共查询到20条相似文献,搜索用时 31 毫秒
1.
Gołębiowski M Boguś MI Paszkiewicz M Stepnowski P 《Analytical and bioanalytical chemistry》2011,399(9):3177-3191
The main function of cuticular lipids in insects is the restriction of water transpiration through the surface. Lipids are
involved in various types of chemical communication between species and reduce the penetration of insecticides, chemicals,
and toxins and they also provide protection from attack by microorganisms, parasitic insects, and predators. Hydrocarbons,
which include straight-chain saturated, unsaturated, and methyl-branched hydrocarbons, predominate in the cuticular lipids
of most insect species; fatty acids, alcohols, esters, ketones, aldehydes, as well as trace amounts of epoxides, ethers, oxoaldehydes,
diols, and triacylglycerols have also been identified. Analyses of cuticular lipids are chemically relatively straightforward,
and methods for their extraction should be simple. Classically, extraction has relied mainly on application of apolar solvents
to the entire insect body. Recently, several alternative methods have been employed to overcome some of the shortcomings of
solvent extraction. These include the use of solid-phase microextraction (SPME) fibers to extract hydrocarbons from the headspace
of heated samples, SPME to sample live individuals, and a less expensive method (utilized for social wasps), which consists
of the collection of cuticular lipids by means of small pieces of cotton rubbed on the body of the insect. Both classical
and recently developed extraction methods are reviewed in this work. The separation and analysis of the insect cuticular lipids
were performed by column chromatography, thin-layer chromatography (TLC), high performance liquid chromatography with a laser
light scattering detector (HPLC-LLSD), gas chromatography (GC), and GC–mass spectrometry (MS). The strategy of lipid analysis
with the use of chromatographic techniques was as follows: extraction of analytes from biological material, lipid class separation
by TLC, column chromatography, HPLC-LLSD, derivatization, and final determination by GC, GC-MS, matrix-assisted laser desorption/ionization
(MALDI) time-of-flight (TOF) MS, and liquid chromatography–mass spectrometry (LC-MS). 相似文献
2.
Manuela Reitz Heike Gerhardt Christian Schmitt Oliver Betz Klaus Albert Michael Lämmerhofer 《Analytica chimica acta》2015
This article reports on the chemical analysis of molecular profiles of tarsal secretions of the desert locust Schistocerca gregaria (Forsskål, 1775) by gas chromatography hyphenated with quadrupol mass spectrometry (GC–MS) as well as 1H-nuclear magnetic resonance (1H NMR) spectroscopy. Special focus of this study was to elaborate on sampling methods which enable selective microscale extraction of insect secretions in a spatially controlled manner, in particular tarsal adhesive secretions and secretions located on cuticle surfaces at the tibia. Various solvent sampling procedures and contact solid-phase microextraction (SPME) methods were compared in terms of comprehensiveness and extraction efficiencies as measured by signal intensities in GC–MS. Solvent sampling with water as extraction solvent gave access to the elucidation of chemical profiles of polar compound classes such as amino acids and carbohydrates, but is extremely tedious. Contact SPME on the other hand can be regarded as a simplified and more elegant alternative, in particular for the lipophilic compound fraction. Many proteinogenic amino acids and ornithine as well as carbohydrate monomers arabinose, xylose, glucose, and galactose were detected in tarsal secretions after acid hydrolysis of aqueous extracts. Qualitatively similar but quantitatively significantly different molecular profiles were found for the lipid fraction which contained mainly n-alkanes and internally branched monomethyl-, dimethyl-, and trimethyl-alkanes in the C23–C49 range as well as long chain fatty acids and aldehydes. Especially, hydrocarbons with >C40 carbon numbers have previously been rarely reported for insect secretions. The results suggest that the investigated insect secretions are complex emulsions which allow the attachment of tarsi on various otherwise incompatible materials of smooth and rough surfaces. The solid consistence of the established alkanes at ambient temperatures might contribute to a semi-solid consistence of the adhesive, amalgamating partly opposing functions such as slip resistance, tarsal release, desiccation resistance, and mechanical compliance. The methods developed can be extended to other similar applications of studying compositions of insect secretions of other species. 相似文献
3.
M Beroza 《Journal of chromatographic science》1975,13(7):314-321
Methods currently in use in the extraction, isolation, and identification of insect sex attractants, which are needed for use in pest control, are described briefly. Because amounts of these materials in insects are generally minute, specialized microanalytical methods and techniques have been developed to aid in the determination of their chemical structures. 相似文献
4.
