首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Premating behavior in the bumblebee Bombus confusus was studied. Visual searching for females is not the only premating strategy of this species, as was believed earlier. Males of B. confusus have a normally developed labial gland and its secretion is used to mark a perch from which they visually search for females. The labial gland secretion contains geranylcitronellol and (Z)-9-octadecenyl acetate as the main components.  相似文献   

2.
Bifunctional catalysts containing (0.1–0.5 wt%) Nickel and 0.1 wt% of Pd supported on H-β zeolite were synthesized by incipient wetness impregnation method and characterized by XRD, TEM, XPS, TPD and TPR techniques. The catalytic activity of Ni containing and Ni free Pd/H-β Catalysts was studied, and it was found that Ni up to a threshold value (0.3 wt% on β) produced increased the n-decane conversion and isomerization selectivity. When Ni content exceeds the threshold value, the conversion increases but isomerized products decrease. Moreover, Ni containing Pd/H-β showed increased sustainability and favored the protonated cyclopropane (PCP) intermediate mechanism in n-decane isomerization. The catalyst containing 0.3 wt% Ni 0.1 wt% Pd is adjudged as one performing better than other catalysts studied because of the isomerized mixture from it shows better octane number.  相似文献   

3.
Western flower thrips (Frankliniella occidentalis) has become a key insect pest of agricultural and horticultural crops worldwide. Little is known about host plant resistance to thrips. In this study, we investigated thrips resistance in F 2 hybrids of Senecio jacobaea and Senecio aquaticus. We identified thrips-resistant hybrids applying three different bioassays. Subsequently, we compared the metabolomic profiles of these hybrids applying nuclear magnetic resonance spectroscopy (NMR). The new developments of NMR facilitate a wide range coverage of the metabolome. This makes NMR especially suitable if there is no a priori knowledge of the compounds related to herbivore resistance and allows a holistic approach analyzing different chemical compounds simultaneously. We show that the metabolomes of thrips-resistant and -susceptible hybrids differed considerably. Thrips-resistant hybrids contained higher amounts of the pyrrolizidine alkaloids (PA), jacobine, and jaconine, especially in younger leaves. Also, a flavanoid, kaempferol glucoside, accumulated in the resistant plants. Both PAs and kaempferol are known for their inhibitory effect on herbivores. In resistant and susceptible F 2 hybrids, young leaves showed less thrips damage than old leaves. Consistent with the optimal plant defense theory, young leaves contained increased levels of primary metabolites such as sucrose, raffinose, and stachyose, but also accumulated jacaranone as a secondary plant defense compound. Our results prove NMR as a promising tool to identify different metabolites involved in herbivore resistance. It constitutes a significant advance in the study of plant–insect relationships, providing key information on the implementation of herbivore resistance breeding strategies in plants. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

4.
α-amylase from Bacillus licheniformis was successfully immobilized on developed support, which was prepared by coating a chitosan-casein film on silica, at 20 °C, pH 6.0 for 5 hr with microbial transglutaminase (MTG) as the cross-linking factor. The optimal support was obtained when 1% chitosan and 1% casein were used in the coating mixture. The optimal condition for immobilization catalyzed by MTG was confined to be at MTG concentration of 15 U/mL, pH 6.0, reacting for 6 hr at 20 °C. The highest specific activity of immobilized α-amylase was achieved as 236 U/g. After immobilization, the obtained enzyme showed broader pH profile and maintained more than 70% of the original activity after 20 reuses.  相似文献   

5.
TPD studies of n-hexane and n-heptane from NaX, Y and ZSM-5 (Na+ or H+ exchanged) in the experimental system with a TCD detector were performed, using pure He or He/n-alkane mixture as a carrier gas. The TPD profiles with one desorption peak for Y and two peaks for ZSM-5, measured using He/hydrocarbon mixture, were similar to the previously reported equilibrated thermodesorption results. TPD profiles were accurately fitted with a model based on the equilibrium control of the desorption and the adsorption functions derived from the Langmuir or dual site Langmuir isotherms.  相似文献   

