排序方式： 共有19条查询结果，搜索用时 15 毫秒
1.
Fauziah Abdullah Partiban Subramanian Halijah Ibrahim Sri Nurestri Abdul Malek Guan Serm Lee Sok Lai Hong 《Journal of insect science (Online)》2015,15(1)
Dual choice bioassays were used to evaluate the antifeedant property of essential oil and methanolic extract of Alpinia galanga (L.) (locally known as lengkuas) against two species of termites, Coptotermes gestroi (Wasmann) and Coptotermes curvignathus (Holmgren) (Isoptera: Rhinotermitidae). A 4-cm-diameter paper disc treated with A. galanga essential oil and another treated with either methanol or hexane as control were placed in a petri dish with 10 termites. Mean consumption of paper discs (miligram) treated with 2,000 ppm of essential oil by C. gestroi was 3.30 ± 0.24 mg and by C. curvignathus was 3.32 ± 0.24 mg. A. galanga essential oil showed significant difference in antifeedant effect, 2,000 ppm of A. galanga essential oil was considered to be the optimum concentration that gave maximum antifeedant effect. The essential oil composition was determined using gas chromatography-mass spectrometry. The major component of the essential oil was 1,8-cineol (61.9%). Antifeedant bioassay using 500 ppm of 1,8-cineol showed significant reduction in paper consumption by both termite species. Thus, the bioactive agent in A. galangal essential oil causing antifeeding activity was identified as 1,8-cineol. Repellent activity shows that 250 ppm of 1,8-cineol caused 50.00 ± 4.47% repellency for C. gestroi, whereas for C. curvignathus 750 ppm of 1,8-cineol was needed to cause similar repellent activity (56.67 ± 3.33%). C. curvignathus is more susceptible compare to C. gestroi in Contact Toxicity study, the lethal dose (LD50) of C. curvignathus was 945 mg/kg, whereas LD50 value for C. gestroi was 1,102 mg/kg. Hence 1,8-cineol may be developed as an alternative control against termite in sustainable agriculture practices. 相似文献
2.
Tay SL Kasapis S Perera CO Barlow PJ 《Journal of agricultural and food chemistry》2006,54(16):6046-6053
The purpose of this investigation is to develop a better understanding of the structure-function relationship of the 2S fraction of soy protein that has not been considered in earnest by the research community. Defatted soy flour was used to extract the three major fractions of the protein (2S, 7S, and 11S). It was found that 2S exhibits better foaming and emulsification properties than the other two molecular fractions. Work was extended to structural properties, which were monitored using spectrophotometry, atomic force microscopy, scanning electron microscopy, small-deformation dynamic oscillation on shear, and large-deformation compression testing. An experimental protocol utilizing glucono-delta-lactone (GDL), GDL with N-ethylmaleimide, or GDL with urea was capable of identifying the nature of molecular interactions responsible for gelation. Surprisingly, it was found that in the initial stages of structure formation, 2S fared better than 7S, with 11S exhibiting the highest rates of aggregation. Given time, however, 7S produced a firmer network with a better water-holding capacity than that of 2S. Non-covalent interactions, as opposed to disulfide bridging, were found to be largely responsible for the changing functionality of the molecular fractions throughout the experimentation from the formation of a vestigial structure to that of a mature gel. 相似文献
3.
Daher RK Filion G Tan SG Dallaire-Dufresne S Paquet VE Charette SJ 《Veterinary microbiology》2011,152(3-4):353-360
Aeromonas salmonicida, a fish pathogen, is the causative agent of furunculosis. It was already shown that growing this bacterium in stressful conditions such as temperature above 22°C might lead to virulence attenuation. Unfortunately, many veterinary microbiology services and reference centers still routinely cultivate A. salmonicida at 25°C. Here we tested the presence of virulence factors by growth on specific medium as well as the integrity of the pAsa5 plasmid, which bears an important virulence factor, the type III secretion system (TTSS), by PCR analysis in twenty strains, most of which were grown at 25°C in their laboratory of origin. The analysis revealed that strains, which encountered the more stressful growth conditions displayed the most frequent absence of A-layer protein and secreted proteolytic activity. Moreover, many strains had lost parts of the pAsa5 plasmid in which the TTSS region was almost always affected. To confirm the effect of stressful growth conditions on the plasmid, three strains with an intact pAsa5 were cultured at 25°C for two weeks. A low but significant fraction of the tested colonies displayed pAsa5 rearrangements. The rearrangement always affected the TTSS region and led to a loss of virulence in the Dictyostelium discoideum co-culture assay. These results demonstrate that the instability of pAsa5 did not lead to its complete loss as previously proposed but to a more complex rearrangement phenomenon and emphasizes the necessity to grow A. salmonicida in appropriate conditions to preserve the complete virulence of the bacterium. 相似文献
4.