Edwards HG Farwell DW Villar SE 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(4):1089-1095
Raman microscope spectra of specimens of Baltic and Mexican amber resins containing insect inclusions have been analysed using near-infrared excitation to assess the potential for discrimination between the keratotic remains of the insects and the terpenoid matrix. For the Mexican amber specimen the insect spectra exhibit evidence of significant protein degradation compared with the insect remains in the Baltic amber specimen. In both cases the Raman spectra of the insect remains are still distinguishable from the amber resins. Despite its better preservation, however, no spectra could be obtained from the inside of the larger insect preserved in the Baltic amber in agreement with the observation that most insect inclusions in amber are hollow. It is noted that the Mexican amber insect is located adjacent to a large gas bubble in the amber matrix, to which the observed degradation of the insect and its poor state of preservation are attributed. It is concluded that Raman spectra of insect inclusions can provide useful information about the chemical composition of the remains and that confocal microscopy is particularly advantageous in this respect. 相似文献
5.
Rajan Katoch Amit Sethi Neelam Thakur Larry L. Murdock 《Applied biochemistry and biotechnology》2013,171(4):847-873
The research on the RNA interference (RNAi) for the control of insect pests has made significant growth in recent years. The availability of the genomic sequences of insects has further widened the horizons for the testing of this technology to various insect groups. Different modes of application of double-stranded RNA (dsRNA) have been tested; however, the practicability of delivery of dsRNA in insects still remains the biggest challenge. Till date, the oral delivery of dsRNA in insects is one of the efficient approaches for the practical application of this technique. The uptake of dsRNA from the insect gut is mediated either by SID-1/SID-2 transmembrane proteins or by endocytosis; however, the systemic RNAi machinery still remains to be revealed in insect species. The RNAi-mediated gene knockdown has shown striking results in different insect groups, pointing it to be the upcoming technique for insect control. However, before the successful application of this technique for insect control, some potential issues need to be resolved. This review presents the account of prospects and challenges for the use of this technology for insect control. 相似文献
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Dr. Koji Sato Prof. Shoji Takeuchi 《Angewandte Chemie (International ed. in English)》2014,53(44):11798-11802
The sensing of vapor odorants is highly demanded in the field of life and medical sciences. Although olfactory receptors (ORs) have potentials to recognize volatile organic compounds, the interaction of ORs, chemical vapors, and peptide components in olfactory mucus has yet to be analyzed to develop OR‐based sensors. A bioinspired electrophysiology technique is shown to record the response of reconstituted insect ORs to chemical vapors. To mimic the interface between ORs and olfactory mucus, OR expressing spheroids were loaded into a hydrogel microchamber array. A negative extracellular field potential shift of spheroids was successfully observed by the stimulation of their vapor cognate ligand. Importantly, the ligand repertoire of the OR of malaria vector mosquito examined by this method differed from that of in vivo studies. Our method is useful to develop protein‐based gas sensing techniques and to examine the binding of ORs and chemical vapors. 相似文献
8.
Yi He 《Chemical Papers》2014,68(8):995-1007
Liquid-based micro-extraction is a novel “green” sample preparation technique using micro-litre levels of organic solvent to extract target analytes from various sample matrices for subsequent instrumental analysis. This technique developed rapidly from its introduction in the mid-1990s. Micro-extraction methods can be conveniently combined with a wide selection of instruments commonly used in a chemical laboratory; they significantly reduce analysis time and costs of solvents’ use and waste disposal. This review focuses on recent advances in several liquid-based micro-extraction methods, including single-drop micro-extraction, hollow fibre-liquid phase micro-extraction, and dispersive liquid-liquid micro-extraction. Examples of application of these methods to environmental, food, and biomedical analysis are listed. 相似文献
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Sonication of aqueous solutions causes cavitation in the liquid which results in the formation of H· and ·OH radical species that can be used to reduce or oxidize certain chemical compounds. This article focuses on the effect of ultrasounds in homogeneous reactions to examine the type of chemistry that ensues. It also deals with a rather novel method of using ultrasounds in combination with photochemical methods of inducing chemical reactions; this sonophotochemical technique remains to be explored and exploited. Finally, we examine and explore the potential utilization of ultrasounds to convert environmental hazardous substances into more benign substrates, or better still to mineralize organics into carbon dioxide. 相似文献
11.
M Isaka M Tanticharoen P Kongsaeree Y Thebtaranonth 《The Journal of organic chemistry》2001,66(14):4803-4808
Bioassay-guided fractionation of the extracts from the insect pathogenic fungus Cordyceps nipponica BCC 1389 led to the isolation of N-hydroxy- and N-methoxy-2-pyridones, cordypyridones A-D (1-4). Structures of these compounds, including absolute configuration, were determined by spectroscopic methods, chemical conversions and single-crystal X-ray diffraction analyses. Codypyridones A and B, atropisomers of each other, exhibited potent in vitro antimalarial activity with IC(50) values of 0.066 and 0.037 microg/mL, respectively, while their cytotoxicity was much weaker. 相似文献
12.