6.
The effects of key parameters on the preparation and regeneration of protoplast from the β-carotene-producing fungus Blakeslea trispora were discussed in this paper, including the combination of various enzymes, mycelial age, digesting time and temperature, pH value, osmotic stabilizers, pretreatment, culture medium and culture method. Under the condition of mixed enzymes in osmotic stabilizer (0.6 M NaCl) combined with 2% lysozyme, 3% cellulase and 3% snailase, the highest protoplast yield, as high as 7.48×106 protoplasts/mL, was obtained when mycelial age was 60 h at pH 5.0–6.0 with digesting for 14–16 h at 28 °C. After purification of the obtained protoplasts, they were regenerated in PDA regenerative medium using bilayer plate culture method. To validate the usability of the protoplasts, a novel plasmid with green fluorescent protein (GFP) was used in transformation for easy visual observation. The results showed that the protoplasts prepared by the optimized method were active and applicable in further gene manipulation experiments. This work was presented at 13 th YABEC symposium held at Seoul, Korea, October 20–22, 2007.  相似文献   

7.
The oil and meal from Monechma ciliatum (black mahlab) and Prunus mahaleb (white mahlab) seeds were characterized for their physicochemical properties. The oil content was found to be 30.95 and 13.15% in white and black mahlab seeds, respectively. The refractive indices of white mahlab oil (WMO) and black mahlab oil (BMO) were 1.475 and 1.470, and specific gravities were 0.8511 and 0.8167 g/cm3, respectively. Saponification values were 184.23 and 180.3 mg KOH/g, peroxide values were 2.54 and 4.43 meq/kg, and unsaponifiable matter was 0.92 and 0.66%, respectively. The major fatty acids were palmitic 4.5%, stearic 16.0%, oleic 47.3%, and linoleic 31.4% in BMO, while in WMO they were palmitic 5.7%, oleic 45.0%, and linoleic acid 47.0%. A moderate amount of tocopherols were found at 45.2 and 28.5 mg/100 g in BMO and WMO, respectively. Protein content was found to be 21% in black and 28% in white mahlab seeds. The total amount of amino acids in black and white mahlab seeds was found to be 783.3 and 1,223.2 mg/g N, respectively. The concentration (on ppm dry-weight basis) of major elements (Ca, K, and Mg) and of minor elements (Al, Pb Ni, Mn, Cu, Cr, Co, and Fe) was also determined in the meals.  相似文献   

8.
Reaction selectivities were determined in multicompetitive reactions mediated by Rhizomucor miehei (RM) lipase at water activity of 0.19 in hexane. Saturated FA (C4–C18 even chain) and oleic acid (C18∶1) were reacted with a single alcohol, glycerol, or α-or β-MAG containing C4, C10, C16, or C18∶1 individually as alcohol cosubstrate. Similar patterns of broad FA selectivity toward C8–C18 FA were generally observed for esterification into specific acylglycerol (AG) pools with the different α/β-CX-MAG cosubstrates. Exceptions were enrichment of C18 in the MAG pool with α-C16-MAG substrate, and a general suppression of C4/C6 FA reactivity and a specific discrimination toward >C8 FA incorporation into the TAG pool, both for reactions with α-C10- and α-C16-MAG. RM lipase selectivity toward MAG was in descending order: β-C18∶1-MAG>α/β-C4-MAG∼β-C10-MAG∼β-C16-MAG>α-C18∶1-MAG >α-C10-MAG∼α-C16-MAG. Selectivity in channeling CX of the original CX-MAG substrates into higher AG species was in descending order: α-C10-MAG∼α-C16-MAG>β-C10-MAGβ-C16-MAG>α-C18∶1-MAG>β-C18∶1-MAG∼ α/β-C4-MAG. Aside from their characteristic FA selectivity, Burkholderia cepacia (PS-30) and RM lipases behaved similarly in terms of MAG selectivity as well as a general conservation of FA selectivity throughout the sequential steps of TAG assembly from FA and glycerol for processes designed to yield specifically structured TAG.  相似文献   

