exhibited faster rates of transformation than on meta positions. Gas chromatography-mass spectrometry analysis with a derivatization method showed that dimers including polychlorinated phenoxyphenols and chlorinated polyhydroxybi-phenyl were among the major products for all CPs. Monomeric products were among the major products of 2,4,6-TCP, 2,3,4-TCP, and 2,3,4,6-TeCP, whereas trimeric products also were among the major products of 2,3,4-TCP and 2,4,5-TCP. It appeared that hydroxylation of CPs and formation of dimeric or trimeric products via oxidative coupling were the major reaction mechanisms involved in the oxidation of CPs by MnO2. [source] Potential mechanism for detection by Apis mellifera of the parasitic mite Varroa destructor inside sealed brood cellsPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2002Caroline Martin Abstract The parasitic mite Varroa destructor Anderson & Trueman is a major pest of the honeybee Apis mellifera L. throughout the world. Chemical agents currently used for mite control leave contaminating residues and promote pesticide resistance. As an alternative means of control, it would be useful to identify natural substances enabling bees to detect Varroa inside brood cells. These substances could then be used to trigger mite hygienic behaviour by bees. In this study several techniques were used to screen substances that might allow detection of infested brood cells by bees. Gas chromatography-mass spectrometry analysis was performed on substances extracted in dichloromethane from the contents of brood cells. Solid phase microextraction and solid injection were performed on substances obtained from living and dead Varroa, respectively. Electroantennography was performed to assess the sensitivity of olfactory receptors in bee antennae to some of these substances. Principal component analysis based on proportions of cuticular substances allowed discrimination between bees and other cell contents. Foundress Varroa exhibited the greatest dissimilarity to healthy pupae that were used as controls. Immature Varroa and faecal material were intermediate. High molecular weight compounds, mainly dimethylalkanes, were proportionally the most characteristic components of foundress Varroa. This finding suggests that these compounds would be the most apt to induce uncapping of cells infested by Varroa. Solid-phase microextraction and solid injection demonstrated the presence of aliphatic acids, esters, and one alcohol, eicosenol, in Varroa. Electroantennographic recordings showed that mite-resistant bees were more responsive to some acids and one ester. We speculate that these compounds may be involved in recognition of living Varroa by honeybees. [source] The fatty acid compositions of predator Piocoris luridus (Heteroptera: Lygaeidae) and its host Monosteria unicostata (Heteroptera: Tingidae) reared on almondINSECT SCIENCE, Issue 6 2007OZLEM CAKMAK Abstract The changes in fatty acid compositions during nutritional interaction among almond Amygdalus communis Linnaeus (Rosales: Rosaceae) (host plant), lacebug Monosteria unicostata (Mulsant and Rey) (Heteroptera: Tingidae) and its predator Piocoris luridus Fieber (Heteroptera: Lygaeidae) were determined by gas chromatography and gas chromatography-mass spectrometry analyses. The fatty acid profiles of phospholipids and triacylglycerols were substantially different. Unlike the general observations for virtually most terrestrial insects, arachidonic and eicosapentaenoic acids were detected in high proportions of phospholipid fractions in both insects, especially in P. luridus. Also the almond tissues provide very little oleic acid to the herbivore diet, yet both insect species developed high proportions of this component. Our data reveals instances of specific accumulation of fatty acid biosynthesis, elongation/desaturation, and not incorporating selected fatty acids into cellular lipids. [source] Isolation and characterization of a bacterial strain of the genus Ochrobactrum with methyl parathion mineralizing activityJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2006X.-H. Qiu Abstract Aims:, To isolate and characterize a methyl parathion (MP)-mineralizing bacterium, and to elucidate the degradative pathway of MP and localize the responsible degrading genes. Methods and Results:, A bacterial strain, designated B2, capable of mineralizing MP was isolated from the MP-polluted soil. Analysis of the 16S rRNA gene sequence and phenotypic analysis suggested that strain B2 had a close relationship with Ochrobactrum anthropi. B2 could totally degrade MP and four metabolites [p -nitrophenol (PNP), 4-nitrocatechol (4-NC), 1,2,4-benzenetriol (BT) and hydroquinone (HQ)] were identified by HPLC and gas chromatography-mass spectrometry analyses. Plasmid curing of strain B2 resulted in the loss of ability of B2 to degrade PNP, but not the ability to hydrolyse MP. Conclusions:,Ochrobactrum sp. B2 can mineralize MP rapidly via PNP, 4-NC, BT and HQ pathway. B2 harbours a plasmid encoding the ability to degrade PNP, while MP-hydrolysing activity is encoded on the bacterial chromosome. Significance and Impact of the Study:, This new bacterial strain (B2) capable of mineralizing MP will be useful in a pure-culture remediation process of organophosphate pesticides and their metabolites such as nitroaromatics. [source] Stability and detection of ,-pinene oxide in aqueous culture mediumENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2000Kimberly K. Kajihara Abstract Methane consumption by methanotrophic bacteria was previously shown to be temporarily inhibited by ,-pinene. Based on literature considerations, loss of inhibition may be due to bacterial degradation of the monoterpene to ,-pinene oxide, an anticipated metabolite. However, since ,-pinene oxide is unstable in aqueous media, detection of its production by methanotrophs or other bacteria is problematic. Therefore, we used gas chromatography-mass spectrometry analysis to study the chemical breakdown of ,-pinene oxide in various buffer systems (Tris[hydroxymethyl]am inomethane, 3-[N-morpholino]propanesulfonic acid, phosphate; pH 7-9) suitable for bacterial whole-cell and cell-free experiments. In every case, aqueous phase ,-pinene oxide was unstable and its disappearance was accompanied by the appearance of five decomposition products in a characteristic fingerprint that was in part buffer dependent. However, this fingerprint was adequately stable in phosphate buffer such that its appearance could be used to infer the intermediacy of ,-pinene oxide if produced by the bacteria at or near their optimal pH. [source] Antibacterial substances of low molecular weight isolated from the blowfly, Lucilia sericataMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2007L. HUBERMAN Abstract Low molecular weight compounds were isolated by high-performance liquid chromatography from the maggot or haemolymph extracts of Lucilia sericata (Meigen) (Diptera: Calliphoridae). Using gas chromatography-mass spectrometry analysis, three compounds were obtained: p -hydroxybenzoic acid (molecular weight 138 Da), p -hydroxyphenylacetic acid (molecular weight 152 Da) and octahydro-dipyrrolo[1,2-a;1,,2,-d] pyrazine-5,10-dione (molecular weight 194 Da), also known as the cyclic dimer of proline (or proline diketopiperazine or cyclo[Pro,Pro]). All three molecules revealed antibacterial activity when tested against Micrococcus luteus and/or Pseudomonas aeruginosa, and the effect was even more pronounced when these molecules were tested in combination and caused lysis of these bacteria. [source] | ||||||||||