The neuroprotective effect of petaslignolide A (PA), a furfuran lignan isolated from butanol fraction of Petasites japonicus (Sieb. et Zucc.) Maxim. (Compositae) leaves, on the oxidative damage in the brain of mice challenged with kainic acid was examined using behavioral signs and biochemical parameters of oxidative stress. PA (40 mg/kg) was administered to ICR male mice through a gavage for 4 days consecutively, and on the final day, kainic acid (50 mg/kg) was administered intraperitoneally. During the 4-day treatment with PA, the body weight gain was not significantly different from that of vehicle-treated control animals. PA (40 mg/kg) alleviated the behavioral signs of kainic acid neurotoxicity and reduced the mortality (50%) by kainic acid to 12.5%. Moreover, the administration of PA restored the levels of glutathione and thiobarbituric acid-reactive substances as well as GSH-peroxidase activity in the brains of mice administered kainic acid to control levels (P < 0.05). In comparison, PA (40 mg/kg) was approximately comparable to the butanol fraction (200 mg/kg) of P. japonicus extract in reducing kainic acid neurotoxicity. On the basis of these results, PA is suggested to be a major neuroprotective agent primarily responsible for the protective action of the butanol fraction of P. japonicus extract against kainic acid-induced neurotoxicity in the brains of mice. 相似文献
5.
以渤海全境内遗址为研究对象,利用GIS空间分析技术,分析了渤海国遗址空间分布与环境之间的关系。结果表明:渤海国遗址数量中国最多,其次为俄罗斯和朝鲜,各类遗址中聚落址和平原城最多,其他遗址相对较少;71.5%的渤海国遗址分布在低洼平原和河谷平原较多的100~400 m高程内,随着海拔的增高,遗址数量逐渐减少;各类遗址中坡度较缓的有平原城、聚落址、建筑址、寺庙址等,其他遗址坡度较大,特别是山城址坡度最大;73.0%的渤海国遗址坡向为日照条件较好的南、西南、东南、东向、坪地,而其他坡向的遗址较少;65.9%的遗址分布在600m以内河流缓冲区内,此范围以外,随着距离的增加遗址数也逐渐减少,显示出明显的距离衰减规律。 相似文献
6.
Szeto YT Wong JW Wong SC Pak SC Benzie IF 《Plant foods for human nutrition (Dordrecht, Netherlands)》2011,66(2):97-100
The genoprotective effect of American and Asian ginseng on human lymphocytic DNA was studied. Using the comet assay, aqueous
extracts of both types of ginseng were shown to diminish hydrogen peroxide-induced DNA damage. In contrast, and in accordance
with traditional Chinese medicine beliefs, addition of the juice from Chinese turnip counteracted the beneficial effect of
ginseng. Results showed that incubating ginseng along with turnip juice abolished the DNA protective effect of both American
and Asian ginseng. Although the exact mechanism has not been elucidated, the counteracting effect of turnip on ginseng seems
unlikely to be mediated by enzymatic action as the effect was seen with boiled as well as unboiled turnip extract. 相似文献
7.
Szweda M Szarek J Babińska I Sokół R Raś-Noryńska M Kołodziejska-Sawerska A Mecik-Kronenberg T 《Polish journal of veterinary sciences》2012,15(2):387-389
The objective of this study was to examine the independent effect of helminths infection on biochemical blood parameters in Beagles intended for laboratory use which may contribute to a change of experimental results. As a result of research, the authors confirmed the negative effect of helminth invasion on the metabolism of the liver and kidney in laboratory dogs. Stool samples from thirty Beagle puppies were examined for parasites before the puppies were moved to the animal facility, and all were dewormed with Vetminth paste on the day they were moved. Stool examination was performed three more times and animals were given Drontal Plus flavor (Bayer) and Baycox 5% (Bayer). A fourth parasitological examination revealed no intestinal parasites in the feces. Three blood biochemical tests were performed. Experimental results clearly indicate the significant impact of intestinal parasites in dogs used in experiments. 相似文献
8.