9.
Dietary trans fatty acids (TFA) are of major concern because of their adverse effects on blood lipid levels and coronary heart disease. In Canada, margarines were significant sources of TFA during the 1980s and 1990s. However, this is expected to change with increased public awareness over their adverse health effects and the introduction of new legislature to include TFA content on the Nutritional Facts table of food labels. In this study, the TFA content of the top-selling 29 Canadian margarines, which represented 96.3% of the market share, was determined by capillary gas-liquid chromatography in order to assess the influence of regulatory development during the 3-year transition period between the announcement of new food labelling regulations in Canada that require mandatory declaration of the trans fat content in most pre-packaged foods in January 2003 and its enforcement on 12 December 2005. The 29 margarines included 15 tub margarines made from non-hydrogenated vegetable oils (NHVO-tub margarines), 11 tub margarines made from partially hydrogenated vegetable oils (PHVO-tub margarines) and three print margarines, which were also made from partially hydrogenated vegetable oils (PHVO-print margarines). The 15 NHVO tub-margarines accounted for 71% of the total margarine market share and generally contained less than 2% TFA (mean value 0.9 ± 0.3% of total fatty acids). The mean total TFA contents of PHVO-tub margarines and PHVO-print margarines, were 20.0 ± 4.5% and 39.6 ± 3.5%, and their market shares were 19.3 and 6.0%, respectively. Although during the last 10 years, increasing number of soft tub margarines that contained very little trans fats have been made available in Canada, the PHVO-tub- and -print margarines still contain high levels of trans fats similar to those margarines that were sold in the 1990s. The market share data suggest that the margarines prepared using NHVO and containing almost no TFA were preferred by Canadians over those margarines prepared using PHVO, even before the mandatory declaration of TFA content came into effect on 12 December 2005.  相似文献   

10.
Acacia nilotica var. tomentosa trees from the Diarra protected forest located in the Senegal River valley were identified for the assessment of both biological nitrogen fixation, using the natural abundance method, and soil bio-functioning parameters (nodulation, root biomass, total microbial biomass, and potential N mineralization). The presence and the genetic diversity of indigenous rhizobia nodulating A. nilotica var. tomentosa was also investigated, taking into account distance from the trunk (0, 1, 2, and 3 m) and depth (0–25, 25–50, and 50–75 cm). Surprisingly, no nodules on the trees root systems were found, whereas under laboratory conditions the presence of indigenous rhizobia nodulating A. nilotica var. tomentosa was demonstrated in the analyzed soils (90% of the nodules harvested on the trapped plants were occupied by the same Inter-Genic Spacer (IGS) group, IGS1). There was no significant influence of trees and/or depth on total microbial biomass and potentials of nitrogen mineralization. Some assumptions were formulated on the possible combined effect of flooding, which usually occurs annually during 4–7 months, and the clayey soils in the Diara forests. Although a deeply natural nodulation of A. nilotica var. tomentosa trees by indigenous rhizobia is not excluded, but it still remains to be demonstrated.  相似文献   