In this paper, we study the numerical long time integration of large stiff systems of differential equations arising from
chemical reactions by exponential propagation methods. These methods, which typically converge faster, use matrix-vector products
with the exponential or other related function of the Jacobian that can be effectively approximated by Krylov sabspace methods.
We equip these methods to an automatic stepsize control technique and apply the method of order 4 for numerical integration
of some famous stiff chemical problems such as Belousov-Zhabotinskii reaction, the Chapman atmosphere, Hydrogen chemistry,
chemical Akzo-Nobel problem and air pollution problem. 相似文献
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Surowiec I Pawelec K Rezeli M Kilar F Trojanowicz M 《Journal of separation science》2008,31(13):2457-2462
CE with UV-Vis and MS detections was investigated as a technique for detection of main components of selected natural dyes of plant and insect origin. The BGE giving the best separation of the investigated flavonoids and anthraquinoids, suitable for MS detection consisted of 40 mM ammonium acetate solution of pH 9.5 with 40% ACN. LODs obtained with MS detection were even one order of magnitude lower than the ones obtained with UV-Vis detection. Application of MS detection enabled determination of eleven dye compounds from three different chemical groups in 15 min. and proved to be more satisfactory than diode-array detection in the electrophoretic analysis of main classes of natural dyes both in terms of selectivity and sensitivity of analysis. 相似文献
15.
T. Keough 《Journal of mass spectrometry : JMS》1984,19(11):551-554
Methyl chloride chemical ionization mass spectrometry has been used to probe molecular stereochemistry in simple model systems such as cyclic diols and cyclic dicarboxylic acids. The methylation technique, which is based on the chemical resolution of hydrogen migrations, often yields ionic fragments that enable the differentiation of cis and trans isomers. This technique, like protonation methods, fails to differentiate the isomers of 1,2-cyclohexanediol. However, it does allow differentiation of the isomers of 1,2-cyclohexanedicarboxylic acid, species that cannot be distinguished via protonation techniques. The utility of methylation in conjunction with MS/MS is also discussed. 相似文献
16.
Total Reflection X-ray Fluorescence (TXRF) is a well-established technique for chemical analysis, but it is mainly employed for quality control in the electronics semiconductor industry. The capability to analyze liquid and uniformly thin solid samples makes this technique suitable for other applications, and especially in the very critical field of environmental analysis. Comparison with standard methods like inductively coupled plasma (ICP) and atomic absorption spectroscopy (AAS) shows that TXRF is a practical, accurate, and reliable technique in occupational settings. Due to the greater sensitivity necessary in trace heavy metal detection, TXRF is also suitable for environmental chemical analysis. In this paper we show that based on appropriate standards, TXRF can be considered for non-destructive routine quantitative analysis of environmental matrices such as air filters. This work has been developed in the frame of the EU-FP6 PHIME (Public Health Impact of long-term, low-level Mixed element Exposure in susceptible population strata) Integrated Project (www.phime.org). The aim of this work was to investigate Mn air pollution in the area of Vallecamonica (Italy). 相似文献
17.
N. Momoshima S. Sugihara K. Hibino Y. Nakamura 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(1):107-111
Elemental concentrations of aquatic insect larvae and attached algae in an uncontaminated river were analyzed by instrumental neutron activation analysis (INAA) via the k0-standardization method. The aquatic insect larvae found were all intolerant species. No significant difference was observed in the elemental concentrations of aquatic insect larvae and attached algae along the river. Similar elemental concentrations were observed in the aquatic insect larvae collected at a fixed sampling point for two years. An analysis by the ratio-matching technique indicated a higher generic relationship between aquatic insect larvae and attached algae than river water. 相似文献
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Electrophoretically mediated microanalysis (EMMA) is a method of accomplishing chemical analyses, typically in an open-tubular capillary, due to the difference in the electrophoretic mobility between the particular reagents. This work reports on combining this technique onto microfabricated systems. Two methods of this technique were applied, constant potential and zero potential EMMA onto chips. A dosage response curve was run using this constant potential mode that resulted in a linear response over three orders of substrate concentration magnitude. The chemical system used here is beta-galactosidase (beta-Gal) as the enzyme and fluorescein mono-beta-D-galactopyranoside (FMG) as the substrate. The zero potential mode was used to amplify product turnover using various incubation times. Using this technique and a 10 min incubation, approximately 40000 enzyme molecules could be detected. The zero potential mode is also used in conjunction with an internal standard to show how one can quantitate using this method. The power and ease of utility of this technique is described. 相似文献