Oxygenation of arachidonoyl lysophosphatidylcholine (lysoPC) or arachidonoyl lysophosphatidic acid (lysoPA) by lipoxygenase (LOX) was examined. The oxidized products were identified by HPLC/UV spectrophotometry/mass spectrometry analyses. Straight-phase and chiral-phase HPLC analyses indicated that soybean LOX-1 and rabbit reticulocyte LOX oxygenated arachidonoyl lysophospholipids mainly at C-15 with the S form as major enantiomer, whereas porcine leukocyte LOX oxygenated at C-12 with the S form. Next, the sequential exposure of arachidonoyl-lysoPC to soybean LOX-1 and porcine leukocyte LOX afforded two major isomers of dihydroxy derivatives with conjugated triene structure, suggesting that 15(S)-hydroperoxyeicosatetraenoyl derivatives were converted to 8,15(S)-dihydroxyeicosatetraenoyl derivatives. Separately, arachidonoyl-lysoPA, but not arachidonoyl-lysoPC, was found to be susceptible to double oxygenation by soybean LOX-1 to generate a dihydroperoxyeicosatetraenoyl derivative. Overall, arachidonoyl lysophospholipids were more efficient than arachidonic acid as LOX substrate. Moreover, the catalytic efficiency of arachidonoyl-lysoPC as substrate of three lipoxygenases was much greater than that of arachidonoyl-lysoPA or arachidonic acid. Taken together, it is proposed that arachidonoyl-lysoPC or arachidonoyl-lysoPA is efficiently oxygenated by plant or animal lipoxygenases, C12- or C15-specific, to generate oxidized products with conjugated diene or triene structure. 相似文献
9.
The structural properties of mixtures of two molecular soy fractions, 11S (glycinin) and 2S, were investigated in the presence of glucono-delta-lactone (GDL) during an isothermal run at 25 degrees C for 1500 min. Analytical methodology included small-deformation dynamic oscillation, visual observations, scanning electron microscopy, and blending-law modeling. The aim of the work was to identify the state of phase separation and the pattern of solvent distribution between the two constituent polymers. It was found that the high molecular weight distribution of 11S supported rapid kinetics of structure formation, with this continuous matrix being concentrated and, hence, further reinforced in the presence of small additions of 2S. Blending-law modeling suggested that 2S was able to retain disproportionate volumes of solvent within its phase. A consequence of such property was that high additions of 2S leading to equal concentrations of the two molecular fractions in the blend resulted in a catastrophic drop in the values of the overall network strength. This behavior is rather unexpected for the structural properties of a phase-separated system, and it has been rationalized on the basis of the high water-holding capacity of the small molecular weight fraction. 2S entraps in its phase the polymeric segments of glycinin, which are then unable to become structural knots of a cohesive three-dimensional morphology observed in single 11S preparations. 相似文献
10.
Lysophosphatidylcholines (lysoPCs) have been known to play a role as lipid mediators in various cellular responses. In this study, we examined whether lysoPC containing linoleoyl, arachidonoyl, or docosahexaenoyl groups or their peroxy derivatives affect lipoxygenase (LOX)-catalyzed oxygenation of native substrates. First, arachidonoyl lysoPC and docosahexaenoyl lysoPC were found to inhibit potato 5-LOX-catalyzed oxygenation of linoleic acid (LA) in a noncompetitive type with Ki values of 0.38 and 1.90 microM, respectively. Likewise, arachidonoyl lysoPC and docosahexaenoyl lysoPC also inhibited 5-LOX activity from rat basophilic leukemia cells-2H3 (RBL-2H3) with IC50 values (50% inhibitory concentration) of 18.5 +/- 3.06 and 30.6 +/- 1.06 microM, respectively. Additionally, arachidonoyl lysoPC and docosahexaenoyl lysoPC also inhibited 15-LOX activity from RBL-2H3 with IC50 values of 16.6 +/- 1.3 and 24.1 +/- 2.4 microM, respectively. In a separate experiment, where lysoPC peroxides were tested for the effect on soybean LOX-1, 15(S)-hydroperoxy-5,8,11,13-eicosatetraenoyl lysoPC and 17(S)-hydroperoxy-4,7,10,13,15,19-docosahexaenoyl lysoPC potently inhibited soybean LOX-1 activity with Ki values of 6.8 and of 1.54 microM, respectively. In contrast, 13(S)-hydroperoxy-9,11-octadecadienoyl lysoPC was observed to stimulate soybean LOX-1-catalyzed oxygenation of LA markedly with AC50 value (50% activatory concentration) of 1.5 microM. Taken together, it is proposed that lysoPCs containing polyunsaturated acyl groups or their peroxy derivatives may participate in the regulation of LOX activity in biological systems. 相似文献