11.
The raspberry cane midge, Resseliella theobaldi, is a widespread pest of cultivated red raspberry in Europe. Pheromone-baited traps could provide a much-needed, accurate means to monitor the pest. Volatiles collected separately from virgin female and male midges were analyzed by gas chromatography (GC) coupled to mass spectrometry (MS) to reveal four female-specific components. In analyses by GC coupled to electroantennographic (EAG) recording from the antennae of a male midge, at least three of these components elicited responses. Based on its GC retention indices and mass spectrum, we propose that the major component is 2-acetoxy-5-undecanone and confirm this by synthesis of the racemic compound in seven steps and 63% yield from 4-pentenoic acid. The three minor components were each present at approximately 30% of the major component and were identified as 2-undecanone, (S)-2-acetoxyundecane, and (S)-2-undecanol by comparison of GC retention times and mass spectra with those of synthetic standards. GC analyses of the female-produced volatiles on an enantioselective column showed that only one enantiomer of 2-acetoxy-5-undecanone was present, and this was found to be the S-enantiomer by hydrolytic kinetic resolution of an epoxide intermediate in the synthesis and also by enantioselective hydrolysis of the racemic acetate with a lipase enzyme. The two enantiomers were also separated by high-performance liquid chromatography on an enantioselective column for field tests. In two field trapping tests, (S)-2-acetoxy-5-undecanone was highly attractive to male R. theobaldi; the R-enantiomer was not attractive. The racemic compound was just as attractive as the S-enantiomer, and addition of the three minor components in racemic form at two different loads did not affect catches. The pheromone could be dispensed from both rubber septa and polyethylene vials for at least 1 month under field conditions, but the former was preferred as it gave more uniform release. 2-Acetoxy-5-undecanone belongs to a new group of pheromone structures in the Cecidomyiidae, most others being mono- or diesters.  相似文献   

12.
Most epidemiological surveys have confirmed the association of low HDL-cholesterol and high triglyceride levels with cholesterol gallstones. Our objective was to analyze the relationship between plasma lipid levels and common polymorphisms of ABCB11 (encoding the bile salt export pump, BSEP) and ABCB4 (encoding the phospholipid transporter into bile, MDR3) genes. Plasma lipids were measured in 108 index patients of sib pairs with gallstones and in 260 controls. Using PCR-based assays with 5′-nuclease and fluorescence detection (TaqMan), the ABCB11 coding SNP p.A444V and four haplotype-tagging SNPs covering the ABCB4 gene (c.504C > T, c.711T > A, p.R652G, rs31653 in intron 26) were genotyped. Plasma lipids were compared in carriers of the common versus rare allele of these polymorphisms using Student’s t test and Pearson’s correlation. BMI and triglyceride levels were higher and HDL-cholesterol levels were lower in affected siblings than in controls. Among cases, triglyceride and cholesterol levels were higher in carriers of the common versus rare (hetero/homozygous carriers) allele of the SNPs p.A444V of ABCB11 and C.504C > T of ABCB4. HDL-cholesterol was lower in carriers of the common allele of rs31653. In controls, significant differences of cholesterol and HDL-cholesterol levels were found in carriers of ABCB4 polymorphisms. Our results do not support the hypothesis of a link between ABCB4 and ABCB11 polymorphisms, lithogenic dyslipidemia, and gallstone risk.  相似文献   

13.
The Ethiopian fruit fly, Dacus ciliatus, is an oligophagous pest of cucurbit crops, particularly melons, cucumbers, and marrows (summer squash). The present study aimed to identify host attractants for D. ciliatus and was guided by a behavioral bioassay and an electrophysiological assay. We tested volatile compounds from the fruits of a host plant, ripe and unripe Galia melon, Cucumis melo var. reticulates. Both sexes were attracted to melon volatiles. Those of ripe melon were preferred. Gas chromatography-electroantennographic detection analysis of the behaviorally active ripe melon volatiles consistently showed that 14 compounds elicited similar antennal responses from both sexes. Twelve compounds were identified by gas chromatography-mass spectrometry (GC-MS) using GC-MS libraries, retention indices (RI), and authentic standards. The electrophysiological activities of the compounds that were present at sufficient levels for identification, benzyl acetate, hexanyl acetate, (Z)-3-hexenyl acetate, (Z)-3-octenyl acetate, octanyl acetate, (Z)-3-decenyl acetate, and (E)-β-farnesene, were evaluated at six different dosage levels by using electroantennography (EAG). Benzyl and hexanyl acetates elicited dose responses only in males, while other tested compounds elicited dose responses in both sexes. The strongest responses were observed for doses between 100 ng and 10 μg. The dose response, in terms of attractiveness to synthetic compounds within the active range (as determined by EAG), also was evaluated in the behavioral bioassay. Synthetic acetates were attractive to both sexes when tested individually. Significant attraction was observed when individual compounds were applied in the bioassay arena at doses of 0.5–1 μg/dispenser. Blends of compounds in equal proportions also were attractive to the insects. The most attractive blend was a mixture of four or five identified acetates. The addition of an equal proportion of (E)-β-farnesene to this mixture had a deterrent effect.  相似文献   

14.
The present work reports the characterization and comparison of Moringa concanensis seed oil from Tharparkar (a drought hit area), Pakistan. The hexane-extracted oil content of M. concanensis seeds ranged from 37.56 to 40.06% (average 38.82%). Protein, fiber, moisture and ash contents were found to be 30.07, 6.00, 5.88 and 9.00%, respectively. The extracted oil exhibited an iodine value of 67.00; a refractive index (40 °C) of 1.4648; its density (24 °C) was 0.8660 mg mL−1; the saponification value (mg of KOH g−1 of oil) was 179.00; unsaponifiable matter 0.78%; color (1 in. cell) 1.90R + 19.00Y; and acidity (% as oleic acid) 0.34%. Tocopherols (α, γ, and δ) in the oil accounted for 72.11, 9.26 and 33.87 mg kg−1, respectively. Specific extinctions at 232 and 270 nm were 3.17 and 0.65, respectively. The peroxide and p-anisidine values of the oil were found to be 1.75 and 1.84 meq kg−1, respectively. The induction periods (Rancimat, 20 L h−1, 120 °C) of the crude oil was 10.81 h and reduced to 8.90 h after degumming. The M. concanensis oil was found to contain high levels of oleic acid (up to 68.00%) followed by palmitic, stearic, behenic, and arachidic acids up to levels of 11.04, 3.58, 3.44 and 7.09%, respectively. The results of the present analytical study, compared with those for other Moringa species and different vegetable oils, showed M. concanensis to be a potentially valuable non-conventional seed crop for high quality oil.  相似文献   

15.
Unusual fatty acids with 24, 26, and 28 carbon atoms were found in triacylglycerols (TAGs) isolated from fat body tissue of bumblebee Bombus pratorum. The most abundant one was (Z,Z)-9,19-hexacosadienoic acid. Its structure was determined by mass spectrometry after derivatization with dimethyl disulfide and by infrared spectroscopy. ECL (equivalent chain length) values of its methyl ester were determined on both DB-1 and DB-WAX capillary columns. (Z,Z)-9,19-Hexacosadienoic acid is quite rare in nature. So far it has been identified only in marine sponges, and this work is the first evidence of its occurrence in a terrestrial organism. HPLC/MS analysis of the bumblebee TAGs showed that (Z,Z)-9,19-hexacosadienoic acid is present in one third of all TAG molecular species. As it was found in all sn-TAG positions, it is likely that (Z,Z)-9,19-hexacosadienoic acid is transported to tissues. Interestingly, labial gland secretion of B. pratorum was found to contain (Z,Z)-7,17-pentacosadiene, a hydrocarbon with markedly similar double bond positions and geometry. Possible biosynthetic relationships between these two compounds are discussed.  相似文献   

16.
Adults of both sexes of the cerambycid beetles Xylotrechus colonus (F.) and Sarosesthes fulminans (F.) were attracted to odors produced by male conspecifics in olfactometer bioassays. Analyses of headspace volatiles from adults revealed that male X. colonus produced a blend of (R)- and (S)-3-hydroxyhexan-2-one and (2 S,3 S)- and (2R,3R)-2,3-hexanediol, whereas male S. fulminans produced (R)-3-hydroxyhexan-2-one and (2 S,3R)-2,3-hexanediol. All of these compounds were absent in the headspace of females. Two field bioassays were conducted to confirm the biological activity of the synthesized pheromones: (1) enantiomerically enriched pheromone components were tested singly and in species-specific blends and (2) four-component mixture of racemic 3-hydroxyhexan-2-one plus racemic 2-hydroxyhexan-3-one and the four-component blend of the stereoisomers of 2,3-hexanediols were tested separately and as a combined eight-component blend. In these experiments, adult male and female X. colonus were captured in greatest numbers in traps baited with the reconstructed blend of components produced by males, although significant numbers were also captured in traps baited with (R)-3-hydroxyhexan-2-one alone or in blends with other compounds. Too few adult S. fulminans were captured for a statistical comparison among treatments, but all were caught in traps baited with lures containing (R)-3-hydroxyhexan-2-one. In addition to these two species, adults of two other species of cerambycid beetles, for which pheromones had previously been identified, were caught: Neoclytus a. acuminatus (F.) and its congener Neoclytus m. mucronatus (F.). Cross-attraction of beetles to pheromone blends of other species, and to individual pheromone components that are shared by two or more sympatric species, may facilitate location of larval hosts by species that compete for the same host species.  相似文献   

17.
The electrochemical behavior of a new G-2-s-triazine-based dendrimer, 2,4,6-tris-{4-{4,6-bis-{4-{4,6-bis-[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-s-triazin-2-yl}-piperazin-1-yl}-s-triazine, (I), was studied in dimethylsulfoxide solution by cyclic voltammetry, on platinum and graphite electrodes. The electrochemical properties of I were compared with that of one of its precursor, N-{4,6-bis{4-{4,6-bis[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-triazin-2-yl}-piperazine), (II), together with that of the starting material, (1S,2S)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol (“p-nitrophenylserinol”), (III).  相似文献   

18.
With a combination of dichloromethane extraction and analysis by gas chromatography–mass spectrometry (GC-MS), we found 39 compounds (corresponding to 38 GC peaks) in the anogenital gland secretion (AGS) of captive adult giant pandas, Ailuropoda melanoleuca, during the non-mating season. In addition to indole, squalene, and some of the straight-chain fatty acids that had been characterized previously from the AGS of giant pandas, we identified several new compounds such as decenal, two isomers of decadienal, phenylacetic acid, 5-methylhydantoin, hydroquinone, phenylpropanoic acid, and erucic acid. Quantitative comparison of the relative abundances of the 20 main GC peaks revealed that 5-methylhydantoin, indole, and erucic acid are putative female pheromones, whereas squalene and hydroquinone are putative male pheromones. In addition to the presence of a few individual-specific compounds, the relative abundances of most of the 21 constituents varied more among individuals than within individuals. This suggests that individual identity might be coded in both digital and analog form. The chemical composition of different AGS samples from the same pandas consistently displayed a minimum cluster distance, much smaller than that between samples from different individuals in a hierarchical linkage cluster (average linkage) dendrogram. Our results indicate that the AGS might contain an “odor fingerprint.” Although putative sex pheromones such as squalene and erucic acid should be assessed further by bioassay, our study suggests that synthetic chemosignals might be useful in modulating the behavior and physiology of giant pandas.  相似文献   

19.
A series of comb like poly(p-n-alkylstyrene)s with linear alkyl groups, containing even numbers of carbon atoms from 12 up to 22 were synthesized by radical polymerization and characterized by FTIR, 1H NMR, TGA, TVA DSC, and WAXS. All polymers were obtained in good yields and were soluble in organic solvents as chloroform, dichloromethane or tetrahydrofuran and insoluble in methanol; they are stable up to temperatures near 300 °C. On the other hand, the alkylic side chains of all series are able to crystallize in a paraffinic phase in which the melting temperature and enthalpy increase with the methylene number of the n-alkyl chain.  相似文献   

20.
We identified 4-methylquinazoline (4-MeQ) as a minor component of the male sex pheromone of the parasitoid Nasonia vitripennis. Like the major components (4R,5R)- and (4R,5S)-5-hydroxy-4-decanolide (HDL), 4-MeQ is synthesized in the abdomen of males. At doses of 6 or 1 ng, 4-MeQ synergized the response of virgin females to the HDL-diastereomers in a still-air olfactometer, but was not attractive as a single component. 4-MeQ is also responsible for the characteristic medicinal odor of N. vitripennis males.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号